By application of the refractive-index method of detecting complex formation in solution to over one hundred systems in various solvents the following conclusions are reached. The hydroxyl group in alcohols is monofunctional in hydrogen-bond formation and when present on vicinal carbon atoms in an aliphatic chain it forms weak five-membered chelate rings ; consequently only one end-group in, e.g., glycerol or mannitol, is normally available for intermolecular bonding. I n aldehydes a variety of reactions demonstrate that the aldehyde group probably forms inter-and intraiiiolecular bonds through its hydrogen atom.In aqueous solutions of carbohydrates the open-chain form of glucose or cellobiose, in presence of certain other solutes, such as pyridine or amines, is stabilised by hydrogen-bond interaction of the aldehyde group ; the hydroxygroups are inactive because of solvation by water, though they are active in ethylene glycol solution. In aqueous solutions the hydroxy-groups are less reactive in the ring than in the open-chain forms of the simple carbohydrates and in the ring forms they do not combine with other solutes, even phenol. The bearing of these facts on the adsorption behaviour of cellulose is discussed.The keto-group of ketones behaves bifunctionally and the quinone oxygen atom of quinones monofunctionally ; ketones do not however form intermolecular complexes in benzene, ether, or water solutions. In nonaqueous solvents water appears to act either bifunctionally, probably by cross-linking, or monofunctionally in forming hydrogen-bond complexes with second solutes.
Studies an Hydrogen-bond Formation. Part I I . 67 Added in Proof.-This change in the curve has now been c o n h e d by use of a refractometer of higher precision.
The lake-forming reactions of the oxidised and reduced forms of the logwood and brazilwood colouring matters with the more important mordanting metals have been investigated. The oxidised forms appear t o be the lake-forming species, the o-hydroxyquinone system of the molecule chelating with the mordanting metal atom; the leuco forma must first be oxidised by air or the mordanting salt before lake formation can take place. When a chromate or a dichromate is used tw mordant, this is first reduced to the chromic cation, at the expense of the total destruction of some of the colouring matter, before lake formation occurs.The logwood oplouring matter, when treated with a chromium salt in solution or on the fibre, forms a deep blue 2 : 1 (dye : metal) complex, which is preceded by a transient purple 1 : 1 complex. Aluminium, cobalt, and (ferric) iron also form 2 : 1 complexes, and copper appears to form E 1 : 1 complex.
An oxidative method of semi‐micro analysis suitable for nitrogen in dyes is described. The results with a representative number of different types of azo dye and some members of other classes agree closely, for the majority of the dyes examined, with those obtained by titanous chloride analysis, and the new method has the advantage of being simple, rapid, and clean in use. The procedure involves measurement of the volume of nitrogen produced on boiling the dye with a dilute solution of potassium dichromate and sulphuric acid.
A still simpler, colorimetric method of determining water‐soluble azo dyes uses ceric, sulphate oxidation. It is useful for some dyes, but many do not react in simple proportion with the oxidant.
A colorimetric method for the determination of the purity of coupling components for azo dyes is also described. This procedure is simpler than the usual method of diazo titration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.