Starch with chloral hydrate

Compounds other than steroids which give colours with this test include chloral hydrate and chloramphenicol (brown-yellow), starch, and tartaric acid (green). 

In his study of the properties of aqueous solutions of chloral hydrate as solvents for starch, Mauch describes the following results, (i) Starch dissolves in aqueous solutions of chloral hydrate containing at least 50 % by wt. of chloral hydrate, (ii) No dextrins can be found in these solutions and, hence, no degradation of the starch occurs, (m) Starch consists of at least two components (which he called amylogeen and amylodextrine ) and these components are present as separate entities in chloral hydrate solutions of starch, (iv) After dilution of the solutions with water, a precipitate is formed consisting of flat spherocrystals of the amylodextrine fraction. 

Unaware of these old findings, the present writer rediscovered the formation of complexes of chloral hydrate with amylose, and established its optimal conditions (Table II gives the critical region of concentration of chloral hydrate). Then, knowing the properties of chloral hydrate as a good solvent for starch, the development of a laboratory fractionation process became obvious. As, to date, no information regarding this work has been published, the details will be given here. 

Chloral hydrate may be reacted with starch to form a product soluble in cold water251 or a. clear antiseptic adheslve250 coacervate252, ... 

In preparing derivatives of whole starch, the granules are reacted directly only at the risk of extensive degradation. Consequently, it is desirable to swell or disorganize the granules by some type of pretreatment employing either water, aqueous chloral hydrate, aqueous pyridine, formamide, or alkali. A readily reactive form of whole starches or of the components is obtained by precipitation of their aqueous solutions with ethanol. 

Starch is a strongly hygroscopic, chemically neutral substance. It swells greatly in water, due to penetration of water molecules into its branched stracture. As mentioned above, long boiling makes it dissolve in water or in weak acids, as well as in solutions with hydroxides of potassium, rubidium, cesium, or francium and concentrated solutions of chloral hydrate. 

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