ホモクロルサイクリジンの水溶液中における分解の動力学的研究

概要

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When aqueous acid solution of Homochlorcyclizine dihydrochloride (HCC・2HCl) is heated, it turns turbid and further gives rise to an oily deposit. This deposit proved to consist of p-chlorobenzhydrol, p-chlorobenzhydryl chloride, and p-chlorobenzophenone. In the water phase, besides intact HCC・2HCl, N-methylhomopiperazine was found as a water-soluble moiety of decomposition products. The degradation shows first-order type process. In the aqueous solution of HCC・2HCl there is a following equilibrium : [chemical formula] where HCC^+ and HCC^<2+> represent uni- and bivalent HCC ions, respectively. The apparent rate constant k of the degradation of HCC・2HCl varies with the mole fraction F of HCC^<2+> according to k=k'F, where k' is therate constant of the decomposition of HCC^<2+>. This indicates that of the two ionic species of HCC, only HCC^<2+> is susceptible to the decomposition, which starts with the cleavage of the bond between p-chlorobenzhydryl group and nitrogen atom. Finally, the activation energy and the frequency factor of the decomposition of HCC^<2+> were calculated and the equation, expressing k as a function of pH and absolute temperature T, was presented : [numerical formula] where pK is negative common logarithm of the equilibrium constant K for the equilibrium (1) at T°K and R is gas constant.
公益社団法人日本薬学会の論文
1968-03-25