ROLANDKAPPAND ALEXANDERKNOLL
2062 of racemic a-ionone.
There was a distinct difference in odor between the d- and the 1-form. Experimental
The dl-a-ionone used had been purified by repeated recrystallization of its semicarbazone until the refractive index n 2 3 =~ 1.4995.8 Preparation of d- and I-a-Ionone-I-menthydrazones.Fifty-seven and six-tenths g. (0.3 mole) of dl-a-ionone was dissolved together with 64.2 g. (0.3 mole) of I-menthydrazide of [ a I r s-70.7" ~ in 240 cc. of 95% ethanol, containing 2% of sodium acetate and 1% of acetic acid. After refluxing for two and one-half hours, 113 g. of a mixture of the diastereomers crystallized on cooling. The specific rotation of the mixture wasahout -20'. its m. p. 163-65". Repeated fractional recrystallizations led to a product of / a ] " D -320" (in EtOH), m. p. 185", and a more soluble fraction of [ a ] ' * D +230" (in EtOH), in. p. 17F" (calcd. for C~aHdoOzNz: N, 7.21. Found: N, 7.3i). Preparation of p-Ionone-I-menthydrazone.-The Zmenthydrazone of ,!?-iononewas prepared for comparison from a sample of &ionone of n z P1.5183. ~ The specific rotation of the recrystallized product was -35", m. p. 178". As this value represents the contribution of the I-menthydrazone moiety to the specific rotation, a 1.1 mixture of d- and I-a-ionone-Z-menthydrazone should approximate this value. Hence, the value of +230° for the dextrorotatory diastereomer is presumably ca. 20" too low in comparison with -320" €or the levorotatory form. The higher purity of the 2-compound accounts for the higher numerical value of the specific rotation for the resulting free I-a-ionone as compared with the d-enantiomer (see below). -
_-
( 8 ) We are greatly indebted to Dr. Ernest Theimer, Director of Kesearch, Van Ameringen-Haebler Iac., Elizabeth, N. J., for supply ing us with highly purified a-ionone and ,9-ionone.
[CONTRI3UTION FROM THE
Vol. 65
Hydroly& of Menthydrazonee.-2.0 g. of purest l-aionone-l-menthydrazone was suspended with 4.5 g. of phthalic anhydride in 35 cc. of water and subjected to steam distillation for two and one-half hours. The distillate was thoroughly extracted with ether and 0.6 g. of an oil was obtained. Its ( a ] * ' D showed the high value of -406', its refractive index was nl"D 1.5000. By the same procedure a dextrorotatory a-ionone was obtained from d-a-ionone-l-menthydramne; its specific rotation [ a I z a ~ was +347", its n**D1.5021. 2,4-Dinitrophenylhydrazones and p-Chlwobenzoylhydrazones of l- and d-donone.-Both optically active a-ionones were characterized by the preparation of the two derivatives. Their melting points are summarized below; N of dinitrophenylhydrazones of d-and I-a-ionone; Found: 15.3 and 15.2; calcd. 15.1. TABLE I Melting points, 'C., of. . . . . . . . . . . . I-a-Ionone d-a-Ionotie dl-a-Ionone 2,4-Dinitrophenyl133 129 113 hydrazone p-Chlorobenzoylhydrazone 200-201 196-198 '214
.
Summary The resolution of dl-a-ionone was accomplished by means of 1-menthydrazone. The use of optically active a-ionone as an indicator for the stability of the double bond system in ionone and its derivatives is discussed. NEW YORK, N. Y. RECEIVED JULY 6, 1943
DEPARTWENT OF CHEMISTRY,
COLUMBIA UNIVERSITY]
Synthesis of 16,17- and 17,18-Octadecenoic Acids'#* BY
ROLANDKAPp3 AND ALEXANDER KNOLL4
illthough several isomeric octadecenoic acids are known, the group is incomplete. The following reports the synthesis of two new members of this important group, and in addition two new keto-octadecenoic acids. Three methods have been used in the preparation of long chain monoetherloid acids: the malonic ester synthesis, the Grignard synthesis and the acetoacetic ester synthesis. The syntheses of the 16,17- and 17,18-octadecenoic acids were achieved by preparing the unsaturated keto acids by means of the acetoacetic ester method, followed by reduction of the keto acids by meails of the Wolff-Kishner method to the respective olefinic acids. The 17,IS-octadecenoic acid was synthesized by the following procedure : 10,lI-undecenoyl chloride was condensed with sodio-diethyl-acetyl stiberate, whereupon a-acetyl-a-10,ll-undecenoyl -di(1) From a dissertation submitted by K. Kapp to the Faculty of Pure Science, Columbia University, N.Y.C., in partial fulfillment of the requirements for the degree of Doctor of Philosophy (2) The authors are deeply indebted to Professor J h.1 Nelson Columbia University. for his encouragement and advice. (2) Address: National Oil Products Co., Harrison, N.J (4) Address: Metals Disintegrating Co , Elizabeth. N. J
ethyl suberate was formed. G. M. Robinson and I
