The Process Optimum Of The Synthesis Of Diethyl Oxalate

Diethyl oxalate (DEO) is one of the basic organic materials in chemical industry. It is widely used in the fields of medicine, plastics, printing and dyeing, and organic synthesis etc. There are mainly two ways in the production of DEO, namely the classical esterification and carbon monoxide of oxidative carbonylation of DEO. The esterification is the traditional way for producing DEO in industry in the way oxalic acid reacts with ethanol while toluene (benzene) as dehydrating agent is added in the system which is in proportion to reactants in quantity.However, the long reaction period and relative high consumption are the main obstacles to the increase of production efficiency.In regard to the above matters, this study intends to improve the process of esterification so as to shorten the reaction period, and reduce the consumption of the reactants using the following ways:1 The nowadays total production periods of esterification is about 35 hours in which the esterification time is 22-24 hours. In order to shorten the period, two steps are necessary: (a) first increase the reaction temperature in the presser reactor. Temperature works on the reaction rate greatly. At 100, to reach the reaction equilibrium only needs 1-1.5 hours. (b) ethanol is continuously added to the production of reaction step (a) and to esterify further at atmospheric pressure, 6 hours are needed in this process. After improvement, 90% of oxalic acid is converted in one period (only 82% in industry), and 8 hours are enough to reach this result.2 The dehydrating agent toluene (benzene) removed from the reaction system and ethanol is used as dehydrator, so ethanol in the system acts as reagent and dehydrating agent. In other word without toluene in the system, the concentration of the reagents oxalic acid and ethanol increase. This means the rate of esterification increases also.3 Based on experiment data, calculation results show that the consumption of reactants drop as compared to that in the now process.4 The rectification process of DEO from batched method is changed to continuous process, this may shorten the process time.5 The four times of ethanol cycle use indicates that there are little side effects on the yield of DEO.6 Brief investigation on the mechanism and kinetics of the reaction process.