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Chloral is produced commercially by the chlorination of acetaldehyde in the presence of hydrochloric acid, producing chloral hydrate. Ethanol can also be used as a feedstock. This reaction is catalyzed by antimony trichloride: H 3 CCHO + 3 Cl 2 + H 2 O → Cl 3 CCH(OH) 2 + 3 HCl. The chloral hydrate is distilled from the reaction mixture.
Chloral hydrate is a geminal diol with the formula Cl 3 C−CH(OH) 2. It was first used as a sedative and hypnotic in Germany in the 1870s. Over time it was replaced by safer and more effective alternatives but it remained in usage in the United States until at least the 1970s. [ 4 ]
This reaction is accelerated at temperatures above about 60 °C. Other reactions occur, such as the self-ionization of water and the decomposition of hypochlorite at the cathode, the rate of the latter depends on factors such as diffusion and the surface area of the cathode in contact with the electrolyte. [9]
Another example is chloral hydrate, CCl 3 −CH(OH) 2, which can be formed by reaction of water with chloral, CCl 3 −CH=O. Many organic molecules, as well as inorganic molecules, form crystals that incorporate water into the crystalline structure without chemical alteration of the organic molecule (water of crystallization).
Melzer's reactions are typically almost immediate, though in some cases the reaction may take up to 20 minutes to develop. [2] The function of the chemicals that make up Melzer's reagent are several. The chloral hydrate is a clearing agent, bleaching and improving
DCA is prepared from chloral hydrate also by the reaction with calcium carbonate and sodium cyanide in water followed by acidifying with hydrochloric acid. [7] As a laboratory reagent, both DCA and TCA [8] are used as precipitants to prompt macromolecules such as proteins to precipitate out of solution. [9]
Typically these reactions would be conducted in the presence of a base which serves to absorb the HCl. Alkyl chloroformate esters degrate to give the alkyl chloride, with retention of configuration: ROC(O)Cl ' → RCl + CO 2. The reaction is proposed to proceed via a substitution nucleophilic internal mechanism. [3]
Similarly, the conversion of chloral (Cl 3 C)HC =O to chloral hydrate is strongly favored by influence of the trichloromethyl group . In some cases, such as decahydroxycyclopentane and dodecahydroxycyclohexane , the geminal diol is stable while the corresponding ketone is not.