Solubility of Hydrogen Halides in Nonaqueous Liquids

An outstanding point which emerged from my early work on the interaction of hydroxy compounds and inorganic nonmetal halides, such as thionyl and phosphorus halides, was the vital function of the hydrogen halide formed in the reaction pattern. The interaction of hydrogen halides with alcohols, esters, and ethers has also operational importance. 

Of particular significance is the reactivity of the carbon-oxygen bond, e.g., 

The interaction of hydrogen chloride with an alcohol such as n-butanol, which I have always looked upon as a convenient standard for reference, appears to entail a reversible interaction followed by an irreversible one resulting in the formation of an alkyl chloride  

By some mechanism or mechanisms. Cl becomes detached from hydrogen and attached to the carbon atom by a severance of the C—O bond. Little or no success has attended attempts to determine the mechanism by kinetic studies on these systems. The last step is not kinetically reversible. The water formed competes with the alcohol for the hydrogen chloride, and therefore the formation of alkyl chloride virtually stops before all the alcohol has been converted into alkyl chloride. This is not because of the reversibility wrongly depicted in the textbooks as 

It is because there is insufficient hydrogen chloride to keep the alcohol in the necessary hydrogen-bonding condition. One mole of n-butanol will quickly absorb about 1 mole of hydrogen chloride at 0°C, but the maximum (by no means 100%) production of n-chlorobutane is achieved only at the end of several months. At -30°C, 1 mole of n-butanol will absorb about 1.5 moles of hydrogen chloride at 1 atm, and when the tube is sealed and allowed to stand at room temperature, the production of alkyl chloride is quicker and reaches almost the 100% amount. Now for an alcohol such as 2,2,2-trichloroethanol, the solubility of hydrogen chloride is very small at 0°C. Consequently, the initial concentration of ROH2CI is very small, and one would expect the instantaneous rate to be small, in contrast to that of the n-butanol system. But what of the specific rate For details of such systems, see the 

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