反应详情

5.0 g of (S)-(−)-2-pyrrolidone-5-carboxylic acid (by Wako Pure Chemical Industries) was suspended in 30 ml of methanol, and 26.8 g of aqueous 40% tetrabutylphosphonium hydroxide (by Aldrich) was dropwise added thereto at 0° C., taking 3 minutes. After being stirred for 10 minutes, this was concentrated under reduced pressure at 40° C., using an evaporator. 50 ml of methanol was added to the residue, and the mixture was concentrated under reduced pressure in the same manner. 100 ml of toluene was added to the obtained residue, and the resulting mixture was concentrated under reduced pressure; and this operation was repeated twice. Next, this was concentrated in ultra-high vacuum at from room temperature to 50° C. for 15 hours. 15.3 g of tetrabutylphosphonium (S)-(−)-2-pyrrolidone-5-carboxylate (purity, 98.0%) was obtained as an oily compound. (This is an ionic liquid A.) In NMR analysis, neither toluene nor methanol was detected.

1. concentrationthis was concentrated under reduced pressure at 40° C.
2. customan evaporator
3. addition50 ml of methanol was added to the residue
4. concentrationthe mixture was concentrated under reduced pressure in the same manner
5. addition100 ml of toluene was added to the obtained residue
6. concentrationthe resulting mixture was concentrated under reduced pressure
7. concentrationNext, this was concentrated in ultra-high vacuum at from room temperature to 50° C. for 15 hours