Process for the preparation of quaternary N-alkyl morphinan alkaloid salts

A composition comprising R-naltrexone methobromide, S-naltrexone methobromide, the C(3)-O-methyl derivative of naltrexone methobromide, and naltrexone wherein the composition contains at least 70% (w/w) of R-naltrexone methobromide, at least 1% of S-naltrexone methobromide, but no more than 0.2% (w/w) of the C(3)-O-methyl derivative of naltrexone methobromide, based upon the combined weight of the R-naltrexone methobromide, S-naltrexone methobromide, C(3)-O-methyl derivative of naltrexone methobromide, and naltrexone in the composition.