The azo-group is particularly active, both the aliphatic and aromatic compounds being coloured.
Aromatic Nitro Compounds.-The aromatic nitro compounds are generally obtained by the direct action of nitric acid.
Cinnamic aldehyde ((3-phenyl acrolein), C6H5ï¿½CH: CHï¿½CHO, an unsaturated aromatic aldehyde, is the chief constituent of cinnamon oil.
His earlier work included an investigation of succinic acid, and the preparation of phenyl cyanide (benzonitrile), the simplest nitrile of the aromatic series; but later his time was mainly occupied with questions of technology and public health rather than with pure chemistry.
By the ancients the country was called regio romataica, from the abundance of aromatic plants which it produced.