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Griffey, P. F. (1961) Interaction of boron trihalides and esters of phosphoric and phosphonic acids. Doctoral thesis, Northern Polytechnic.
Interaction of boron trichloride with each of eleven trialkyl phosphates (alkyl = Me, Et, Prn , Pri , Bun, Bui, Bus, n-pentyl, neopentyl sec.-octyl, 2-chloroethyl) first involves the formation of a complex (RO)3P=O, BCl3, at temperatures below 0°, and then elimination of alkyl chloride, olefin, and hydrogen chloride and formation of a network of -P-O-B-O- links giving a substance identical with , or closely related to the so-called boron phosphate, [BPO4]n. The elimination occurred approximately stepwise as the temperature was raised to 500° by stages, 120° (1 hr.), 180° (1 hr.), and 300° (1 hr.). The residue was heated in an open crucible to about 1000°, and the final residue (except when R = Me) contained practically all the boron and phosphorus in the system.
The bulk of the elimination of chlorine and alkyl group occurred during the first stage of heating. During the elimination of alkyl group, some rearrangement, where possible, in that group occurred especially during the second and third stage of heating. In the case of R = (+) sec.-octvl the sec.-octyl chloride produced was optically inactive. Olefin and hydrogen chloride are formed mainly in the second stage, except in the example of R = Bus. Thus the formation of carbonium ion is indicated.
In contrast, the slow decomposition of the complexes at 20° afforded unrearranged alkyl halide. The system R = (+) sec.-octyl gave (-) sec.-octyl chloride of high activity, while, significantly, the complex R = neopentyl was alone in being stable at this temperature.
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