不同醇解聚己内酯的反应特性研究

Study on the reaction characteristics of different alcoholysis of polycaprolactone

选取常见的一元醇为介质,对聚己内酯进行醇解反应研究,研究了在常压下不同醇解聚聚己内酯的反应温度对醇解率、醇解产物回收率的影响,通过醇解率,比较不同醇解聚聚己内酯的反应活性。通过气相色谱-质谱联用仪对醇解产物进行定性分析,红外光谱对醇解产物进行表征,气相色谱仪对醇解产物进行定量分析。结果表明:不同醇解聚一元醇和二元醇解聚聚己内酯的反应活性顺序为甲醇>乙醇>正丙醇,这是因为醇解聚聚己内酯是亲核取代反应,在解聚过程中醇的反应活性与分子结构有关,醇的羟基氧原子亲和活性越大、空间位阻越小,解聚速率越快,解聚率越高。醇解产物为ε-己内酯和相应酯的混合物。

Select a common monohydric alcohol as medium, the alcoholysis reaction of polycaprolactone was stud- ied. The effects of reaction temperature of different alcoholysis depolymerization of polycaprolactone under atmos- pheric pressure on alcoholysis rate, the recovery rate of alcoholysis products were studied. Through the alcoholysis rate, the reaction activity of different alcohols depolymerization of polycaprolactone was compared. The alcoholysis products were qualitative analyzed by gas chromatography-mass spectrometry, were characterized by infrared spec- trum, were quantitative analyzed by gas chromatography. The results show that reaction activity order is methanol 〉 ethanol 〉 n-propanol for monohydric alcohols. This is because the alcoholysis of polycaprolactone is nucleophilic substitution reaction. The reaction activities of the alcohol in the depolymerization process are related to the molecu- lar structure. The greater affinity activity of hydroxyl group oxygen atom of the alcohol, the smaller the steric hin- drance, the faster the rate of depolymerization, the depolymerization rate is higher. The alcoholysis product is the mixture of caprolactone and corresponding esters.