Salicylic Aldehyde 156

Salicylic aldehyde (ohydroxybenzaldehyde) has been found in the oils of Spiraea (S. Ulmaria, S. Filipendula, S. digitata, S. lobata), in the leaves of Homalium tomentosum, in Cordia asperrima (?), and in the oil of Crepis foet/da.

Formerly it was obtained by the oxidation of saligenin prepared from willow bark. At present it is produced according to the well-known synthesis of Reimer and Tiemann1) by the action of chloroform and aqueous alkali on phenol.

According to Perkin,2) salicylic aldehyde boils at 197°. Its sp. gr. is d15o 1,1698. In the ordinary solvents it is readily soluble, and but slightly in water. The latter solution is colored a deep violet by ferric chloride.

For the purpose of isolating salicylic aldehyde, its phenol nature (solubility in alkali) as well as its aldehyde character

1) Berl. Berichte 9 (1876), 824.

2) Journ. chem. Soc. 69 (1896), 1200.

(acid sulphite addition product) can be utilized. When reduced it yields saligenin, m. p. 86°, when oxidized salicylic acid, m. p. 155 to 156°. The oxime melts at 57°, the phenyl hydrazone at 96°. Salicylic aldehyde is of special importance as the starting point in the manufacture of coumarin.