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Doctoral Thesis
The Synthesis of acylaminoanthraquinone vat dyes from 1,2-benzanthraquinone-carboxylic acids
Author(s): Kotob, Zuheir Anwer
Publication Date: 1956
Permanent Link: https://doi.org/10.3929/ethz-a-000095849
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Prom. Nr. 2616
The Synthesis
of Acylaminoanthraquinone Vat Dyes
from 1,2-benzanthraquinone-carboxylic acids
THESIS
presented to the
Swiss Federal Institute of Technology
Zurich
for the Degree of Doctor of Technical Science
by
ZUHEIR ANWER KOTOB
M. Sc. Textile Chemistry and Dyeing
Citizen of Syria
Accepted on the recommendation of Prof. Dr. H. Hopff
and Prof. Dr. L. Ruzicka
Juris-Verlag Zurich
1956
Leer - Vide - Empty
This is dedicated to my
beloved and highly esteemed parents
to whom I am indebted for
everything in my life.
Leer - Vide - Empty
ACKNOWLEDGMENT
I Wish to express my thanks and gratitude to Professor Dr.
H. Hopf f to whom I am greatly indebted for his help and valuable
guidance which were essential for the fulfilment of this work. I am
thankful to my colleague, Mr. J. Schneller, who was so kind to
carry out the analysis of all products. To Messrs. J.R. Geigy S.A.
of Basle, I am very grateful for the painstaking task of testing and
evaluating the dyestuffs.
Leer - Vide - Empty
CONTENTS
Introduction 11
THEORETICAL PART 14
I. Review of Literature 14
n. Intermediate Products 18
A. Derivatives of alpha-methylnaphthalene 18
3-methyl-l, 2-benzanthraquinone 18
Oxidation of 4-methyl-l-naphthoyl-o-benzoic acid 19
1,2-benzanthraquinone-3-carboxylic acid and its carbonylchloride 20
B. Derivatives of beta-methylnaphthalene 21
Reactivity of beta-methylnaphthalene 21
Keto acids and 2*-methyl-l, 2-benzanthraquinone 22
Diphthalic acid and its esters 24
Crystalline mixture of two methyl-benzanthraquinones 26
1,2-benzanthraquinone-2*-carboxylic acid and its carbonylchloride 29
HI. Dyestuffs 30
General properties of acylaminoanthraquinones 30
Color and constitution of anthraquinone derivatives 30
Dyes prepared in this work 32
Fastness properties 36
EXPERIMENTAL PART 37
I. Derivatives of alpha-methylnapnthalene 37
4-methyl-l-naphthoyl-o-benzoic acid 37
3-methyl-l, 2-benzanthraquinone 38
4-carboxy-l-naphthoyl-o-benzoic acid 38
Oxidation of 4-methyl-l-naphthoyl-o-benzoic acid with CrO, 39
with KMnO. in acid medium 39
with dilute nitric acid under pressure 40
1, 2-benzanthraquinone-3-carboxylic acid by the condensation
of 4-carboxy-l-naphthoyl-o-benzoic acid 40
l-2-benzanthraquinone-3-carboxylic acid by the oxidation
of 3-methyl-l, 2-benzanthraquinone 40
1, 2-benzanthraquinone-3-carbonyl chloride 41
4-methyl-l-naphthoic acid 41
II. Derivatives of beta-methylnapthalene 42
Condensation of beta-methylnaphthalene with phthalicanhydride 42
2-methyl-8-napthoic acid (7-methyl-l-naphthoic acid) 43
2'-methyl-l, 2-benzanthraquinone 44
1,2-benzanthraquinone-2'-carboxylic acid 44
l>2-benzanthraquinone-2'-carbonyl chloride 45
Oxidation of 2'-methyl-l, 2-benzanthraquinone with excess
potassium permanganate in acid medium 45
Chromatography 46
Reduction of the quinones 47
Diphthalic acid 48
Diethyl esters of diphthalic acid 49
Dimethyl ester of diphthalic acid 50
m. Preparation of dyes 51
General procedure 51
Summary 53
Chart 1. Derivatives of alpha-methylnaphthalene 55
Chart 2. Derivatives of beta-methylnaphthalene 56
Chart 3. Derivatives of beta-methylnaphthalene 57
Zusammenfassung 58
Bibliography 60
- 11 -
INTRODUCTION
Natural dyes and mineral pigments were the only means available for
coloring textiles up to the middle of the nineteenth century. These dyes were
obtained from various plants as in the case of logwood, indigo, and madder;
others were obtained from insects. All these and related coloring matters
have lost their importance at present, after being replaced by better and
cheaper synthetic dyes. Furthermore, the coloring substance in many a na¬
tural dye is now synthesised from simple chemical compounds.
The manufacture of synthetic dyes or "coal-tar dyes", as they are refer¬
red to because of the predominent use of coal tar as a starting material, star¬
ted a hundred years ago when W. H. Perkins discovered mauveine, the first
synthetic dye, in 1856.
The synthetic dyes produced commercially nowadays have complex che¬
mical structure, and they cover the complete color range. They are divided
into various classes characterized by particular groups in their chemical
constitution. Another method of classification used quite frequently and spe¬
cially by dyers is based on the method of application. To the latter belong the
directs, mordants, vats and others.
All vat dyes fall into two main groups, the indigoids whose structure
is related to that of indigo, and the anthraquinones which have anthraquinone
as the essential building unit in their structure. Anthraquinone vat dyes are
further divided into several subdivisions based on specific units in their che¬
mical constitution:
1. Acylaminoanthraquinones
2. Anthraquinoneazines
3. Anthrimides and anthraquinonecarbazoles
4. Anthraquinoneoxazoles, thiazoles, imidazoles
5. Anthraquinoneacridones
6. Highly condensed ring-systemso
The first anthraquinone vat dye was discovered by Rene Bonn in 1901,
when he was trying to prepare a vat dye corresponding to indigo '
, starting24
with beta-aminoanthraquinone instead of aniline. However, the caustic
fusion reaction did not proceed in the required direction; fortunately it followed
- 12 -
another course resulting in a blue vat dye of outstanding properties. This is
called Indanthrone or commercially indanthrene Blue RS and was found to
have the following structure:
NH OHN
O50In the same year Rene Bohn found that caustic fusion of beta-amino-
o 9anthraquinone at temperatures above 300 would result in a yellow vat dye,
Flavanthrone, whose structure was later determined and verified by Ro¬
land Scholl31:
The discovery of Indanthrene Blue RS was a milestone marking a new
starting point of incessant research carried out by Ren6 Bohn, Roland
Scholl, Oscar Bally, Max H. Isler, and Robert E. Schmidt. Their work along
this new line of dyes was very successful, resulting in many anthraquinone
vat dyes of varying colors and chemical structure. Deinet noticed that the con¬
densation of aromatic acids with aminoanthraquinones gives rise to valuable
vat dyes.
The rapid development of anthraquinone vat dyes and the leading place
they are enjoying today among all other classes of dyes applied to cotton and
viscose rayon, is based primarily on their remarkably good all-round fastness
properties. They are applied to the fiber in their soluble leuco form from an
alkaline hydrosulfite bath, and the dye is later regenerated in the fiber by
oxidation. An aftertreatment in boiling soap and soda solution improves the
35fastness and brings out the true shade
.
- 13 -
The once considered complicated method of application of vat dyes
requiring plenty of skill and experience holds no more true today. These
dyes are so widely spread that they are known and used by every dyer. Even
the laymen appreciate their good qualities to the extent of stressing their de¬
mand for vat dyed articles when purchasing textiles which will be exposed to
drastic weather conditions, warm bright sunshine, and/or to repeated wa¬
shings. It should be pointed out, however, that there are few vat dyes which
have drawbacks such as abnormal fading or tendering of the dyed material.
It is the duty of the dyer, therefore, to make the proper choice of dyes to
be used in each case according to the final use of the dyed articles.
At the same time numerous institutes and chemical firms are making
continuous efforts to find dyes with improved and superior qualities. Such
was the aim of my present research project about the synthesis and investi¬
gation of new acylaminoanthraquinone dyes having acyl-1,2-benzanthraquinone
residue in their molecule starting with phthalic anhydride and both isomers of
methylnaphthalene. The unsubstituted 1,2-Benzanthraquinone itself is a yellow
pigment with good fastness.
- 14 -
THEORETICAL PART
I. REVIEW OF LITERATURE
3- methyl-1,2-benzanthraquinone was first prepared by R. Scholl and
33W. Tritsch
,whose aim was to prepare from it dyes with stilbene and py-
ranthrone structure. They first condensed alpha-methylnaphthalene with
phthalic anhydride in warm carbon disulphide in the presence of aluminum
chloride. This led to the formation of 4-methyl-l-naphthoyl-o-benzoic acid,
which was condensed in concentrated sulfuric acid to 3-methyl-l, 2-benzan¬
thraquinone:
^COOH ^CH3 "
Uy^CHg
Starting with beta-methylnaphthalene in place of the alpha-isomer, they
obtained 2-methyl-l-naphthoyl-o-benzoic acid which did not condense to a qui-
none derivate by the dehydrating action of concentrated sulfuric acid or other
similar dehydrating agents:
^COOH HgC^
2 3 4 5Other methyl- 1,2-benzanthraquinones were prepared by Cook ' ' '
in characterizing the corresponding hydrocarbons which he synthesized to
be tested for carcinogenic activity. The hydrocarbons were prepared by con¬
densing dimethylnaphthalene with benzoyl chloride, and the resulting ketone
was pyrolysed by Elbs reaction to the corresponding hydrocarbon:
15
The yields of pure hydrocarbons were about 5-10 % calculated with reference
to the ketones. By this method, using the appropriate acid chloride and me¬
thylated naphthalene, Cook arrived at all possible monomethyl-1,2-benzan-
thracenes and subsequently the quinones.
