Succinimide, reaction with sulphur

V,/V-Dithiobis(succinimide). A hot solution of succinimide (lOOg) in absolute ethanol (1 litre) is poured into an ice-cold solution of potassium hydroxide (58 g) in absolute ethanol (300 ml). The mixture is stirred and cooled to 0 °C. Potassium succinimide crystallises from the mixture as colourless crystals, and is collected by suction filtration. After washing with light petroleum (b.p. 60-80 °C) the crystals are dried (110.3 g, 79.1%). A solution of sulphur monochloride (54 g) in dichloromethane (50 ml) is added over 5 minutes to a vigorously stirred suspension of the potassium succinimide (110.3 g) in dichloromethane (400 ml) at 0 °C. After the initial exothermic reaction, the mixture is stirred for a further 5 minutes, filtered and the filtrate evaporated in vacuo to leave a solid residue, which is washed three times with light petroleum (b.p. 60-80 °C) and once with water. Crystallisation from methanol gives colourless plates of Ar,Ar -dithiobis(succinimide) (83 g, 79.3%), m.p. 192— 193 °C m/z 260, 162, 134, 102, 99 and 55. 

Furfurol (fural), the aldehyde of furan, was obtained by Fownes (1845, see p. 271) by distilling bran with dilute sulphuric acid. W. E. Stone and B. Tollens found that this reaction is quantitative with pentoses. Furan was discovered in pine-wood tar by Limpricht, who also obtained it by distilling barium pyromucate. He called it tetraphenor, the name furfurane being proposed by Baeyer. H. B. HilF pointed out its relation to pyromucic and maleic acids. Pyrrole was discovered, but not isolated in a pure state, by Runge (1834, see p. 184). H. Schwanert obtained it by distilling ammonium mucate, and A. C. Bell by distilling succinimide with zinc dust. 

Cleavage of benzylic sulphoxides and t-butyl dialogues with N-bromo- or -chloro-succinimides gives the benzyl or t-butyl halide and an ethyl alkane-pr arene-sulphinate, the ethanol in the CHCh used as solvent providing the nucleophile for attack at sulphur on the intermediate bromosulphoxonium cation. " Use of an optically active sulphoxide leads to the conclusion that the reaction is largely of SnI character. 

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