SOME DERIVATIVES OF DIMETHYLDIHYDRORESORCINOL. 771

LXXI I I. -8oii ie De rkat ives of 23 iine t hyldihycl~o rcso rc iiiol . By ARTHUR WILLIAM CROBSLEY.

A SHORT time ago, Professor Perkin and the author (Trans., 1898, 73, 5 , 83), by fusing camphoric acid ,with potash, obtained dihydro- camphoric acid, CIOHISOI, which, from its reactions and behaviour on oxidation, mas thought to be most probably au$P-tetramethyladipic acid, COOH* CH(CH,)* C(CH,),* CH,* CH(CH,)* COOH. The constitu- tion of dihydrocamphoric acid is of great importance in assigning a formula to camphoric acid, and it mas therefore decided to attempt the synthesis of t'his substituted adipic acid, in the hope that the two would prove to be identical.

The reaction of isobutylenic bromide and ethylic sodiomethyl- malonate was first studied, in the hope that it might take place accord- ing to the following equation,

NaC( CH,)( COOC2H,), - - (CII,) 2 p r + CH,Br NaC(CH,)(COOC,H,),

2NaBr -I- (CH,),~*C(CH,)(COOC,H,), CH,*C(CH,)(COOG'2H5)2 '

as from such a condensation product the tetramethyladipic acid could be obtained by hydrolysis and subsequent elimination of two molecular proportions ol carbon dioxide, Although tried in alcohol, toluene, and xylene solution, and also in alcoholic solution under pressure, the ethylic methylmalonate was recovered unchanged, and only in toluene solution was any evidence of condonsation observed, the product, how- ever, being formed in much too small an amount for investigation. Further experiments in this direction were therefore abandoned.

It has been noticed by Bentley (Trans., 1895, 67, 266) and othora that bromides containing a methyl group next to the carbon atom attached to bromine are of little use for synthetical work, as apparently hydrogen bromide is eliminated, which reacts with ethylic sodio- malonate, giving rise to sodium bromide and ethylic malonate j pre- sumably, the reaction takes this course i n the present case.

In order to see whether the unsymmetrical nature of the bromide exerted any influence, the action of ethylic sodiomethylmalonate on symmetrical butylenic bromide, CH,* CHBr*CHBr* CH,, was tried, but again condensation did not occur.

The next method which suggested itself was the interaction of mesityl oxide and ethylic sodiomalonate, in which it was expected that addition of the elements of the latter mould take place a t the double linking in the oxide. Unfortunately, the work of Vorlander on this

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772 CROSSLEY : SOME DERIVATIVES OF

subject had been overlooked, as the reaction is not suited for the synthesis of the required substituted ndipic acid. Vorliinder (AmaZen, 1897, 294, 253, 300) has shown that when rnesityl oxide and ethylic sodiomalonate react in alcoholic solution, direct addition takes place at first, but loss of the elements of ethylic alcohol also occurs, giving rise to ethylic dimethyldihydroresorcylate, a substance which is easily converted into dimethyldihydroresorcinol by hydrolysis,

After the publication of a short preliminary notice of my work (Proc., 1898, 14, 247), Dr. Vorliinder called my attention to his research on the same subject, and further work with the substance was therefore abandoned (Proc., 1899, 15, 52). The following com- munication, giving a brief account of some derivatives of dimethyl- dihydroresorcinol not previously described, is published with the know- ledge and consent of Dr. Vorliinder, to whom I desire to tender my thanks both for his courtesy and for leaving in my hands the investi- gation of the interaction of ethylic sodiomethylndonate and mesityl oxide, which is being continued in the hope that it may ultimately lead to the synthetical production of tetramethyladipic acid.

'Vorliinder (AnnuLen, 1898, 304 ,15) has shown that when dimethyl- dihydroresorcinol is oxidised with alkaline permanganate at a tempera ture of 40-50", the main product of the reaction is unsymmetrical dimethylsuccinic acid. Under these conditions, P/3-dimethylglutaric acid was not isolated, although its formation might reasonably be expected as a result of disruption of the ring at the positions indicated by the dotted lines,

CH C H * C O .- CH~>C<CH?. CO>CH,.

and also in view of the fact that dihydroresorcinol, as Merling (AnmZen, 1894,278,31) has shown, is readily oxidised by permanganate, yielding glutaric acid. The experiments described in this paper show that if dilute nitric acid, or a mixture of potassium dichromate and sulphuric acid, is substituted for potassium perrnanganate, there is no diEcuItg in isolating considerable amounts of PP-dimethylglutaric acid.

