2322
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Receiried July 19, 1920,
In connection with the preparation of the optically-active (2,-sacchari n k acids undestakeni in this laboratory i t was found that success depended in each case on the ability to resolve the dl-acid into the components by means of optkally-active alkaloids. Such separations a.re usually very tedious, require many recrystallizations, and sonirretin~sleave one in doubt as to whetber a complete separation has actualty been effected. It has seemed highly desirable, therefcore t o make mzva.ilable other reagents .than the alkaloids for such work. ~ ~ ~ e n y l h y d r a zis i nkriowri e to form with many oxy acids easily crystdliza5le compounds, the phenylhydrazi Some of the homologs s ~ c has ,lolyl-bydrazine form at times even more easily crysltallizable comyourzds. It was thought, therefore, that an optically-active p ~ e ~ y l ~ y (might ~~az~~e be a possible substitute for t,he alkaloids when the latter do not give good results or when t.here is any doxiht as to the compXet.eness of the resohitions. A search in the literature of optically-active hydrazines dkchsed tbc fact that only 3 such c~mpo~iiids have been prepared, namely, d-a-optically-active amyl-phenylhydrazine;z 2- ar-ethyl-nnenthy!hyd~a~~ne,and l-rnenthylhydrazine.4 The few known derivatives of these substances indicated that they might be very helpful in work with the oxyacids. None of the. hydrazines mentioned aibove was available, however, an.d it was decided to attempt the preparation sf a number of racemic phenylhydrazines, and the resolution sf these itito active isomers in the hope that in this work some fairly easily-prepared active hydrazine would be dis.. corered which could be used as a reagent in the separation of the saceharinic acids to supplement the alkaloids. The present paper is the report of ail. aktempt t o prepare the first. pair. of these hydrazines decided upon, namely, the active trimethylethyl plienylhydrazines. The hydrazine in its dl form was prepared, but alii The dissertation of which this paper is a condensation was presented by C. 9. Miliigau as part fulfihen-t oi the requirements for the degree of Doctor of Philosophy in the University of Chicago. The original dissertation is on file in the Ilniversity library. 2 Der., 38, 867 (rgog). J. Xzrss. Plzys. Chenz. Soc., 27, 534 (1896). 1.prakt. Chem., 11, p1425 (1895).
PR@PARATION Ol? OP’1’ICALI,l’ ACTIVE HYDRAZINES.
2323
attempts t o resolve i t into the components failed, due largely, we think, t o the instability of the free hydrazine in the air under ordinary conditions. The instability of the dl form suggested that the active components would also be very unstable and thus be useless as reagents. On the other hand, some of the derivatives of the dl form (see below) are perfectly stable compounds, and it was thought possible that the derivatives of the active forms would also be stable. We therefore decided to proceed with attempts to obtain the active forms. After much experimentation one of the amines, d-p-trimethylethyl-aniline, was obtained in the pure condition. It was intended t o prepare from this the corresponding active phenylhydrazine by diazotization and reduction but time was lacking t o complete this. This work will be continued, however, as soon as opportunity offers and attempts will b e made to prepare other active phenylhydrazines.
Experimental Part. This paper is a report on the preparation of dl-p-trimethylethyl-phenylhydrazine. H H E1 XI IISC
l I
i ‘
- c - c - (-->-N
l
l
- N - E1
CH3 CHI
I n order to prepare this substance, i t was necessary first to prepare, in turn, the following corresponding compounds : ( I )triniethylphenyl-ethylene ; (2) trimethylethyl-benzene; (3) ;o-.trimethylethfrl-~~lr~~~enzene; (4)~trimethylethyl-aniline. Only the second of these compounds is mentioned in the literature, under the name of seco~dary-amyl-benzene.l It seems probable in the light of our experiments, however, that the compound there discussed was tortzary
