EEKHOFF-PA RAME TERS OF EXPLOSIVES 447 by a method similar to that used by Erdmann & Erdmann5 for the potassium salt, reacts smoothly with chlorosulphonic acid under the general conditions of Spryskov & Apar'eva6 to give a good yield of the required 2 : 4-dinitrobenzenesulphonyl chloride. The over-all yield from chlorodinitrobenzene was 5540%.
Experimental
To a solution of 2 : 4-dinitrochlorobenzene (200 g.) in ethanol (400 ml.), heated almost to boiling on the steam bath, was added with vigorous stirring a solution of crystalline sodium sulphite (260 g.) in water (350 ml.). The deep orange reaction mixture was refluxed, with stirring, for 4 h. and then cooled to 0-5". The yellow crystalline sodium salt was filtered and washed with cold aqueous ethanol (50% v/v; 100 ml.) and ether (50 ml.) (yield 277 g.). Crystallization from aqueous ethanol (50% v/v) gave the pure salt (215g.; 81%). (Found: S, 12.1. Calc. for C,H,O,N,SNa: S, 1 1 -82%).
2 : 4-Dinitrobenzenesulphonyl chlcride Finely powdered sodium 2 : 4-dinitrobenzenesulphonate (69 g.; dried a t 90" for 48 h.) was added slowly with stirring to chlorosulphonic acid (250 ml.; redistilled or reagent quality) and the mixture was heated at 95" for 2 h. The brown liquid was cooled and then poured cautiously on to crushed ice (approx. 800 g.) with vigorous stirring. The precipitated creamcoloured solid (48 g., 71%) was filtered, washed well with water and dried in vacuo: m.p. 101-102". Use of unrecrystallized sodium salt gave 63% sulphonyl chloride, m.p. 100-101 ". Crystallization from light petroleum (b.p. 60-80") gave the pure sulphonyl chloride, m.p. 102" (Willgerodt & Mohr' gave m.p. 101-102").
The method has been used for quantities up to 500 g. of sulphonyl chloride without significant decrease in yield.