DIXAR : A COMPARATIVE STUDY IN T ~ I E XANTHONE SERIES.. 1053

CXVIII.--A Comparative Study in the Xait ihone

By SURENDRA NATH DHAR.

IN t3he selries of investigations of which this is Part I, it is intended to compare1 xanthone with other compounds having simi- laritkiee in structure o r properties. In the fir& place, such it

comparison is attampteld with anthraquinone, whioh has the greatelst similarit*y tot xnnthons. Not comparative study seems to have been made systematically by anyone1 except, Helrtzig (NonatsA. , 1891, 12, 161), who found that euxanthone is more stable than queroetin (a flavone), and Graelbe and Eiclhengrun (Bey., 1891, 24, 967), who1 compareid somet hydroxyxanthones with certain h y d roxy anthr aquin ones and h y d r ox y benzo p hen ones. 0 t her attempts at a comparison af xanthoinel with anthraquinone with resplsot to the colouring properties of their hydrmy-derivativee are etvidelncetd from a few isdatIed instances. Thus Graebe and Aders (AnmaLm, 1901, 318, 365) shotwed the similarity of the hydroxyl group in poBition 1 in both the series. A. G. Perlrin and Everest

Series. Part I.

R R*

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online / Journal Homepage / Table of Contents for this issue

1054 DHAR: A COMPARATIVE STUDY

have incidentally r a i s d the same quehon (“ The, Natural Organic Colouring Matters,” pp. 126-127). They compare1 alizarin with 3 : 4-dihydrosyxanthone, but, rn a matter of fact, 1 : 2-dihydroxy- xanthonel, and not the) 3 : 4-derivative, colrreaponds with alizarin. Attempt6 are being made tot synthesise 1 : 2-dihydroxyxanthone, and the reaults will be uommunicated in duel course. At the same time, a systelmatia comparison is being attemptetd in the, following directions : (1) nitration ; (2) direct displacetment? of nitro-groups by halogens, methaxy-group, etc., and certain other important! relaotions with nitro-compounds, such as Skraup’s synthesis, Doebnes and Miller’s and Knorr’s syntheses, etc. ; (3) halogen- ation; (4) mobility of halogen atoms; (5) migration of diazo- groups.

It is interestling to notel that xanthonel has been found to he much more reactive than antthraquinone~. Thus with nitric acid alone!, xanthone giveis two dinitroxanthones (a and P) , whereas anthraquinone gives a motnonitro-derivative only (Bey . , 1883, 16, 363). Again, quite a number of tri- and tstra-nitroxanthones have very easily been prelpared, whilst no such polynitro-deriv - ativea of anthraquinonel are known, and further nitration of the dinitro-compounds has not yet been effecteld.

Xanthone seems notl only t o be more reactivel, but, also more stable, altjhough from the structure of theisel compounds such a fact is quite unelxpected. It is well known that wheln fuseid with potassium hydroxide, xanthone decomposes into 1 : 1’-dihydroxy- b eln z op h e n o ne , w h elreas an th r a qu i n on e is co m pl e t d y d egr ad ed to two molecules of benzoic acid. Similarly, itl has beeln found that when furthelr nitration of 1 : 5- or 1 : 8-dinitroanthraquinone is attempted with mixtures of nitria and sulpliuric acids, they decom- pose completely, whilst both a- and P-dinit4rolxanthones are con- velrted into tekranitroxanthones a t an earlielr stage of such a treatr ment, and the products are not, decomposed on subsequent trelat- ment. It may also be nolted that tetrabromoxanthonel is nitrated and not decomposed by such a mixture (Dhar, T., 1916, 109, 740).

So far as the behaviour of nitroxanthone has been studied, it has bmn found thah the nitrot-groups in the xanthone series are much more reladily displaced by direct bromination than is the case in the anthraquinonei series (see this vol., p. 994).

Skraup’s synthesis is effected much more readily in the xanthane ssries than in the anthraquinone selries, and xanthone has also been found ta be muoh more reactive towards halogens than anthraquinone. Thus two hexabromo- and an ootabromo- xanthone have been prepared, whereas no such corresponding

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

IN THE XANTHONE SERIES. PART I. 1055

bronio-compounds a4re known in the anthraquinone wries. Wheln trefated wit.h bromine in s d e d tubes, xanthone givee the 2 : 7-dibrmol-derivast~ive (Graebe, Anwlen, 1889, 254, 284), whilst antIhraquinom gives 1 : 2-dibromoanthraquinone.

Theov-y of the Fwmation of Xamtholne. Staohbach has discussed in detail the va,rious theories put for-

ward to elxplaJn the formaf,iotn of xa,nthone (Ber., 1901, 34, 4136). He attacked mainly the theories of Graebe a,nd Seifert, and, after proving them incapabllel of exphining all the1 experimental fa,& then known, he t,ried to establish a new the,oy of his own, tioget,her with a few empirical rules. One t,hing is, however, common to a.11 the t,heories, and that is the supposition t<hat pheaol does not t8&e part in t'ha formatioln of xanthone or its derivatives. On the other hand, i f phenol is supposed to take part in the relackion, t,he formation of xantlhona bmmnes very simple and does not necessitate the suppmition of various int8ermediab products, the existelnm od which is doubtdul, or any tra.nsposit.ion of groups which Strohbach was compelleld to make. Thus, in order to ascerhin whether phenol takes part or not, experiments were ma,de on the prepa,ration of xanthone from salicylic acid, using in ela.ch ca,se a.n equimo1ecula.r proportion of phenol. It is remark- a.ble t,hat the yie'ld of xanthone in each case was just doub,le whsn phenol was employed. That phenol a\otively takea pa,rt in the relarct,ion and ra,ises t!he yield in such a reimarkable a'nd systematio way is p rovd beyond doubt by t.he facts tha.t when nitrobenzene is used instead of phenol, no increase in the yield of xanthone is etff eicted, and whe'n oinitrophenol is used, 4-nitroxant.hone is abstained. The formation of xant,hone may therefore be explained thus :

C,Tf4(0H).C0,1L + C?,H,*OH = C,H4(O*C,H5)*C0,R + H2 0 Salicylic acid. Phenol. J.

C,IT,<;~>C,Hg + H,O Xan t hone.

Wheln only salicylic acid is used, half is decomposed into phenol, and tra8ms of phenol oan act,ually be dehected in suclh experiments. The use of a dehydra,t.ing agent increasea t.he yield by removing the water formed in tha reaction. When acetic anhydride is weld, the! first re.action is most probably the a.cetylat.ion of the phenolia group, and this seems t,o be a.n import,ant facto'r in the yield. That is why +aceltoxybenzoic a.cid gives xa.nthone, and t,he yielld is not a,ffecteld in the1 least, whether ac&o anhydride is used or not.

