Hydrogen 787 persulphide

Under suitable conditions, certain chemical reactions will give rise to nacreous sulphur the most satisfactory result is obtained by allowing slow inter-diffusion of solutions of sodium thiosulphate and potassium hydrogen sulphate to occur.7 Another method involves the gradual decomposition of sulphur chloride or bromide by the vapour of water or methyl alcohol at the ordinary temperature.8 The decomposition of calcium polysulphidcs by hydrochloric acid,9 and of hydrogen persulphide by the addition of alcohol, ether, ethyl acetate or other organic solvents, also yields sulphur of the desired modification. 

Hydrogen Disulphide, H2S2, in addition to being obtained from the distillation of crude hydrogen persulphide, is also formed when hydrogen trisulphide is distilled at 100° C. under a pressure of 20 mm. approximately one-third of the trisulphide is converted into disulphide, whilst the remainder passes into hydrogen sulphide and sulphur. The disulphide, therefore, is the most stable of the hydrogen polysulphides towards heat, and can actually be distilled under atmospheric pressure at 71° to 75° C. with only partial decomposition. 

It is difficult not to conclude however that some result do reflect higher barriers to rotation about single bonds in acyclic compounds. The barriers to rotation in hydrogen peroxide and hydrogen persulphide are 7.0 and 6.8 kcal/mol compared with a value of 2.9 kcal/mol for ethane 8), and these larger barriers seem to be reflected in the ring inversion barriers for the compounds 24—26. 65,87-89)... 

Hofmann investigated many synthetic dyes and determined their empirical formulae, particularly what he called rosaniline derivatives (see p. 818). He did little work with alkaloids, nitrogen compounds which should have interested him. He described a red compound of strychnine with hydrogen persulphide which he first formulated (C21H22N2O2), H2S3, later (C2iH22N202)2, 2 % He first determined the correct formula of coniine and showed its relation to pyridine and piperidine. ... 

Hydrogen sulphide ( stinking svilphurous air ) and crude hydrogen persulphide... 

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