溴化十六烷基三甲基铵对青霉素G钠盐碱水解反应速率的影响

Affect of Cetyltrimethylammonium Bromide on Basic Hydrolisis Rate of Penicilloics G Sodium Salt

用紫外分光光度法测定不同浓度的溴化十六烷基三甲基胺（简称ＣＴＡＢ）对青霉素Ｇ钠盐（简称ＰＧＳ）碱水解速率常数研究发现：当ＣＴＡＢ浓度小于２．２５０×１０－３ｍｏｌ·ｄｍ－３时，随着ＣＴＡＢ浓度的增大ＰＧＳ碱水解速率减小；当ＣＴＡＢ浓度在２．２５０×１０－３～３．７５０×１０－３ｍｏｌ·ｄｍ－３之间，随着ＣＴＡＢ加入量增加，其反应速率又增大；在实验曲线后段又出现下降。从理论上对上述现象给予解释。

The basic hydrolisis rate of penicilloics G sodium salt (PGS) with cetyetrimethylammonium bromide (CTAB) was determined ty UV spectrometry. It was found that ①when the concentration of CTAB is smaller than 2.25×10 -3 mol·dm -3 , which was much higher than the critical micelle concentration(CMC), the rate constants of basic hydrolysis of PGS decreased with the increase of the concentration of CTAB, being attributed to intermediating of micelles of CTAB; ②when concetration of CTAB was from 2.250×10 -3 to 3.75×10 -3 mol·dm -3 , the rate constant increased with increase of the concetration of CTAB, indicating proximity effect caused by electrostatic and hydrophobic interaction between the reactants and micelles; ③Because the shape of micelles changed, the rate constants were decreased again.