Many cyclic ketones are known, and in most respects they resemble the ordinary aliphatic ketones (see Polymethylenes; Terpenes).
These formulae, however, only apply to aliphatic amines; the results obtained in the aromatic series are in accordance with the usual formulae.
This is obviously unsymmetrical, consisting of an aliphatic and an aromatic nucleus; Claus explained the formation of the same phthalic acid from the oxidation of either nucleus by supposing that if the aromatic group be oxidized, the aliphatic residue assumes the character of a benzene nucleus.
Meyer, which are formed when nitrous acid acts on primary aliphatic nitro compounds.
We now proceed to discuss the types of aliphatic compounds; then, the characteristic groupings having been established, an epitome of their derivatives will be given.
The aromatic aldehydes resemble the aliphatic aldehydes in most respects, but in certain reactions they exhibit an entirely different behaviour.
On the other hand, they are much weaker bases than the aliphatic amines, their salts undergoing hydrolytic dissociation in aqueous solution.
The introduction of hydroxyl groups into the benzene nucleus gives rise to compounds generically named phenols, which, although resembling the aliphatic alcohols in their origin, differ from these substances in their increased chemical activity and acid nature.
Hantzsch (Ber., 1889, 22, p. 1238) succeeded in ob R taining derivatives of o-diketo-R-hexene, which yield R-pentene and aliphatic compounds on decomposition.
For example: nitric acid and sulphuric acid readily react with benzene and its homologues with the production of nitro derivatives and sulphonic acids, while in the aliphatic series these acids exert no substituting action (in the case of the olefines, the latter acid forms an addition product); another distinction is that the benzene complex is more stable towards oxidizing agents.