ORGANIC CHEMISTRY 543 



stable in the dark, but decomposes on exposure to light ; its solu- 

 tion in benzene is unstable even in the dark. It dissolves in 

 benzene to a yellow solution, and molecular weight determina- 

 tions in this solvent show that it exists as the simple molecule. 

 The solution reacts at ordinary temperatures quantitatively 

 with iodine, with the formation of lead tricyclohexyl iodide, 

 Pb(C6Hii)3l, which with potassium hydroxide gives the hydrox- 

 ide Pb(C6Hii)30H. This is converted into the chloride and 

 bromide by the corresponding halogen acids. On warming 

 lead tricyclohexyl iodide in benzene with iodine, lead dicyclo- 

 hexyl di-iodide, Pb(C8Hii)jl2, is formed, and the corresponding 

 dibromide is quantitatively produced by the action of bromine 

 in chloroform solution. By the action of magnesium cyclohexyl 

 bromide on lead tricyclohexyl bromide, lead tetracyclohexyl 

 is obtained. 



(3) Bismuth. Challenger and Allpress (Trans. Chem. Soc, 

 1 92 1, 119, 913) have published a further contribution to the 

 study of the tertiary aromatic bismuthines. In consequence 

 of the failures which accompanied many attempts to prepare 

 mixed aromatic bismuthines of the type BiR'R"2 and bis- 

 muthonium haloids, BiR'gR^X, by the action of magnesium 

 aryl haloids, the reaction of this reagent on halogen derivatives 

 of the type BiRgX, BiRXg, and BiRgXa has been more 

 thoroughly investigated. The action of magnesium-4-w-xylyl 

 iodide on diphenyl-chlorobismuthine and di-/)-tolyl-chlorobis- 

 muthine gave tri-phenyl- and tri-/)-tolyl-bismuthines re- 

 spectively. Similar results were obtained in a number of other 

 cases, the triarylbismuthine produced corresponding to the 

 halogen bismuthine employed. When, however, a large excess 

 of the Grignard reagent is employed, interchange of groups 

 seems to take place, a-naphthyldibromobismuthine with 

 six molecular proportions of magnesium phenyl bromide gives 

 triphenyl-bismuthine and diphenyl-a-naphthyl-bismuthine 

 in almost equal amounts ; and phenyl-dibromo-bismuthine 

 with five and a half molecular proportions of magnesium 

 a-naphthyl bromide gives much tri-a-naphthyl-bismuthine. 



(4) Mercury. An increasing amount of attention is being 

 paid to organo-mercury compounds, partly on account of their 

 pharmacological importance, and a number of papers have 

 been published recently, though not many are of much theo- 

 retical interest. In a long paper (Annalen, 1921, 424, 23) 

 Steinkopf continues his work on the mercury compounds oif 

 thiophen. In a previous paper (Annalen, 191 4, 403, 50) he 

 came to the conclusion that thiophens in which the 2 and 

 5 positions were unsubstituted gave mono- and di-mercuri- 

 chlorides, those in which one of these positions was substituted, 

 mono-mercurichlorides, and those in which both positions were 



