Acetic Acid → Sodium Hydroxide

Participants

Reaction Conditions

Reaction Steps

A solution of 144 kg. of N-(2-chloroethyl)-N-methyl-o-benzoylbenzamide (481 moles) in 378 kg. of dichloroethane was prepared. A mixture of 50 kg. of this solution, sodium borohydride (273 kg., 721.5 moles, 1.5 equivalents) and dichloroethane (120 liters) at 46° C., was treated with acetic acid (0.5 kg.). The temperature rose steadily to reflux at 86° C. The remaining dichloroethane solution was added slowly, the exotherm maintaining the mixture at reflux without applied heat during the addition and for two hours after addition was complete. Thin layer chromatographic analysis was used to check for the completeness of reaction (had the reaction been found to be incomplete, a small further addition of sodium borohydride could then have been made). The complex was then decomposed by cautious slow addition of 100 liters of water at the reflux temperature and then 50 liters of 40% (w/w) aqueous sodium hydroxide solution to form 2-[N-(2-hydroxyethyl)-N-methylaminomethyl]benzhydrol in dichloroethane. The benzhydrol in dichloroethane was water washed to pH 8 and subsequently cyclized to 5-methyl-1-phenyl-1,3,4,6-tetrahydro5H-benz(f)-2,5-oxazocine as follows:

Provenance & Evidence