Process Study Of Downstream Products Of ?-acetyl-?-butyrolactone

Prothioconazole is a broad-spectrum and highly effective fungicide developed by Bayer,which is mainly used to prevent and cure diseases and insect pests of cereal crops.As an important intermediate for the synthesis of prothioconazole,1-chloro-1-chloroacetyl cyclopropane has been the main factor affecting its industrial production.Because there are some defects in the existing route,our work is to improve the existing process conditions to make it more suitable for industrial production.4-methyl-5-(2-hydroxyethyl)thiazole is not only an important intermediate for the synthesis of vitamin B,but also an important food spice with barbecue and nuts,which can be used for dairy products,nuts,bread as well as seasoning flavor.Because the domestic production of the product has great defects,it is difficult to remove from the thiazole flavor which cannot play its proper taste.In this thesis,the synthesis of 1-chloro-1-chloroacetyl cyclopropane and 4-methyl-5-(2-hydroxyethyl)thiazole is introduced in details,which makes it more suitable for industrial production.(1)The synthesis of 1-chloro-1-chloroacetyl cyclopropane.?-acetyl-?-chloro-?-butyrolactone was synthesized at a low temperature using ?-acetyl-?-butyrolactone as the starting material and sulfonyl chloride as the chlorinating agent.The product was subjected to ring-opening decarboxylation in hydrochloric acid to give 3,5-dichloro-2-pentanone.3,5-dichloro-2-pentanone was added dropwise to the sodium hydroxide solution with phase transfer catalyst to give 1-chloro-1-acetylcyclopropane.and finally chlorinated 1-chloro-1-acetylcyclopropane with sulfonyl chloride as a chlorinating agent to give intermediate 1-chloro-1-chloroacetyl cyclopropane.The total yield of the reaction is more than 60%,which is obviously improved relative to the reported yield of 41.7%.(2)The preparation of 4-methyl-5-(2-hydroxyethyl)thiazole.?-acetyl-?-chloro-?-butyrolactone was synthesized at a low temperature using ?-acetyl-?-butyrolactone as the starting material and sulfonyl chloride as the chlorinating agent.The product was subjected to ring-opening decarboxylation in hydrochloric acid to give 3,5-dichloro-2-pentanone.3,5-dichloro-2-pentanone thiocyanated by thiocyanration to give 3-thiocyanato-5-chloro-2-pentanone.3-thiocyanato-5-chloro-2-pentanone was cyclized in ethyl acetate under hydrogen chloride gas to give 2-chloro-4-methyl-5-(2-chloroethyl)thiazole.2-chloro-4-methyl-5-(2-chloroethyl)thiazole was hydrolyzed in ethanol under the condition of sodium acetate trihydrate to give 2-chloro-4-methyl(2-acetoxyethyl)thiazole and 2-chloro-4-methyl-5(2-hydroxyethyl)thiazole.Afterwards,the mixed product was hydrogenated and dehalogenated under zinc and acetic acid condition to give 4-methyl-5-(2-acetoxyethyl)thiazole.Finally 4-methyl-5-(2-acetoxyethyl)thiazole was hydrolyzed under sodium hydroxide solution to give 4-methyl-5-(2-hydroxyethyl)thiazole.Based on the feasibility study on the synthesis of 1-chloro-1-chloroacetyl cyclopropane and 4-methyl-5-(2-hydroxyethyl)thiazole,we screened each of the relatively economically feasible synthetic routes.The influence of various factors on the yield of the reaction was analyzed.A relatively ideal parameter for the 1-chloro-1-chloro acetyl cyclopropane and 4-methyl-5-(2-hydroxyethyl)thiazole have been obtained,which laid a good foundation for industrial production.