It should be pointed out that positions of substitution in these compounds
are numbered according to the regular method shown below:
Methyl-1,2-benzanthraquinones
Position of m.p. of m.p. of
methyl group hydrocarbon quinone
3 155 179
4 125 168
5 158 174
6 151 174
7 182 167
8 107 191
1» 138 189
2' 150 190
3' 160 168
4» 194 220
It was reported above that 2-methyl-1-naphthoyl-o-benzoic acid, due to
the hindering position of its methyl group, does not undergo ring-closure un¬
der the effect of usual dehydrating agents. There are other cases, however,
where compounds show methyl group migration when subjected to a drastic
- 16 -
5 27ringclosure treatement such as Elbs or Scholls reaction '
. Rearrange¬
ments of this sort involving methylated derivatives of alpha-naphthoyl-o-13
benzoic acid have been investigated by Fieser & Peters . They prepared
for this purpose several dimethyl-1-naphthoyl-o-benzoic acids in which
one of the methyl groups accupied the 2-position in the naphthalene nucleus,
thus hindering a regular ring-closure.
Likewise, they condensed beta-methylnaphthalene with phthalic anhy¬
dride in ice-cold tetrachloroethane in the presence of aluminum chloride.
The resulting keto acid was found to be 2-methyl-l-naphthoyl-o-benzoic
acid whose structure was proved by oxidizing it in alkaline potassium per¬
manganate to diphthalic acid which in turn was converted to its colorless
and yellow methyl esters. Treatment of the keto acid with molten sodium
13aluminum chloride resulted in two isomeric quinones which were identi¬
fied as 2'-methyl- and 3'-methyl-l, 2-benzanthraquinones identical with those
2prepared by Cook . The quinone formation was attributed to the mobility of the
aroyl group of the phthalic acid residue attached at the alpha position of naphtha¬
lene. Methyl group migration facilitating ring-closure was shown to be less
probable in this case. Similar observation of aroyl-radical migration was
2also recorded by Cook .
15In a further study on this subject, Fieser & Fieser reported that it
was possible for both methyl and aroyl groups to rearrange at the same time
15during condensation in molten aluminum chloride. In the same paper it
was pointed out that by careful study of the Friedel-Crafts reaction product
resulting from beta-methylnaphthalene and phthalic anhydride the authors
were able to isolate two isomers: 2-methyl-l-naphthoyl-o-benzoic acid
m.p. 197 and 7-methyl-1-(or 2-)naphthoyl-o-benzoic acid m.p. 190°.
\^VorCOOH H,
Total yield of completely pure material amounted to 47 % and 3 % respecti¬
vely. The structure assigned to the second isomer was deduced from its
- 17 -
smooth condensation in concentrated sulfuric acid to 2'-methyl-l,2-benzan-
thraquinone.
Another method leading to the formation of 2'-methyl-l,2-benzanthra-
quinone was the rearrangement of 2-methyl-l,8-phthaloylnaphthalene in hot
15sulfuric acid :
CH3
The synthesis of 1,8-phthaloylnaphthalene derivatives was achieved
.14.through the following steps
R R
^YCH2-Q .r^r-CH2-0
__
(X'M - a
- 18 -
II. INTERMEDIATE PRODUCTS
A. Derivatives of alpha-methylnaphthalene
3-methyl-l, 2-benzanthraquinone
Pure alpha-methylnaphthalene was brought into reaction with phthalic
anhydride in the presence of aluminum chloride. In this Friedel-Crafts
reaction benzene was chosen as a solvent because it was very convenient to
work with and it does not itself take part in the reaction as long as naphtha¬
lene or its alkylated derivates are available.
One single keto acid was obtained from this reaction. It was 4-methyl-
1-naphthoyl-o-benzoic acid (I) which was easily dehydrated in concentrated sul¬
furic acid to 3-methyl-l, 2-benzanthraquinone (n).
The angular structure of (n) is quite obvious from the red vat it pro¬
duces in alkaline hydrosulfite solution. This is a characteristic feature of
all angular benzanthraquinones, whereas linear benzanthraquinone produces10 12 ^fi
a green vat in aqueous alkaline hydrosulfite ' '.Another proof of the
structure is shown by the nitration and subsequent reduction of the compound33
performed by Scholl.
It delivered the mononitro derivative and then the
corresponding amine minus one mole of water. The only possibility leading
to this result would be for the amino group to accupy number 1' position:
- 19 -
The methyl group in (n) must be at number 3 carbon atom since the other
two alpha positions in the naphthalene residue, namely 1' and 4', would
4 5lead to quinones of different physical properties '
. Besides, caustic fu¬
sion of the keto acid (I) gave rise to 4-methyl-l-naphthoic acid (m) which
serves as a proof of structure (I) and subsequently (n):
Pi (^ COOH
3CH3
(I) (III)
All this is in full agreement with the reactivity of alpha-methylnaph-
thalene which directs substitutions to position 4, para to the methyl group.
Countless such examples are encountered in the literature involving both
organic and inorganic reactants.
Oxidation of 4-methyl-l-naphthoyl-o-benzoic acid
The angular benzanthraquinone product ultimately required in this
synthesis is to have a carboxyl group in its structure. This could be achie¬
ved by oxidizing the methyl group of (I) either before or after ring-closure.7
It is claimed that the preparation of anthraquinone beta-carboxylie
acid by oxidation of toluylbenzoic acid followed by ring-closure gives much
purer product than if the ring is first closed and then the methyl group oxi-
20dized. On the other hand, there are cases where the presence of a car¬
boxyl group seems to hinder ring-closure.
Oxidation of the keto acid (I) into 4-carboxy-l-naphthoyl-o-benzoic
acid (IV) was best achieved in alkaline potassium permanganate solution.
Excess of permanganate, about triple the stoichiometric amount, had to be
used to bring all the keto acid into reaction. Consequently, the yield is ex¬
pected to be low. In fact the amount of oxidized product (IV) obtained in a
very pure state was about 20 % theoretical calculated with reference to
the keto acid (I). The use of less permanganate left an amount of unreacted
- 20 -
4-methyl-l-naphthoyl-o-benzoic acid besides the part which was trans¬
formed to (IV).
The oxidation with other reagents was similarly investigated. Potas¬
sium permanganate in acid medium, and chromic acid in acetic acid were
both unsatisfactory, since part of the keto acid (I) was recovered in pure
condition while the rest could not be isolated. In some cases a tiny amount
of an impure oxidation product was isolated. Dilute nitric acid under pres¬
sure was likewise unsatisfactory and resulted in an oxidation product from
which a reasonable amount of phthalic acid was obtained.
These results indicate that 4-methyl-l-naphthoyl-o-benzoic acid is not
stable enough to offer its methyl group for oxidation without complete de¬
struction of a considerable amount of the keto acid under the above oxidizing
conditions.
l,2-benzanthraquinone-3-carboxylic acid and its carbonyl chloride
The condensation of 4-carboxy-l-naphthoyl-o-benzoic acid (IV) to
l,2-benzanthraquinone-3-carboxylic acid (V) took place in concentrated sul¬
furic acid with great ease, resulting in a very clean product with high yield.
However, these advantages of ease in processing and purity of the end pro¬
duct are outbalanced by the 20 % yield obtained from the oxidation process.
<IV> (V) (vi)
Consequently, it was preferred to bring about the transformation of the
methyl into carboxyl group after ring-closure, that is by oxidizing the 3-me-
thyl-l,2-benzanthraquinone (n). The best oxidizing medium in this case was
found to be dilute nitric acid under pressure. The yield was quite good but
could not be quantitative, since the acid (V) which is solid under the working
conditions would, in the process of its formation, entrap within its particles
- 21 -
some of the methyl-benzanthraquinone thus preventing it from further oxi¬
dation. The oxidized product was readily soluble in boiling aqueous potas¬
sium hydroxide. It was soluble in nitrobenzene but had rather low solubili¬
ty in glacial acetic acid.
Transformation of l,2-benzanthraquinone-3-carboxylic acid (V) into
the corresponding acid chloride (VI) was accomplished with excess thionyl
chloride in benzene. The acid being insoluble in benzene to start with, slowly
dissolved as it formed the extremely soluble acid chloride.
B. Derivatives of beta-methylnaphthalene
Reactivity of beta-methylnaphthalene
Unlike alpha-methylnaphthalene, the beta-isomer has more than one
reactive position at which substitutions can take place. This is frequently
influenced by the prevailing conditions under which the reaction is taking
place. Generally, however, the alpha position adjacent to the methyl group
is strongly activated, while both 6- and 8-positions are weakly activated.
Beta-methylnaphthalene reacts with succinic anhydride in nitrobenze¬
ne in the presence of aluminum chloride to give beta-(6-methyl-2-naphthoyl)-
propionic acid .
