论文部分内容阅读
合成了衣康酸的三种烯丙酯:2-甲叉丁二酸双烯丙酯(双酯),2-甲叉丁二酸1-烯丙酯(α-单酯)和2-甲叉丁二酸4-烯丙酯(β-单酯)。α-单酯和β-单酯的化学性质极其相似,很难用一般方法区分。我们比较了它们的红外吸收谱和 NMR 谱,发现后者比前者能更好地分析和鉴别它们。在 NMR 谱中,两种单酯的甲叉基(=CH_2)上的氢核有不同的化学位移,我们根据 NMR 谱中两者的吸收峰峰值之比,成功地测定了混合单酯中α-单酯和β-单酯的含量。研究了在强酸催化下衣康酸和丙烯醇的直接酯化和衣康酸双烯丙酯的部份酸性水介过程中各种酯含量的变化。发现在酯化和水介反应过程中,不仅是双酯和单酯的相对含量而且α-和β-单酯的相对含量也与酯化程度和水介程度有密切关系。在直接酯化过程中只得到少量的α-单酯,而主要得到β-单酯。但在双酯酸性水介过程中刚巧相反。从而找到了合成α-单酯的合适条件。
Three kinds of allyl esters of itaconic acid were synthesized: diallyl 2-methylidene succinate (diester), 2-allyl 2-methylidene succinate (α-monoester) 4-allyl fumarate (β-monoester). The chemical properties of α-monoesters and β-monoesters are very similar and are difficult to distinguish by common methods. We compared their IR spectra and NMR spectra and found that the latter were better able to analyze and identify them than the former. In the NMR spectrum, the hydrogen nuclei on the methylidene (= CH 2) of the two monoesters have different chemical shifts. Based on the ratio of the absorption peak and the peak value of the two in the NMR spectrum, α Monoesters and β-monoesters. The changes of various esters in the direct esterification of itaconic acid and allyl alcohol and the partial acid hydrolysis of the diallyl itaconate catalyzed by strong acid were studied. It was found that during the esterification and water-mediated reaction, not only the relative content of diester and monoester but also the relative content of α- and β-monoesters are also closely related to the degree of esterification and the degree of water-mediated degree. In the direct esterification process, only a small amount of α-monoester is obtained, but mainly β-monoester. But the opposite happens during the di-ester acidic water-mediated process. Thus, suitable conditions for the synthesis of α-monoester were found.