2-亚甲基-1,3-二氧己烷衍生物的合成及自由基开环聚合

本文报道了四种2-亚甲基-1,3-二氧己烷类单体:4-甲基-2-亚甲基-1,3-二氧己烷(Ⅱ)、4,6-二甲基-2-亚甲基-1,3-二氧己烷(Ⅳ)、5,5-二甲基-2-亚甲基-1,3-二氧己烷(Ⅵ)和5,5-二乙基-2-亚甲基-1,3-二氧己烷(V Ⅲ)的合成以及自由基开环聚合。结果表明,上述单体在聚合过程中出现异构化开环现象。Ⅲ和Ⅳ的甲基位置在环上氧原子的α-碳原子上时,显示对异构化反应的影响比Ⅵ及Ⅷ的甲基和乙基在β-碳原子上时更显著。上述现象与异构化开环形成仲碳自由基中间体的倾向更大有关。 Ⅳ在苯溶液中及过氧化二叔丁基存在下,120℃反应,得到全部是聚-δ-戊内酯骨架结构的聚合物。提出了一种合成聚-δ-戊内酯类链结构的聚酯的新的途径和方法。

SYNTHESIS AND FREE RADICAL POLYMERIZATION OF 2-METHYLENE-1,3-DIOXANE DERIVATIVES

Synthesis and free radical polymerization of four alkyl substituted six-membered cyclic ke-ten ascetals; 4-methyl-2-methylene-l, 3-dioxane (II), 4,6-dimethyl-2-methylene-1,3-dioxane (IV), 5, 5-dimethyl-2-methylene-1,3-dioxane (VI), and 5,5-diethyl-2-methylene-1, 3-dioxane (VIII) have been studied. Results indicated that introduction of methyl or ethyl substituents into β-position of oxygen atom in ring slightly effected ring-opening polymerization, but substituents at a-posi-tion of oxygen atom showed significant effect on the competition of polymerizations, that the ring-opening favored to form a more stable radical species. A complete ring-opening polymerization of (IV) was occured in a dilute benzene solution and in the presence of DTBP at 120℃ to give a polymer with polyester structure.