Similarly a CH group may be replaced by a nitrogen atom with the production of compounds of similar stability; thus benzene gives pyridine, naphthalene gives quinoline and isoquinoline; anthracene gives acridine and a and 3 anthrapyridines.
This view has been fairly well supported by later discoveries; but, in addition to pyridine and quinoline nuclei, alkaloids derived from isoquinoline are known.
It may be separated from the quinoline which accompanies it by means of the difference in the solubility of the sulphates of the two compounds, isoquinoline sulphate being much less soluble than quinoline sulphate.
It may be prepared by passing Isoquinoline.
Numerous derivatives of isoquinoline are obtained in the decomposition of various vegetable alkaloids.