Method for preparing 2,4-dimethyl thiophane-3-ketone

Abstract

The invention relates to a method for preparing a 2,4-dimethyl thiophane-3-ketone. In the presence of a main catalyst and a catalyst promoter, methacrylic acid and 2-thiohydracrylic acid are taken as raw materials to react and synthesize 2,4-dimethyl thiophane-3-ketone. A cheap lewis acid and / or an aquo-complex of the lewis acid are / is taken as the main catalyst for the reaction, one or more of carboxylate, citrate, sulfonate, antioxidant, and aquo-complexes of the carboxylate, the citrate, the sulfonate and the antioxidant is / are taken as the catalyst promoter, and the 2,4-dimethyl thiophane-3-ketone with high yield is obtained through a one-pot method; the method has the characteristics of being low in cost, convent to operate, high in yield, and easy for in industrial production.

Description

Technical field

[0001] The invention relates to the technical field of organic synthesis, in particular to a method for preparing 2,4-dimethyltetrahydrothiophen-3-one. Background technique

[0002] Dimethenamid is an acetamide herbicide, which is widely used in pre-sowing soil treatment of corn, sunflower, soybean, sorghum, peanut, and vegetables and in removing gramineous weeds and broad-leaved weeds before seedling after sowing. 2,4-Dimethyltetrahydrothiophen-3-one is the main intermediate for the preparation of dimethenamid, which has important industrial value.

[0003] The Chinese patent application with the application number 85106474 reported the synthesis of 2,4-dimethyl methyl with 2-mercaptopropionic acid and methacrylic acid as raw materials under the catalysis of Fe, Ni(II) and Co(II) acetate. Based on the method of tetrahydrothiophen-3-one, the process route is as follows:

[0004]

[0005] The catalysts used in the route reported in this patent are acetates of Fe, Ni(...

Examples

Embodiment 1

[0036] A method for preparing 2,4-dimethyltetrahydrothiophen-3-one, the specific operation is: 94.7g (1.1mol) methacrylic acid and 106.1g (1mol) 2-mercaptopropionic acid are added to the reaction flask and mixed Stir, add 1.0g (0.01mol) of ketone chloride, 2.91g (0.015mol) of sodium p-toluenesulfonate, stir for 2h at 140℃, add 1.0g (0.01mol) of ketone chloride; continue heating to 160 Reaction at ℃ for 2h. The temperature was gradually increased to 180-190°C and the distillate was collected until no liquid came out. The remaining solid is reserved as a catalyst, the distillate is dissolved in toluene, washed with 1M sodium hydroxide aqueous solution to alkaline, dried over anhydrous magnesium sulfate, and toluene is removed to obtain 118.5g of 2,4-dimethyltetrahydrothiophene-3- The ketone has a purity of 99.2% and a yield of 91.0%.

[0037] The aqueous layer is acidified with hydrochloric acid, extracted with dichloromethane, the organic phase is washed with water, dried with a...

Embodiment 2

[0039] A method for preparing 2,4-dimethyltetrahydrothiophen-3-one, the specific operation is: adding 94.7g (1.1mol) of methacrylic acid and 106.1g (1mol) of 2-mercaptopropionic acid to the remainder of Example 1 In the solid, the reaction was stirred at 140°C for 2h, and 1.0g (0.01mol) of ketone chloride was added; the temperature was continued to rise to 160°C for 2h, and the temperature was gradually increased to 180-190°C to collect the distillate. The distillate was dissolved in toluene, washed with 1M sodium hydroxide aqueous solution until alkaline, dried over anhydrous magnesium sulfate, and toluene was removed to obtain 117.6g 2,4-dimethyltetrahydrothiophen-3-one with a purity of 99.2% The yield was 90.35%.

[0040] The aqueous layer was acidified with hydrochloric acid, extracted with dichloromethane, the organic phase was washed with water, dried with anhydrous magnesium sulfate, and the solvent was removed to obtain 14.6 g of a mixture of methacrylic acid and 2-mercap...

