Chloroacetyl chloride → n'-(2-Chloroacetyl)benzohydrazide

Participants

Reaction Steps

A suspension of 500 g (3.67 mol) of benzenecarbohydrazide in 3.75 liters of THF was heated at reflux, where the benzenecarbohydrazide went into solution. 497.7 g (4.41 mol) of chloroacetyl chloride, dissolved in 125 ml of THF, were added dropwise to this solution, and the solution was stirred under reflux for 30 min. After the reaction had gone to completion (monitored by TLC, mobile phase dichloromethane/methanol 9:1), 22.5 liters of water and 10 liters of ethyl acetate were added to the reaction mixture, and the pH was adjusted to pH 7 using solid sodium bicarbonate. The aqueous phase was extracted once with 2.5 liters of ethyl acetate. The combined organic phases were dried and the solution was then concentrated to dryness under reduced pressure. The white solid obtained was dissolved in a 1:1 mixture of dichloromethane and methanol and applied to 3 kg of silica gel. The product was chromatographed on two portions of silica gel (in each case 8 kg) initially with 50 liters of dichloromethane/ethyl acetate 7:3 and then with 125 liters of dichloromethane/ethyl acetate 1:1 as mobile phase. Concentration of the product fractions gave 424 g (1.99 mol, 54% of theory) of the title compound as a white solid.

Provenance & Evidence