反应详情

1,035 grams of 3-mercapto-1-propyltrimethoxysilane, 1,096 grams of a 25 weight percent methanolic solution of sodium methoxide, and 1,764 grams of toluene were charged to a 5-liter flask under an atmosphere of nitrogen. The stirred mixture developed a pinkish color. The flask was placed into a water bath at 64° C. Methanol was removed from the flask by distilling off a methanol-toluene azeotrope under a partial vacuum. The vacuum was kept such that the temperature in the distillation head was maintained at 30° to 35° C. during which time 1,500 ml of distillate, consisting of a toluene-methanol azeotrope, was collected. During this time the contents of the flask turned colorless. An additional 429 grams of toluene were added, and the distillation resumed. The appearance of a strong density current in the distillate, which coincided with an increase in distillation head temperature from 35° to 55° C., and the appearance of a changing liquid surface tension in the condenser signaled the point at which methanol removal from the flask was complete. The contents of the flask had become a viscous fluid. With continued stirring, the contents of the flask were allowed to cool. The flask was placed in an ice-water bath, resulting in what appeared to be a thick paste. 427 grams of propionyl chloride was added to the flask dropwise and/or in small portions with continued stirring in an ice-water bath until the reaction was complete. Aliquots of the stirred mixture were taken periodically. An alkaline reading indicated the completion of the reaction. The final mixture was a white suspension of NaCl in a toluene solution of the product. This mixture was filtered, and the solvent was removed from the filtrate to yield a nearly colorless product. Gas chromatography indicated (by weight) 3 percent of 3-mercapto-1-propyltrimethoxysilane, 1 percent of 3-(methylthio)-1-propyltrimethoxysilane, and 96 percent of 3-(acetylthio)-1-propyltrimethoxysilane (product). Flash distillation from one to two grams of powdered sodium methoxide yielded a colorless product. The sodium methoxide was added to ensure that any remaining acidity was neutralized. Further optional fractional distillation yielded a product in excess of 98 percent purity by GC.

1. customThe flask was placed into a water bath at 64° C
2. customMethanol was removed from the flask
3. distillationby distilling off a methanol-toluene azeotrope under a partial vacuum
4. temperaturewas maintained at 30° to 35° C. during which time 1,500 ml of distillate
5. customwas collected
6. additionAn additional 429 grams of toluene were added
7. distillationthe distillation
8. temperaturean increase in distillation head temperature from 35° to 55° C.
9. customat which methanol removal from the flask
10. temperatureto cool
11. customThe flask was placed in an ice-water bath
12. customresulting in what
13. stirringin small portions with continued stirring in an ice-water bath until the reaction
14. customthe completion of the reaction
15. filtrationThis mixture was filtered
16. customthe solvent was removed from the filtrate
17. customto yield a nearly colorless product
18. distillationFlash distillation from one to two grams of powdered sodium methoxide
19. customyielded a colorless product
20. distillationFurther optional fractional distillation
21. customyielded a product in excess of 98 percent purity by GC