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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。
Four kinds of 2-methylene-1,3-dioxane-based monomers are reported here: 4-methyl-2-methylene-1,3-dioxane 2-methylene-1,3-dioxane (IV), 5,5-dimethyl-2-methylene-1,3-dioxane (VI) Synthesis of 5-diethyl-2-methylene-1,3-dioxane (V III) and free-radical ring-opening polymerization. The results show that the above monomers appear isomerization ring-opening phenomenon during the polymerization. The effect of the methyl position of III and IV on the alpha-carbon atom of the oxygen atom in the ring on the isomerization reaction is more pronounced than for the methyl and ethyl groups of VI and VIII on the beta-carbon atom. The above phenomenon is associated with a greater tendency toward isomerisation to form secondary carbon radical intermediates. Ⅳ in benzene solution and di-tert-butyl peroxide in the presence of 120 ℃ reaction, all are poly-δ-valerolactone skeleton structure of the polymer. A new route and method for synthesizing poly-δ-valerolactone chain polyesters were proposed.