ay-DIALDEHYDOPROPANE- p P-DICAEBOXYLIC ACID ETC. 19 1 X X X.-a y-Diald ehydopropane-PP-dicarbox ylic and a y -Dialdehydopropane-P-carbox ylic Acid. B y WILLIAM HENRY PERKIN jun. and HERBERT SHEPPARD PINK. THIS communication is a continuation of the work of Perkin and Sprankling (J. 1899,75 1 l) who showed that ethyl acetalmalonate, obtained when ethyl sodiomalonate is heated with bromoacetal, yields on hydrolysis acetalmalonic acid and that this acid when heated with water at 180° loses carbon dioxide with the formation of P-aldehydopropionic acid : (EtO),CH*CH,*CH(CO,Et) -+ (EtQ),CH-CH,*CH(CO,H), -P CHO*CH,*CH,*CO,H. The oxidation of the latter acid to succinic acid its reduction to butyrolactone and its conversion into terephthalic acid by treat-ment with alkali were described.It is now shown that the potas-sium derivative of ethyl acetalmalonate reacts with bromoacetal with the formation of ethyl diacetalmalonate (A) and that this ester on hydrolysis with baryta yields diacetalmalonic acid, (Et O),CH *CH,=C( CO,H),*CH,*CH( OEt),. When the ester (A) is left in contact with N-hydrochloric acid in the cold it is converted into the ester of ay-dialdehydopropane-pp-dicarbozylic acid CHO*CH2*C(C0,Et),*CH2=CH0 but if concen-trated hydrochloric acid is employed further hydrolysis takes place and uy-dialdehydopopane- PP-dicarboxylic acid is produced. Apart from the method of synthesis the constitution of this acid is demonstrated by the facts that it is converted on reduction into bis-y-butyrolactone-aa-spiran (I) which Leuchs and Gieseler (Ber., 1912 44 2114) obtained by the action of ethylene bromoacetate on ethyl sodiomalonate and that on oxidation it yields propane-aPPy-tetracarboxylic acid (11) which a t its melting point is decom-posed with elimination of carbon dioxide and formation of tri-.carballylic acid (compare Bischoff Ber. 1896 29 267). Acid When ay-dialdehydopropane- PP-dicarboxylic acid is heated wi+h water a t 180" it is decomposed with elimination of carbon dioxide. and formation of ay-dialdehydolwolxtne- p-car~oxylic mid, CHO*CH,*CH( CO,H)*CH,*CHO. E X P E R I M E N T A L . Ethyl Dimetcclmalonate.-The ethyl acetalmalonate required for-the preparation of this substance was obtained by a d m g ethy 192 PERKIN AND PINK: malonate (100 9.) and bromoacetal (80 g.) to sodium (14.2 g.) dissolved in alcohol (200 c.c.).The mixture was heated in an autoclave fitted with a mechanical stirrer for 4 hours the temper-ature of the surrounding oil-bath being kept at 180". The product was worked up as described in the previous communication (J. 1899, 75 13) and the ester (72 g.) distilled a t 163-165"/20 mm. In the preparation of the diacetal derivative potassium (8 g.) is melted under boiling toluene (50 c.c.) pulverised by shaking cooled and ethyl acetalmalonate (55 9.) added very gradually. A vigorous action takes place and if the ester is added too rapidly the heat generated is sufficient to raise the toluene to the boiling point and the solution turns brown. When all the ethyl acetalmalonate has been introduced and the last traces of metal have disappeared bromo-acetal (40 g.) is added and four such portions are united and heated in the autoclave during 6 hours with constant stirring the temper-ature of the oil-bath being maintained a t 200".After standing over-night the product is transferred to flasks the toluene removed under reduced pressure the residue mixed with water and ether, the ethereal extract well washed dried over anhydrous potassium carbonate and the ether distilled off. The distillation is continued under reduced pressure when unchanged ethyl acetalmalonate (80 g.) comes over a t 140-170"/20 mm.; the thermometer then rises rapidly to 187" between which temperature and 200" the main portion of the ethyl diacetalmalonate passes over ; there is a further fraction a t 200-250" which has not been examined.On redis-tillation ethyl diacetalmalonate is obtained as a colourless rather viscid oil b. p. 192-196"/18 mm. dg 1.031 (Pound C = 58.3; H = 9.2. The ester (5 g.) was mixed with a methyl-alcoholic solution of barium hydroxide (32 C.C. of a solution of 16 g. of Ba(OH),,8H20 in 100 C.C. of