Acetic Acid → 2-Thenylamine, N,N-bis(2-chloroethyl)-, hydrochloride

One millimole of DCTA-bromide was added to 5 ml of 50% DMF containing 0.2 ml of 1,2-dithioethylene and 0.5 ml of triethylamine. The mixture was incubated under argon for 2 hours at 60°-70° C. After reaction the mixture was diluted with oxygen-free H2O to 50 ml, the pH was adjusted to 4.0-4.5 with glacial acetic acid and the excess HS--CH2 --CH2 --SH was extracted three times with 15 ml benzene by stirring (not shaking). The water phase was then loaded onto a Dowex AG-1 column, 9 ml bed volume. The column was washed with 50 ml of 0.1M acetic acid solution until the flowthrough was thiol free. The DCTA-SH was then eluted with 0.25M HCl. The thiol containing fractions were combined, evaporated to dryness under reduced pressure at 40° C. and the free acid (300 mg) was stored at -20° C. under argon.