Am'ides — Chambers's Encyclopaedia

Am'ides was the name originally applied to a group of organic compounds, derived from ammonia, $\text{NH}_3$ , or $\text{NHHH}$ , by the exchange of one or more atoms of hydrogen for a corresponding number of atoms of a metal or a compound radical. At present, the term amide is restricted to the case in which one or more atoms of hydrogen are replaced by an acid radical, and the amides are called primary, secondary, or tertiary, according as one, two, or all three of the atoms of hydrogen are replaced by the acid radical. The primary amides may be obtained in various ways, of which we shall mention two: (1) If we heat an ammoniacal salt, two atoms of water are given off, and the amide corresponding to the acid is left; thus, acetate of ammonia ( $\text{NH}_4\text{O}\cdot\text{C}_2\text{H}_3\text{O}$ ) - water ( $\text{H}_2\text{O}$ ) = acetamide ( $\text{C}_2\text{H}_5\text{ONH}_2$ ). (2) If an anhydride is submitted to the action of ammonia, there are simultaneously formed an amide and an ammoniacal salt. Thus valerianic or valeric anhydride ( $\text{C}_5\text{H}_9\text{O}$ )₂O + ammonia ( $\text{NH}_3$ )₂ = valerate of ammonia ( $\text{NH}_4\text{OC}_5\text{H}_9\text{O}$ ) + valeramide ( $\text{C}_5\text{H}_9\text{ONH}_2$ ). The amides are, for the most part, capable of being obtained in a crystalline form, and are fusible volatile bodies. If, in place of an acid radical, a base radical replaces one or more atoms of hydrogen in ammonia, a class of compounds termed amines is formed. See ALKALOIDS.