Reactions of the stearoylated enolic form of acetone, involving hexadecylketene as the reactive intermediate

Abstract

Enol esters, such as isopropenyl stearate, are useful intermediates capable of forming interesting derivatives of saturated aliphatic fatty acids. Under given conditions, whereas methyl stearate remains unreactive up to 400C, by contrast the isopropenyl stearate ester efficiently liberates hexadecylketene at 170C with the simultaneous expulsion of “isopropenyl alcohol,” i.e., acetone. In the presence of even difficulty acylatable OH or NH compounds the liberated aldoketene combines, usually quantitatively, with these hydrogen-bearing compounds to form esters or imides. In this manner such resistant materials as barbituric acids, hydantoins, N-butylstearamide, acetanilide, t-butyl alcohol, and succinimide may be converted to stearoylated derivatives.

In the absence of reactable substrate and with strong dependence on the nature of the reaction medium, liberated hexadecylketene tetramerizes to derivatives ofgamma pyrone, or forms stearone, or stearoylates the enolic rearrangement product, heneicosane-2,4-dione. The latter compound, in forming, has increased the 18 carbon chain-length to 21 continuous carbon atoms. Di-isopropenyl esters with polyfunctional acetylatable materials, such as bis-N-alkylazelaamide or sucrose, give rise to unusual linear polyimides, three-dimensional network polymers, or oligomers.