Embodiment 3

[0042] The operation of this embodiment is the same as that of embodiment 1, the only difference is: replacing the ketone chloride added in two batches with adding ferrous chloride tetrahydrate in two batches, adding 4g (0.02mol) ferrous chloride tetrahydrate in total Finally, 112.8g of 2,4-dimethyltetrahydrothiophen-3-one was obtained, the purity was 99.1%, the yield was 86.6%, and 15.2g of a mixture of methacrylic acid and 2-mercaptopropionic acid was recovered, methacrylic acid The ratio with 2-mercaptopropionic acid is 2.3:1.

Technical field

[0001] The invention relates to the technical field of organic synthesis, in particular to a method for preparing 2,4-dimethyltetrahydrothiophen-3-one. Background technique

[0002] Dimethenamid is an acetamide herbicide, which is widely used in pre-sowing soil treatment of corn, sunflower, soybean, sorghum, peanut, and vegetables and in removing gramineous weeds and broad-leaved weeds before seedling after sowing. 2,4-Dimethyltetrahydrothiophen-3-one is the main intermediate for the preparation of dimethenamid, which has important industrial value.

[0003] The Chinese patent application with the application number 85106474 reported the synthesis of 2,4-dimethyl methyl with 2-mercaptopropionic acid and methacrylic acid as raw materials under the catalysis of Fe, Ni(II) and Co(II) acetate. Based on the method of tetrahydrothiophen-3-one, the process route is as follows:

[0004]

[0005] The catalysts used in the route reported in this patent are acetates of Fe, Ni(...

Examples

Embodiment 1

[0036] A method for preparing 2,4-dimethyltetrahydrothiophen-3-one, the specific operation is: 94.7g (1.1mol) methacrylic acid and 106.1g (1mol) 2-mercaptopropionic acid are added to the reaction flask and mixed Stir, add 1.0g (0.01mol) of ketone chloride, 2.91g (0.015mol) of sodium p-toluenesulfonate, stir for 2h at 140℃, add 1.0g (0.01mol) of ketone chloride; continue heating to 160 Reaction at ℃ for 2h. The temperature was gradually increased to 180-190°C and the distillate was collected until no liquid came out. The remaining solid is reserved as a catalyst, the distillate is dissolved in toluene, washed with 1M sodium hydroxide aqueous solution to alkaline, dried over anhydrous magnesium sulfate, and toluene is removed to obtain 118.5g of 2,4-dimethyltetrahydrothiophene-3- The ketone has a purity of 99.2% and a yield of 91.0%.

[0037] The aqueous layer is acidified with hydrochloric acid, extracted with dichloromethane, the organic phase is washed with water, dried with a...

Embodiment 2

[0039] A method for preparing 2,4-dimethyltetrahydrothiophen-3-one, the specific operation is: adding 94.7g (1.1mol) of methacrylic acid and 106.1g (1mol) of 2-mercaptopropionic acid to the remainder of Example 1 In the solid, the reaction was stirred at 140°C for 2h, and 1.0g (0.01mol) of ketone chloride was added; the temperature was continued to rise to 160°C for 2h, and the temperature was gradually increased to 180-190°C to collect the distillate. The distillate was dissolved in toluene, washed with 1M sodium hydroxide aqueous solution until alkaline, dried over anhydrous magnesium sulfate, and toluene was removed to obtain 117.6g 2,4-dimethyltetrahydrothiophen-3-one with a purity of 99.2% The yield was 90.35%.

[0040] The aqueous layer was acidified with hydrochloric acid, extracted with dichloromethane, the organic phase was washed with water, dried with anhydrous magnesium sulfate, and the solvent was removed to obtain 14.6 g of a mixture of methacrylic acid and 2-mercap...

Embodiment 3

[0042] The operation of this embodiment is the same as that of embodiment 1, the only difference is: replacing the ketone chloride added in two batches with adding ferrous chloride tetrahydrate in two batches, adding 4g (0.02mol) ferrous chloride tetrahydrate in total Finally, 112.8g of 2,4-dimethyltetrahydrothiophen-3-one was obtained, the purity was 99.1%, the yield was 86.6%, and 15.2g of a mixture of methacrylic acid and 2-mercaptopropionic acid was recovered, methacrylic acid The ratio with 2-mercaptopropionic acid is 2.3:1.

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