反应详情

Into a 500 ml 3-neck flask was added 17.1 grams (0.1 mole) 1,2,2,6,6-pentamethyl-4-piperidinol and 300 mls of methyl t-butyl ether (MtBE). The flask was equipped with a magnetic stirrer, thermometer, reflux condenser and dropping funnel containing 15.6 grams (0.1 mole) phenyl chloroformate. The phenyl chloroformate was slowly added to the 1,2,2,6,6-pentamethyl-4-piperidinol solution without any appreciable exotherm. Then 11.2 grams (0.1 mole) of 1,4-diazabicyclo(2.2.2)octane (DABCO) was added at room temperature. The temperature rose to 50° C. and a precipitate formed. The reaction was stirred for 2 hours, an additional 2 grams of DABCO and 1.25 grams of phenyl chloroformate was added, the reaction heated to reflux and refluxed 2 hours. The reaction mixture was cooled, transferred to a separatory funnel and washed with water to remove DABCO, DABCO hydrochloride and a small amount of 1,2,2,6,6-pentamethyl-4-piperidinol. The product was then extracted out of the MtBE layer with 100 mls of 5% HCl diluted with water to 400 mls. The MtBE layer which contained diphenyl carbonate was discarded. The acid layer was made basic with 100 ml of 10% NaOH. The product was extracted out of the aqueous layer with 200 ml MtBE. The MtBE extract was washed with 100 ml 5% NaHCO3, dried over anhydrous MgSO4, filtered and the MtBE stripped off on a rotating evaporator under reduced pressure. The residue was a white solid weighing 20.4 grams (70.1% crude yield) which had a melting point of 63°-67° C. Liquid chromatography indicated the product was essentially one component. The infrared spectrum contained a strong carbonyl peak at 1755 cm-1.

1. customThe flask was equipped with a magnetic stirrer
2. temperaturethermometer, reflux condenser
3. customrose to 50° C.
4. customa precipitate formed
5. temperaturethe reaction heated
6. temperatureto reflux
7. temperaturerefluxed 2 hours
8. temperatureThe reaction mixture was cooled
9. customtransferred to a separatory funnel
10. washwashed with water
11. customto remove DABCO, DABCO hydrochloride
12. extractionThe product was then extracted out of the MtBE layer with 100 mls of 5% HCl
13. additiondiluted with water to 400 mls
14. extractionThe product was extracted out of the aqueous layer with 200 ml MtBE
15. extractionThe MtBE extract
16. washwas washed with 100 ml 5% NaHCO3
17. dry with materialdried over anhydrous MgSO4
18. filtrationfiltered
19. customthe MtBE stripped off on a rotating evaporator under reduced pressure