头孢菌素结构和其聚合反应关系的探讨——Ⅱ.结构对反应速度的影响

STUDIES ON RELATIONSHIP BETWEEN STRUCTURE OF CEPHALOSPORINS AND ITS POLYMERIZATION II. RELATIONSHIP BETWEEN STRUCTURE OF CEPHALOSPORINS AND RATE OF POLYMERIZATION

通过对不同3位取代基和不同7位取代基的头孢菌素在水溶液中聚合反应速度的比较,发现3位、7位取代基的结构对头孢菌素N型聚合反应速度均有影响。7位取代基的吸电子效应越强,聚合反应速度越快;当3位取代基的吸电子效应不太强时,增大取代基的吸电子效应,聚合反应速度加快;但取代基的吸电子效应超过某一界限,再增大取代基的吸电子效应,聚合反应速度减慢。据此,对头孢菌素N型聚合反应的机制进行了讨论。

Comparing the rate of polymerization of Cephalosporins with a different structure at C3 or(and) C7 substituent, it is found out that both C3 and C7 substituent could influence the rat of the polymerizacion of type N. The more 7-substituent attracts electrons strongly, the easier the polymerization goes on. However, the inductive effect of 3-substituent influencing the polymerization has a limit, below which raising the effect of attracting electrons of 3-substituent increases the polymerization and above which decreases the reaction. According to the facts, the mechanism of the polymerization of type N was discussed.