Study On The Synthetic Process Of Ethephon

The preparation of ethephon from ethylene oxide and phosphorous trichloride via esterification reaction, Michaelis Arbuzov and acidolysis reaction was studied in this paper. The optimum reaction conditions were determined. The crude ethephon was purified by means of extraction and chemical reaction respectively. Moreover, the exploratory research to form bis-ethyl-2-chloroethylphosphonate as intermediate for producing ethephon was carried out by using phosphite trimester and alkane halide as the substrates.The experimental results showed that tris(2-chloroethyl)-phosphite could be prepared with yield of 89.1% under conditions as follows:the molar ratio of ethylene oxide and phosphorous trichloride was 3.15:1 at reaction temperature below 30℃, reaction was made an end after the addition of ethylene oxide. Then, bis(2-chloroethyl)-2-chloroethylphosphonate was prepared with yield of 90.8% after adding 6% weight of ethylene dichloride and reflux for 12 hours at 160℃. Finally, the bis(2-chloroethyl)-2-chloroethylphosphonate reacted with hydrogen chloride gas for 20 hours under 0.6MPa pressure at 150℃, the crude ethephon with purity of 82.4% can be obtained with mass yield of 44.2%.The study results shows that the means of extraction is a superior method for the purified of ethephon. The crude ethephon was dissolved in water (water:ethephon= 3.5:1 mass ratio) and extracted four times with ethyl acetate (ethyl acetate:water= 1:7 volume ratio). After removed water and other low boiling point compounds by distillation under vacuum, the purity of ethephon could reach up to 91.1% with yield of 93.7%, that meet the requirement of ethephon in new national standards.