Ex P ER I M E N T A L .

was prepared from ethylic sodiomalonate and mesityl oxide in a manner similar to that already described by Vorliinder (AnmZen, 1897, 294, 273, 300). It was first obtained as a thick, faintly yellow oil,

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DIMETHY LDIHY DRORESORCINOL. 773

of which only a small amount passed over on distillation in a vacuum, the residue being transformed into a brilliant red resin, which has not been further examined. After a long time, the yellow oil solidified to a mass of colourless crystals melting at 76-78', which after re- crystallisation from a mixture of benzene and light petroleum separated in clusters of short, transparent, flattened needles melting at 78.5-78' (uncorr.). When heated above its melting point, the substance decom- poses, evolves gas, and is transformed into the red resin.

0.1552 gave 0.3286 CO, and 0.0978 H,O. C = 61.72 ; H = 7.48. 0.1478 ,, 0.3354 GO, ,, 0.0996 H,O. C = 61.88 ; H= 7.49.

C,,H1,O, requires C = 63.36 ; H = 7.54 per cent.

Di~~tet~~ZEil~~droresorcinoZ, ( CH,),C<CH,. CH,*CO CO>CH,.

Dimethyldihydroresorcinol was obtained from ethylic dimethyl- dihydroresorcylate in a manner differing but slightly from tha t employed by Vorliinder (AnnuZen, 1897, 294, 314; 1898, 304, 18). The ethylic resorcylate was hydrolysed with alcoholic potash, and after adding water the alcohol wag removed by evaporation, During this operation, a strong odour of peppermint was observed, and when the alkaline liquid mas subsequently extracted with ether, a small amount of an oil having this characteristic odour was obtained ; this substance partially solidified after long standing, but has not been further investigated.

The residual alkaline liquid, after acidifying with sulphuric acid, was extracted with ether, and the ethereal solution dried over calcium chloride; the solid residue obtained after evaporating the ether was purified by one or two recrystallisations from acetone, and analysed.

0.1458 gave 0.3674 CO, and 0.1124 H,O. C! = 68.72 ; B = 8.56. 0.1146 ,, 0,2876 CO, ,, 0.08S4 H20. C=68*44; H=8*57.

C,H,,O, requires C = 68.57 ; H = 8-57 per cent. On allowing the acetone mother liquors to slowly evaporate, a viscid

residue was obtained, which probably contains the bye-products de- scribed by Vorlander (Anden, 1898, 304, 17).

Dimethyldihydroresorcinol, the yield of which is from 70-75 per cent, of the theoretical, is insoluble in cold light petroleum and only slightly soluble on boiling ; it dissolves in water, chloroform, ethylic acetate, benzene, or acetone on boiling, and separates on cooling in needle-shaped crystals ; these melt at 148.5' (uncorr.), and at the same time give off 8 red liquid, which settles in the upper part of the capillary as 8 red film. When heated above its melting point, i t is transformed into a red liquid, and on cooling sets to a hard, amber-like mass, which is completely soluble in alcohol, acetone, or aqueous potass- ium hydroxide (compare RIerling, Zoc. c i t , ). Auric chloride and platinic

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774 CROSSLEY: SOME DERIVATIVES OF

chloride do not precipitate a neutral solution of dimethyldihydrores- orcinol in ammonia, but are reduced when the solutions are warmed.

I am indebted to I&*. W. J. Pope for kindly supplying the following crystallographic details :-

' I The substance crystallises from acetone in large, transparent, monosymmetric prisms with a calcite-like lustre. The crystals are elon- gnted in the direction of the axis b, and the form u{ 100) is dominant ; the forms in the zone [OlO] are well-developed, and usually striated pqrallel to the axis 6. The forms p(110) and o(121) are small, but give good reflections on measurement ; the pinacoid b(010) is rarely present, and is always very small. The plane of symmetry is the optic axial plane, and a bisectrix of positive double refraction emerges through the face c(OO1) ; the angular dispersion is marked.

After melting on a microscope slide, the substance solidifies readily from centres in large individual flakes, frequently perpendicular to a bisectrix of negative double refraction,

6 ' Crystalline system :-Monosymmetric. u : b : c = 1.5445 : 1 : 0.9433.

p= 77" 17.5'. 'IForrns observed :--a{100),6(010), c(OOl}, r(lOl), yIllO), and o{1211.

4' The following angular measurements were obtained :

Angle.

ap = l o o : 110 pp = 110 : i i o b p = O l O : 110 a)' = l o o : 101 TC = l o 1 : 001 nc = l o o : 001 nc =Too : 001 vp =lo1 : 11g po =110:121 TO = l o 1 : 121 cp =001 : I10 co =001 : 121 00 = i 2 1 : ~ 2 1 bo =010 : 121 00 = 1 2 i :121 a0 = l o o : 121

~

Number of observations.

42 18 6

25 37 16 21 44 25 27 19 19 1 5 7

12 1s

Limits.