R R* 2

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

1056 DHAR: A COMPARATIVE STUDY

Now the folrmatkm of xanthone from phenyl salicylatle, as well as all the other typical instances cited by Strohbach, may be elxplaineld by t-his tlhelory, and thel yield is necessarily poor wheln neither the phenolio groups are aceitylated nor any delhydrating agent is used. Thus the formation of xanthonel from phenyl salicylate promtds according to Graebei's first two1 equations (Zoc. &.), and the liberated salicylic acid and phenol are not wasted, as he has supposed, but give xanthonel again, although the yield in such a, caw is quite inappreciable, as will be sholwn in tkel experi- meatlal part (p. 1061). The1 formation of 5-methyl- and 4 : 5 - dimelthyl-xanthone from phenyl homosalicylate supplies another instance in supportl of this theory. Thus:

C,:R,Me(OH) *CO,*C,HI, --+ C,H3Rle(O*C,H,)*C0,H + Pheiiyl homosalicylate.

c,H,M~<$->c,H, + H,O 5 -Meth ylxan thone.

The watm formed here hydromlyses one, mole,cule of the, ester, giving phenol1 a*nd homosalioylic atcid, which masy give a, furt,hec amount of the same metqhylxanthone, but the main reactlion takes the following co'urse. One olf a pair oaf homojsalicylic a.cid moleoulee gives o1-crem1, just as salicylia acid gives phenol, and t,he con- densatlion t.akee plaaa in the usua,l way, giving 4 : 5-dimethyl- xanthonel. It is interesting t o note that, according t'o Grmbe's theory, only 5-rnelthylxantfholnei, and according t'o Strohbach's the80ry, only 4 : 5-dimethylxant.hoael, is poasiblei, and according to Seifeirt's t.he-ory none1 of these) is possible, whelrea.s, a,ocording to t,he preeelntl theory, both prolducta can be forme'd. The other instanow cited in Stsohba.ch's pap& may bei exp1a.ine.d simihrly.

After elucidafing t.he mechanism of the formation of xa.nt8hone, a few e,xperiments were ma.ds in order t o asoest'ain whether the cha,ngel takes pla.ce gra,dually or suddenly, a,nd in t,hei case of a sudden change to find the temperatare a.t which it t,akes pla,ce. The tempe,ratare( of thet relaction mixture1 was t,he:refore recmded, particularly c,asefully when a single1 subst,ance wa,s used. The results show conclusively that the: conversion take5 place gradu- ally, as t'here was no sudden change1 in tahei tempelra.ture. Athmpts ha,vel also bete8n ma.del to syntlhesise xa,ntholne by various oither me't'hods, and it has been found that the1 condeinsa,hion of 01-chloro- benzoia acid with pheno,l (Ullrna,nn's met'hod) gives most satis- f a,ct<ory reclult,s, the1 yield of xanthone b'eing almostl t3helore~tica~l and the procms very simple.

o.-Thiolbenzoic acid condeaseea with benzene1 a,nd ita simplei deriv-

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

IN THE XANTHONE SERJES. PART I. 1057

actives in the presence of sulphurio acid, giving thiolxanthone and its derivative ( A m d e n , 1896, 149, 250), but salioylio acid does nolt condense with benzene or its derivatives eithes under theee cmditions o r undelr the influence of phosphoryl chloride or with acetic anhydride in sealed tube .

Fluorescence of Xanthomne and i ts Dei-ivatives.

The fluorescelnw of the two nitroxanthones (2- and 3-) is rather unexpected, as itl is generally found that the introduction of a nitro-group destroys the1 fluomscence (Ullmann, A n w l e n , 1907, 355, 312). Still more striking is the fact that the d o u r of ths fluoreecenm is deeper in the case of the nitrscompounds. Thus xanthone shows only blue fluorescence(, whelrelas 2- and 3-nitro- xanthone show greenish-blue and green fluorescence respectively. Very few di-derivatives o l a flnolrcacent substancel are found to1 be fluorescentl, and of all the1 di-derivatives describeid in this paper, only dichloroxanthone is fluorescent.

n’itroxan tholzea.

Only four nitlra-derivatives of xanthone have been described. One, (3-nitroxanthone) was prepared by Ullmann by condensing 2-c;hlorcr-4-.~itrobemoia acid with phenol (Annder t , 1904, 355, 341), and 2 : 4-dinitroxanthoine was prepared by Mayer (Ber., 1909, 42, 1132) by a similar method. The other tlwa (u- and P-dinitlrofxanthones) welre prepared by Perkin fT., 1883, 43, 1870) by the1 direct nitratioln of santhone with nitlrio and sulphuria adds. By a slighb modification of this methoid, these compounds were obtained in a purer condition (T., 1916, 109, 746), but it4 has now been found tha t they can be preipareld from xanthone by tselating ib with nitric acid alone. As has been stateld, xanthone diffelrs from anthraquinonel in its remarkable capacity for yielding nitIra- derivatives, and the1 numbelr of these! has been increased from four to) fifteen, and it is expected that many more can be prepareid without diffioulty. Two methods have mainly been employed, namely, nitratioln and synt<hesis by Ullmann’s method (Zoc. cit .) .

3-Nitroxanthone, which had prelviously been obtained only by synthesis, has now been prepared by the careful nitratioln of xanthone. The othes three isomeric moiionitroaanthones have beein obtaineld by synthesis. 4-Nitroxamthovze is formeld whein salicylic acid and o-nitrophenol are heateid with acetio anhydride, but i t has not been possiblel to1 obtain tlhis compound by the con- densation of 0-chlorobenzoie acid with o-nitrophenol. The remark- able fact has beea observeld that nitroxanthones are! much more

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

1058 DHAR A COMPARATIVE STUDY

easily nitrated than xantqhone ikelf under t,he same conditions. Whereas xanthone give8 only dinitrolxanthonels, 1 - and 4-nitlro- xan thone give tets anit'r oxantqhones, and 2- and 3-ni t r oxant,hone give t8rinit,rolxanthones. As many as six te:t8ranitroxanthones have b,wn prepareid f r m lolwer nitroxa.nthones wit,h velry grelat ease. The orie8nta,t*ion of t,hesel telt'r a.nit8r occom p ou nds is still undelr invsstiga;tion, but, they have been distinguisheld from e a h othelr mainly by their bromination products. By t>his metho'd it has beeln found that thel al- and &teitranitrol-compounds are ident.ioa1, a8nd two of their nit,rol-groups a.re so stable tha.t t'hey are not removed by bromine, even whea belated at 300° for twenty-six ho,urs (this vol., p. 995).

