Ladenburg rearrangement

Quinolinium 2-dicyanomethylene-1,1,3,3-tetracyanopropanediide dimensions, 2, 110 Quinolinium iodide, 1-alkyl-Ladenburg rearrangement, 2, 300 Quinolinium iodide, 1-methyl-Ladenburg rearrangement, 2, 300, 335 Quinolinium iodide, [l-methyl-4-[3(5)-pyrazolyl]-blood sugar level and, 5, 291 Quinolinium perchlorate, 1-ethoxy-hydroxymethylation, 2, 300 Quinolinium perchlorate, 1-methyl-nitration, 2, 318 Quinolinium salts alkylation, 2, 293 Beyer synthesis, 2, 474 electrophilic substitution, 2, 317 free radical alkylation, 2, 45 nitration, 2, 188 reactions... 

Alkylquinolinium iodides also undergo the Ladenburg rearrangement. 1-Methylquinolinium iodide was found to yield, on heating, at 300 °C, a mixture that contained 2-, 4-, 5- and 8-methylquinolines, and perhaps the 6- and 7-isomers as well (79UP20500). 1-Ethoxyquinolinium perchlorate may be hydroxymethylated by irradiation in methanol (equation 176) (69CPB2633),... 

Alkylpyridinium halides give mixtures of alkylpyridines on heating, e.g. (964) gives 2- and 4-picoline, with other minor products. This reaction is known as the Ladenburg rearrangement, and involves /V-alkyl bond homolysis. 

Ladenburg rearrangement. Thermal rearrangement of an alkyl- or benzylpyridinium halide to an alkyl- or benzylpyridine. 

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