COCH„CH0COOH^v\coc¥H2
H3C^^
With acetyl chloride in nitrobenzene, or in carbon disulfide, it gives 6-
23acetyl-2-methylnaphthalene and a small amount of the 2,8 isomer . It also
reacts with benzoyl chloride and its homologues, with naphthoylchloride
and with phthalic anhydride in the presence of aluminum chloride, to give
2-methyl-l-aroylnaphthalene11'13,27'33.
- 22 -
Keto acids and 2'-methyl-1,2-benzanthraquinone
A Friedel-Crafts reaction was carried out in benzene to condense
beta-methylnaphthalene with phthalic anhydride in the presence of aluminum
chloride. From the resulting crude keto acid two isomers were isolated in
very pure condition, after repeated fractional crystallization. The one ob¬
tained in smaller amount was 2-methyl-8-naphthoyl-o-benzoic acid (VII)
while the main product was 2-methyl-l-naphthoyl-o-benzoic acid (VHI).
(vn) (ix) (vra)
Upon treatment with concentrated sulfuric acid, the keto acid (VII) under¬
went ring-closure with the elimination of water, forming thereby 2'-methyl-
1,2-benzanthraquinone (IX). Like other angular benzanthraquinones this gave
the characteristic red vat in alkaline hydrosulfite solution. To further identi¬
fy the product, it was reduced to the corresponding hydrocarbon (X) and
2 5compared with the properties cited by Cook '
.
The highly crystalline structure of the product made its reduction with
zinc dust and ammonia difficult. Most of it was recovered unchanged after
20 hours treatment. The reduction of its finely divided particles, formed by
pouring its sulfuric acid solution into water, was confronted with the same
difficulty under the same conditions. Hence, a two step reduction process2
adopted by Cook for similar quinones was apllied with good results. The
treatment consisted of the reduction with stannous chloride and hydrochloric
acid to the anthranol intermediate step, followed by reduction with zinc dust
and sodium hydroxide to the hydrocarbon.
The reduction of 2*-methyl-l,2-benzanthraquinone (IX) by this two step
process delivered 2'-methyl-l,2-benzanthracene (X) which crystallized from gla
cial acetic acid or methanol in the form of shiny white leaflets.
- 23 -
CHar ^
oja — coa(IX) (X)
The smooth transformation of the keto acid (VII) into the quinone (IX)
by the action of concentrated sulfuric acid indicated that the acid must have
its phthalic acid residue attached to position 7 or 8 in the 2-methylnaphtha-
lene. Obviously, the latter is more probable due to its activated status. This
was supported by the fact that ring-closure resulted in one single methyl-
benzanthraquinone while the second possibility, 2-methyl-7-naphthoyl-o-
benzoic acid, could lead into two different quinones. Furthermore, caustic
fusion of the keto acid produced 2-methyl-8-naphthoic acid (XI) (7-methyl-
1-naphthoic acid):
CHgO A, HOOC
(vn) (xi)
Hence, it could be concluted that the keto acid (VII) possesses without doubt
the structure assigned to it.
It was observed that pure 2-methyl-l-naphthoyl-o-benzoic acid (Vm)
could be regenerated unaffected by a mild treatment with concentrated sul¬
furic acid. But when the treatment was carried out one hour at 80 followed
by pouring the solution onto ice, a small amount of a yellow product was
obtained amounting to 2.5 % yield; the rest of the keto acid was sulfonated
and thus remained in solution. The yellow product was isolated and proved
to be 2'-methyl-l, 2-benzanthraquinone (IX) identical with that derived from
(VII). The ring-closure which occurred in this case should have been effec¬
ted by an aroyl group migration analogous to the results and discussion pre-
13sented by Fieser . Besides, the purity of the quinone and the fact that it
consisted of one isomer only, led to the assumption that the phthalic acid
- 24 -
residue should have migrated from the most reactive position adjacent to
the methyl group to the second reactive one which is position 8 in the beta-
methylnaphthalene nucleus. This would subsequently be followed by ring-
closure resulting in merely one isomer, namely the 2'-methyl-l,2-benzan-
thraquinone.
Diphthalic acid and its esters
The structure of 2-methyl-l-naphthoyl-o-benzoic acid (VIK) was con¬
firmed by its oxidation in alkaline potassium permanganate solution to diph¬
thalic acid (XII) which in turn was converted into its known colorless dime¬
thyl ester (Xm) and yellow diethyl ester (XTV); similarly, a new colorless
diethyl ester (XV) was prepared.
(vin)°
(xii)°
The subject on diphthalic acid and its derivatives is thoroughly discus-
18sed by Hantzsch and Schwiete
. However, I must add that the solubility of
diphthalic acid in nitrobenzene is very low, though it was suitable for re-
crystallizing small amounts for analytical purposes.
The acid was obtained in small white crystas of high purity with a mel¬
ting point 262-264°. The melting point recorded ' for this product as
270-272 could not be reached. The acid (xn) has a lactone structure indi¬
cated by its white (colorless) crystals, since the free acid configuration
would give a yellow color.
The reaction of diphthalic acid with methanol in the presence of concen¬
trated sulfuric acid proceeded very smoothly, building nice colorless crystals
of dimethyl ester (Xm).
- 25 -
OCH, OCH,
o o
(xm)
In a similar manner, the yellow (XIV) and colorless (XV) diethyl esters
were prepared and separated by fractional dissolution and crystallization.
O O OC0Hc 0CoH,II
-C-
2"5 |-2"5
cc cr^ ci^—<^o2 5 5 2 [I ||
O O
(XIV) (XV)
The colorless isomer (XV) had a melting point of 200-202.5°. The analysis18
proved its being diethyl ester, whereas the product reported in literature
as diethyl ester of diphthalic acid is fairly doubtful.16
Graebe obtained colorless ethyl ester of diphthalic acid which melted
at 174 . According to the analysis, the product was a monoethyl ester:
found calculated
%C 66.10 65.99 66.61 66.22
%H 4.50 4.92 4.73 4.24
Hence, he suggested a half lactone structure for the compound basing his
reasoning on the results of analysis, the colorless crystals, and its difficult
solubility in soda solution:
OHII I
k^> COOC2H- \ Ks
18A similar product was later reported by Hantzsch . Likewise
,it was color¬
less and melted at 174°. He described it as diethyl ester, stating that analysis
of the product gave the following results:
- 26 -
found calculated
%C 67.1 67.3 67.8
%H 5.5 5.5 5.1
It is very clear that his argument regarding the constitution is not suppor¬
ted by his analytical results which show a carbon content laying about half¬
way between mono and diethyl ester.
The exact colorless diethyl ester is certainly the one obtained in this
work and presented above with m. p. 200-202.5 .
Crystalline mixture of two methyl-benzanthraquinones
It was pointed out in the previous pages that pure 2-methyl-8-naph-
thoyl-o-benzoic acid (VII) as well as pure 2-methyl-l-naphthoyl-o-benzoic
acid (VHI) gave, upon ring-closure, 2'-methyl-l,2-benzanthraquinone (IX)
which was free of other isomers. A mixture of both keto acids in their pure
states subjected to the same treatment with concentrated sulfuric acid resul¬
ted, likewise, in isomer-free 2'-methyl-l,2-benzanthraquinone.
On the other hand, ring-closure of the raw keto acid as such, or after
one crystallization from benzene, resulted in two different methyl-benzan¬
thraquinones. Besides the expected 2'-methyl-l,2-benzanthraquinone, there
was a second product which crystallized from glacial acetic acid in yellow
needles melting sharply at 148-149,and after repeated crystallization its
melting point was raised to 150-151.
It was noticed during crystallization of the crude keto acid from ben¬
zene that a large part remained in solution. All efforts to make the rest
crystallize was in vain. Concentration by evaporating part of the remai¬
ning solution turned it simply into a thick sirupy mass. Other solvents were
similarly unsatisfactory. Hence, it was evaporated to dryness, converted
to its water soluble sodium salt, and then acidified to precipitate the free acid.
Upon usual treatment with concentrated sulfuric acid, the recovered
keto acid gave rise to only one methyl-benzanthraquinone, which in this case was
the lower melting product, m.p. 150-151°. All these observations led to the
conclusion that the raw keto acid, prepared from beta-methylnaphthalene and
phthalic anhydride, must contain a third isomer besides (VH) and^THI). It
- 27 -
was then tried to isolate the third isomer by high vacuum distillation of the
above recovered keto acid, which is the part that did not crystallize out.
This method also failed; it only split the keto acid resulting in beta-methyl-
naphthalene as a distillate.
The work was then continued with the methyl-benzanthraquinone m.p.
150-151 trying to clarify its constitution. It was obvious that it has an an¬
gular structure, since it was reduced easily in alkaline hydrosulfite solu¬
tion giving the characteristic red color. At the same time no single com-
5pound of all possible angular methyl-benzanthraquinones melts at this
temperature. It was thought, therefore, that this product could be a cry¬
stalline mixture of two or more of these compounds. A similar case was
28encountered by Rivett
,who showed that equal amounts of the 6-methyl-
and 7-methyl-1,2-benzanthraquinones m.p. 174° and 167 respectively were
crystallized together forming, thereby, yellow needles, m.p. 139-140,
which could not be separated by crystallization, vacuum sublimation, or
chromatography into its components.