Furt!helr nit'ratioln of some of them t&ranit;roIxa.nthones (ul-, a2-? and P2-) has been a,t.te,mpted by boiling them with mixt8ums of sulphuric acid and fuming nitxio aoid in various proportioas, but wi thou t8 su coess.

A New Heterocyclic Type .

Skraup's reactioa was utilisad by F. Mayelr (Ber., 1909, 42, 3064) in order to fuse a pyridine ring on ta a thiolxanthone nucleus. He obtained thereby one thioxanthquinoline from 2-a;minot~hioxanthone, but he neither studied this compound bhoroughly nor extended this relaction to any other melmber of the thioaanthona 'or xanthoae seriea. It was thered ore proposed to study this reaction, particularly in the xanthone se~ies, wihh the expsotation of obtaining a wries of tetracyclic compounds where1 one pyridine ring would bel uniteld with a pyroae ring together with tlwo belnzetne rings :

co N co

It will be see,n that the pyrone ring is protected on both side& by benzene rings, whereas the pyridine ring is protected only on one side]. Accordingly, the respective1 stability of them pyrone and pyridine rings oan bei usefully studied.

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

IN THE

It has beteln found, treateld with glyoelrol compound eixactly of ta8kee place witb such

XANTHONE SERIES. PART I. 1059

as eispect8eld, thatl an aminoaanthonel, whe'n and sulphurio a,cid, gives a heiterotoyclic

thel type represented above. The reaction great readiness that i t is sufficient to use

the nitroc instead of the amino-derivative. This naturally simplifies the1 syntheeis considerably, and Dey and Goswavni (T., 1919, 115, 531) have noticed the1 same1 fact in similar syntheses in the, coumarin selries. I n this way, P-dinitlroxanthone gives nitrolltniiti~opzcinoliiz e. The utilisation of the othelr nitro+groap for fusing another pyridine ring to1 the already existing tetracyclio nucleus, as well1 as the synthesis of this type1 of tetraclyclic com- pounds from othelr nitro-derivatives of xanthone, are under investigation.

d ciioii of Sodiunz Methox d e o n Sitroxnnthones.

One1 remarkable relaction of the1 nit'roanthraquinoaes is the etase wit,h which a nitro group is displaceld by a methoxy-group. All the knowii dinitroanthraquinones have been converted into1 their correspondjng dimethoxy-compounds by boiling them with soldium methouide. Although xanthone bechaves like, anthraquiiioneq in many important reactions, i t differs entirely in this particular case. Nolnel of thel nitro-groups of a- o r @-dinitrosanthone is dis- placed by a methoxy-group when trelated with soldium metholxide, but, the corresponding nitroxan thhydrols are produceld. Them substance8 dissolve in alkali hydroxide as well as in concentrated acids with distinctive colours.

Colour in solutions of _- -_ - - -__L__

Substance. NaOH. H,SO,. HCI. HNO,. CH,'C02H. a-Dinitroxanthhydrol Yellow Deep yellow Yellow Pink Orange-red p-Dinitroxanthhydrol ,, Pale yellow - -

Although xanthhytirol is quickly converteld into an ethelr, these dinitroxanthhydrols dot not undergo this reaction, perhaps because of the influeace, of the1 nitro-groups. When boiled with mild oxidising agents, they are convelrtsd into the1 origina,l nitro- xanth ones.

Halogelintion.

Three diffelrent methods have beeln employeld f o r the1 preparatioa of halogeln derivativm of xant'hone, namely : (1) direct halogen- at(ion ; (2) synthesis according t'o Ullmann's method (AnnaJen, 1907, 355, 359), and (3) direct, d i sp lament of the! nitro-group by halogen.

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

1060 DlIhR A COMPARATIVE STUDY

Ch Zoroxanthon es.

2-Chlorolxanthoael was prelpareld by Ullmann (Zolc. ci , t . ; compare Ullma,nn and Wagnelr, Annalen,, 1910, 371, 388) while studying the condeasa,t,ioNn of 01-chlorobenzoic ac'id a.nd its delrivatives wit'h phenol, 3-chloroxanthone~ was synthe'sised by Gombelrg and Cone (Anmailen, 1909, 370, 142) by a. similar melthold, and oct,a.chlo,ro- xanthone was prepa,re,d by Stediier (Monatsh., 1915, 36, 175) whilst stadying t'hel chlorinatio'n of cyclic kelt'oaes by means of antJmony pelnt,achlolride. It, is proposed t'o study the1 chlorinat'ion of xa.nthoIne1 systema,t,ica.lly by ad1 the1 t8hre,el me8tlhods meat8io'ned abovel, but, a,t prelsent attention has mainly beea confined t o the second method, by which all the1 poasiblel isomeric monochloroc xanthonea have! besen synt'hesiseld a

ChlwinntioVn.--The direct' chlo,rinatdon of xant.hone has notl yet been casrield oiut syste,matically, and the1 only melthold t.ha.t has been t'rield is by dissolving xamnt8holnei in a&io a,cid and passing chlolrine int.0 t,hel sodution, using a, trawl o f iodine1 as a, ca,t,alyst. The produc.ts ase 3-0hlo~roxa.nthonel and a, di,chZo.rolxarntholn.e ; the la,t'telr can easily be obtaine,d pure, b,ut itl is very difficult' to remove t'he last tmces of it' from t.he formelr.

UEZmtm's Synth.esi.s.-Of the four possible moao,chloro- x a,n t horn es, 2 - and 3 -chl o'r o'xa n t<h one1 w elr e s y n th eeise'd b,y Ullni a nn and by Gomberg a.nd Conel respelctlvelly (Zoc. c d .) . The other two isolmerides havet now been prepareld.

Bronmxan t hones.

5' r Omii~a~t,ioiz ,--JV hen x a.n thone in amtic acid solution is heateld wi th ojne molemlel of bromine and a' tmcel of ioldine, S-bromo- xant,honei is obt,ained (Dhar, T., 1916, 109, 745 ; compa,re: A n n d e n , 1909, 370, 142), butl whe'ii conc,etnt8rateld sulphuric acid is used as a, so$lveat4 instea,d of acet8ic acid, thet prodmt is 2-bromolxantmhoael. Each of the,se brornohcompounds whe.n helat,e,d wit,h bromine1 passes elasily into the1 same1 dibromot-derivative, and thelretolrel wheln a. slight e(xcelss oaf bro4minel is used in t'he preparation of a. molno- bromn-c,ompound, dibromoxa,nthone is always formed. This is tlhe( maJn product of t'hel dire:& bromina,tioln otf xant,ho'ne when t,he opra.tJon is carried on under differentl. condit,ioNns and wit,h diffelrent oatdysts. One1 stxiking fact, in connexian with tlhel direlott bromin- afio'n of xanthonet is that alt'hough xa,nt;honel is bmrominated in sulphurio acid solution by liquid b'rorninel, it is nolt attacked by a mixtsre of potassium b,romide mid ptlassium b,romatel in sulphuric ac;id so1ut.io.n.

