Benzoyl, the radical of the benzoic series, represented by the formula , is a hypothetical substance supposed to exist in benzoic acid and many other bodies. Thus, benzoic acid, from this point of view, is regarded as hydrate of benzoyl, , and the oil of bitter almonds as the hydride of benzoyl, . As further examples of this group of bodies, we may mention benzoyl chloride, , and benzoyl cyanide, . Dibenzoyl ()2, or benzoyl, as it is sometimes called, may be looked on as the above-mentioned radical in the free state, and is prepared by the action of sodium amalgam on benzoyl chloride, in small colourless prisms, soluble in alcohol and ether.
HYDRIDE OF BENZOYL is the volatile or essential oil belonging to the benzoic series. It is represented by the formula , and has been already considered under ALMONDS, VOLATILE OIL or ESSENTIAL OIL of (q.v.).