The product obtained in this work, m.p. 150-151°, was inseparable
into its components by means of recrystallization from various solvents or
by vacuum sublimation. However, when it was passed through a chromato¬
graphy column filled with highly activated neutral aluminum oxide, two dif¬
ferent methyl-benzanthraquinones were obtained. The first was 2'-methyl-
1,2-benzanthraquinone (IX) and the second formed gold yellow needles
which melted at 168-168. 5°. Recrystallization of equal amounts of these
two components together resulted in yellow needles which melted at 148.5-
150, indicating that these components are the only constituents of the star¬
ting crystalline mixture.
The component melting at 168° could be 3'-methyl-1,2-benzanthraqui-
none (XVI) or 4-methyl-l,2-benzanthraquinone (XVH)
O CH3
(XVI) (XVII)
aW
- 28 -
both of which melt at this temperature, but whose parent hydrocarbons melt
5differently .
To decide, therefore, which structure it possesses it was ne¬
cessary to reduce it to the corresponding anthracene derivative. The amount
obtained by chromatography seperation was not enough for such a reaction.
Consequently, the crystalline mixture was reduced and the resulting hydro¬
carbons were separated by fractional crystallization. The first to be isola¬
ted (XVm) formed yellow leaflets with green fluorescence, m.p. 159-160 .
CH3
(xvra)
Hence, it was concluded that the quinone melting at 168 obtained from the
chromatography separation must be 3'-methyl-l,2-benzanthraquinone (XVI).
The second hydrocarbon, resulting from the fractional crystallization,
formed white short needles which seemed to remain always contaminated
with traces of the yellow isomer. It was expected to be 2'-methyl-l, 2-
benzanthracene derived from the 2'-methyl-l,2-benzanthraquinone compo¬
nent, but its melting point of 140-142° was a few degrees lower than that of
the pure product. However, it showed no melting point depression in ad¬
mixture with an authentic sample (X).
If we think once more in terms of the reactivity of beta-methylnaphtha-
lene, we see that the result obtained above is very logical and should really
be anticipated. It will be recalled that beta-methylnaphthalene has three
reactive positions, the 1,6, and 8 carbon atoms. Consequently, three keto
acids might result by condensing it with phthalic anhydride. The products
corresponding to the first and third possibilities were isolated and identified.
The second possibility would lead to 2-methyl-6-naphthoyl-o-benzoic acid
(XIX) which should have been the keto acid that was detected but not isolated.
'6 °
(XIX) (XVI)
- 29 -
This would easily undergo ring-closure in concentrated sulfuric acid to
give 3'-methyl-l,2-benzanthranthraquinone (XVI).
l,2-benzanthraquinone-2'-carboxylic acid and its carbonyl chloride
2'-methyl-l,2-benzanthraquinone (IX) was oxidized in dilute nitric
acid under pressure to l,2-benzanthraquinone-2*-carboxylic acid (XX).
The oxidized product was dissolved in boiling potassium hydroxide solu¬
tion to free it from the unoxidized portion. The acid was completely inso¬
luble in glacial acetic acid, but was easily crystallized from nitrobenzene.
COOH COC1
(XX) (XXI)
Oxidation of 2'-methyl-l,2-benzanthraquinone with excess potassium
permanganate in acid medium similar to the procedure described by32 34
Scholl 'was carried out with the intention of breaking the side ring. How¬
ever, most of the product did not react, and a small amount of an oxidized
product was obtained which was found to consist of 1,2-benzanthraquinone-
2'-carboxylic acid (XX).
Transformation of the acid (XX) into the acid chloride (XXI) was achieved
with excess thionyl chloride in nitrobenzene. It was not possible to use benze¬
ne as a solvent in this case because the resulting compound, unlike 1,2-ben-
zanthraquinone-3-carbonyl chloride (VI), was practically insoluble in it.
- 30 -
III. DYESTUFFS
General properties of Acylaminoanthraquinones
Acylaminoanthraquinone vat dyes are characterized by having one or
more acyl-amino linkages in their molecule. They are largely prepared by
condensing aromatic acid chlorides with alpha-aminoanthraquinones at ele¬
vated temperatures in an inert organic solvent such as o-dichlorobenzene
or nitrobenzene. Beta-aminoanthraquinones are not used because they give
rise to weak dyes of no commercial importance.
To transform these dyes into their soluble leuco form, they are usual¬
ly vatted in a stock vat held at 40-50 for a short period of 10-15 minutes.
Then they are applied to the fiber from a cold dyebath at 25-30. Prolon¬
ged heating in sodium hydroxide solution is liable to bring about saponifi¬
cation of the dyes to various extents, depending on their sensitivity to al¬
kalis29.
Normally, acylaminoanthraquinone dyes have low affinity to the fiber,
thus large additions of common salt or Glauber's salt to the dyebath is ne¬
cessary to help salting them out.
Color and constitution of anthraquinone derivatives
The introduction of auxochrome groups into the anthraquinone nucleus
brings about a remarkable change in color, causing it to shift from very light
yellow all the way through to green. This is greatly influenced by the sort,
number, and position of substitutions. The color is said to get "colder", i.e.
deeper, by shifting from yellow through orange, red, violet, blue to green;
and it gets "warmer", i. e. lighter, by shifting in the opposite direction.
The effect of the various substituents on the shift in color can be outlined
22 30in the following set of rules '
,which are general but very useful in pre¬
dicting the color of a certain compound of this sort:
- 31 -
1. Auxochrome groups such as NH„, SH and OH bring about significant
depth of color, NH„ being most effective followed by SH and OH. Ha¬
logens and nitro groups have no appreciable effect.
2. Etherification of the OH group decreases the effect; replacement of
the hydrogen in the amino group by alkyl or aryl radicals deepens the
color, whereas acylation of the amino group has the opposite effect.
3. Substitution in the alpha-position produces deeper colors than the cor¬
responding beta-derivative.
4. With disubstituted anthraquinones the 1,5 and 1,8 positions have about
the same effect, while 1,4 gives considerably deeper colors.
In the presence of more than one auxochrome or substituted auxo¬
chrome groups, the effect is additive and the resulting color depends,
therefore, on the contributions of all groups.
The color of acylaminoanthraquinone dyes is affected by these rules,
and it depends largely on the aminoanthraquinone radical in the molecule.
They cover a range from yellow through orange and red to violet. The con¬
densation of different acid chlorides with the same aminoanthraquinone
gives rise to dyes which fall in the same color category such as yellow, red
or violet. On the other hand, the condensation of the same acid chloride with
different aminoanthraquinones leads to dyes having totally different colors.
This is clearly demonstrated by the following examples:
NH-CO-'"O O NH-CO-(3
(_/CO-HN"
O NH-cO-(_)Indanthrene Yellow GK Indanthrene Red 5GK
HooNH-co-Q-ocHgo NH-co<3
H3C0^)C0-HN O OH5 J-CoQ
OCH3
OCH3Ind. Brilliant Violet RK Indanthrene Red BK
- 32 -
Dyes prepared in this work
The following list shows the various dyestuffs prepared by the con¬
densation of l,2-benzanthraquinone-3-carbonyl chloride (VI) with the par¬
ticular aminoanthraquinones:
Formula Color of vat Color on fiber
NH-C'
O NH-C
ceoCO-HN O
O NH-CO
^ceo °
(VCO-HNO Dye A
bright red very light yellow
deep red light reddish
yellow
violet red bright goldyellow
O
HO O NH-C
I^Yy^rc0-101° 0H
brown red light reddish
violet
- 33 -
Formula Color of vat Color on fiber
O
O NH-CO
OCOo
o
O NH-CO
deep red
5#>
very light reddish
orange
Q NH-COJ^^ ^ ^ deep bluish light rosa
O red
cCO_
O NH-CO-/ >
0NH-CO
O OCH,
bright red light orange
CI
NH
NH-C
Dye B
bright red reddish orange
- 34 -
Formula Color of vat Color on fiber
H
N N
X T^ x. ^ deep red greenish yellow
0nh-co-y^Vt^i
Dye C
ss°
Three of these dyes having in their molecules 1-amino-5-benzoyl-
aminoanthraquinone, 4-amino-l,2-(o-chlorophenyl) anthrimidazol, and 4-
amino-1,9-anthrapyrimidine were found to possess fairly good affinity and
to produce deep shades. They are referred to as dyes A, B and C respecti¬
vely. They were subjected to a series of standard tests to assess their
fastness properties and to compare the results with those of commercial
dyes of the same nature. The rest of the dyes listed above were generally
weak and had poor affinity to the fiber.
The condensation of l,2-benzanthraquinone-2'-carbonyl chloride (XXI)
with several aminoanthraquinones gave rise to the dyes listed below:
Formula Color of vat Color on fiber
6&O NH-CO deep bright light yellow
red
OCO
- 35 -
Formula Color of vat Color on fiber
O NH-CO
CO-HN° Dye0
ceo
0
DyeE
very deepbluish red
bright deepred
bright gold yellow
reddish orange
H
N N
CCOO NHCO
Dye F
very deep greenish yellowred
- 36 -
In contrast to the first set of dyes these produced brighter deeper
shades and had better affinity to the fiber. The last three dyes in this set
were tested according to standard methods to evaluate their fastness pro¬
perties. They are referred to as dyes D, E and F respectively.