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

TN TI'EF: XANTHONE SERIES. PART I. 1061

Synthesis.-2-Bromoxantlhonet has also been synthesised from oLchlolr otb elnzolic acid and p- bromo p helnol , and 4 - br om ox an thone has been oibtained by a similar melthod.

Direct Displacement of nTitro-grmp by Bromine.--By this method, sevetral bromoxanthonels ha've beeln prepared. The met+hod serves as the only means of preparing certlain bromoc-derivativels, and there is a remarkable economy of bromine as the whole m o u n t of bromine entws the nucleas.

E X P E R I M E N T A L.

Xanthone. One1 hundreid grams of salicylio acid whetn boileld with 100 grams

of acetic anhydride and dist,illeld gave only 20 grams of xanthone (compa,re Graelbe, Rn.nden, 1889, 254, 280). The yielld wa,s not improved hy a.n increase in the amount' olf acetio anhydride1 or by extending the1 period of he,a,ting, nor was' it. affect,eld a.pprecia.bly whea differmt samples od the1 ima,tesials we,ro used. It was, how- ever, raisetd to1 40 per ce'nt,. of t'hel sa,licylio a80id usetd by the1 addi- tioln of a, molelcular proport,ion of phelnol t'o the mixturel. Thus a, mixture of 50 gra;ms of sa*lioylic acid and 50 grams of phetnol, wheln b,oileld for six hours with 100 grams of amt'ic anhydride and distrilleld, yielldeld 20 grams o t xanthoael. In a,ll t.helsel casm the yield is oxt-remely poior when no acetic, aahydrida is employed, and acet.ic a.cid has no ejffelct a't all.

Whea o-acelto8xybenzoic a.cid is similarly boiled elit-her alone or wit.h acetic a,nhydridel, it yiellds xanthonel elquiva'lent t'ol 20 per cent,. of its salicylic acid contentl.

Mon omit r o xan t h ones . l-Nitro~xa.nthone.-m-Nit8rophe~no1 (1.6 grams) was dissolved in

20 C.C. of met'hyl alcohol1 contlaining 0.4 gram of soldium. 0-Chloro- benzoic a.cid (1.5 grams) was then a,dded to the1 solution, and adso a, tra.cet of copper powder. The! adcoho1 was emapora,td, a,nd the dry, brown substance began to soft'eln at ab,outl looo; the1 tempelra- t,uret o d the1 bat,h was raised tn l l O o , wheln the1 cont,ents of the! vessed me(lted to a dark brown liquid which so~lidifield pa.r.tly a t ab,out 140O. When cod, the ccate,nts were powdereid and he,at-eld o(n a st8eta,m-ba,t.h fo,r ten miiiutels wit,h 15 c.c8. od concelnttra,t~eld sulphuric acid. Thei solution was cooleld, poureld int'ot water, and t.he precipita,tei co,ilect.e.d. The1 subst'ance orystdlised from a.lcoho,l in slendes, bmwn needles mellting at 210° (Foand: N=5*99. C,,H,O,N requires N = 5-80 pelr celnt.).

It, shows no fluolrescelnoe in coiicelnt,ra,teld sulphurio acid solut'ion, but givw a yellow d o u r o.nly.

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

1062 DHAR: A COMPARATIVE STUDY

2 -Nit rotxm tho n e .-p-Ni t r ophen 01 (4 * 2 grams) was dissolved in 20 C.O. of methyl alcolho3, and 0.7 gram of mehallio sodium was then a.dded to the solution. When i t waa clear, 4.7 grams of 0-chlo'robenzoIc acid we're addeld, and a, trace o'f coppe,r powder was introduceld a's a' cat,alyst,. The alcohol1 wa,s e,vaporat8eld off slowly, aad then the telmpe,rature of the bath was raised very slowly tcr 14O0, when the orangebrolwn, hard mass meIlt,ed to a, viscid liquid olf the same1 colour. After some1 t,weat,y minut'es, the colour began tto oha.nge1, and the liquid t'heln becamel convelrt'ed int,o a greyish- red, jelly -1i kel substanc,eI. T he1 t,e'mper a tur e was very caatiousl y ra.iseld to 1 60°, whe.n the1 dark-coloareld subst(a.nce1 solidified. The whole mass, however, bursts into flame1 a t about. this t,emperat,ure if more t.han one at'omic proportion of sodium is taken or i f the tempera'ture is raJssd sudde,nly. Tha substlance, when cool, was powdered and heat'ed on a ste'am-bakh with 50 C.C. of concentrated sulphuric acid for twenty-five minutes. The sotlution, when cod, was poured int,o watec, and t'he precipitate was collected (7 grams). The sub,stanm cryst.allised f ro'm alcohol in slender, brown needles me31tling at 200° a,nd dissolving in sulphuric acid with a, greenish- blue1 fluoreewnca (Found : N = 5.56. C,,€I,O,N requires N = 5.SO per oe.nt.).

3-iVitroxan,thone.-This was first, prelpareld by Ullmann (koc. cit .) by the condelnsatkm of 2-chloro-4-nitmbenzoic acid with phelnol. It has, however, been possible' t o obtain this compound direlctly ,from xant'honel by nit,rat.ion in the folllowing way. Six g r a m o.f xant.ho,ne we're1 dissolved in 1 2 U.C. of conwntsateld sulphurio acid, and 1.4 C . C . of nitric acid (D 1.500) a 'ddd with shaking. Much heat was developd. The solution was kept over- night, and then poureld into wat.er, the1 precipitia8t,e (about 7 grams) being oollecteid and waaheld with water. Ab'out' 2 grams of the subst4anm, which did not dissolve: in alcohoil, consisbid of P-dinitm- xan t,honei. From the1 alcohdi c s 01 u t,ion , yelllow ish - whi te need l a were obtained, which were found to conta.in tra,ces ot xa.nthone,. The nitro-compound was purified by furthelr crysta.llisat,ion from alcohol. Tra.ces of xa,nthone were: found still to1 be assotdateld with it,, and could b's relmoved only wit,h very gre8a,t difficulty, because of the almo,st equal solubility of oach of these compoands in alcohol.

On reduction, tra,cm of xa.nt3hom welrel removed, as this is in- soluble, in dilutei hydrochloric ac.id, whe,reias the1 amino#-compound was obtained as hydro:chlo.ride in tthel solutio'n. The1 frele amino- c.ompound, isolatelcl by precipitation wit.h ammonia, melts at' 232O (as given by Ullmann, loc . ci t . ) .

