Synthesis Of Methy L,3-hydroxypropionate From Ethylene Oxide Catalyzed By Sodium Tetracarbonylcobaltate

Methy3-hydroxypropionate（MHP） is an important chemical raw material. It isoften used as chemical reagent, intermediate products of drugs and materials.Compared to3-hydroxypropionaldehyde, MHP has an advantage of avoidance oftoxicity and unstability in the production process of1,3-propanediol, which is thekey raw materials for preparation of very promising new polyester fiber PTT.Because MHP is expensive and less research about its synthesis method wasconducted, more and more attention has been paid to the process of synthesizingMHP by polyester academia.Cobalt carbonyl and rhodium are commonly used catalysts in the synthesisreaction of carbonylation. Although the latter has better activity, it is expensive andrequire synthesis gas to have higher puring, which limits its usage. Because it iscostly and hard to prepare Co₂（CO）₈, more research was conducted on Na[Co（CO）₄]catalyst due to its mild synthesis condition and low cost.In this paper, both preparation conditions and synthesis process for MHP werestudied. To seek a new process of MHP preparation, the optimal synthesis conditionswere selected and the reaction mechanism was studied by comparison of conversionand the yield of products. The main research work and conclusions are as follows.1. The reducing ability of sodium dithionite, Zn powder, Fe powder and Mnpowder were investigated in detail in the process of synthesis of Na[Co（CO）₄]catalystlies.2. The structure of Na[Co（CO）₄] is characterized by IR. The IR （νco） spectrumshowed a strong band at1905cm^-1, indicating the formation of tetrahedral[Co（CO）₄]^-1anion. Reaction mechanism in the preparation process of theNa[Co（CO）₄] catalyst is discussed. 3. According to the yield of MHP, the optimum reaction conditions of catalystpreparation is as follows: temperature80℃, pressure3MPa, reaction time5h,n（cobalt acetate）: n（sodium dithionite）=1:2, and n（cobalt acetate）: n（zinc powder）=3:4. The preparation of Na[Co（CO）₄] showed some of features including easyoperation, mild reaction condition and no pollution, and so on.4. Catalyst’s activity is evaluated according to the reaction of synthesizing MHPfrom ethylene oxide catalyzed by Na[Co（CO）₄] and reducing steps greatly. At thesame time, the effect of different ligands on the reaction was investigated. It is foundthat the order of reaction activity of ligands was as follows: N-heterocycle>Quaternary ammonium salts> Phosphorous, and3-hydroxy pyridine is better thanimidazole in the N-heterocycle ligands.5. The reaction products of synthesis of MHP were qualitatively analyzed, andcomposition and formation of the by-products were identified by GC-MS.6. The target product of MHP was quantitatively analyzed by GC with areanormalization method. The results show that the optimum reaction conditions ofsynthesis of MHP with ethylene oxide catalyzed by Na[Co（CO）₄] was as follows:temperature65℃, pressure5MPa, reaction time7h, n（catalyst）: n（EO）=1:100, andn（methanol）: n（EO）=3:2. Under the optimized conditions, the conversion ofethylene oxide and selectivity of MHP were nearly100%and95.56%, respectively.7. The reaction mechanism of preparating MHP from ethylene oxide catalyzed byNa[Co（CO）₄] was investigated based on catalytic cycle of hydroformyla and reactionmechanism of carbonyl synthesis from olefin.8. The catalyst of Na[Co（CO）₄] can be used to synthesize MHP on line, whichcan not only simplify the synthsis process, improve conversion of ethylene oxide andselectivity of MHP, but also avoiding separation of cobalt carbonyl catalyst. At thesame time, it provides a new process for synthesizing MHP.