γ-Radiolysis of Stearic Acid: Studies of Nongaseous Products

A number of products of ^{60}{\rm Co}\text{-}\gamma \text{-radiolysis}$ of crystalline stearic acid have been identified and quantitated by gas-liquid chromatography. n-Heptadecane, the major (decarboxylation) hydrocarbon product (G ca. 2.5 at 100 Mrads; G0 3.6), is accompanied by n-hexadecane (G 0.033) and the ${\rm C}_{34}$ n-tetratriacontane (G 0.060) in amounts necessitating consideration of the formation of the C16 via α,β-bond fission, and of the ${\rm C}_{34}$ hydrocarbon from geminate pairs of heptadecyl radicals produced by double decarboxylation of the H-bonded stearic acid "dimers" of which the crystalline acid consists. Di-n-heptadecyl ketone (G 0.47), a product exceeded in quantitative importance only by those of dehydrogenation and decarboxylation reactions, is apparently formed by closely analogous, simultaneous formation of two radicals from such "dimers." The G-yield of stearaldehyde ($G\cong G_{0}$ 0.32) passes through a maximum ($G_{{\rm max}}$ 0.7) at about 12 Mrads; that of heptadecane shows complementary variation, suggesting possible common origin of the aldehyde and part of the hydrocarbon. α-Linked dehydrodimers (approximately equal amounts of the two possible diastereoisomers) are obtained in quantity (G 0.18) far less than stoichiometrically equivalent to heptadecane plus stearaldehyde, indicating extensive annihilation of α-radicals during irradiation, possibly via hydrogen atom or electron capture. Dehydrodimers linked elsewhere (than in the α position) are also present, but in still smaller quantity (G 0.025).