methyl alcohol = 25% excess) and boiled on the steam-bath for 4 hours. Water (10 vols.) was then added the whole saturated with carbon dioxide and the filtrate from the barium carbonate concentrated on the steam-bath, but the salt did not crystallise On evaporation to dryness a pale yellow brittle salt remained which is moderately soluble in water (Found Ba = 31.0. C,,H,,O,Ba requires Ba = 29.1%). The powdered barium salt (5 g.) was mixed with a little water and slightly less than the calculated quantity (21 c.c.) of N-sulphuric acid added with vigorous stirring.After standing over-night the whole was filtered the filtrate extracted repeatedly with pure ether, the ethereal solution dried over anhydrous magnesium sulphate, and the ether allowed to evaporate when diacetalmalonic acid was left as a pale viscid syrup which showed no tendency to crystallise. C,,H2608 requires C = 58.2; H = 9.2%). Hydrolysis.-(i) By Alkali Cty-DIALDEHYDOPROPANE- PP-DICARBOXYLIC ACID ETC. 193 After remaining for 3 days in a vacuum desiccator over solid potassium hydroxide this was analysed (Found C = 53-3; H = 8.3. On titration with N/10-alcoholic potassium hydroxide 0.22 neutralised 0-0533 KOH whereas this amount of a dibasic acid C,5H2808 should neutralise 0-0524 KOH).(ii). By Concentrated Hydrochloric Acid. Ethyl diacetal-malonate (10 g.) was well shaken with concentrated hydrochloric acid (30 c.c.) when complete solution took place and after 24 hours, the rather dark liquid was diluted with water filtered from a little tarry matter and evaporated to a small bulk under reduced pressure the temperature not being allowed to rise above 30". After further evaporation over sulphuric acid in a vacuum desiccator, a pale brown syrup resulted and this was mixed with water and again evaporated the operation being repeated several times. The syrup remained as such for 7 weeks and then suddenly crystal-lised and the mass was drained on porous porcelain and crystallised from water from which it separated in colourless prisms (Found : C = 44.7; H = 4.5.C,H,06 requires C = 44.7; H = 4.3%). a y-Dialdehydopropane- PP-dicarboxylic acid melts a t 122" with decomposition and is readily soluble in water alcohol or acetone, sparingly so in ether and almost insoluble in petroleum benzene, chloroform or carbon tetrachloride. On titration 0,1562 neutra-lised 0.0665 NaOH whereas this amount of a dibasic acid C,H,O& should neutralise 0.0664 NaOH. A neutral solution of the ammon-ium salt gives with silver nitrate a white precipitate which rapidly darkens and silver is deposited. The di-p-nitrophenylhydrazone separated as a yellow crystalline precipitate when the aqueous solution of the acid (0.6 9.) was mixed with p-nitrophenylhydrazine (0.85 g.) dissolved in dilute acetic acid and separated from alcohol in glistening plates m.p. 156" (decomp.) (Found N = 18.2. C19H1808N6 requires N = 18.3%). The ethyl ester was obtained when ethyl diacetalmalonate (15 g.) was well shaken with N-hydrochloric acid (30 c.c.) and after remain-ing for 24 hours the whole was several times extracted with ether, the extract washed with sodium carbonate dried over potassium carbonate and distilled when the ester passed over a t 174-178"/18 rnm. The p-nitrophenylhydrazone prepared in dilute acetic acid solution crystallised from alcohol as a microcrystalline powder, m. p. 170" (Pound N = 16.2. C2,H,,O8N6 requires N = 16.3%). Reduction of ay-Dialdehydopropane-PP-dicarboxylic Acid.-The dibasic acid (4 g.) dissolved in water (75 c.c.) was mixed with sodium bicarbonate (15 g.) and treated with sodium amalgam (150 g.of 404,) in a flask fitted a-it5 a mechanical stirrer and cooled in ice the C,,H,,O requires C = 53.6; H = 8.3%. VOL. CXXVII. € 194 ay-DIALDEHYDOPROPANE- ~~-DICARBOXYLIC ACID ETC. reduction being complete in about 8 hours. The alkaline solution was acidified with dilute sulphuric acid (10 g.) in water (20 c.c.), concentrated on the steam-bath repeatedly extracted with chloro-form the extract dried over anhydrous magnesium sulphate and the chloroform allowed to evaporate. The colourless crystalline residue separated from water in plates m. p. 109-llO" and was evidently identical with bis- 7-butyrolactone-aor-spiran described by Leuchs and Gieseler (loc.cit.). Oxidation of ay-Dialdehydopropane- p p-dicarboxylic Acid.