水溶液中におけるモノアセトアセチンの加水分解反応に及ぼすpHと温度の影響

概要

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The kinetics of hydrolysis of monoacetoacetin (MAA ; 1,2-dihydroxy-3-acetoacetyloxypropane) in 300 mM phosphate buffer was studied by means of high performance liquid chromatography. MAA was hydrolyzed to glycerin (Glyc) and acetoacetate (AA), the latter of which furthermore decomposed to acetone (Acet) and CO_2 at high temperature. The rate constant, k_1,for the reaction of MAA→AA+Glyc increased with increases in temperature and pH. On the other hand, another one, k_2,for the reaction of AA→Acet+CO_2 increased with an increase in temperature but showed a minimum around pH 7.5 when pH was changed at a given temperature. The activation energy for k_1 was almost constant in the range of studied pHs (5-8) but the pre-exponential factor, k_<1,0>, increased with an increase in pH. It was concluded that the decomposition reaction of MAA is consecutive in a sequence of MAA→AA→Acet. Calculated concentrations of MAA, AA, and Acet through the obtained k_1 and k_2 together with a given initial concentration of MAA(=40mM) were compared with those experimentally observed on the time course of the hydrolysis. They were in good agreement with each other.
公益社団法人日本薬学会の論文
1992-09-25