Hydrochloric Acid → 1,3-Dihydro-4-isobenzofuransulfonyl chloride

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Reaction Steps

A suspension of 22.1 g of the crude hydrochloride salt prepared in Example 2 in a mixture of 30 ml of concentrated hydrochloric acid and 30 ml acetic acid was cooled to 0°-5°. A solution of 6.2 g of sodium nitrite in 15 ml water was added dropwise at 0°-5°. The thick suspension was diluted with 19 ml of concentrated hydrochloric acid to facilitate stirring and 1.0 g of sodium nitrite was added; stirring was continued for 1 hour. The suspension of the diazonium salt was added portionwise at 0°-5° to a stirred mixture of 80 ml of acetic acid, 25 ml of sulfur dioxide and 1.6 g of copper (II) chloride dihydrate. The resulting pale green suspension was allowed to warm to ambient temperature and stirred for 4.5 hours. The yellow-green solution was poured into 1000 ml of cold water and the aqueous mixture extracted three times with 1-chlorobutane. The combined organic solution was washed three times with water and saturated sodium bicarbonate solution, then dried over magnesium sulfate, and filtered. Evaporation of the solvent in vacuo gave 9.8 g of 1,3-dihydrobenzo[c]furan-4-sulfonyl chloride as a yellow oil which crystallized on cooling and scratching, m.p. 40°-43°.

Provenance & Evidence