Gattermann reaction bromination

The interesting research of Votocek, Zenisek 4 and Sebor 5 may also be referred to in this connection. This permits the Sandmeyer-Gattermann reaction (substitution of the diazo-group by chlorine and bromine) to be carried out electrolytically. For this purpose the diazotized solution of the amine is electrolyzed —for instance 50 g. aniline, 120 g. HC1, 38.5 g. NaN02—between copper electrodes with addition of cuprous chloride or copper sulphate. At the end of the experiment (ceasing of the nitrogen... 

Amino groups at the 3-, 4-, 5-, or 6-positions in pyridazine 1-oxides have been successfully replaced by chlorine or bromine in the Gattermann reaction, but yields of 3-chloro (or bromo) derivatives are low. As there are no other suitable methods, this reaction provides the most convenient synthesis of 5- and 6-halo-pyridazine 1-oxides. In this manner 3-, 4-, 5-, and 6-bromopyridazine... 

Earlier work is discussed in Ref. 2 (p. 308). b With molecular bromine, unless slated otherwise. c Gattermann reaction. d Vilsmeier-Haack. Contrast... 

Karrer introduced cyanogen bromide in place of HCN in the Gattermann reaction in 1919 and prepared resorcinol- and phloroglucinaldehyde in unspecified yields. The excess aromatic substrate acts as a bromine acceptor in the reaction (Eq 1.18). ... 

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