Synthesis Of Crotonic Acid From Oxidating Crotonaldehyde Extracted From The Industrial Waste Liquid

The method to extract and purify crotonaldehyde from the industrial waste liquid was studied in this paper.The obtained crotonaldehyde from the purification was used to oxidation synthesize crotonic acid.After extract crotonic acid,Vinyl Crotonate was extracted from industrial waste liquid,and can be polymerized as monomer.To extract and purify crotonaldehyde from the industrial waste liquid which contents 30%of crotonaldehyde,after 3 times of batch distillation under normal pressure crotonaldehyde of 98%purity could be obtained.The azeotropic distillation with water under normal pressure was ready to obtained the distillate containing 80%of crotonaldehyde and about 10%of water.Further distillation of this crotonaldehyde could not increase the purity of the crotonaldehyde.If purer crotonaldehyde is wanted,other methods must be used.The optimum reaction condition of synthesizing crotonic acid from 60g of 90%of crotonaldehyde without catalyst was the following:the flow rate of air was 200mL/min, reaction time～12 hours,temperature～30℃.The yield of crotonic acid was 66.9%mensurated with the gas chromatography,the primary recovery yield was 38.1%.The optimum reaction condition of synthesizing crotonic acid from the same material with H₃PO₄ as catalyst was the following:the flow rate of air was 200mL/min,the dosage of catalyst was 4.5‰reaction time～12 hours,temperature～30℃.The yield of crotonic acid was 67.9%mensurated with the gas chromatography,the primary recovery yield was 39.5%.The optimum reaction condition of synthesizing crotonic acid from same material with Cu(Ac)₂ as catalyst was the following:the flow rate of air was 200mL/min,the dosage of catalyst was 5.84‰reaction time～16 hours,temperature～30℃.The yield of crotonic acid was 63.4%mensurated with the gas chromatography,the primary recovery yield was 28.4%.The optimum reaction condition of synthesizing crotonic acid from same material with Cu(Ac)₂/Co(Ac)₂ as catalyst was the following:the flow rate of air was 200mL/min,the dosage of catalyst was 5‰and the ratio of Cu(Ac)₂:Co(Ac)₂ was 30%:70%,reaction time～16 hours,temperature～30℃.The yield of crotonic acid was 62.4%mensurated with the gas chromatography,the primary recovery yield was 25.2%.Comparing the yields of these catalysts and conditions,it could be found that the reactive effectiveness and the yield of H₃PO₄ as the catalyst was best,the purity of its crude products was also higher.