長鎖アルキルリン酸エステルの熱分解
1991 年 40 巻 12 号 p. 1095-1099
詳細
1991 年 40 巻 12 号 p. 1095-1099
Assessment was made of the thermal stability of long-chain alkyl phosphate by thermal analysis (TG/DTA/DSC). Several monoalkyl phosphates (Cn-MAP) differing in chain length (C12, C14, C16) showed essentially the same thermal stability. The decomposition temperature of didodecyl phosphate (C12-DAP) was 257.8°C [40-50°C higher than that of monododecyl phosphate (C12-MAP)]. C12-MAP·2 Na salt was thermally more stable than C12-MAP, but C12-MAP·Na salt was less stable than this.
Gas chromatographic analysis of the decomposition gas indicated dodecene to be mainly formed from C12-MAP, whereas 1-dodecanol from C12-MAP·Na salt and C12-MAP·2 Na salt.
31P-NMR analysis of C12-MAP decomposition mixtures revealed that the disproportionation of C12-MAP to phosphoric acid (PA) and C12-DAP and condensed phosphate formation fromC12-MAP were competetive with the elimination of olefin from C12-MAP.
The elimination of olefins from monoalkyl pyrophosphate [Py- (1.0)] and dialkyl pyrophosphate [Py- (1, 1)] besides from C12-MAP thus must be taken into consideration for assessement of the thermostability of long-chain alkyl phoshates. The formation of [PA+ Py- (0, 0)] from [MAP+DAP +Py- (1, 0) +Py- (1, 1)] appears to be a zero order reaction with an activation energy of 26.2kcal/mol.