-The acid (5 g.) dissolved in water (20 c.c.) was mixed with potassium dichromate (5.2 g.) in sulphuric acid (6.9 g.) and water (75 c.c.) and allowed to stand for 12 hours during which the colour changed t o green. The product evaporated on the steam-bath to 50 c.c. was extracted with ether the extract dried over anhydrous magnesium sulphate and the ether allowed to evaporate over sulphuric acid. The oily residue remained for weeks without crystallising but did SO rapidly when a crystal of propane-appy-tetracarboxylic acid was introduced. After contact with porous porcelain the substance separated from ether in needles melted a t 151" with decomposition into carbon dioxide and tricarballylic acid and was thus identified with propane- @Py- tetracarboxylic acid.a y- Dialdehydopropane- p-carboxylic Acid .-This acid was obtained when ay-dialdehydopropane- pp-dicarboxylic acid (4 g . ) dissolved in water (16 c.c.) was heated in a sealed tube a t 180" for 4 hours. On opening the tube carbon dioxide escaped and the solution, evaporated in a vacuum over sulphuric acid deposited a syrup which even on long standing did not crystallise (Pound C = 49-5 ; H = 5.5. C6H804 requires C = 50.0; H = 5.5%). The di-p-nitrophenylhydraxone obtained by adding a solution of p-nitro-phenylhydrazine in dilute acetic acid to the aqueous solution of the acid and heating for an hour on the steam-bath is a yellow amor-phous powder sparingly soluble in the usual solvents.The substance could not be recrystallised and was pursed by extraction with hot alcohol and then with ether when the residue melted a t about 198" (decornp.) (Found N = 20.3. C,&,80$6 requires N = 21.3%). One of us (H. S. P.) desires to thank the Department of Scientific and Industrial Research for a maintenance grant and the Govern-ment Grant Committee of the Royal Society for a grant for materials. THE DYSON PERRINS LABORATORY, OXFORD. [Received November 12tl2 1924. ay-DIALDEHYDOPROPANE- p P-DICAEBOXYLIC ACID ETC. 19 1 X X X.-a y-Diald ehydopropane-PP-dicarbox ylic and a y -Dialdehydopropane-P-carbox ylic Acid. B y WILLIAM HENRY PERKIN jun. and HERBERT SHEPPARD PINK. THIS communication is a continuation of the work of Perkin and Sprankling (J.1899,75 1 l) who showed that ethyl acetalmalonate, obtained when ethyl sodiomalonate is heated with bromoacetal, yields on hydrolysis acetalmalonic acid and that this acid when heated with water at 180° loses carbon dioxide with the formation of P-aldehydopropionic acid : (EtO),CH*CH,*CH(CO,Et) -+ (EtQ),CH-CH,*CH(CO,H), -P CHO*CH,*CH,*CO,H. The oxidation of the latter acid to succinic acid its reduction to butyrolactone and its conversion into terephthalic acid by treat-ment with alkali were described. It is now shown that the potas-sium derivative of ethyl acetalmalonate reacts with bromoacetal with the formation of ethyl diacetalmalonate (A) and that this ester on hydrolysis with baryta yields diacetalmalonic acid, (Et O),CH *CH,=C( CO,H),*CH,*CH( OEt),.When the ester (A) is left in contact with N-hydrochloric acid in the cold it is converted into the ester of ay-dialdehydopropane-pp-dicarbozylic acid CHO*CH2*C(C0,Et),*CH2=CH0 but if concen-trated hydrochloric acid is employed further hydrolysis takes place and uy-dialdehydopopane- PP-dicarboxylic acid is produced. Apart from the method of synthesis the constitution of this acid is demonstrated by the facts that it is converted on reduction into bis-y-butyrolactone-aa-spiran (I) which Leuchs and Gieseler (Ber., 1912 44 2114) obtained by the action of ethylene bromoacetate on ethyl sodiomalonate and that on oxidation it yields propane-aPPy-tetracarboxylic acid (11) which a t its melting point is decom-posed with elimination of carbon dioxide and formation of tri-.carballylic acid (compare Bischoff Ber. 1896 29 267). Acid When ay-dialdehydopropane- PP-dicarboxylic acid is heated wi+h water a t 180" it is decomposed with elimination of carbon dioxide. and formation of ay-dialdehydolwolxtne- p-car~oxylic mid, CHO*CH,*CH( CO,H)*CH,*CHO. E X P E R I M E N T A L . Ethyl Dimetcclmalonate.