Fastness properties
tyedyeing color
process of vat
washing c
alteration bleeding
soda boilingalteration bleeding
A IK violet red 5 5 4-5 4
B IW bright red 5 5 4-5 4-5
D IK bluish red 4-5 5 4 4
E IW bright red 5 5 4 4-5
chlorine soda
0,5 2gr/l 1:10
tartaric
acid 1:10 rubbingironing
immediately after 2 hours
A 3-4 3-4 4 4 5 3 5
B 3-4 3-4 5 5 5 3 4
D 4-5 4 3 4 4-5 3-4 5
E 5 4-5 3-4
change in shade
by soaping
5 5 3-4 4-5
A a little yellower, somewhat redder
B somewhat weaker, distinctly redder
D a little greener
E somewhat duller, somewhat redder
Note: The results of the light fastness tests are not yet available at the time
of printing.
- 37 -
EXPERIMENTAL PART
I. DERIVATIVES OF A LPHA - METHY LNA PHTHA LENE
4-methyl-1-naphtoyl-o-benzoic acid (I)
The apparatus used in this Friedel-Crafts reaction consisted of a 2-li¬
ter round bottom flask provided with a reflux condenser, an electrically
driven stirrer, and an opening for the continuous addition of aluminum chlo¬
ride. The procedure adopted here was similar to that followed by Heller &
20Schuelke in condensing naphthalene with phthalic anhydride.
150 gr. of pure alpha-methylnaphthalene and 156 gr. of phthalic an¬
hydride were put in the above described apparatus containing 1000 ccs. of
benzene. The flask was surrounded with ice, cooling the contents down to 0.
Following this, 300 gr. of anhydrous aluminum chloride were added in por¬
tions within 1-1V2 hours keeping the temperature always at 0-5. Effective
stirring was taking place continously. The phthalic anhydride dissolved gra¬
dually and the contents formed a thick red brown solution. The flask was
then removed from ice and was heated very slowly on the water-bath, brin¬
ging the contents to a boil, thus keeping them in a homogeneous mass all
the time. The reaction was continued 4-5 hours at a boil until the evolution
of HC1 gases slowed down and came almost to an end.
The reaction mixture was added right away onto ice, forming semi¬
solid brownish layer floating on the surface. It was steam-distilled remo¬
ving the solvent, leaving the keto acid in the form of a solid mass. This was
later dissolved in soda solution and filtered free of aluminum hydroxide
which settled down. The clear filtrate was poured into cold dilute hydro¬
chloric acid, liberating the free keto acid which was filtered by suction,
washed well and dried at 110 to a constant weight. It weighed 285 gr. which
corresponds to a yield of 93 %, and after one crystallization from benzene
it resulted in a pure product weighing 247 gr., a yield of 80.7 %, calculated
with reference to the phthalic anhydride. To achieve absolute purity it was
recrystallized from glacial acetic acid after decolorizing it with activated
- 38 -
charcoal. The keto acid, 4-methyl-l-naphthoyl-o-benzoic acid thus obtained,
was in the form of colorless large plates or white prisms, m.p. 170.5-
171.5°. In monohydrate sulfuric acid it forms deep red solution with a vio-
33let hue. (The same product was reported by Scholl as large, light yellow
crystals, m.p. 167-169°).
3-methyl-l, 2-benzanthraquinone (n)
The keto acid prepared above was treated with ten times its weight of
concentrated sulfuric acid at 70 for a period of three hours. The solution
was then poured onto ice, forming olive green precipitate. It was filtered
and boiled in sodium hydroxide solution to remove any alkali soluble part.
Upon filtration or centrifugation it resulted in a yellow precipitate which
was washed free of alkali and dried at 100-105, giving a yield of 50-55 %.
It was treated with activated charcoal and crystallized repeatedly from gla-o 33
cial acetic acid giving rise to gold yellow needles, m.p. 179-180. (Lit.
m.p. 176-177°). Analysis:
%C %Hfound 83.83 4.48
calculated 83.80 4.44
4-carboxy-l-naphthoyl-o-benzoic acid (IV)
A solution of 5 gr. 4-methyl-l-naphthoyl-o-benzoic acid in dilute aqueous
sodium hydroxide was placed on a boiling water-bath, then 15 gr. potassium
permanganate in hot water were slowly added to it within half an hour. The
keto acid was oxidized immediately reducing the permanganate to manganese
dioxide. This was filtered and boiled twice in dilute sodium hydroxide. The
filtrate and washings were later acidified with dilute hydrochloric acid, cau¬
sing the organic acid to separate in the form of light yellow precipitate. It
was filtered and crystallized from glacial acetic acid after being treated with
activated charcoal. The product formed colorless plates which turned light
yellow upon drying. After repeated crystallization, the product reached a
melting point of 235-237 and gave the following analysis:
- 39 -
%C %H
found 71.48 3.85
calculated 71.24 3.77
The yield of pure product was about 20 %.
When the stoichiometric amount of potassium permanganate required
to oxidize the methyl group was applied, (5.45 gr. instead of 15 gr. in the
above case) a large amount of the starting keto acid did not react and none
of the oxidized product was obtained. On the other hand, the use of double
the stoichiometric amount of potassium permanganate resulted in a reaction
mixture which was found to contain both the starting keto acid as well as the
4-carboxy-l-naphthoyl-o-benzoic acid.
The addition of the potassium permanganate solution very quickly or
at a slow rate showed to have no influence on the results whatsoever.
Oxidation of the keto acid (I) with CrOa
4 gr. of 4-methyl-l-naphthoyl-o-benzoic acid (I) were dissolved in
excess glacial acetic acid and set on the water-bath. 2.76 gr. CrO,, dis¬
solved in 50 % acetic acid, were added within one hour. It was then brought
to a boil and kept under reflux for 3V2 hours. After cooling, the contents
were poured into water, filtered, the residue dissolved in dilute sodium
hydroxide, and reprecipitated with hydrochloric acid. The resulting product
was boiled with activated charcoal and crystallized from glacial acetic acid in
the form of white crystals which were identified as the starting keto acid. The
desired oxidation product could not be detected.
Oxidation of the keto acid (I) with KMnO. in acid medium
2 gr. of 4-methyl-l-naphthoyl-o-benzoic acid (I) were dissolved in
concentrated acetic acid plus one cc. monohydrate sulfuric acid. 1.3 gr.
of potassium permanganate dissolved in 50 % acetic acid were added slowly
and the whole thing brought to a boil and kept under reflux W/2 hours. The
- 40 -
contents of the flask gave, upon addition to water, a dark colored suspen¬
sion which was separated and treated with activated charcoal in boiling
acetic acid. A product crystallized out later which, in this case as in the
previous one, was found to consist wholly of the starting keto acid.
Oxidation of the keto acid (I) with dilute HNO3 under pressure
2.5 gr. of 4-methyl-l-naphthoyl-o-benzoic acid (I) were put in a
250 ccs. autoclave together with the stoichiometric amount of 20 % nitric
acid (4.85 ccs.) required to oxidize the methyl group. The autoclave and
its contents were then heated at 150° for six hours and a half. After cooling,
the contents were removed, extracted with ether, and the product remaining
ofter drying the ether was crystallized from glacial acetic acid. A conside¬
rable amount of phthalic acid was obtained.
1,2-benzanthraquinone-3-carboxylic acid (V) by the condensation of (IV)
One part of 4-carboxy-l-naphthoyl-o-benzoic acid (IV) was treated with
ten parts of concentrated sulfuric acid at 90 for a period of 45 minutes.
Then it was poured onto ice, giving a yellow precipitate which, after washing
and drying, amounted to more than 75 % yield. It crystallized from nitro¬
benzene in the form of fine gold yellow needles which were sublimed twice
at 210 under high vacuum. The resulting sublimate had a melting point of
301-304°. Analysis:
%C %Hfound 75.22 3.34
calculated 75.49 3.33
l,2-benzanthraquinone-3-carboxylic acid (V) by the oxidation of (II)
20 gr. of 3-methyl-l, 2-benzanthraquinone (n) were put with 41. 2 ccs.
- 41 -
of 20 % nitric acid in a 500 ccs. rotating autoclave and heated at 180° for
a period of seven hours. It built up a pressure of 15 Kg./sq. cm. The
amount of nitric acid used here corresponded to what was theoretically
needed to oxidize the methyl group. The oxidation product, which formed
gold yellow solid mass, was removed and washed free of acid. Then it was
dissolved in boiling potassium hydroxide solution and reprecipitated with
hydrochloric acid. The resulting product weighed 15.1 gr., corresponding
to 68 % yield calculated with reference to the total amount of methyl-ben-
zanthraquinone used. The unoxidized portion which separated as alkali in¬
soluble was reoxidized in the same manner.
l,2-benzanthraquinone-3-carbonyl chloride (VI)
10 gr. of 1,2-benzanthraquinone- 3-carboxylic acid (V) were put in
100 ccs. benzene plus 30 ccs. thionyl chloride and set under reflux for eight
hours. The resulting solution was treated with activated charcoal, filtered
and concentrated by evaporating part of it. Upon cooling, the acid chloride
crystallized out in the form of yellow needles amounting to 63 % yield (6.6
gr.). It was dried well under water-jet vacuum on a boiling water-bath.
