Since the molecule contains an asymmetric carbon atom, the acid exists in three forms, one being an inactive "racemic" mixture, and the other two being optically active forms. The inactive variety is known as paramandelic acid.
Their constitution follows from their formation from dibromosuccinic acid and from their synthesis from glyoxal cyanhydrin, these two methods producing the inactive racemic form which may then be split into the active components.
By mixing equal quantities of the two forms in aqueous solution heat is evolved and racemic acid, (C4H606)2.2H20, is obtained.
The a-propyl piperidine so obtained is the inactive (racemic) form of conine, and it can be resolved into the dextroand laevo-varieties by means of dextro-tartaric acid, the d-conine d-tartrate with caustic soda giving d-conine closely resembling the naturally occurring alkaloid.
The racemic trans-acid is produced by the reduction of the dihydrobromide of A 4 -tetrahydrophthalic acid or dihydrophthalic acid.