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Charalambous, John (1962) Interaction of boron halides with organic compounds of sulphur containing oxygen. Doctoral thesis, Northern Polytechnic.
The literature on the preparation and properties of di-esters of sulphuric acid and esters of chlorosulphuric acid is comprehensively reviewed to the end of 1961. n-Propyl, n-butyl, and n-octyl sulphate reacted with boron trichloride in n-pentane to give alkyl chloride (mainly s-RCl) and a yellow precipitate approximating to the mixed anhydride (B₂S₃O₁₂)n. Methyl and ethyl sulphates did not react with boron trichloride in the presence of methylene chloride. In the absence of solvent boron trichloride reacted with each of four dialkyl sulphates (alkyl = Me, Et, Prⁿ, Buⁿ) to give alkyl chloride (mainly s-RCl from Prⁿ and Buⁿ), hydrogen chloride, sulphur dioxide, and a solid residue having S-O-B linkages. Phenyl sulphate did not react with boron trichloride. Methyl or phenyl chlorosulphate did not react with boron trichloride, but the ethyl, n-propyl and n-butyl compounds did so violently, even at -80°, giving sulphur dioxide, hydrogen chloride, and a brown (hydrocarbon polymer) residue; only the ethyl compound gave the alkyl chloride. Interaction of boron trichloride with alkyl esters of alkane- and arene-sulphonic acids involves the elimination of alkyl chloride and the formation of alkane- or arene-sulphonyl dichloroborinate, RSO₂OBC1₂. During the elimination of alkyl chloride, considerable skeletal rearrangement, where possible, occurred. The sulphonyl dichloroborinates afforded on pyrolysis boron trichloride, boron oxide and the corresponding sulphonyl chloride. Reactions of alkyl sulphonates, in excess, with boron trichloride revealed that only the two chlorine atoms of the latter are replaceable. In contrast, 2-chloroethyl p-toluenesulphonate and boron trichloride afforded p-toluenesulphonyl chloride and chloroesters of boron. Phenyl p-toluenesulphonate did not react with boron trichloride. Methyl methanesulphonate reacted with methyl dichloro borinate to give methyl chloride and methanesulphonyl metaborate. n-Butyl p-toluenesulphonate and n-butyl dichloroborinate behaved similarly, but there was no reaction between n-butyl p-toluenesulphonate and di-n-butyl chloro boronate. The results obtained are compared with those of other systems and possible reaction mechanisms are suggested. The experimental work also included the preparation of phenyl sulphate and aryl chlorosulphates, and the original examination of the infrared spectra of six alkyl esters of alkane- and arene-sulphonic acids, of three di-esters of sulphuric acid and of six esters of chlorosulphuric acid.
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