52O23'- 53" 4' 74 17 - 74 53 37 5 - 37 21 46 7 - 46 51 30 16- 31 0 76 59 - 77 31

10226-103 4 65 12 - 65 32 3219- 35 1 70 38- SO 5 81 58 - 82 56 66 31- 67 0 60 54 - 61 22 3 3 2 9 - 34 9

118 16-119 2 76 45 - 77 19

Mean 01)- ervcd vitluo.

52'41' 74 34 37 15 46 32 30 39.5 77 14

102 47 65 24 34 43 79 52 82 24 66 48 61 7 33 48

11s 4s 77 1

Calculated valuc.

- 74"38' 37 19 46 38

77 17.5 102 42'5

34 4a

-

-

70 48 82 20 66 42 61 10 33 41

118 50 76 59 "

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DIMETHYLDIHY DRORESORCINOL. 775

The &her salt, C,H1,O,Ag, was obtained by precipitating an accu- rately neutralised solution of dimethyldihydroresorcinol in ammonia with silver nitrate. It is a white, flocculent precipitate, and is some- what readily soluble in hot water, separating, on cooling, in fine, grey, feathery needles.

C ~ 3 8 . 9 7 ; 0.3033 gave 0.4335 CO,, 0.1234 H,O, and 0.1322 Ag.

Additional silver determinations gave Ag = 43.59 and 43.9'7. H = 4.52 ; Ag = 43.58.

C,HIIO2Ag requires C = 35.86 j H = 4.45 ; Ag = 43.73 por cent.

The etlylic ether, (CH,),. C<CH2. CH2-C0 C(OC2H-)>CH, was prepared by

heating the silver salt, suspended in dry ether, with the requisite amount of ethylic iodide in a reflux apparatus for 2 hours. The colourless oil, obtained after evaporation of the ether, and possessing a slight smell somewhat resembling that of celery, solidified to a mass of needle-shaped crystals, and was recrystallised from light petroleum (b. p. 40-60').

0.1248 gave 0.3268 CO, and 0.1069 H,O.

Determinations of the xnolecultlr weight by Raoult's method, using

Found, (I) 175, (11), 174 ; CIoH,,O, requires mol. wt. = 168,

The ether crystallises from light petroleum in stout, transparent, lustrous prisms, which are usually twinned and apparently belong to the monosymmetric system; it melts at 59-5-60", distils without decom: position at 252' under the ordinary atmospheric pressure, and is readily soluble in cold acetone, chloroform, alcohol, or ether, but only sparingly so in cold light petroleum, When treated with alcoholic potash, it is converted quantitatively into dimethyldihydroresorcinol, melting at 148.5' as already described.

B~o~ , zod in ie t l~~ l ih~d~o~esorc ino l , ( C H , ) , * C < ~ ~ ~ & ) > co CBr+H20c

-Dimethyldihydroresorcinol was dissolved in dry chloroform, and a solution of dry bromine in chloroform gradually added in the dark until the colour became perinanent. As soon as this occurred, hydrogen bromide was evolved, and a white solid separated, which was collected, spread on a porous plate, and purified by recrystallisation from dilute alcohol. The crystals eMoresce in a vacuum over sulphuric acid, and by this means the water of crystallisation in the air-dried salt was determined, In the second analysis, the substance was heated at 80' in aq air-bath until a constant weight was attained.

C=71*41 ; H = 9 . 5 1 . CI,H,,O, requires C = 71.63 ; H = 9.52 per cent.

acetic acid as solvent, gave tho following results :

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776 CROSSLEY : SOME DERIVATIVES OF

I. 0.5414 lost 0.0416 H20 = 7.68. IT. 0.5947 lost 0'0470 H20 = 7.90. C,H,,O,Br + H20 requires H,O = 7.59 per cent.

Bromine determinations in the anhydrous substance gave the

I. 0,2714 gave 0.2346 AgBr. Rr=36*78. 11. 0.2306 gave 0.1997

following numbers :

AgBr. Br = 36.84. C,H,,O,Br requires Br = 36.53 per cent.

Bromodimethyldihydroresorcinol is insoluble in light petroleum or chloroform, slightly soluble in toluene, and readily so in alcohol, acetone, or acetic acid. It crystallises best from dilute alcohol in white, glistening leaflets, or after repeated crystallisation in long, needle-shaped crystals containing lH,O, and melting with slight de- composition at 173-1 73.5' (uncorr.). The dried substance melts, decomposes, and gives off gas at 143-144O.

When dissolved in dilute aqueous potassium hydroxide and treated with sodium amalgam, it is converted quantitatively into dimethyldi- hydroresorcinol, behaving in this respect like dihydroresorcinol (Merling, Zoc. cit.). Alcoholic potash, however, seems to have littlo or no action on it, as potassium bromide did not separate after it had been heated for 43 hours on a water-bath with twice its weight of potassium hydroxide dissolved in alcohol, and on acidifying and extracting with ether, bromodimethyldihydroresorcinol was recovered in nearly theore- tical amount.

