Action of Iodine on Ethyl Methylcyanoacetate.

In the action of iodine on the sodium compound, as in the action of bromine on ethyl sodiocyanacetate, there appears to be no tendency for any secondary product to be formed. On adding an ethereal solution of iodine to the finely divided sodium compound suspended in dry ether, rapid decolorisation ensues, and on extracting the product in the usual way, it was found to consist of a heavy oil, decomposing on distillation under diminished pressure. On analysis:

CH2ONI requires I=50·19 per cent.

No trace of ethyl dimethyldicyanosuccinate could be detected in this product.

The iodo-compound slowly deposits iodine on exposure to sunlight.

Condensation of Ethyl BB-Dimethylacrylate with Ethyl Sodiomethylcyanacetate.

This condensation was carried out with the object of determining whether ethyl sodiomethylcyanacetate condensed with unsaturated ethyl esters in the same manner as ethyl sodiocyanacetate, which, as already stated, yielded a product consisting largely of an ethyl hydrogen salt.

Twenty-three grams of sodium dissolved in alcohol were mixed with 127 grams of ethyl methylcyanacetate and 128 grams of ethyl dimethylacrylate, the whole being heated on the water-bath for 24 hours. On distilling off the excess of alcohol, adding water, extracting with ether, &c., only unchanged products were obtained on evaporation and fractionation.

On acidifying the mother liquor, an oil separated which, after extraction, was distilled three times under the ordinary pressure, during which process it evolved carbon dioxide and was converted into a mobile oil boiling constantly at 224°. On analysis, numbers were obtained corresponding with those required for ethyl y-cyano-ẞß-dimethylbutyrate, CN CH2 C(CH3)2°CH(CH ̧)·CO2Et.

0.1638 gave 0.3930 CO2 and 0.1374 H2O. C-65.48; H=9.31. C10H17ON requires C=65.57; H=9.29 per cent.

On hydrolysing this oil with 50 per cent. sulphuric acid, a process requiring from 6-7 hours, and extracting the product, a solid acid was obtained which, after recrystallisation from water, melted at 87°, and was in every respect identical with aßß-trimethylglutaric acid, CO2H.CH(CH)•C(CH3)2°CH2•CO2H. The yield of this compound is

only 5 per cent. of that theoretically possible. It is interesting to note, however, that the reaction in this case proceeds in the same way as the corresponding reaction in the case of ethyl cyanacetate. In the present instance, however, no traces of the diethyl ester could be detected.

Formation of cis- and trans-aa,ßß-Tetramethylglutaric Acids. Ethyl a-Cyano-aa BB-tetramethylglutarate,

CH, C(CO2Et)(CN)·C(CH3)2°CH(CH) CO2Et,

is formed to the extent of 17 per cent. of the theoretical yield in the following way. Sodium (dissolved in alcohol) and ethyl methcyanacetate, in molecular proportion, were mixed with an equivalent quantity of ethyl dimethylacrylate, and heated on the water-bath for 24 hours; excess of methyl iodide was then added, and the heating continued for a further 6 hours. On isolating the product in the usual way, it was found to consist of an oil which distilled at 174-176° under 30 mm. pressure. On analysis:

0.1778 gave 0.4062 CO, and 0·1356 H2O. C=62·32; H=8·47. CHON requires C=62.45; H=8.55 per cent.

141

23

aa'ßß-Tetramethylglutarimide, (CH),C<CH(CH) CONH.
CH(CH,)•CO

Ethyl a-cyano-aa,ßß-tetramethylglutarate was first heated on the water-bath for 2 hours with an equal weight of potassium hydroxide, dissolved in methyl alcohol, evaporated several times with water to dryness, and extracted with ether, the oily product being further heated with concentrated hydrochloric acid for one hour.

During this process, vigorous evolution of carbon dioxide occurred, and after extracting with ether and shaking out the ethereal solution three times with dilute sodium carbonate solution, the ether, on evaporation, left a solid residue, which crystallised from water in long, white needles melting at 108°. On analysis:

0.1570 gave 10.9 c.c. nitrogen at 15° and 769 mm. N = 8.34. CHO,N requires N = 8.28 per cent.

15

The silver salt, prepared by adding a solution of silver nitrate in water to an aqueous solution of the imide to which a few drops of ammonia had been added, is a white, crystalline substance.

0.1114

gave 0.0434 Ag. Ag=38.91.

CH1NO,Ag requires Ag = 38.95 per cent.

This acid is obtained by boiling the imide for 2 hours with 50 per cent. sulphuric acid. In this process, a small quantity of the cis-acid is converted into the trans-isomeride, but the change is not sufficient to prevent the cis-acid from being isolated in a pure form by recrystallisation from water, from which it separates in white plates melting at 140°. On analysis:

0-2171 gave 0.4558 CO2 and 0.1692 H2O. C=57.25; H=8.65. CH1604 requires C-57.44; H=8.51 per cent.

The silver salt is a white, amorphous precipitate.

0.1673 gave 0.0894 Ag. Ag= 53.44.

CH140,Ag2 requires Ag=53.50 per cent.

aa BB-Tetramethylglutaric Anhydride, C,H140, is formed by boiling the cis-acid with acetyl chloride for 2 hours. It is an oil which does not appear to exist at the ordinary temperature in a crystalline condition; it boils at 155-158° under 30 mm. pressure. On analysis:

0.1957 gave 0 4569 CO2 and 0·1412 H2O. C-63.57; H=8.01. CHO requires C=63·53; H=8.23 per cent.

