Copulated compounds

Some time ago I communicated some views on so-called copulated compounds and the theory of polyatomic radicals, whose further development and completion seems appropriate in order to prevent misunderstanding. 

The so-called copulated compounds, according to Kekuld s article by that name, are complex compoimds whose formulas did not fit at the time into any of the general schemes for constructing formulas. In his 1857 article he described how these formulas can be made rational by the combination of several type formulas, whether alike or unlike. The linking of unlike types by polyatomic radicals became known as the theory of mixed types. It was originated by Odling. 

Effect of Sulfuric Acid on Organic Compounds. The continuing controversy regarding the constitution and formation of the so-called sulfo acids, etc., makes it appropriate to discuss in somewhat more detail those reactions of sulfuric acid on organic compounds in which so-called copulated compounds are formed. 

In his conjugate theory, which used terms and ideas corps copule borrowed from Gerhardt, Jons Jacob Berzelius (1779-1848) viewed metal-ammines as conjugated or copulated compounds consisting of ammonia and a conjugate or copula. The conjugate cannot be removed by reaction with an acid, and it neither decreases nor increases the saturation capacity of a base, that is, a metal conjugated with ammonia can still combine with other substances. 

Before leaving Berzelius s later theoretical views something must be said of an important idea contained in them, viz. the presence in the same molecule of an active and an inactive part (see p. 368), which he had developed gradually. This was his theory of copulated compounds his last important theoretical paper attempted to extend this to the whole of organic chemistry and so... 

Sulphovinic acid (C2H5HSO4) is a copulated compound of ethyl sulphate and sulphuric acid ... 

In a modification of the rule proposed by Strecker the basicity of a copulated compound is the sum of those of the compounds minus half the number of atoms of water (HO = 9) removed or the basicity is diminished by one unit for each pair of hydrogen atoms removed. Beketoff, who found that such rules did not always give the right result, proposed a new one, but Kekule eliminated the idea of copulated compounds altogether and showed by several examples that these so-called laws are merely rules which are valid within certain limits, viz. for bodies or groups of bodies from which they are derived . 

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