~ r o m o d ~ ~ n e t h ~ ~ t e t r c 6 h ? / ~ ~ o ~ * e s o r c ~ n o ~ ~ (CH,),* c < ~ ~ , C H 2 - P - . cH(OH) "o>CHBr. -Dimethyldihyd roresorcinol mas dissolved in glacial acetic acid pre- viously saturated with dry hydrogen bromide, and after some time beautiful, transparent crystals separated. The excess of acetic acid containing hydrogen bramide WRS poured off, and the crystals were rapidly and repeatedly washed by decantation with cold acetone, dried in a vacuum, and analysed.

0,1638 gave 0.1391 AgBr. CsH1,O,Br requires Br = 36.20 per cent.

This substance crystallises from an acetic acid solution of hydrogen bromide in large, transparent, rhombic plates, which melt at 168-169' with decomposition and evolution of gas. It deliquesces rapidly on exposure to the air, is insoluble in cold acetone, light petroleum, or chloroform, and soluble in hot alcohol or acetone, but could only be obtained crystalline in the manner just described. When treated with alcoholic potash or with sodium amalgam, it is reconverted into dimeth y ldiliy droresorcinol.

Br= 36.14.

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DIMETHY LDIHYDRORESORCINOJi. 777

Oxidcction of DimetlL~Z~lclih?lclroresorcinoZ.

Oxidation with Dilute Nitric Acid.-Dimethyldihydroresorcinol was boiled with ten times its weight of nitric acid of sp. gr. 1.15 in a reflux apparatus. The mixture gradually changed in colo~ir, and after about 15 minutes became a deep cherry red, and the oxidation violent ; when the vigorous reaction had subsided, the heating was continued for about half an hour to complete the oxidation. The excess of nitric acid was removed by evaporation ou a water-bath, and after treating repeatedly with water to ensure the removal of all but the last traces of nitric acid, the residue solidified to a mass of crystals. These were spread on a porous plate, dissolved in water, neutralised with atninonia, and boiled with excess of calcium chloride solution. After removing the precipitate, which gave off carbon monoxide on heating with concentrated sulphuric acid, the 61 trste was evaporated to a small bulk, acidified with hydrochloric acid, and extracted repeatedly with pure ether, the ethereal solution being dried over calcium chloride and the ether evaporated. The solid residue was then heated with acetic chloride for two liours, and after removal of the excess of the solvent by evaporation, the product soon solidified as a mass of glistening plates, which, although repeatedly recrystal- lised from petroleum boiling at 100-120", did not melt sharply. The crystals dissolved for the most part readily in cold benzene, and after filtering from a small amount of insoluble material and allowing the solution to evaporate spontaneously, long, flat needles separated which melted at 124-1 35' and gave the folIoming numbers on analysis.

0.1094 p v e 0.2373 CO, and 0.0702 H,O. C7H1,,03 requires C = 59.15 ; H = 7.04 per cent,

The substance had all the properties ascribed to PP-dimethyl- glutaric anhydride by Perkin and Goodwin (Trans., 1896, 69, l475), and was characterised by converting it, by boiling with water, into the corresponding acid nielting a t 1OO-l0lo, into the aizilic cccid melting at 134-135', and into the ccniZ melting at 1 5 8 O (compare Perkin and Goodmin, Zoc. cit.).

I n a second oxidation, the product, after removal of the nitric acid by evaporation, was treated directly with acetic chloride, with exactly similar results, Oxidation witlh Potassium Diclwontate and Sulpl~uric Acid.-A

solution of 16 grams of potassium dichromste in dilute sulphuric acid was gradually added to 5 grams of dimethyldihydroresorcinol dissolved in 100 C.C. of water, and the mixture heated for half an hour on the water-bath to complete the oxidation, which takes place very readily. The product was isolated by removing the chromium by

C=58*13; H=7*13.

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778 RUHEMANN AND CUNNINCITON : CONDENSATION OF ETHYLlC

precipitation with sodium carbonate, evaporating the filtrate to a small bulk, acidifying with hydrochloric acid, and extracting ten times with pure ether, The residue left after evaporating the ether solidified on cooling, and after drying on a porous plate was treated with acetic chloride exactly as described uuder the oxidation with nitric acid. The crystalline solid thus obtained melted at 134--125O, and was identi- fied as /3P-dilnethylglutaric anhydride by analysis,

0.1143 gave 0.247 CO, and 0*0722 H,O. . C = 58.99 ; 13 = 7-03, C71’IloO;, requires C = 59.15 ; H = 7.04 per cent.

and by conversion into the correspondiug acid melting at 100-101*. CqEnrIcAL LABor,hTonY,

ST. TIIOIIAS’s HOS~ITAL.

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