Our knowledge of the alkyl hypochlorites begins with the work of Sandmeyer (1) in 1885 who prepared methyl hypochlorite by chlorinating a mixture of
alcohol and sodium hydroxide. The esters are relatively insoluble in water, and separate as yellow oils, unstable towards heat and light and
possessing very irritating odors. Very recently Chattaway and Backeberg (2) described other hypochlorite including the various isomeric propyl,
butyl, and amyl hypochlorites. They found that the hypochlorites of tertiary alcohols are much more stable then those of the corresponding primary
and secondary alcohols.
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The unstable nature of the pure material made is unsuitable for use in a technical process, but it was found that a solution of the ester in carbon
tetrachloride, or any other solvent immisible with water, was stable for several hours below 25C.
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Twenty to 25 g of precipitated chalk or ground limestone is added to a liter of water and the mixture chlorinated with stirring until about 25 g of
chlorine has been absorbed. With this excess chalk, the available chlorine is present almost entirely as hypochlorous acid. The excess of carbonated
is filtered off and the filtrate shaken immediately with and equal volume of carbon tetrachloride containing about 2% or more of ethyl alcohol. About
two minutes shaking is sufficient to cause reaction between hypochlorous acid and alcohol to such an extent that the greater portion of chlorine is
removed as ethyl hypochlorite from the water to the solvent layer which can then be separated.
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A pure solution of ethyl hypochlorite in carbon tetrachloride made in this way lost only 10% of the available chlorine on standing for two days at 20C
in the diffused light of the laboratory.
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Such a solution of ethyl hypochlorite liberates iodine quantitatively form potassium iodide and acetic acid. It reacts rapidly with phenol, aniline,
methylaniline, sodium picrate and similar easily oxidized substances and in general shows most of the reactive properties of hypochlorous acid. When
ethylene is passed into a mixture of ethyl hypochlorite, slightly acidified water and carbon tetrachloride, absorption occurs with the probable
formation of ethylene chlorohydrin, which dissolves in the carbon tetrachloride. We did not, however, carry out this experiment to the point of
isolating the chlorohydrin.
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Ethyl hypochlorite decomposes on standing, giving high yields of ethyl acetate, probably by the following steps:
C2H5OCl ----> CH3CHO + HCl
CH3CHO + C2H5OCl ----> CH3COOC2H5 + HCl
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Ethyl hypochlorite reacts with alkali to form alkali hypochlorite free form chlorides.
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The constitution of the ethyl hypochlorite has been shown by our work to be that of a true ester. The oil was prepared by the method of Sandmeyer,
washed with sodium bicarbonate solution and dried with calcium chloride. It was kept in the dark at 0C during analysis. Six different determinations
of chlorine content were made, of which the average value is 44.13% as compared with the calculated value of 44.05.
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If the substance had been a double compound of one molecule of alcohol to one of acid, EtOH.HOCl, the molecular weight would have been 98.5. This
shows that the compound which we have assumed to be ethyl hypochlorite is a true ester. Although, as we will show below, hypochlorite is largely
hydrolyzed in water, its insolubility in water permits esterfication by removing the reaction product from the water phase. Solvents aid in this
removal of ester from water, giving even greater yields of ester then when no solvent is used.
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We investigated the formation of hypochlorous acid esters of various alcohols by the method which Sandmeyer used for preparing ethyl and methyl
hypochlorite. Yellow, insoluble, unstable oils were obtained with propyl, isopropyl, sec.butyl, tert.butyl, isoamyl, sec.amyl, and tert.amyl
alcohols. Benzyl alcohol is oxidized to benzaldehyde by hypochlorous acid. Glycerol, glycol and ethylene chlorohydrin gave no appreciable amounts of
insoluble oil. |