Later it was recrystallized from benzene forming yellow needles, m.p.
147-149°. Analysis:
%C %H
found 71.40 2.86
calculated 71.15 2.83
4-methyl-l-naphthoic acid (HI)
One gram of 4-methyl-l-naphthoyl-o-benzoic acid (I) was put in a
250 ccs. autoclave containing 3 gr. chlorate-free sodium hydroxide and
3 ccs. of water. It was heated eight hours at 220°. At the end of this pe¬
riod the contents were removed and dissolved in hot water. Many oily
droplets were noticed floating on the surface of the solution which presu¬
mably were alpha-methylnaphthalene. The alkaline solution was filtered
- 42 -
and acidified. The resulting precipitate was crystallized from alcohol and
sublimed twice at 145 under high vacuum giving snow-white crystals,
m.p. 175-177°. (Lit. 25'26m.p. 175°). Analysis:
%C %Hfound 77.43 5.47
calculated 77.40 5.41
II. DERIVATIVES OF BE TA - ME THYLNA PHTHA LENE
Condensation of beta-methylnaphthalene with phthalic anhydride
The Friedel-Crafts reaction carried out in this case was quite simi¬
lar to that described under the preparation of 4-methyl-l-naphthoyl-o-ben-
zoic acid (I) with the following slight changes. This time 700 ccs. of benze¬
ne were used as a solvent, an amount which was enough to assure a homo¬
geneous mixture. The second change was in the temperature at which the
reaction was allowed to take place as will be pointed out below:
1. In the first set of experiments, the aluminum chloride was added to the
reaction mixture held at 0-5° in the course of 1-1V2 hours. The reac¬
tion was then continued at room temperature for a period of six hours.
The deep red solution was poured immediately afterwards onto ice,
forming yellowish brown layer on the surface. This was processed by
steam distillation, dissolution in soda, and reprecipitated with hydrochlo¬
ric acid. The product was dried for a long period at 60-70°, pouring
away from time to time the water which separated from it. Later on it
was dried at higher temperatures until it became completely dry. The
product became temporarily soft during the drying process. The dry
keto acid was obtained in 80 % yield. Crystallization from benzene gave
40 % yield calculated with reference to the starting phthalic anhydride.
After repeated fractional crystallization from glacial acetic acid,
two isomers were isolated in very pure states. One was obtained in 25 %
- 43 -
yield in the form of clusters of white needles, m.p. 192-194. This was
identified and proved to be 2- methyl-1 -naphthoyl- o-benzoic acid (Vm)
(Lit.33 m.p. 191°; 15 197°). Analysis:
%C %H
found 78.40 4.77
calculated 78.60 4.85
In monohydrate sulfuric acid it dissolved with deep blue color.
The second isomer was obtained in about 5 % yield. It crystallized
from glacial acetic acid in the form of colorless plates which sometimes
turned light yellow in color. This isomer was proved to be 2-methyl-8-
naphthoyl-o-benzoic acid (VTI), m.p. 206-210. In monohydrate sulfuric
acid it dissolved with deep blue color.
2. A second set of experiments was performed in which the Friedel-Crafts
reaction was also carried out at room temperature, but the reaction mix¬
ture was left standing overnight before pouring it on ice. The resulting
keto acid, 90-95 % yield, was very difficult to crystallize from benzene
or other organic solvents.
3. In the third set of experiments, the aluminum chloride was added to the
reaction mixture held, as usual, at 0-5. The reaction was then continued
at a boil during a period of five hours followed by pouring the solution onto
ice right away. This resulted in 90-95% yield of raw keto acid. Crystalli¬
zation from benzene gave about 45 % yield. After repeated fractional
crystallization from glacial acetic acid, it was separated into about 25 %
of 2-methyl-l-naphthoyl-o-benzoic acid and about 3 % of 2-methyl-8-
naphthoyl-o-benzoic acid, percentages always calculated with reference
to the phthalic anhydride used at the very beginning.
2-methyl-8-naphthoic acid (XI) (7-methyl-1 -naphthoic acid)
One gram of 2-methyl-8-naphthoyl-o-benzoic acid (VII) was put in a
250 ccs. autoclave, containing 3 ccs. water and 3 gr. chlorate-free sodium
hydroxide. It was then heated eight hours at 220. The product resulting
from this caustic fusion was dissolved in hot water. Few droplets of beta-
methylnaphthalene were observed floating on the surface of the warm solu-
- 44 -
tion and solidified after cooling. The alkaline solution was filtered and
acidified with hydrochloric acid. The resulting precipitate was crystallized
from alcohol and sublimed twice at 120° under high vacuum. Snow white
crysatals were formed, m.p. 146-147,5°. (Lit. 1>23m.p. 147-148°).
Analysis:
%C %Hfound 77.49 5.55
calculated 77.40 5.41
2'-methyl-l,2-benzanthraquinone (IX)
This was obtained by treating 2-methyl-8-naphthoyl-o-benzoic acid
(VII) with ten times its weight of concentrated sulfuric acid for one hour at
70.An amount of boric acid equal to that of keto acid was used in this
17treatment as inhibitor of sulfonation. The solution was poured onto ice
giving a yellow precipitate which was separated, boiled in alkaline solution,
filtered, and washed well. The resulting product amounted to 65-70 % yield.
It was crystallized from glacial acetic acid forming thereby long canary
yellow needles, m.p. 190-191° (Lit. m.p. 190°). Analysis:
%C %Hfound 83.87 4.61
calculated 83.80 4.44
l,2-benzanthraquinone-2'-carboxylic acid (XX)
5 gr. of 2'-methy1-1,2-benzanthraquinone (IX) were put in a 500 ccs.
rotating autoclave together with 20.6 ccs. of 20 % nitric acid and heated at
200 for seven hours long. The amount of oxidizing agent used was twice what
was theoretically needed to oxidize the methyl group. The use of such an ex¬
cess was necessitated by the voluminous size of the 2'-methy1-1,2-benzan¬
thraquinone. A pressure of 11 kg. /sq. cm. was built up in the autoclave. At
the end, the contents were removed and washed free of acid then treated
with boiling potassium hydroxide solution to dissolve the oxidized part which
- 45 -
amounted to about 50 %. The rest of the product was available for reoxidation.
The alkaline solution was acidified, giving l,2-benzanthraquinone-2'-
carboxylic acid which was crystallized from nitrobenzene. For analytical
purposes, it was sublimed twice at 250 under high vacuum. The sublimate
was obtained in yellow needles with a melting point somewhere above 345 .
Analysis:
%C %H
found 75.46 3.36
calculated 75.49 3.33
l,2-benzanthraquinone-2*-carbonyl chloride (XXI)
10 gr. of l,2-benzanthraquinone-2'-carboxylic acid were put with
50 ccs. thionyl chloride in 150 ccs. nitrobenzene. It was boiled eight hours
under reflux. Temperature of the contents was about 120°. At the end, the
solution was filtered and soon afterwards yellow needles were formed in the
filtrate. These were filtered by suction and dried free of thionyl chloride.
They weighed 6 gr. which corresponds to a yield of 57 %. They were sublimed
twice at 180 under high vacuum, resulting in bright canary yellow needles,
m.p. 251-253. Analysis:
%C %Hfound 71.55 2.96
calculated 71.15 2.83
Oxidation of 2'-methyl-l,2-benzanthraquinone with excess potassium
permanganate in acid medium
This oxidation was carried out following the procedure cited by32 34
Scholl '. One gram of 2'-methyl-l,2-benzanthraquinone was dissolved
in 15 ccs. concentrated sulfuric acid and then poured into 100 ccs. of very
hot water, causing precipitation of the substance in finely divided particles.
5 gr. potassium permanganate were then added to it in portions as quickly
as possible. It was heated afterwards on the water-bath for a couple of mi-
- 46 -
nutes until the pink permanganate color disappeared. Thereafter oxalic
acid was added to dissolve the manganese dioxide, liberating 0.65 gr. of
a yellow substance. It was boiled in ammonium hydroxide and the alkaline
filtrate was then acidified resulting in a product which sublimed at 250 to
yellow needles of l,2-benzanthraquinone-2'-carboxylic acid. Most of the
yellow substances was, however, insoluble in alkali and it was found to be
unreacted methyl-benzanthraquinone.
Chromatography
One of the methyl-benzanthraquinone derived from beta-methylnaphtha-
lene was obtained in yellow needles, melting sharply at 150-151.This will
be shown below to consist of two different isomers forming together a crystal¬
line mixture. All efforts to separate it to its individual components, whether
by sublimation or by recrystallization from glacial acetic acid, benzene, or
methyl-ethyl ketone, were in vain resulting always in the mixed crystalline
product. Analysis:
%C %C
found 83.82 4.31
calculated 83.80 4.44
The separation was finally achieved by chromatography. 0.2 gr. of the
above substance was dissolved in benzene- ligroin mixture (volume ratio 1:2)
and passed through a chromatography column 12,5 mm. in diameter filled
with 25 grams of highly activated neutral aluminum oxide, "Alox", activity
1-2. The substance was eluted, using 30 ccs. fractions of the benzene-li-
groin (1:2) mixture used above.