14 3

When boiled with water, the anhydride gradually dissolves, and, on cooling, the cis-acid, melting at 140°, separates from the solution.

trans-aa'ßß-Tetramethylglutaric Acid, CO,H•CH(CH,)•C(CH,),•CH(CHg) CO,H.

The trans-acid is obtained from the sodium carbonate extracts of the ethereal solution (p. 940) by acidifying, saturating with ammonium sulphate, and extracting with ether. It crystallises from hydrochloric acid in needles, and melts at 98°.

2

0.1952 gave 0.4105 CO2 and 0.1514 H2O. C-57-35; H=8.61. CH1604 requires C=57·44; H=8.51 per cent.

The trans-acid does not yield an anhydride when treated with acetyl chloride, and is recovered unchanged on evaporating the solution. The silver salt is an amorphous powder.

0-1692 gave 0.0910 Ag. Ag=53.42.

CHO,Ag2 requires Ag=53.50 per cent.

14

The trans-acid, mixed with cis-isomeride, can also be obtained on

hydrolysing the imide with hydrochloric acid in a sealed tube for 6 hours at 180°.

The trans-acid is converted into the cis-isomeride by heating with acetic anhydride in a sealed tube for 5 hours at 150°; on removing the acetic anhydride by evaporation and boiling the residue with water, the cis-acid separates on cooling.

cis- and trans-Tetramethylglutaric acids are therefore quite normal in their behaviour. The fact that the trans-acid melted at a lower temperature than the cis-isomeride seemed to point to the possibility of the former being a mixture of the two, corresponding to the aa1-dimethylglutaric acid, melting at 103°, which was long thought to be the transform, but was subsequently shown to be a mixture of the stereoisomerides. We have seen no reason to doubt the homogeneous character of the acid melting at 98°, however, and all attempts to detect the presence of any cis-acid in it have been unsuccessful.

THE OWENS COLLEGE,

MANCHESTer.

LXXXIII.—B-Isopropylglutaric Acid and cis- and transMethylisopropylglutaric Acids.

By F. H. HOWLES, JOCELYN F. THORPE, and WILLIAM UDALL. ETHYL a-BROMISOBUTYLACETATE is best prepared in the following manner. Isobutylacetic acid, obtained by treating ethyl sodiomalonate with isobutyl bromide, hydrolysing the product after fractionation with ethyl alcoholic potash, and distilling the tribasic acid obtained, is brominated by the Volhard method with phosphorus pentabromide and bromine, and the product poured into absolute alcohol.

The bromo-ester separates as a heavy, yellow oil on pouring the alcoholic solution into water and extracting with ether.

Ethyl B-Isopropylacrylate.

Fifty grams of the bromo-ester without further purification are mixed with 75 grams diethylaniline and boiled on the sand-bath for 9 hours; the solid mass is then treated with hydrochloric acid (1:1) and shaken out with ether, the ethereal solution being washed repeatedly with hydrochloric acid until the last traces of diethylaniline have been washed out; the unsaturated ethyl salt obtained on distilling off the ether boils at 174° under 757 mm. pressure.

I. Condensation of Ethyl B-Isopropylacrylate with Ethyl Sodiocyanacetate.

Ethyl cyanacetate (19.9 grams) was added to an alcoholic solution of sodium (4 grams) and, after the addition of ethyl ẞ-isopropylacrylate (25 grams), the mixture was heated on the water-bath for 10 hours. On adding the unsaturated ethyl ester, considerable heat was evolved. The product, which consisted of a dark coloured gelatinous solid, was mixed with water and extracted with ether, the ethereal solution giving an oil on evaporation which, on distillation under 30 mm. pressure, gave 13 grams of an oil boiling at 195°; this proved to be ethyl a-cyano-ẞ-isopropylglutarate, CO2Et-CH(CN) CHPr®-CH2 CO,Et. On analysis:

0-2215 gave 0.4989 CO2 and 0.1618 H2O. C-6143; H=8.12. CH21ON requires C=61·17; H=8.23 per cent.

13

On acidifying the mother liquor, a quantity of oil separated, which after extraction was found to weigh 10 grams. On distillation under ordinary pressure, a vigorous evolution of gas ensued, the liquid after three distillations passing over as a mobile oil boiling at 234° under 755 mm. pressure and consisting of ethyl y-cyano-ẞ-isopropylbutyrate, CN CH2 CHPrs·CH2 CO2Et.

0.2113 gave 0.5060 CO, and 0.1731 H2O. C=65·31; H=9·10. C10H17ON requires C=65.57; H= 9.29.

Another experiment, in which the time of heating was only 3 hours instead of twelve, the same quantities being used, yielded only a trace of diethyl ester, but 30 grams of ethyl hydrogen salt.

Hydrolysis of the Diethyl Ester.

On adding an equal weight of potash dissolved in methyl alcohol to the ester, a large quantity of a crystalline potassium salt separated; this was filtered off, washed with methyl alcohol, dissolved in water, and the solution boiled until the last traces of methyl alcohol had been removed. The solution on acidifying, saturating with ammonium sulphate, and extracting with ether, yielded a liquid substance which when boiled for 10 minutes with concentrated hydrochloric acid evolved large quantities of carbon dioxide, and on cooling deposited crystals of B-isopropylglutarimide, CHPr<CH2CONH,

CH2∙CO

2

separating from hot water in glistening plates melting at 120°.

0.3036

gave 24.2 c.c. nitrogen at 20° and 756 mm.

CHON requires N = 9.07 per cent.

N=9.03.

this