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Colclough, Terence (1955) Interaction of boron trichloride with phenols. Doctoral thesis, Northern Polytechnic.
The preparations of triaryl borates from the phenol and either boron trichloride or boric acid are described. The advantages and limitations of these procedures are mentioned, and earlier work on the preparation of triaryl borates is reviewed. The essential differences between aryl boron compounds and the aliphatic analogues are discussed.
The preparation and influence of polar and steric factors on the formation of 1:1 and non-stoichiometric triaryl borate-amine addition compounds are discussed. Molecular models were used to explain steric effects, and as a result, it is proposed that singly ortho-substituted triaryl borates and their addition compounds can exist in isomeric forms, and intramolecular or B-strain is to be expected in boron compounds. An alternative explanation for the formation of isomeric addition compounds of tri-α-naphthyl boron is offered. Ammonia was found to be capable of forming ionic complexes with triaryl borates. The relative acid strengths of substituted triphenyl borates were investigated. Ethers and dialkyl sulphides were found to be incapable of forming addition compounds with triaryl borates.
Boron trichloride formed a 1:1 addition compound with nitrobenzene, but was unreactive towards diphenyl ether.
The aryloxylation of boron trichloride was stepwise, and the intermediate aryloxyboron chlorides readily dis- proportionated, for which a mechanism is proposed. o-Nitrophenyl dichloroboronite however is exceptionally stable and this is attributed to an intramolecular co ordinate link. The chloro-esters were characterized by the formation of stable 1:1 pyridine complexes.
Mixed alkyl-ary1 borates of the type (RO) B(OAr)2 have been prepared, and the instability of unsymmetrical boron esters discussed.
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