-The ethyl acetalmalonate required for-the preparation of this substance was obtained by a d m g ethy 192 PERKIN AND PINK: malonate (100 9.) and bromoacetal (80 g.) to sodium (14.2 g.) dissolved in alcohol (200 c.c.). The mixture was heated in an autoclave fitted with a mechanical stirrer for 4 hours the temper-ature of the surrounding oil-bath being kept at 180". The product was worked up as described in the previous communication (J.1899, 75 13) and the ester (72 g.) distilled a t 163-165"/20 mm. In the preparation of the diacetal derivative potassium (8 g.) is melted under boiling toluene (50 c.c.) pulverised by shaking cooled and ethyl acetalmalonate (55 9.) added very gradually. A vigorous action takes place and if the ester is added too rapidly the heat generated is sufficient to raise the toluene to the boiling point and the solution turns brown. When all the ethyl acetalmalonate has been introduced and the last traces of metal have disappeared bromo-acetal (40 g.) is added and four such portions are united and heated in the autoclave during 6 hours with constant stirring the temper-ature of the oil-bath being maintained a t 200". After standing over-night the product is transferred to flasks the toluene removed under reduced pressure the residue mixed with water and ether, the ethereal extract well washed dried over anhydrous potassium carbonate and the ether distilled off.The distillation is continued under reduced pressure when unchanged ethyl acetalmalonate (80 g.) comes over a t 140-170"/20 mm.; the thermometer then rises rapidly to 187" between which temperature and 200" the main portion of the ethyl diacetalmalonate passes over ; there is a further fraction a t 200-250" which has not been examined. On redis-tillation ethyl diacetalmalonate is obtained as a colourless rather viscid oil b. p. 192-196"/18 mm. dg 1.031 (Pound C = 58.3; H = 9.2. The ester (5 g.) was mixed with a methyl-alcoholic solution of barium hydroxide (32 C.C.of a solution of 16 g. of Ba(OH),,8H20 in 100 C.C. of methyl alcohol = 25% excess) and boiled on the steam-bath for 4 hours. Water (10 vols.) was then added the whole saturated with carbon dioxide and the filtrate from the barium carbonate concentrated on the steam-bath, but the salt did not crystallise On evaporation to dryness a pale yellow brittle salt remained which is moderately soluble in water (Found Ba = 31.0. C,,H,,O,Ba requires Ba = 29.1%). The powdered barium salt (5 g.) was mixed with a little water and slightly less than the calculated quantity (21 c.c.) of N-sulphuric acid added with vigorous stirring. After standing over-night the whole was filtered the filtrate extracted repeatedly with pure ether, the ethereal solution dried over anhydrous magnesium sulphate, and the ether allowed to evaporate when diacetalmalonic acid was left as a pale viscid syrup which showed no tendency to crystallise.C,,H2608 requires C = 58.2; H = 9.2%). Hydrolysis.-(i) By Alkali Cty-DIALDEHYDOPROPANE- PP-DICARBOXYLIC ACID ETC. 193 After remaining for 3 days in a vacuum desiccator over solid potassium hydroxide this was analysed (Found C = 53-3; H = 8.3. On titration with N/10-alcoholic potassium hydroxide 0.22 neutralised 0-0533 KOH whereas this amount of a dibasic acid C,5H2808 should neutralise 0-0524 KOH). (ii). By Concentrated Hydrochloric Acid. Ethyl diacetal-malonate (10 g.) was well shaken with concentrated hydrochloric acid (30 c.c.) when complete solution took place and after 24 hours, the rather dark liquid was diluted with water filtered from a little tarry matter and evaporated to a small bulk under reduced pressure the temperature not being allowed to rise above 30".After further evaporation over sulphuric acid in a vacuum desiccator, a pale brown syrup resulted and this was mixed with water and again evaporated the operation being repeated several times. The syrup remained as such for 7 weeks and then suddenly crystal-lised and the mass was drained on porous porcelain and crystallised from water from which it separated in colourless prisms (Found : C = 44.7; H = 4.5. C,H,06 requires C = 44.7; H = 4.3%). a