1Vhe.n 1 gram of 3-nit,rosaat.hoiie is dissolved in I0 C.C. o f con-

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

IN THE XANTHONE SERIES. PART T. 1063

centrated sulphuric acid and 5 C.C. of nit,ric a.cid (D 1.42) are added to the solution and the mixture kepb overnight, a, trinitro- xanthone is olb,t.ained.

S-Nitr~~xant~hoInne dissolves in sulphuric acid wit,h it bluer fluorescence much st'ronger than that shown by xaathone itself.

4-Ni,trolxa3nn$hone.-A mixture of 50 grams of salicylio acid and 50 grams of o~-nitrophejiiol was boile'd with 100 grams of awtio anhydride for ten hours and t,hen dist,illed. Soma tarry matter pa'ssed over at a very high temperature. This was boiled with alcohol wit'h the additbon of anima,l chascoal, a,nd from the filtra,te a.bout 2.5 grams of yellow needles were obt,a.ined melltJng atl 1 2 7 O (Found : y= 5.71. C,,H,O,N requires N L= 5.80 per cent.). The mmpound disso1ve:s in sulphuric acid with a green colour and without fluorwcence. It is remarkable thah no xanthone c,ould be traced in the distilhte. At,tempts were1 ma,de, to condense oLnitro- phenol witch o-chlorobenzoic a.cid by Ullma,nn's method, but without' succe~s.

Dz'nitrosan t h ones.

This compound is deiscribed sub,setquelntly.

a- and P-Dinit,roxanthoaes are ordinarily obtained by nitrating xanthone wit'h a, mixture of nitric and sulphuric a,cids. They have also been prepared by nitrating xsnthonei wit.h fuming nitric acid alone.

When 2 grams of xanthone are dissolved in 5 C.O. of nitric a,cid (D 1.500) and the solution is helatsd on a water-bath for ambout ten minuteea, fine neeldlee oif P(or 2 : 7)-dinit.roxantmhone prec cipit,ahe, and from the solution a-dinitroxanthone is obt,aine:d by precipit,ation with water a,nd purification with nit'ric acid. Similar r-ults are obtained with welaketr nitric a.oid (D 1*42), but t.he quant'ity of acid shofuld be proportionately grelater, namely, 10 c.c. for ea.ch gra,m of xanthone, and the) mixture should be heated for about three hours.

B(or 2 : 7)-Dinitrox~ntho.ne.-Onet gram of 2-nit,roxa8nthone was dissolved in a cold mixture of 25 C.O. of nitria acid (D 1.42) and 25 0.0. of conceatrat(ed sulphuric acid. The solut'ion was kelpt overnight, and t,hen poureld into water. The yellow precipitate (1.5 grams) was collected and crystallised from nitrio a.cid, when i t was obtained in whik needles melting at 254O. When mixed with 2 : 7-dinitroxanthone (m. p. 262*), i t mellted a t 254-260' (Found : N = 9.79. Cab. : N = 9-81 per .miit.). From the nitric acid filtmte a trinitroxanthonne was oIbt,aineld (see below).

2 : 4-Dirfl.it~oxnnthome.-Thie componnd was prepared by Maym (Zoc. cit.) by the oondensation of sodium phsnoxide and 2-chloro~ 3 : 5-dinitrobenzoia acid. It, ca,n also1 be1 prepared by condensing 2 : 4-dinitrophenol with 01-ohlorobenzoic acid in the following way.

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

1064 DHAR: A COMPARATIVE STUDY

2 : 4-Dinitrophe'nol (1.25 grams) and so,dium (0.17 gra,m) are dissollveid in met(hy1 alcohol (20 o.o.), a,nd to the olea,r solution o-chlocob,elnzolio acid (1.2 grams) and a, t.race olf copper powder addeld. After eivaporamting the a81c.ohoNl, t'he ye'llo'w residue mellts pa.rt!ly ah 160' and solidifies, in a, fe'w minutes. It is aolole:d, powdelred, and helat,ed again to 160', wheln i t mellts and reaolidifiels as befo,re. This proloess is re,pelateld ab,outl ten t.imes, when the condelnsatioa is compl.e8tel, and t,he substance doss not mellt on heat ing t'ol 160O. If the temperature of the bahh is raiseld with the1 vietw of co~mpleIting the1 rea.ct.ioa in one1 olpelra'tion, the whole mass suddenly inflamee. a,t, a.bout. 200' without melting. Aft,er the mmpleItion of the condensathn, the1 powdelred substanw is he.a,t'ed oin a st,elam-b,ath witch 20 C.C. olf concentrated sulphurio acid for fift,een minut,es. Whea co,ol, the solution is poareld into1 wa,tes and t'hel pre8cipit,attel is collecteld . The substlance, whe.n decoflorised witb animal charoolal in alcoholic, solutlioa, crystallism from t,his soJve.nt, in yelllow nesdles melting atl 206" (Fomiznd : N = 9.91. Calo. : N = 9-81 per cant,.),

l'ri?z:'t.ro xan t homes.

2 : 3 : 7-T&nit?-oixan~t h0n.e .-When 2-nitroxantmhonel Wafs nit'rate,d (see &ow), 2 : 7-dinitmroxanthone was the first product, and fromm the nitaria acid filt,rate a, yellowish-whiter precipitla,te! was obtaineld by a,dding wa;t.elr. Aftlelr b'eling boiletd with alcohol1 to1 remove impuritJes, it melteld a,t 205O (Found : N = 12.74. C,3H,0,N, reiquirea N'= 12.63 per cent.). The same1 trinitroxa,nthone was obt,ained when 6 grams of 2 : 7-dinitroxmt~ho~ns were1 dissolved in 50 0.0. of c,oncelnt>ra,t.eld sulphuric a,cid, 1 .2 O.C. olf nitria a.cid (D 1.500) addeld, aad the solut'ion was he1afe:d on a watsr-batlh fo,r twelnty-folur hoars. The unohangeid dinitrot-oompound was cryst'al- l i s d from nit,ric a,cid and collected, and the filt,ra;tei on ooacentra- tion ga,vve yellow needlea melting a.t 205'.

This cojmpound was a,lsoi obt,a.ineld by nitra,t'ing 3-nitlroxantlhoae8. B i m i t r o m o n oa.mirz oxan t hon e .-T hel trinihr 01-compound w a6 reduced

wit'h a.lcolho3ic ammoaium sulphide, a,nd the product separafed from alaohol as a, dark brown po'wdeir mellt,ing and decomposing a8t 230' (Foand : N = 14.55. D initrolzant h olnea'z 01-/3-n aph t h 01 .-T he1 dinit r oaminoxa.nt.hone1 was

dia,zotised in the usuad way and coupled with P-naphtholl. Thel a.zo-compo1und separate6 from. aloohol as a dark red, amorphous potwdelr meltling at' 370° (Found : N = 12.25. C,3H,20,N, requires N = 12.28 pelr cent.).

