Chloroacetyl chloride → 8-Acetyl-6-(benzyloxy)-2H-1,4-benzoxazin-3(4H)-one

Participants

Reaction Conditions

Reaction Steps

15.00 kg (52.22 mol) 1-[2-hydroxy-3-nitro-5-(phenylmethoxy)-phenyl]-ethanone 4a, 0.165 kg platinum (IV) oxide and 45 l 2-methyltetrahydrofuran are hydrogenated at 3 bar hydrogen pressure and an internal temperature of 25° C. until no further hydrogen uptake is discernible. The catalyst is filtered off and washed with 20 l of 2-methyltetrahydrofuran. 23.09 kg (167.09 mol) potassium carbonate are placed in another reactor, and the reaction mixture from the first reactor is added. It is rinsed with 22 l of 2-methyltetrahydrofuran. Then within 30 minutes 9.44 kg (83.55 mol) chloroacetyl chloride are metered into the suspension. After 2.5 hours reaction time at 65° C., 101 l water are added. The aqueous phase is separated off at 55° C. Then 34 l 2-methyltetrahydrofuran are distilled off from the organic phase in vacuo. After heating to reflux temperature, 180 l methylcyclohexane are metered in within 30 minutes at reflux temperature. The suspension obtained is cooled to 20° C. and stirred for another 1 hour at this temperature to complete the crystallisation. Then the precipitate is removed by centrifuging, washed with 113 l methylcyclohexane and dried at 50° C.

Provenance & Evidence