y-Dialdehydopropane- PP-dicarboxylic acid melts a t 122" with decomposition and is readily soluble in water alcohol or acetone, sparingly so in ether and almost insoluble in petroleum benzene, chloroform or carbon tetrachloride.On titration 0,1562 neutra-lised 0.0665 NaOH whereas this amount of a dibasic acid C,H,O& should neutralise 0.0664 NaOH. A neutral solution of the ammon-ium salt gives with silver nitrate a white precipitate which rapidly darkens and silver is deposited. The di-p-nitrophenylhydrazone separated as a yellow crystalline precipitate when the aqueous solution of the acid (0.6 9.) was mixed with p-nitrophenylhydrazine (0.85 g.) dissolved in dilute acetic acid and separated from alcohol in glistening plates m. p. 156" (decomp.) (Found N = 18.2. C19H1808N6 requires N = 18.3%). The ethyl ester was obtained when ethyl diacetalmalonate (15 g.) was well shaken with N-hydrochloric acid (30 c.c.) and after remain-ing for 24 hours the whole was several times extracted with ether, the extract washed with sodium carbonate dried over potassium carbonate and distilled when the ester passed over a t 174-178"/18 rnm.The p-nitrophenylhydrazone prepared in dilute acetic acid solution crystallised from alcohol as a microcrystalline powder, m. p. 170" (Pound N = 16.2. C2,H,,O8N6 requires N = 16.3%). Reduction of ay-Dialdehydopropane-PP-dicarboxylic Acid.-The dibasic acid (4 g.) dissolved in water (75 c.c.) was mixed with sodium bicarbonate (15 g.) and treated with sodium amalgam (150 g. of 404,) in a flask fitted a-it5 a mechanical stirrer and cooled in ice the C,,H,,O requires C = 53.6; H = 8.3%. VOL. CXXVII. € 194 ay-DIALDEHYDOPROPANE- ~~-DICARBOXYLIC ACID ETC.reduction being complete in about 8 hours. The alkaline solution was acidified with dilute sulphuric acid (10 g.) in water (20 c.c.), concentrated on the steam-bath repeatedly extracted with chloro-form the extract dried over anhydrous magnesium sulphate and the chloroform allowed to evaporate. The colourless crystalline residue separated from water in plates m. p. 109-llO" and was evidently identical with bis- 7-butyrolactone-aor-spiran described by Leuchs and Gieseler (loc. cit.). Oxidation of ay-Dialdehydopropane- p p-dicarboxylic Acid.-The acid (5 g.) dissolved in water (20 c.c.) was mixed with potassium dichromate (5.2 g.) in sulphuric acid (6.9 g.) and water (75 c.c.) and allowed to stand for 12 hours during which the colour changed t o green.The product evaporated on the steam-bath to 50 c.c. was extracted with ether the extract dried over anhydrous magnesium sulphate and the ether allowed to evaporate over sulphuric acid. The oily residue remained for weeks without crystallising but did SO rapidly when a crystal of propane-appy-tetracarboxylic acid was introduced. After contact with porous porcelain the substance separated from ether in needles melted a t 151" with decomposition into carbon dioxide and tricarballylic acid and was thus identified with propane- @Py- tetracarboxylic acid. a y- Dialdehydopropane- p-carboxylic Acid .-This acid was obtained when ay-dialdehydopropane- pp-dicarboxylic acid (4 g . ) dissolved in water (16 c.c.) was heated in a sealed tube a t 180" for 4 hours. On opening the tube carbon dioxide escaped and the solution, evaporated in a vacuum over sulphuric acid deposited a syrup which even on long standing did not crystallise (Pound C = 49-5 ; H = 5.5. C6H804 requires C = 50.0; H = 5.5%). The di-p-nitrophenylhydraxone obtained by adding a solution of p-nitro-phenylhydrazine in dilute acetic acid to the aqueous solution of the acid and heating for an hour on the steam-bath is a yellow amor-phous powder sparingly soluble in the usual solvents. The substance could not be recrystallised and was pursed by extraction with hot alcohol and then with ether when the residue melted a t about 198" (decornp.) (Found N = 20.3. C,&,80$6 requires N = 21.3%). One of us (H. S. P.) desires to thank the Department of Scientific and Industrial Research for a maintenance grant and the Govern-ment Grant Committee of the Royal Society for a grant for materials. THE DYSON PERRINS LABORATORY, OXFORD. [Received November 12tl2 1924.