C,,H70,N, relquires N = 14.43 per uent.).

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

IN THE XANTHONE SERIES. PART I. 1065

Trinitrolxarithone.-Twol grams of xanthoae were dissolved in 7 C.C. of conaelntrahd sulphurio acid wit,h the1 aid of heat, and 2 C.C. of nitric acid (D 1.500) addeld to the cooled solutioin. The lattelr was the11 kelpt over the &earn-bath, wheln a, copious pre- cipitatel appelared in a few minutes oonsisting of yelloiw, glisbning needlea, which were filtered through asbestos and washed with dilute nitrio acid, and finally with water. The1 substance dissolves freely in cold nitric acid (D 1.42). It melts a t 225O, and is not i den tti ca 1 with the t r i n i t rot- c om p oun d p r eviolu sly m ein t i o iietd (Found : N = 12.72. Cl3H,O8N3 relquireis N = 12-63 per celnt.).

Dinitrom uoz oiamino xanth o n e .-T his was ob t ainetd by reducing the trinitro-derivative with aloohollic ammonium sulphida in the, usual way. It was obtained as a yelllow powder melting at 290° (Found: N = 14.47. C,,H,O,N, requiree W = 14.43 peir cent.).

T e tranityoxaot t hones.

l-Tetmnitroimmthone.-This compoand was oIbt8aine,d by dis- so'lving 0.5 gram of l-nitlro~xa.nthons in 5 0.c. of concent,ra;te.d sulphuric a.cid and adding 2.5 C.O. of nit*ria acid (D 1.42). The solution, oa keelping o~vvernight, depo,sit'ed yellowish-whitsel nseidles me~lting af? 250O. It is elvideat~ly different from al-, %-, or &-tqetrajnit8roxanthones, which do1 nost melltl a t 300° (Found : N = 14.64. C,,H,O,,N, requires N = 14-89 per celnt,.).

4,-T e t ra,nilt rolxunt h one .-Half a, gram omf 4-iiit.ro'xa.nt,h~llet was dissohwd in 5 C.C. of conoentlrat,eld sulphuric acid, and 2.5 C.C. of nit'ric a,cid (D 1-42) were t3hsn added gra,dually with shaking. A t t,hel firstl a,ddition olf nitlrio a,cid a. viojlentl re,act.ion ensueid, a.nd the reaction veasel was cooled. After keeping the mixture for a, fe'w days, a reddish-yellow precipit4ate wa.s obtaineld, which did not meilt at 300" (Foand : N = 15.32. C,,H,O,,N, require's N =14*89 per cent.).

4,-Te tranit ro,xan,t home .-When the1 fi1t.r a tie, from the nitr 01-mm- pound dacribed aboIvve was a,ddeld t,ol watw, the're was obt'a.ineld a brown polwder, whioh c.ould not be1 cryst,allised from alcoho'l, benzene, or nitrio acid. It, melts and de1compose.s a t 200° (Found: N = 14.70. CI3H4Ol0N4 relquirems N = 14.89 per cent'.). a,- Te t r m i tmxan t h o n e .-Thir tsen grams of a-dinitr oxa#nthoae

were a,dded t o a, mixture1 of 150 C.C. of co~iment,rated sulphurio acid a.nd 150 U.C. off nitric acid (D 1.42). The mixtnre wag heat.ed on a stelam-ba,tqh, when a, deas solution was obt8aJned in a few minutes and shining, yellowish-white c,ryst,als (10.7 grams) separated in about ~x hoars. Theeel did n o t melt a,t 300° (Found : N'=14.79. C131~,01,N4 relquires M = 14-89 pe'r cent.). This substanw when

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

1066 DHAR: A COMYARATlVE STUDY

helat,ed wit.h bromine1 and a t)race of iodine in a, seialed tube gives dib~romo~dinitro~xa8nthone (m. p. 265') (see this vd . , pp. 998-999).

~-Tetra,nitroea,n.tholrLe .-From the1 fi1t.ra.k frolm tho precelding compound, cryst,als, in the form olf broke'n plafes, were obtained by adding watelr. They a.lso do nob medt a t 300° (Found: N = 14-69. C,,H,O,,N, require6 N = 14-89 pelr oentl.).

This subst,ance, whelii treahd simihrly with b'rominel, gives a tat8rab,romo~xanthme (m. p. 255').

P2-Tet;mstitroxa,ntho.ne .-Tea grams od 2 : 7-dinit~ro~xantho~e were a,dded t'o a& mixture of 150 C.C. olf c:oncelntrateld sulphuric a'oid a.nd 150 0.0. of nitric a,cid (D 1.42). The mixture was heiat8eld fo!r about six hours, wheln bright yellowish-white crystals (9 grams) wetre precipit,a,t.e<d. The c.ompoaad was found to be identical with a1 - tletr a ni tar olxa 11 thonet, as b o'th these1 substlaac:es g a8vel the same d ib r omoldi ni t r olx a n th o 110 when t mat ed simil a,rly with bromine. From the1 filtrate, 3.5 grams of shining, white, b'rolken plabes were olbt.aineId, which did n o t melt at 300" (Found: N=14*69. C,,H,O,,N, re,quires N = 14.89 per Gent.). When this substiamnce is heate,d with bromine exa&ly in t,ha same1 way as the1 other tet.ra.- nitro+compounds, a, helxabromoxanthone is obta.ineld, which melts at 28'5'.

Slz ra up's Sym t h esis w .i t h Din it r oxa1n t h owe .

Three grams of 2 : 7-dinitIro.xa,nthonei were dissolveid in 5 C.O. of concent,rated sulphuriu acid, and 12 C.C. of glycelro3 addeld. The additioln of the lat,ter precipita,ted the nit,rcE-compound. The mix- tlure was heatteld in a paraffin-bsath, and act about 140' it began to froth, whe,n the flask was shakea and tho tempelrature lowereld t o l l O o . Heating was continued folr four hours at about 120°, and then for a further two hours at, about 140°, when a se:mi-sollid rna,ss resulteld. This was then hegateid fo r a, further three hours untlil tbe bla,ok mixture became solid. The ma'ss was polwdelred, and t'hhs crude product boileld wit+h water and filtered. The filtrate, on being rendered alkaline, gave a,n orange-red, colloidal prelcipitate, which sehtled on keeping otvelrnight. a,nd was collected. The sub- stlance separa,teea f rom alco,holl as an ora.nge-red po,wde,r, whioh sintms a t 200° and rnelte a,t 205-210' (Found: N=9*75. C16B804N2 requirea N = 9.59 pelr mnt.). The substance dissolves re.adily in aloo,hol, acids, or exoefss of alkali hydroxidel.

