Organic 2 Review Problem 195

Organic 2 Review Problem 195 - PREPARATIONS 179 cool the...

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Unformatted text preview: PREPARATIONS 179 cool the mixture (whilst still in the flask) in ice-water, when the lower layer of the crude sulphonic acid will solidify. Decant off and discard the upper layer of toluene. Now add 25 ml. of concentrated hydrochloric acid, attach the condenser, and heat the mixture gently until a clear solution is just obtained, and then cool as before. (If the boiling is prolonged, and the con- centration of the hydrochloric acid thus reduced, the sulphonic acid will subsequently remain dissolved.) The toluene- p-sul- phonic acid separates as white crystals, which are contaminated with the deliquescent o-sulphonic acid. Therefore filter off the crystals using a small Buchner funnel, drain quickly, and return the crystals to the flask. Now add 15 ml. of concentrated hydro- chloric acid and repeat the recrystallisation as before. The crystalline toluene- p-sulphonic acid can now be drained more thoroughly at the pump, and should then be dried in a vacuum desiccator. Yield, 6-3 g. M .p. 103-105.desiccator....
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.

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