The first six fractions gave a product which, after one crystallization
from glacial acetic acid, formed canary yellow needles m.p. 187-188 iden¬
tical with 2'-methyl-l,2-benzanthraquinone. The next 26 fractions resulted
in a product with a melting point varying between 140-155.
It was followed
by 16 fractions giving a product, which after two crystallizations from gla¬
cial acetic acid, formed gold yellow needles with a constant melting point of
168-168.5. This component was found to be 3'-methyl-l, 2-benzanthraquinone
proved by its reduction to the corresponding hydrocarbon.
- 47 -
About equal amounts of both components, 2'- and 3'-methyl-l,2-ben-
zanthraquinone, were crystallized together from glacial acetic acid, giving
well formed yellow needles m. p. 148.5-150° identical with the starting
mixed crystals.
Reduction of the quinones
The reduction of 2'-methyl-l,2-benzanthraquinone with ammonia and
zinc dust in aqueous medium proved unsatisfactory even though the reaction
was carried out at 75 for a period of 20 hours. The reduction was then
2achieved in two steps, following the procedure described by Cook . 0.5 gr.
of 2'- methyl-1,2-benzanthraquinone (IX) was dissolved in 15 ccs. of glacial
acetic acid. Then 2 grams of stannous chloride, dissolved in 4 ccs. of con¬
centrated hydrochlorid acid, were added to it. Boiling under reflux conti¬
nued for 1V2 hours, after which the solution was cooled and diluted with
water. A yellow precipitate separated which was filtered, washed, and put
in 15 ccs. 2N sodium hydroxide solution. 1.5 gr. zinc dust were added and
the reduction was carried on at a boil for 7l/2 hours. The reaction mixture
was then cooled, filtered, and the unreacted zinc was digested with concen¬
trated hydrochlorid acid. The remaining product was separated and crystal¬
lized twice from glacial acetic acid and then from methanol, giving crystals
in the form of white leaflets, m.p. 146-148° (Lit. m.p. 150°). Analysis:
%C %Hfound 94.18 6.00
calculated 94.18 5.82
The second quinone, consisting of a crystalline mixture, m.p. 151,
was reduced by the above method with very good results. It was also re¬
duced in a single step in the following manner: Two grams of the quinone
were put with 4 grams zinc dust in 20 ccs. water plus 40 ccs. 25 % NH,.
Upon heating, the contents turned into a red solution. After three hours
of heating at 75,the reaction slowed down; the temperature was then
raised to 85 and heating continued two hours longer. To make sure that the
reduction was complete, 10 more ccs. of NH, were added and heating con¬
tinued another hour until the solution became light orange in color. After
- 48 -
cooling, the contents were filtered and the sediment was extracted with
boiling alcohol, filtered, and left to cool. A crude product precipitated
which was fractionated by crystallization from glacial acetic acid. The first
fraction was then repeatedly crystallized from glacial acetic acid and final¬
ly from methanol. It resulted in light yellow crystals in the form of leaflets
with green fluorescence, m.p. 159-160. Analysis:
%C %Hfound 94.25 5.76
calculated 94.18 5.82
This component was 3'-methyl-1,2-benzanthracene (Lit. m.p. 160 ).
The second fraction consisted of a white product which, after repeated
crystallization from glacial acetic acid, formed short white needles, m.p.
140-142. It seemed to be impossible to get this fraction free of slight tra¬
ces of the yellow isomer. However, it could not be anything else but 2'-
methyl-1,2-benzanthracene, as shown by the chromatography results. Fur¬
thermore, a mixture of it with a pure sample of 2'-methyl-l,2-benzanthra-
cene was found to melt at 141-147, indicating no depression in melting
point.
Diphthalic acid (XH)
2 gr. of 2-methyl-l-naphthoyl-o-benzoic acid were dissolved in warm
sodium hydroxide solution. Six grams of potassium permanganate dissolved
in hot water were added slowly to the alkaline solution, whereby the perman¬
ganate was converted continuously to manganese dioxide. Finally, a few drops
of alcohol were added to remove any traces of unreacted potassium permanga¬
nate. The reaction mixture was filtered and the manganese dioxide extracted
twice with boiling sodium hydroxide solution. The filtrate and washings were
acidified with hydrochloric acid, resulting in a precipitate which was sepa¬
rated and treated with boiling glacial acetic acid to dissolve any traces of
unoxidized keto acid. The oxidized part, which was practically insoluble in
acetic acid, was later purified by dissolving it in chemically pure sodium
hydroxide and then acidified with chemically pure hydrochloric acid. The
resulting white precipitate, in spite of its low solubility in glacial acetic acid
or nitrobenzene, was recrystallized from the latter forming fine snow-white
- 49 -
shiny crystals, m.p. 262-264° (Lit. 'm.p. 270-272°). Analysis:
%C %Hfound 64.50 3.59
calculated 64.43 3.38
An experiment was run under the same conditions, using an amount
of potassium permanganate (2.18 gr. in the above case) which was theore¬
tically needed to oxidize the methyl group. This trial gave rise to a small
amount of diphthalic acid besides part of the keto acid which was left unoxi-
dized.
Diethyl esters of diphthalic acid (XIV) & (XV)
0.4 gr. of diphthalic acid were put in 30 ccs. absolute ethanol to which
a small amount of concentrated sulfuric acid was added as a water-binding
agent. This mixture was boiled under reflux during a period of four hours.
The diphthalic acid went into solution within the first 45 minutes. At the end
of the four hour period, the solution was filtered and poured into water,
giving a white suspension. It was then neutralized with cold soda solution until it
reacted alkaline to litmus paper. Upon standing for sometime, the suspen¬
sion settled down in the form of a white precipitate which was filtered and
purified by fractional dissolution and crystallization from methanol, ethanol,
and glacial acetic acid.
Two different diethyl esters were isolated. One was obtained in the
form of yellow prisms, m.p. 151-153 (Lit. m.p. 154-155°). Analysis:
%C %Hfound 68.09 5.24
calculated 67.78 5.11
The second diethyl ester was obtained in the form of colorless crystals, m.p.
200-202.5°. Analysis:
found calculated
%C 67.63 67.87 67.78
%H 5.10 5.28 5.11
- 50 -
Dimethyl ester of diphthalic acid (XIII)
0.5 gr. of diphthalic acid was put in 40 ccs. methyl alcohol with 1.5
ccs. monohydrate sulfuric acid. It was boiled under reflux during a period
of five hours. The diphthalic acid dissolved completely within the first
11/2-2 hours. Later, white crystals started to fall out of solution. At the
end of refluxing, the contents were left to cool down and then filtered. The
crystals which thus separated were crystallized twice from glacial acetic
acid. This gave rise to snow-white crystals, m.p. 272.5-275° (Lit. '
m.p. 275 ). Analysis:
%C %Hfound 66.55 4.53
claculated 66.25 4.32
- 51 -
III. PREPARATION OF DYES
General procedure
Equivalent amounts of the acid chloride and aminoanthraquinone were
condensed in abundant amount of o-dichlorobenzene at a boil, or in nitro¬
benzene at 180-200.At first the reactants went into solution but shortly
afterwards the dyestuff began to precipitate. Heating continued 3-5 hours
after which the reaction mixture was allowed to cool down before being fil¬
tered by suction. The resulting dyestuff was then boiled in benzene, filtered
again, washed with alcohol, and dried.
In a few cases the dye powders were not clean and bright enough. These
were boiled in strong sodium hypochlorite solution for 15-30 minutes, filte¬
red, and washed well.
All dyes were finally purified by dissolving them in concentrated sul¬
furic acid and pouring the solution onto ice, giving finely divided paste
which was filtered and washed free of acid.
The time of reaction and amount of solvent used in each case are summed
up in the list below:
Acid chloride
1,2-benzanthra-quinone-3-carbonylchloride 1 gr.
1 gr.
2gr.
0.5 gr.
0.5 gr.
Aminoanthraquinonederivative Solvent
Time of
reaction
Yield of
pure dye
alpha-amino¬anthraquinone
0.73 gr.
nitro¬
benzene
30 ccs.
2 hours 75%
1,5-diamino0.37 gr.
nitro¬
benzene
35 ccs.
4 73%
l-amino-5-ben-
zoylamino2.14 gr.
o-dichloro¬
benzene
100 ccs.
5 91%
diaminoanthra-
rufin
0.21 gr.
o-dichloro¬
benzene
25 ccs.
5 65%
1,4-diamino-anthraquinone
0.19 gr.
nitro¬
benzene
20 ccs.
4 81%
- 52 -
Acid chloride
Aminoanthraquinonederivative Solvent
Time of
reaction
Yield of
pure dye
0.3 gr.
l-amino-4-ben-
zoylamino0.32 gr.
o-dichloro-
benzene
20 ccs.
5 hours 71%
0.3 gr.
1-amino-4-
methoxy0.24 gr.
o-dichloro-
benzene
20 ccs.
5 71%
0.85gr.
4-amino-l,2-(o- chlorophenyl)anthrimidazol
1 gr.
nitro¬
benzene
40 ccs.
3 70%
1 gr.
4-amino-1,9-anthrapyrimidine
0.77 gr.
nitro¬
benzene
40 ccs.
3 79%
1,2-benzanthra-quinone-2'-car-bonyl chloride
0.65gr.
1.5 gr.
