The thesis reports the Lewis acidic properties and new reactions of borate esters
and some related chemistry. In particular an investigation of the reaction between (CH₃O)₃B₃O₃ and Si(OCH₂CH₃)₄. Products were identified as borosilicate glasses by IR, ¹H, ¹¹B, ¹³C and 29Si NMR, 11B and ²⁹Si MAS NMR, elemental analysis and powder XRD, and a possible reaction mechanism is described. Under similar conditions crystalline metal dioxides of titanium and zirconium were obtained from the metal tetra alkoxides.
The synthesis of 8 orthoborate, B(OR)₃ {R = CH₂CH₂Cl, CH₂CH₂CH₂Cl,
CH₂CH₂CH₂CH₂Cl, CH₂CHCl₂, CH₂CCl₃, CH₂CH₂Br, CH₂CH₂I, CH₂CF₃} and 6
metaborate, (RO)₃B₃O₃ {R = ClCH₂CH₂, ClCH₂CH₂CH₂, ClCH₂CH₂CH2CH₂,
Cl₂CHCH₂, Cl₃CH₂ and CF₃CH₂} esters are reported. The Lewis acidities were
determined by Gutmann's Acceptor Number method and a correlation with Taft's
substituent parameter was obtained. The orthoborate, B(OCH₂CF₃)₃, and the metaborate, (ClCH₂CH₂CH₂CH₂O)B₃O₃, were shown to initiate for epoxide polymerisation of PGE and PY306. The Lewis acidity of tris(pentafluorophenyl)boroxine was also determined and its 1: 1 adducts with TEPO and 4-picoline were prepared. The effectiveness of
tris(pentafluorophenyl)boroxine and metaboric acid as Oppenauer oxidation catalysts has also been discussed.
A series of 9 previously unreported cyclo-boratetrasiloxanes, Me₆Si₃O₄BR {R =
2-CH₃C₆H₄, 3-CH₃C₆H₄, 4-CH₃C₆H₄, 3-CH₃OC₆H₄ , 4-CH₃QC₆H₄, 2-BrC₆H₄, 3-BrC₆H₄ , 4-BrC₆H₄ and CH₃CH₂CH₂CH₂} were prepared and the Lewis acidities of selected examples has been determined by Gutmann's Acceptor Number method.
The reaction between mono- and diisocyanates with metaborate esters leading to boroxine carbonate esters is described. The nature of the polymers and gels formed has been investigated. The products were hydrolytically unstable and hydrolysis products were characterised as the corresponding carbamates and B(OH)₃.