The Diazonium Method

As 2ArN2Cl-FeClj + AsClj + Fe ArAsClj + N2 + FeClj + FeCh 20 0 (15, 32) 

If I had worked up the mixture (as I subsequently did in 1959), diphenyl-bromonium (and diphenylchloronium) salts could have been reported some thirty years before their actual discovery (4). 

But the diazo method still had its grip on me. Which metals, apart from mercury, could be subjected to the method To answer this, many years were to pass because simultaneously I was working on other problems of interest to me. Eventually, the method of synthesis was extensively developed for aromatic derivatives of such elements as Hg, Tl, (Ge), Sn, (Pb), As, Sb, Bi. For the metals in parentheses the method was shown to just work, while for the others it is an excellent preparative procedure. In Table I the best versions are exemplified. At the same time, I and the first generation of my disciples, and also other scientists, applied the method to various organomercurials substituted at the aromatic nucleus (19-21), and to the naphthalene (22), triphenylmethane (23), and pyridine (24) series. 

This work was initiated in 1927, and in 1953 the last paper of the series was published. Intermittently, other related investigations were accomplished. Here, I would like to mention the reaction of aliphatic diazo compounds with mercuric chloride. The reaction of methylamine with mercuric chloride under the conditions of the diazo method was unsuccessful. Instead of the methylmercuric chloride expected, the synthesis gave negligible amounts of chloromethylmercury chloride, a compound obtained by Hellerman from mercuric dichloride and diazomethane in good yield. With diazoacetic ester, the compound (ClHg(Cl)y—C(=0)0C2H5 2Hg 

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