Hydrochloric Acid → HCID 53759908, compound

Participants

Reaction Conditions

Reaction Steps

7.1 g of 3-hydroxy-5-methyl-7-(1,1,3,3-tetramethylbutyl)-3H-benzofuran-2-one (U.S. Pat. No. 5,614,572, Column 35, Compound No. 111) are introduced into 12.5 ml of toluene as initial charge and admixed with 3 drops of DMF and 2.7 ml of thionyl chloride. The solution is then gradually heated to 100° C. so that the evolution of HCl and SO2 remains lively but still controllable. Thereafter the reaction mixture is stirred at 100° C. for a further 1 h. About 12 ml of liquid are subsequently distilled off to remove excess thionyl chloride. The residue is diluted with 37.5 ml of toluene and admixed at room temperature with 3.5 ml of triethylamine added dropwise. The thick red reaction mixture is then refluxed for 30 min. The precipitated triethylamine hydrochloride is filtered off after cooling to room temperature and the filtrate is concentrated in a rotary evaporator to an oily consistency. The isoxindigo is crystallized out by addition of 25 ml of acetonitrile, filtered off, washed with acetonitrile and dried to leave 3.45 g (53% of theory) of 5,5′-dimethyl-7,7′-bis(1,1,3,3-tetramethylbutyl)[3,3′]bibenzofuranylidene-2,2′-dione of the formula

Provenance & Evidence