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Pratt, David Edward (1962) The investigation of phenyl substituted borazoles. Doctoral thesis, Northern Polytechnic.
Interest in semi-inorganic polymers based on boron-nitrogen systems has prompted this work on borazole derivatives which have aromatic groups attached to boron or nitrogen.
The interaction of boron trichloride with primary aromatic amines in refluxing benzene or toluene has resulted in the formation of a series of B-trichloro-N-triarylborazoles (ClBNAr)3.
Pyrolysis of B-trichloro-N-triarylborazoles results in the formation of polymers with the elimination of hydrogen chloride. Polymers formed by pyrolysis below 500° are soluble in organic solvents, but are easily hydrolysed, those formed above 500° are stable towards hydrolysis but are intractable.
The interactions of B-trichloro-N-triarylborazoles with some primary aliphatic amines and ammonia have been performed and a series of B-tris(alkyl)amino-N-tri-p-bromophenylborazoles (RNHBN-p-BrC6H4)3 was prepared. N-triarylborazoles (HBNAr)3 were prepared by reduction of B-trichloro-N-triarylborazoles using lithium aluminium hydride and B-trimethyl-N-triarylborazoles (MeBNAr)3 were prepared by reaction of the B-trichloro compound with methylmagnesium iodide. B-trimethyl-N-triarylborazoles are hydrolytically stable. This is postulated as being due to the electron deficiency of the boron atoms being compensated by the hyperconjugative effect of B-methyl groups.
Arylboron dihalides, prepared by the interaction of boron trichloride with arylmercury chlorides, have been used to prepare B-triarylborazoles (ArBNH)3 and B-triaryl-N-trimethyl borazoles (ArBNMe)3, by reaction with ammonia and methylamine.
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