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

Dl THE XANTHONE SERIaS. PART I. 1067

Santhhydrols. a -17 ) i~~ i t roaa t~ t l~~~y~~~~o l . -a -Din i t ro~an tho~ ie (2.5 grams) was

suspelnded in 100 C.C. olf methyl alcohol, and 1 gram of sodium added in small pieces wit-h shaking. The colour of the mixture became first! orange, and finally deep reld. It was boiled under relflux f o r half an hour, when a char, dark red solution was obtaimd; the boliling was continued f o r a further pelriokd of one and arhalf hours, and the solution filtered hot. A yelllowish-brown precipitate was obtained on acidifying the solution with hydror chlolric acid, and this crystallised from acetic acid in brown needles melting a t 185O (Foand : N = 10.11. C,,M,O,N:, requires N=9*72 pelr cent.). The substance dissolveis in alcolhol and in cold dilute alkali hydrolxide, in the, latter solvent with a yeillow colour. Its solution in concentrated sulphuria o r hydrochlorio acid is pale yelllow, and in nitric acid it dissolves with a pink colloration. When helateld with glacial acedtic acid, it dissolvea to an orange-red solution.

@(or 2 : 7)-DinitrolxainthhydroZ.-This substance was obtained by trelating 2.5 grams of 2 : 7-dinitroxanthone with sodium and methyl alcohol, as in the1 case of the1 a-dinitro-compound. It crystallised from alcohol in slelnder, yeillowish-white needles melting and deem- posing at 196O (Found : N = 9.65. C,,H,0,N2 requires N = 9-72 per cent.). The substance dissollves in colld aqueous alkali hydr- oxide as well as in concentrated sulphuric acid with a yellow coloration, and in concentrated hydrochlolric acid to a pale yeillow solution.

Each of thdse dinitroxanthhydrols, when boiled with a mild oxidising agentr, such as al dilute solution off hydrogea perolxide or potassium permanganate, is converted into the corresponding di ni t r olxaii t hone.

Chlwoxamt hones.

1-Chloroxantholne.-o-Chlorobenzoio acid (1.6 grams), m7chlore phenol (1.4 grams), and sodium (0.4 gram) were dissoflveid in methyl alcohol (10 c.c.), a trrace od cotpper powdelr beling added as a catalyst. The solutioln was heateld o n an oil-bath, and the alcohol evapolrated, when the1 substance medted a t about 200° and solidified a4t abolut 215O. It was cooleld, powdered, and belated on a steam- bsahh with 15 C.O. of coacentrated sulphuric acid f o r fiftelen minutee. Wheln cool, the solution was poured into watelr, and the pre- cipitate oolleoted. The substance crystalliseid from aqueous alcohol in whit0 neetdles melting a t looo. It dissolves in sulphuric acid with a green fluorescence. I n this synthesis, elither 1-chloro-

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

1068 DHAR: A COMPARATIVE STUDY

xanthone or 3-chloroxanthone or both may possibly be Polrind, but only one produck was obtained. As it differed from 3-chloro- xanthone, which m e l t a t 130°, i t must be l-ckZolroxmthowe (Found : C1= 15-46.

l-A.n/iZ~~olccamth~ne.-One gram of the substance desuribed above was boiled with 3 C.C. of aniline and a trace of copper powder for six hours. A blue precipitate1 was obtained by poluring the solu- tion into water acidifisd with hydrwhloria acid. After being purified by extraction with alcohol, it melted at 120-125° (Found : N,=4.86. C19H130,N requires N =4.87 per cent.).

1 -Ch 2orolt et ram i t r ox an t h o n e , -H a1 f a gram of 1 -chlo r ox an thone was dissolved in 7 C.C. of concentrated sulphuria acid, and 5 C.C.

of nitria acid (D 1.42) were added to the solution with shaking. The solution wa5 kept overnight, when white needles were obtained, which melted at 195O (Found : N = 13.70. Cl,H,O,N,C1 requirw N=13*69 per cent.). From the filtrate, a white, pre- cipitate was obtained, which was to^ mall in amount for any detailed amina t ion .

Z - C ' ~ Z ~ ~ . ~ ~ ~ . n t ~ ~ ~ e . - ~ - C h l ~ r o F h e n o l (1 *4 grams) was dissolved in methyl aloohol (10 C.G.), and sodium (0-4 gram) and ol-chlorobenzoic acid (1.6 grams) and a trace of copper polwder were added to t$he solution. The alcohol was evaporated, and the viscous, semi-solid mass was heated to1 140°, and kept at that temperature for half an hour, when it darkened. It dried to a blaok solid mass a t 150O. The temperature was further raised to 200°, and then the substa;lice was cmld, powdered, and heated on a water-bath with 15 C.U. of concentrated sulphuric acid for fifteen minutes. When cool, the solution was poured into water; the precipitate was wlled,,ed, crystallised from alcohol, and obtained in white needles melting a t 165O (Ullmann, Zolc. cit., givee 171O). It dissolves in sulphuric acid with a blue fluorescence (Found : C1= 1 5 7 2 . Calc. : C1= 15.40 per cent.).

2-ChI~otetr~~trolxamth.one.--This compound was obtained by ni tlrati ng 2 -chloroa an thonel with concentrated sulphur ic and nitric acids. For each gram of substance, 10 C.C. of sulphuric aoid and 7 C.C. of nitria auid were used. The substance was obtained in slender, yellowish-white needl63 melting at 205O (Found : N = 13.75. C,,H30,,N,C1 requires N = 13.69 per cent.).

4-Chtorolx~n.tho71e.--This substance was obtained by the con- densation of a-chloaolbenzoic aoid with o-chlorophenol in the manner dmcribed in the syntheses of l-chloroxanthone. It crystal- lised from alcohol in slender, whib needlee mdting at 130O. It diwlves in concentrated sulphuric acid witqh a green fluoresmnce (Found : C1= 15.36.

4 - C ~ Z ~ ~ t r i n c i t r ~ x a n t ~ ~ ~ n e .-This compound ww obtained by

C,,H70,C1 requires C1= 15.40 per cent.).

C13H,0,Cl requires C1= lii.40 per cent.).

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

I N THE XANTIIONE SERIES. PART I. 1069

ni ttr a.tdng 4-ohlor oxanth one' w i t.h concedr ated sulphuric a.nd ni t r io acids. Fo'r eNalch gram osf the! subst,anm, 5 c o . o,f sulphurio acid and 4 0.0. od nitric acid weire used. IBrolwnish-ye8110w nwdles were obt'aineld on keeping t*hel relaction mixture overnightl. The sub- stlalncce melts a,t 235O (Fo'und : N = 11.14. C13H403N3Cl requires N = l l . 4 9 per cent.). 4-Chtwol&mits-oxanthone.-This substance was obtained from the

filtrate of t'he tlriiiitmro-mmponnd as a' pale yellow powde,r melting and decomposing at 195--200° (Found : N = 8.81. C,,H,O,N,Cl require8 N=8*73 per cent.).

