Hydrochloric Acid → p-Toluenesulfonic acid

Participants

Reaction Conditions

Reaction Steps

A mixture of 15.0 g (47.5 mmol) PRON-HCl, 170 mL MTBE and 20 mL water is cooled to 5 to 10° C. in a 250 mL vessel. After addition of 12.8 g of a 20% NaOH solution the mixture is stirred for further 15 min, while phase separation occurs. The organic phase is washed with water (60 mL) and the aqueous phase is extracted with MTBE (2×50 mL). The combined organic phases are cooled to below 10° C. and within 15 min a suspension of 8.6 g (45 mmol) p-toluenesulfonic acid monohydrate in 400 mL MTBE is added. An oily suspension is formed. The volume of the solvent is reduced to approximately the half. The reaction mixture is heated under reflux and 250 mL heptane are added. The mixture is cooled to RT and stirred for 30 min. The solid matter is filtered off, washed with MTBE (2×60 mL) and dried in vacuo at 50 to 55° C. affording 14.3 g of product (tan solid matter).

Provenance & Evidence