Surfactant Research Chair, Department of Chemistry, College of Science, King Saud University, Riyadh, Saudi Arabia.
J Colloid Interface Sci. 2011 Sep 1;361(1):205-11. doi: 10.1016/j.jcis.2011.05.005. Epub 2011 May 19.
The alkaline hydrolysis of carsalam (2H-1,3-benzoxazine-2,4(3H)-dione), denoted as I, and its N-substituted derivatives i.e., N-methyl-1,3-benzoxazine-2,4-dione (II) and N-benzoyl-1,3-benzoxazine-2,4-dione (III) was studied spectrophotometrically at physiological temperature. The rate of hydrolysis was found to be independent on the substrate concentration. In case of I, the reaction was fractional order with respect to [OH(-)] while for II and III, reaction obeyed the first order kinetics. Effect of cationic surfactants with varying hydrophobic chains (cetyltrimethylammonium bromide, CTAB, tetradecyltrimethylammonium bromide, TTAB and dodecyltrimethylammonium bromide, DTAB) and with different head-group (cetyl pyridinium chloride, CPC) and anionic surfactant (sodium dodecyl sulfate, SDS) was also seen on the rate of alkaline hydrolysis of the carsalam and its derivatives. Cationic surfactants first catalyzed the rate of hydrolysis at lower concentrations followed by the inhibition at higher concentrations. The length of the alkyl chain had remarkable effect on the catalytic efficiency of the surfactants. Similarly N-substitution on substrate also increased the catalysis by micelles. The anionic surfactant SDS inhibited the rate of hydrolysis at all of the concentrations studied. The catalysis by cationic micelles followed by inhibition was treated in terms of the pseudophase ion-exchange model, while for the inhibition by SDS micelles the Menger-Portnoy model was used to fit the data. The effect of salts (NaCl, NaBr and (CH(3))(4)NBr) was also seen on the hydrolysis of II and it was found that all salts inhibited the rate of reaction. The inhibition follows the trend NaCl<NaBr<(CH(3))(4)NBr.
在生理温度下，对 carsalam（2H-1,3-苯并恶嗪-2,4(3H)-二酮）及其 N-取代衍生物，即 N-甲基-1,3-苯并恶嗪-2,4-二酮（II）和 N-苯甲酰-1,3-苯并恶嗪-2,4-二酮（III）的碱性水解进行了光谱研究。水解速率被发现与底物浓度无关。对于 I，反应是关于[OH(-)]的分数阶，而对于 II 和 III，反应遵循一级动力学。具有不同疏水链（十六烷基三甲基溴化铵，CTAB、十四烷基三甲基溴化铵、TTAB 和十二烷基三甲基溴化铵、DTAB）和不同头基（十六烷基吡啶氯化物、CPC）的阳离子表面活性剂以及阴离子表面活性剂（十二烷基硫酸钠、SDS）对 carsalam 及其衍生物的碱性水解速率也有影响。阳离子表面活性剂在较低浓度下首先催化水解速率，然后在较高浓度下抑制水解速率。烷基链的长度对表面活性剂的催化效率有显著影响。同样，底物上的 N-取代也增加了胶束的催化作用。阴离子表面活性剂 SDS 在所有研究的浓度下都抑制了水解速率。阳离子胶束的催化作用随后是抑制作用，用假相离子交换模型进行处理，而对于 SDS 胶束的抑制作用，用 Menger-Portnoy 模型来拟合数据。盐（NaCl、NaBr 和(CH(3))(4)NBr）对 II 的水解也有影响，发现所有盐都抑制了反应速率。抑制作用遵循 NaCl<NaBr<(CH(3))(4)NBr 的趋势。