Dic htorolxm t home .-Xa,nt hom (7 * 5 grams) was dissolved in metic a8cid (50 o.c.) wit'h the aid of heat. A current of dry chlorine Wacs passed int'o tqhel sdutioln, which was kept wa,rm by heafing t'hei relaction ve'ssetl ovetr a, st,ea,m-b'ath until approximat,dy one molecular proportion of chlorine was absorbed. A trace oC iodine, was use'd as a, ca,talystl. The1 product (10 grams) crystallised fro'm a.lcoholl i n slelnde:r, whit'el nesdles mellting a t 225O (Found : C1=26*86. C,,H,O,Cl, requires C1= 26.8'0 per cent.). The sub- stance dissolves in conce.ntra.ted sulphuric acid witah a' strong green fluo,re,scenwl. From t'hel a.lcoholia filtra.tle from the dichloroxant8honel anothelr product, mixed with it was obtained, which a.ppa.re,d to be 3 -chloroixant8ho~ne f rorn it,s mellt,ing point and chlorine1 contelnt, bcut it has not yet, been polssiblel to1 purify itl c:o,mpletely.

D.icl~toro~~~Lit~ollt.antjLone.-The dichlo~ro~conipound was nitrated in the, cold with a mixture) of equal volumes o,f nitric (D 1-42) and coaceat,ra.teid sulphuric a,cids (180 0.c. foil- e.ach gram of t~hei sub- st4aiicel). On ke,eping thel solutiion o,ve:rnight,, yellow iieeldles weire obt,ained, which mellted at, 240° (Found : N = 8.10. C,,H,O,N,Cl, retquiree N = 7.88 per cent'.).

Bronzozanthon es.

2 -Browzolxaaz t h0.n.e . -p-Bromopheno81 (2 * 5 grams) and sodi um (0.6 gram) we:re dissolve'd i n methyl alcohol (15 c.e.) and o~-chlcm- beinzcic acid (2.3 grams) a.nd a, trace of copper polwdelr were added to1 the1 solution. It was helat.ed to1 160°, when a, hasd, blaok mass was obtlaineld. The1 t,emperatturel was raise'cl to 220°, but the1 sub- sta.nce did not4 fusei. It was cooled, po,wdelreid, and helated aver a steam-b,a,th with 25 C.C. of colnoentrated sulphuric acid f o r twenty- five minutee. Whea O O ~ O ; ~ , the solution was8 poured into! wat.er a.nd the preicipit ate; colle.ctied. It cryatallised f rojm aqueous alcohol in brown needles melting a.t 150°, and dissolveld in sulphuric aaid with a yelllow colour, but. no, fluoresoelnoel (Found : Br = 29-00. C,,E,O,Br retquires Br = 29- 16 pelr aent,.). 2-Bromoxant,hone 'is also1 ob,tained when xantho,ne is b'rominated in concentra.hd

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online

1070 DHAR : A COMPARATIVE STUDY IN THE XANTHONE SERIES.

sulphuria acid so3ution with bromine! and a' trace olf ioldinel. It is vezy difficult,, however, Log isolatel the1 substance in at pure oondition, because the last. traaes of eithelr xanthone or dibrolmoxanthone, which a.re a,lwaysl assoc,iated with this compound, cannotl easily be rmnoved .

(0 - 7 gram) was dissolveld in c,oncelnt,ratad sulphuria acid (1 0 c. c .), and nitric acid (5 C.C. od D 1-42) then addeld gradually t'ot the! solutioa with shaking. No precipit'ats was formeld a,ft,er keleping it. for a few days. The solution wa's poured into1 watm, and the1 pre,cipit,ate was boiled with alcohol, in which it pastly dissolved. From the alcoholia solution, the subst'ance was obtained in slender, brown neodlee melting a.t' 210° (Found : N = 12.02. C13H3010N,Br requires N = 12.31 pe'r mat.).

2-Bromo-~-tetra/nitro~xamtho~ne.--The residue of the nit,ro-com- pound describe.d abo'vve wa.s dissolved in benzene, a,nd cryst?allised from this solution in brolwn needles melting at 270° (Found: N'= 12.21. C;,H3OloN,Rr requires N = 12.31 per cent-.). When 2-bmromoxa.ntthoner w8.s hela.te8d with bromine (1 or 2 molls.) in aceltic acid solut,ion and a t ram off ioldinel, oves a sa#nd-b,ath, a dibromo- aompound was ota.ined which melt,ed atl 212O. This colmpound was identified as 2 : 7-dib,ronioxa,ntlhone by the1 mebhod of mixed mellt,- ing points. It is also olbt8a,ined by brominating xanthoine with bromine, using iron filings as a catalyst,.

4-Brom.ox~;rt.tho~ze .-This compound was ob,t'ained by condenaing o-bromophelno'l wit'h o-chlo,robe,nzoio a,cid in t4hei usual way. It crystallised from alcohol in greyish-whits needles melting a t 140O. It shows no Auorescenm in sulphuric acid s,olution (Found: Br = 29.28. C,,H70,Br requires B r = 29.16 pe,r cent.).

4-Brom~in~itro~xa~thone.-4-Brorno~xant~honel was dissolved in the requisite amount off concentlramte:d sulphurio acid in t'he, c,old, and nitric acid (D 1.42) was addod to the sodution (20 C.C. fo8r elach gram of the substance). On keeping the solution owrnight, yellowish-white ne'eldles were1 o,bt&ned, which melted at 295O (Found : N = 8.09.

2-Brom.ol- a-t e t mni trosant h o n e . -2 -Br omo~xa~nt,ho~n.e

C,,H,O,N,Br requires N = 7.67 per cent.).

The author takea this olpportunity off elxpressing his thanks to Prolfessor J. F. Thorpe and Dr. M. A. Whitelely for their kind encouragement, and to the Van't4 Hof? Memorial Fund Committee and to1 the, Chemiclal Society for Reselasch Grants whicfh met4 part of the1 expensels.

IMPERIAL COLLEGE OF SCIENCE AND TECHNOLOGY, LONDON. [ R t ~ ~ i w d ~ .J217?/ 12th, 1920 1

Publ

ishe

d on

01

Janu

ary

1920

. Dow

nloa

ded

by U

nive

rsity

of

Nev

ada

- R

eno

on 2

5/08

/201

4 00

:50:

40.

View Article Online