Organic 2 Review Problem 185

Organic 2 Review Problem 185 - P REPARATIONS 169 sulphur to...

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PREPARATIONS 169 sulphur to sodium sulphide. In these circumstances the dinitrobenzene is Na 2 S + S = Na 1 S, C 8 H 4 (NO 1 ), + Na 2 S 2 + H 2 O = C 6 H 4 (NO 2 )NH, + Na 8 S 8 O, readily reduced to w-nitroaniline, the sodium disulphide being^ oxidised mainly to sodium thiosulphate. Required: Sulphur, 4-2 g.; sodium sulphide, 16 g.; m-dinitro- benzene, 10 g. The crystalline sodium sulphide (Na 2 S^H 2 O) used to prepare the disulphide is very deliquescent, and only a sample which has been kept in a well-stoppered bottle and therefore reasonably dry should be used. A sample from a badly-stoppered bottle may contain, in addition to the crystals, a certain amount of aqueous solution, in which hydrolysis and partial decomposition will have occurred: such a sample should therefore be rejected. Add 4-2 g. of finely powdered sulphur to a solution of 16 g. of the crystalline sodium sulphide in 60 ml. of water, and boil the mixture gently for a few minutes until a clear solution of the disulphide is obtained. Heat a mixture of io g. of pure
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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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