I am forming silyl enol ethers using Chloro(trimethyl)silane (TMSCl), and below is an experimental protocol I am following
Silyl Enol Ether Synthesis
- In an oven-dried 100 mL three-necked flask, Et3N (37.2 mmol) and carbonyls (30.0 mmol) were added. The mixture was stirred and heated to 30~35 ºC, and TMSCl (37.2 mmol) was added dropwise over 15 minutes. The mixture was stirred at the same temperature for 0.5 hour.
- A solution of NaI (37.2 mmol) in acetonitrile (35 mL) was added dropwise to the mixture over 0.5 hour and stirred for 1 hour. The mixture was then heated to 40-45 ºC and stirred at this temperature for 2 hours.
- The mixture was then cooled to room temperature and 30 mL of cold pentane was added. The mixture was poured into 30 mL of ice-cold water and extracted with pentane (15 mL × 2). The combined organic phases were dried over anhydrous Na2SO4, filtered and concentrated in vacuo. After distillation under reduced pressure, the products were obtained as colorless oils and stored at 0 ºC under an atmosphere of nitrogen for use.
I don't understand the mechanistic background of Step 2. What does NaI do?
Side question: when adding TMSCl in Step 1, I saw some white fume. I am guessing TMSCl was reacting with moisture in the air but what would be the product of H2O+ TMSCl? Is it HCl and TMS-OH?