1.5 gr.
0.45gr.
alpha-amino-anthraquinone
0.45 gr.
1-amino-5-
benzoylamino1.6 gr.
4-amino-l,2-(o-chlorophenyl)anthrimidazol
1.75gr.
4-amino-l,9-anthrapyrimidine
0.35 gr.
nitro¬
benzene
30 ccs.
o-dichloro-
benzene
100 ccs.
o-dichloro-
benzene
100 ccs.
nitro¬
benzene
30 ccs.
31/2
2V2
60%
87%
69%
78%
- 53 -
SUMMARY
Acylaminoanthraquinones derived from 1,2-benzanthraquinone
carboxylic acids with different aminoanthraquinones were prepared and
their properties studied.
Alpha-methylnaphthalene and phthalic anhydride were condensed
to 4-methyl-1-naphthoyl-o-benzoic acid which was then converted to
3-methyl-1,2-benzanthraquinone, with the elimination of water in con¬
centrated sulfuric acid. The methyl group of the resulting quinone was
oxidized in dilute nitric acid under pressure, producing 1,2-benzanthra-
quinone-3-carboxylic acid. The same compound was also obtained by first
oxidizing the methyl group of the keto acid with alkaline potassium per¬
manganate to the corresponding 4-carboxy-l-naphthoyl-o-benzoic acid
and then bringing about ring-closure by means of concentrated sulfuric
acid. The l,2-benzanthraquinone-3-carboxylic acid was finally trans¬
formed with excess thionyl chloride in benzene to 1,2-benzanthraquino-
ne-3-carbonyl chloride.
The condensation of beta-methylnaphthalene with phthalic anhydri¬
de gave rise to three keto acids of which 2-methyl-l-naphthoyl-o-ben-
zoic acid and 2-methyl-8-naphthoyl-o-benzoic acid were isolated and
identified. The former acid was predominating. Dehydration of 2-me-
thyl-8-naphthoyl-o benzoic acid with concentrated sulfuric acid gave
rise to 2'-methyl-1,2-benzanthraquinone which was oxidized in dilute
nitric acid under pressure to the corresponding 1,2-benzanthraquino-
ne-2*-carboxylic acid. This was then transformed with excess thionyl
chloride in nitrobenzene to the corresponding acid chloride.
The 2-methyl-1-naphthoyl-o-benzoic acid was oxidized with alka¬
line potassium permanganate to diphthalic acid from which the known
colorless dimethyl and yellow diethyl esters were prepared. In addi¬
tion, a colorless diethyl ester was also prepared.
The 2-methyl-l-naphthoyl-o-benzoic acid underwent rearran¬
gement during its treatment with concentrated sulfuric acid at elevated
temperature, bringing about migration of the phthalic acid residue from
position 1 to position 8 in the beta-methylnaphthalene with subsequent
- 54 -
ring-closure to 2'-methyl-1,2-benzanthraquinone. The amount of quino-
ne obtained by this means was, however, very small.
5) The third keto acid, resulting from the Friedel-Crafts reaction,
was concluted to be 2-methyl-6-naphthoyl-o-benzoic acid, but it could
not be isolated free of the other two isomers. Ring-closure of the crude
mixture of keto acids gave rise to a methyl-1,2-benzanthraquinone which
was identified as crystalline mixture of 2'-methyl- and 3'-methyl-l,2-
benzanthraquinone. Separation into its components was achieved by
chromatography.
- 55 -
Chart 1.
Derivatives of alpha-methylnaphthalene
^ScOOHk^rH *"
k^V^^CH,
CHg n 3
(I) (II)
COOH
ooCH,
(III)
CCCOOH^-^COOH
(IV)
- 56 -
Chart 2.
Derivatives of beta-methylnaphthalene
a
CH,
COOH
(VII)
CH,
O
(IX)
COOH
(XX)
COCl
o
(XXI)
COOH HgC
(VIII)
(X)
(XIX)
CHQ
O
(XVI)
CHQ
(XVIII)
- 57 -
Chart 3.
Derivatives of beta-methylnaphthalene
HOOC
0acEs(XI)
(VIH)
OH OH
a: vu
(XII)
IIo
OCH,
I 3
c,
OCH,
00—co
(xni)
V
o
?C2H5.C,
?C2H5
a>~o
(XV)
aCOOC2H5 HgCgOOC
O
(XIV)
- 58 -
ZUSAMMENFASSUNG
Acylaminoanthrachinone, abgeleitet von 1,2-Benzanthrachinon-
carbonsauren und verschiedenen Aminoanthrachinonen, wurden herge-
stellt und ihre Eigenschaften untersucht.
o(, -Methylnaphthalin und PhthalsSureanhydrid wurden zur 4-Me¬
thyl- 1-naphthoyl-o-benzoesaure kondensiert, welche dann durch Was-
serabspaltung mit konzentrierter Schwefelsaure in das 3-Methyl-1,2-
benzanthrachinon ubergefiihrt wurde. Die Methylgruppe des erhaltenen
Chinons wurde mit verdiinnter Salpeters&ure unter Druck oxydiert, wo-
bei man die l,2-Benzanthrachinon-3-carbonsSure erhielt. Dieselbe
Verbindung wurde auch erhalten bei vorg&ngiger Oxydation der Methyl¬
gruppe der Ketosaure mit alkalischer Permanganatlosung zur entspre-
chenden 4-Carboxy-l-naphthoyl-o-benzoesSure und anschliessendem
Ringschluss mittels konzentrierter Schwefelsaure. Die 1,2-Benzanthra-
chinon-3-carbonsSure wurde schliesslich mit iiberschiissigem Thionyl-
chlorid in Benzol zum l,2-Benzanthrachinon-3-carbonsaurechlorid um-
gesetzt.
Die Kondensation von /3 -Methylnaphthalin mit PhthalsSureanhydrid
lieferte drei KetosSuren, von denen die 2-Methyl-1-naphtoyl-o-benzoe-
sSure und die 2- Methyl- 8-naphtoyl-o-benzoes&ure isoliert und identifi-
ziert wurden. Die erstere SSure war in iiberwiegender Menge vorhan-
den. Dehydratation der 2-Methyl-8-naphthoyl-o-benzoesSure mit konzen¬
trierter Schwefelsaure lieferte das 2'-Methyl-l,2-benzanthrachinon, wel¬
ches mit verdiinnter Salpetersaure unter Druck zu der entsprechenden
l,2-Benzanthrachinon-2'-carbonsaure oxydiert wurde. Die letztere wurde
mit iiberschiissigem Thionylchlorid in Nitrobenzol zum entsprechenden
Saurechlorid umgesetzt.
Die 2-Methyl-l-naphthoyl-o-benzoesSure wurde mit alkalischer
Permanganatl5sung zur Diphthals&ure oxydiert, von welcher man den
farblosen Dimethylester und den gelben Diathylester herstellte, die beide
schon beschrieben waren. ZusStzlich wurde ein farbloser Diathylester
dargestellt.
Die 2-Methyl-l-naphthoyl-o-benzoesSure erlitt bei der Behandlung
- 59 -
mit konzentrierter Schwefels&ure bei hoherer Temperatur eine Umla-
gerung, wobei der Phthalsaurerest von der Stellung 1 zur Stellung 8
des (h -Methylnaphthalins wanderte, mit anschliessendem Ringschluss
zum 2'-Methyl-l,2-benzanthrachinon. Die Menge des derart erhaltenen
Chinons war indessen sehr gering.
5) Die dritte Ketos&ure aus der Friedel-Crafts'schen Reaktion konn-
te nicht von den anderen zwei Isomeren getrennt werden; es handelte
sich um die 2-Methyl-6-naphthol-o-benzoesSure. Ringschluss des ro-
hen Gemisches der KetosSuren lieferte nSmlich ein Methyl-l,2-ben-
zanthrachinon, welches als Mischkristall von 2'-Methyl- und 3'-Methyl-
1,2-benzanthrachinon identifiziert wurde. Die Trennung in die beiden
Komponenten erreichte man mittels Chromatographic.
- 60 -
BIBLIOGRAPHY
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Curriculum Vitae
I was born at Damascus, Syria in 1924. After finishing the elementary
school in Damascus, I joined the American University of Beirut in Beirut,
Lebanon where I terminated the Preparatory Section in June 1944 and
went through three years of college in the Chemistry Department until June
1947. Then I continued my education at North Carolina State College in
Raleigh, N.C., U.S.A. and graduated in June 1949 with a B.Sc. in Textile
Chemistry and Dyeing. After one year of graduate study and research at the
same institute, I got my M.Sc. in Textile Chemistry and Dyeing, in June
1950.
During summer of 1950, I had a three months training period in the
laboratories of CIBA Company Inc. at New York. This was followed by four
months at the Imperial Chemical Industries in Blackley, England and five
months in the various branches of the former I. G. Farbenindustrie in Ger¬
many (Bayer, Cassella, Naphthol Chemie, Hoechst and B.A.S. F.). Later
I worked for one and a half years as Dyehouse Assistant Manager at the
United Commercial Industrial Corporation in Damascus.
In October 1953, I joined the Swiss Federal Institute of Technology in
Zurich, Switzerland to carry out a graduate work for my doctorate under
the supervision of Professor Dr. Heinrich Hopff.
Zurich, May 1956.
