94 Messrs Jones and Tasker, A coloured thio-oxalate. 



A coloured thio-oxalate. By H. O. Jones, M.A., Clare College, 

 and H. S. Tasker, B.A., Emmanuel College. 



[Read 8 February 1909.] 



In investigating the action of substances on oxalyl chloride, 

 (C0C1)2, in the hope that chlorine might be removed and C2O2 be 

 produced, thiophenol and its metallic compounds were used, since 

 the easy formation of diphenyl disulphide renders these substances 

 good reducing agents. 



Sodium thiophenolate reacts violently with oxalyl chloride, but 

 in place of C2O2 two molecules of carbon monoxide are produced. 



The action of thiophenol itself is less violent. On mixing 

 equivalent quantities of oxalyl chloride and thiophenol a yellow 

 colour is immediately produced and hydrogen chloride is evolved. 

 The evolution of gas continues until the mixture finally sets to 

 a solid mass. By crystallization from ether long sulphur-yellow 

 prisms are obtained, melting at 119 — 120° C. The substance 

 distils unchanged at atmospheric pressure. 



On treatment with aqueous potash the substance dissolves, 

 giving in solution potassium thiophenolate and potassium oxalate, 

 the colour disappearing. 



This behaviour, coupled with the mode of formation, indicates 

 that the substance is diphenyl-dithio-oxalate, formed according to 

 the equation 



2C6HbSH + (COCIX = (COSCeHs)^ + 2HC1. 



On combustion '2857 gms. of the substance gave '6402 gms. of 

 CO2 and -0951 gms. of H^O. 



Observed percentages C 61*12 H 3"70. 



Calculated for diphenyl-dithio-oxalate C 61"31 H 8"85. 



The substance is the first member of the class of dithio-oxalates, 

 and is interesting by reason of its colour (which is undiminished 

 by heating in ethereal solution with animal charcoal or by repeated 

 recrystallization), since diphenyl oxalate and monothioxalic esters 

 are colourless, while glyoxal is yellow. 



