Study On Synthesis Technology Of2,3-dialkyl Succinic Acid Ester

This article applies oxidative coupling reaction promoted by titanium tetrachloride or iodine to synthesize2,3-dialkyl succinate. The process route, in which butyl isovalerate undergoes dehydrogenation in the presence of LDA to give lithium ester enolate, and then the oxidative dimerization of lithium ester enolates with TiC takes place to give dibutyl2,3-diisopropylsuccinate,is given in detail. This section includes three parts.First is the preparation of raw materials. The optimal process conditions are:the molar ratio of isovaleric acid to butanol is1:5, reaction time is3h, and catalyst is thick sulfuric acid. A series of raw materials for synthesizing2,3-dialkyl succinate is prepared by this method.Second is preparation of LDA. While styrene is used as an electron acceptor which deprotonates the amine to synthesize LDA, dimerization of styrene appears in the reaction. This phenomenon has not been reported. Dimerization of styrene would go against the purification of dibutyl2,3-diisopropylsuccinate. We therefore tried to find other reactive conditions which have high yield but do not have dimerization of styrene. The optimization process condition is researched, and the yield of LDA is up to95%.Third is preparation of dibutyl2,3-diisopropylsuccinate. It takes a two-fold approach mentioned above to synthesize2,3-diisopropylsuccinate.The second step process can be directly went along without purification after the first step process.The influence of the mole ratio of the raw materials, reaction temperature, reaction time and reaction solvent on the coupling reaction was investigated. By using GC-MS some important components of the accessory substances produced from the two reactions are analyzed. Under the optimal condition, the yield of dibutyl2,3-diisopropylsuccinate is up to85%, while the selectivity is near95%. The reaction is expanded with stable result. The dibutyl2,3-diisopropylsuccinate is tested by some plant. It is showed that the succinate as internal electronic donors of Ziegler-Natta catalyst results in good effect; the productivity is62.5KgPP/gCat and the isotacticity of polymer exceeds97%. A series of succinate derivatives is also synthesized by this synthesis method, and the yield of dibutyl2,3-diethylsuccinate is92.8%, closer to the literature values.The paper finds that using LDA as one strong base, Claisen condensation method is more simple and effective to preparing butyl2-isopropyl-5-methyl-3-oxohexanoate. It is the first report at present. The reaction system is cooled down by vaporizing the liquid nitrogen, which do not participate in chemical reactions. An innovational operation for liquid nitrogen into the reactor directly is proposed.