Addition compounds definition

The function of the aluminium chloride is catalytic, and its amount is therefore independent of stoicheiometrical proportions. But since, in the ketone synthesis, a fairly definite complex addition compound with one molecule A1C1S, is formed, at least one mole must be used. 

Discovery by Bengen (7) that urea forms addition compounds with the aliphatic straight-chain hydrocarbons has opened new possibilities for the removal and separation from petroleum of such materials as waxes which are preponderantly nonbranched. Urea-wax addition compounds are apparently formed readily at ordinary room temperatures, and as these compounds have very definitely defined crystal structure (75), their separation should be easily accomplished. 

Many chlorides, especially those of the metals, combine with sulphur tetrachloride to produce unstable crystalline additive compounds 2 thus, iodine trichloride, antimony pentachloride, titanium tetrachloride, stannic chloride, ferric chloride, and also arsenic fluoride, yield crystalline products containing the added molecule SC14 this provides strong evidence of the definite existence of this chloride of sulphur. 

Many aromatic hydrocarbons, for example, benzene, ethylbenzene, toluene, cymene and tetrahydronaphthalene, yield additive compounds.5 Such are also formed with liquid cyclic hydrocarbons in the absence of moisture and phenols, and use has been made of this fact to remove sulphur dioxide from a dry gas containing it.6 Additive compounds are also formed with methyl alcohol, thus CH30H.S02 and 2CH30H.S02, the existence of which has been demonstrated definitely by means of the freezing-point curve.7 The additive compound with camphor has already been mentioned (p. 109). 

Definite compounds of niobium and iodine are unknown. The preparation of an iodide from the pentabromide has been reported2 but no details are supplied. A pyridine addition compound of the pentiodide, NbIB.(C5H5N.HI)6, has been described,2 but its existence lacks confirmation.4... 

Bismuth(III) oxide, Bi O is the compound produced by heating the metal, or its carbonate, in air. It is definitely a basic oxide, dissolving readily 111 acid solutions, and unlike the arsenic or antimony compounds, not amphiprotic in solution, although it forms stoichiometric addition compounds on heating with oxides of a number of other metals. It exists in three modifications, white rhombohedral, yellow rhombohedral, and gray-black cubical, Bismuth(II) oxide. BiO, has been produced by heating die basic oxalate. 

An addition compound is one that is formed by the junction or union of two simpler compounds. Effectively die same as a molecular compound (see definition on the following pagel. 

The fact that the co-ordination number for so many elements is six, and is generally independent of the nature of the co-ordinated groups, has made A. Werner suggest that the number is decided by available space rather than affinity, and that six is usually the maximum number which can be fitted about the central atom to form a stable system. Consequently, the co-ordination number represents a property of the atom which enables the constitution of molecular compounds to be referred back to actual linkings between definite atoms. A molecular compound is primarily formed through the agency of secondary valencies and, just as primary valencies determine the number of univalent atoms or their equivalent which can be linked to a central atom, so secondary valencies determine the number of mols. which can be attached to the central atom. The secondary valency is often active only towards definite mol. complexes, and hence the formation of additive compounds with other mol. complexes does not occur. Accordingly, the number of secondary valencies which are active towards different molecules is not always the same. 

This was determined by diluting the solution to hydrolyse the addition compounds. Precipitation of recovered a- trinitrotoluene gives the transient solubility (S3). By definition S2 = SrS3. 

If the viscosity curve is convex, the molecules of both components are polar. This increase in viscosity may also be explained by the electrostatic forces of attraction of the dipoles, which result in an increase of the viscosity. The occurrence of a maximum in the convex curve often corresponds to the presence of a definite additive compound of the components, the existence of which may be verified by other physico-chemical methods. 

From the time of his first paper on the coordination theory in 1893 30, 98), Werner had been aware of the role of the solvent in electrolytic dissociation and had insisted that hydration, i.e., aquation, preceded ionization. In his paper, Zur Theorie der Basen" (1907) 91), he applied this concept to his new definition of a base Any compound, which with water forms a hydrate which dissociates in aqueous solution into a complex positive ion and hydroxyl ions, is an anhydro base.. . . Aquo bases, or simply bases, are water addition compounds which in aqueous solution dissociate into hydroxyl ions." For example ... 

Vanadium(IV) oxy(acetylacetonate) is a blue to blue-green compound, crystallizing in the monoclinic system with refractive indexes of a, 1.520 0, 1.676 y, 1.739.7 The compound was originally believed to be a 1-hydrate but is now known to be anhydrous. It forms addition compounds with pyridine, methylamine, and other amines.8 Vanadium(IV) oxy(acetylacetonate) decomposes at elevated temperatures and has no definite melting point. The compound is soluble in ethanol, benzene, chloroform, and acetylacetone but is only moderately soluble in acetone or ethyl ether. 

It has been mentioned that addition compounds which consist of more than one zone are ionogens by definition or description, and that if the components in one zone are hydrogen or hydrated hydrogen, the compound is an acid. The hydrogen bearing this relation to the addition com-... 

The views so far presented in this chapter may be summarized as being based upon the primary formation of addition compounds when two or more molecules react, these addition compounds then breaking down to form new molecules. In catalytic reactions, the first stage of the reaction is the same, but. in the second stage, one of the substances formed in the breaking down of the intermediate compound is identical in composition with one of the substances which took part initially in the reaction in the formation of the addition compound. While the experimental evidence is favorable to this view of catalytic reactions in many cases, it may be objected that physical influences may often modify the velocity of the reaction between gases. At present there is no experimental evidence of any kind available to prove or disprove the formation of definite chemical compounds in such cases, but on the other hand, evidence is accumulating that adsorption (or perhaps the solution of a gas or a liquid in a solid) is the important factor here. Just how far phenomena of this nature may be identical with the formation of definite chemical compounds (possibly so-called loose combinations) on a surface is not at present certain, but until direct evidence is obtained that such reactions must be included in a... 

This reaction is particularly instructive, since the composition of the intermediate addition compound is perfectly definite. With equilibria (a) and (d) it is seen that the platinic chloride acts as the catalyst for the reaction (either formation or decomposition, depending upon the concentrations of the reacting substances) between ammonia, hydrogen chloride, and ammonium chloride. ... 

The infiuence of water on the reaction between ammonia and hydrogen chloride to form ammonium chloride may be taken up in the same way. Although very little is known of the way the water actually catalyzes the formation of ammonium chloride, the reaction considered in Chapter IV in the formation of tetraethylammonium iodide from triethyl amine and ethyl iodide in the presence of different solvents indicated the method of action of the catalyst. It was found that unsaturation of the solvent paralleled to a certain extent the increase in the velocity of the reaction. Ability to form addition compounds, intermediate or otherwise, seemed to be the controlling factor. Unfortunately, the composition of the intermediate addition compound is not so definite in the present case. In order... 

In a further generalization, Lewis [4] advanced a definition that was no longer restricted to proton-exchange reactions. An acid was defined as any substance that can accept a pair of electrons from a donor substance, and a base as any substance able to donate an electron pair and form a "dative" covalent bond. In these more general terms, the acid-base interaction includes the formation of covalent bonds and applies to any chemical reaction in which an addition compound (adduct) is formed through a coordinative bond ... 

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