Azocarboxylic esters useful as polymerisation initiators, especially for polymerisation in aqueous medium, have the general formula
in which R is the residue of an aliphatic polyhydroxy compound R(OH)q+1 after removal of one hydroxyl group therefrom, R, is a methyl or ethyl group or a grouping of the formula -COO(CnH2nO)p-R(OH)q; R2 is a methyl group or a βcarboxyethoxy group and R3 is a methyl group or an ethyl group, or R2 and R3 together with the intermediate carbon atom form a cyclohexyl group: R4 is a methyl group and R6 is a methyl group, an ethyl group, a β-carboxyethoxy group or a β-methoxy-ββ-dimethylethyl group, or R. and R5 together with the intermediate carbon atom form a cyclohexyl group n has one or more of the values 2. 3 and 4. p is zero or an integer from 1 to 100, preferably from 1 to 50, and q has the value 2 or 4. The esters can be prepared by reacting a corresponding azonitrile or azobisnitrile with a stoichiometrically equivalent amount of an aceral or ketal of the formula
wherein R6 is hydrogen or an alkyl or aryl group and R7 is an alkyl or artl group, or R6 and R7 together with the intermediate carbon atom form a cyclohexyl group, in the presence of hydrogen chloride gas under anhydrous conditiond, followed by hydrolysis of the product.
可用作聚合
引发剂,特别是用于
水介质聚合的偶氮
羧酸酯通式如下
其中 R 是去掉一个羟基后的脂肪族多羟基化合物 R(OH)q+1 的残余物,R 是甲基或乙基或式 -COO(CnH2nO)p-R(OH)q 的基团;R2 是甲基或 β羧基乙氧基,R3 是甲基或乙基,或 R2 和 R3 与中间碳原子一起形成环己基:R4 是甲基,R6 是甲基、乙基、β-羧基乙氧基或 β-甲氧基-β-二甲基乙基,或 R 和 R5 与中间碳原子一起形成环己基 n 具有 2、3 和 4 中的一个或多个值。p 为零或 1 至 100 的整数,最好为 1 至 50,q 的值为 2 或 4。这些
酯类可通过相应的偶氮腈或偶氮二腈与等量的式中的
乙醛或酮反应来制备
其中 R6 是氢或烷基或芳基,R7 是烷基或芳基,或 R6 和 R7 与中间碳原子一起形成环己基,在无
水条件下,在
氯化氢气体存在下反应,然后
水解产物。