Konigs, expressed the opinion that the alkaloids were derivatives of pyridine or quinoline.
Hofmann had shown that conine on distillation with zinc dust gave a-propyl pyridine (conyrine).
This view has been fairly well supported by later discoveries; but, in addition to pyridine and quinoline nuclei, alkaloids derived from isoquinoline are known.
In the first category there are two varieties: - (T) A mixture of ioo litres of spirit and 22 litres of a mixture of 4 parts of wood-naphtha and 1 of pyridine bases; this spirit, the use of which is practically limited to heating and lighting purposes, may be mixed with 50 grs.
The crystallized anthracene is then removed by a centrifugal separator and the process of solution in the pyridine bases is repeated.
Formulae have been proposed by Pschorr and Knorr explaining this and other decompositions (in Pschorr's formula the morphine ring system is a fusion of a phenanthrene and pyridine nucleus); another formula, containing a fusion of a phenanthrene with a pyrrol ring, was proposed by Bucherer in'1907.
The amount of eugenol in oil of cloves can be estimated by acetylation, in presence of pyridine (A.
The ketoketenes are coloured compounds, which undergo autoxidation readily, form ketene bases on the addition of pyridine and quinoline, and yield addition compounds with substances containing the C:N and C:0 groupings.
Moissan, contains only a trifling amount of morphia, and the effect produced by it is apparently due, not to that alkaloid, but to such decomposition products as pyrrol, acetone and pyridine and hydropyridine bases.
The subjoined table shows the chief homologues of pyridine: Pyridine carboxylic acids are usually prepared by oxidizing the homologues of the base; they also result as decomposition products of various alkaloids.