Hydrochloric Acid → N,S-Diacetylcysteamine

Cysteamine hydrochloride (50.0 g) is added to a 1-L 3-neck round bottom flask fitted with a magnetic stir bar, 2 addition funnels, and a pH electrode. Water (300 ml) is added and the stirred solution is cooled on ice. The pH is adjusted to 8.0 by addition of 8 N KOH. Acetic anhydride (125 ml) is placed in one addition funnel, and 8N KOH (350 ml) is placed in the other addition funnel. The acetic anhydride is added dropwise to the cysteamine solution, with 8 N KOH being added so as to keep the reaction pH at 8+/−1. After addition of acetic anhydride is complete, the pH was adjusted to 7.0 using 1 N HCl and the mixture is allowed to stir for 75 min on ice. Solid NaCl is added to saturation, and the solution is extracted 4 times using 400 ml portions of CH2Cl2. The organic extracts are combined, dried over MgSO4, filtered, and concentrated under reduced pressure to yield 68.9 g (97% yield) of a pale yellow oil, which crystallizes upon standing at 4° C. 1H-NMR (CDCl3, 400 MHz): δ 6.43 (br s, 1H), 3.42 (q,2H,J=7), 3.03 (t,2H,J=7), 2.36 (s,3H), 1.98 (s,3H). 13C-NMR (CDCl3, 100 MHz): δ 196.09, 170.45, 39.42, 30.56, 28.71, 23.06.

1. customfitted with a magnetic stir bar
2. addition2 addition funnels
3. temperaturethe stirred solution is cooled on ice
4. additionadded so as
5. extractionthe solution is extracted 4 times
6. dry with materialdried over MgSO4
7. filtrationfiltered
8. concentrationconcentrated under reduced pressure

ORD record

ord-21da1403205144aa9ae29ee8c42ca8de

Source dataset

uspto-grants-2006_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07022825B2