The Reactions of Ald-Chlorimines With Grignard Reagents

Abstract

In connection with a study of the reactions of compounds of the type RCH=NX (where X is halogen, acetate, etc.) with bases1, it seemed of interest to investigate the reactions of these compounds with Grignard reagents. The results obtained with ald-chlorimines and certain Grignard reagents are reported in this paper.The characteristic group of ald-chlorimines, (-CH=NC1), should be capable of undergoing at least three different types of reaction, involving, (1) the elimination of hydrogen chloride, (2) a reaction in which the nitrogen-chlorine group is attacked (as in hydrolysis), or (3) addition to the carbon-nitrogen double bond. A previous study10 has shown that in the presence of certain bases, such as alcoholic alkali, only the first reaction occurs to an appreciable extent, giving in certain cases practically quantitative yields of nitrile. The present investigation shows that in the presence of Grignard reagents, the first two types of reaction occur, the second predominating; apparently, addition to the carbon-nitrogen double bond (third type) does not take place to an appreciable extent with these reagents.The reactions of ald-chlorimines with Grignard reagents has been carried out by slowly adding the latter to the chlorimine in ether solution. In this way secondary reactions of the Grignards with the products (e. g., nitriles) was minimized. The products obtained from the reactions of aldchlorimines with ethyl-, phenyl-, or p-chlorophenylmagnesium bromide may be accounted for by equations (I) and (II). In I, the Grignard reagent removes hydrogen chloride from the ald-chlorimine to form a nitrile and R'H, while in II, the Grignard reagent is chlorinated, giving R'Cl and a nitrogen-magnesium compound.

The Chemistry of Imines.

“…The slow addition of Grignards to N-chloroimines in ether gives the nitrile in 20% and the imine in 50% yield (162). R,C=NC1 + R'MgX -> RCN + R2C=NR' + RC1 + MgX, D. DEHYDROGENATION OF AMINES Ritter (231) was the first to dehydrogenate amines to give imines.…”

Imines

“…The chlorine group of iV-chloroimines [21] and C-chloro-7V-benzylideneanilines [22] react with Grignard reagents in fair to good yields to give the corresponding imines as described in Eqs. (11) and (12).…”