αγ (Alpha Gamma) dibenzyl-glutaconic acid

Abstract

The glutaconic acids constitute a group of unsaturated dibasic acids in which geometrical isomerism coexists with that of tautomeric mobility; the latter reaches its maximum in glutaconic acid itself where the three carbon system is activated by two terminal keto-enol systems so the whole is really a heptad system. [diagram] In glutaconic acid the mobility is such that the only one form of the acid, the trans, is stable, although the cis form has been obtained by careful hydration of the anhydride, (Malanchowaki, Ber. 1929, 623, 1323). Introduction of electron releasing groups in the α, and/or β, and/or γ reduces this mobility so that in some cases most of the theoretically possible forms have been isolated. Modern theory demands that unsymmetrically substituted glutaconic acids should exist in six firms, cis Δαβ, trans Δαβ, d-and 1-trans Δ βγ and d- and 1- cisΔβγ due to structural and geometrical and optical isomerism. The optical active forms have not been isolated. However, in symmetrically substituted acids the theoretically possible number of forms is four d- and 1- cis and d- and 1- trans, these being due to geometrical and optical isomerism; no structural isomerism resulting from the position of the double bond occurs.