Description
Borazole (borazine) is a colourless liquid with an aromatic smell. With water, it decomposes
to form boric acid, ammonia, and hydrogen. The reaction product of boron and
ammonia at high temperatures is also known as inorganic benzene.
Chemical Properties
inorganic analog of benzene; colorless liquid; preparation: heating equimolar mixture of ammonia and BH3 at 250°C–300°C for 30min [MER06] [HAW93]
Uses
Borazine can be useful in the study of structural stability and the low-lying singlet and triplet states of BN - n -acenes, n = 1-7.
Application
Films that were deposited thermally
from borazine vapor were found to be too reactive to be suitable for fabricating masks for X-ray
lithography. However, films containing
predominately cubic boron nitride, CBN
[10043-11-5], were deposited using ions extracted from a borazine plasma via an ion beam.
Very hard, adherent films were deposited on
ceramic, glass, stainless steel, etc. An
obvious practical application is the hardening of
tool surfaces to markedly extend their life.
A thermally deposited film of hexagonal BN
[10043-11-5], from B3N3Cl6 [19087-72-0] at
900 ℃, protected SiO2 tubes from halide corrosion.
A copolymer between 2,4,6-tributylborazine
[7325-06-6] and an unsaturated N,N'-hexamethylenebiscarboxamide was useful for hardening epoxy resins.
Trichloroborazine was used as part of a catalyst mix for the polymerization of propene.
Flexible BN coatings on copper or copperbase alloys were formed from gaseous 2,4,6-
trichloroborazine. The films were stable to
700℃ in air.
General Description
Borazine can be prepared by
copyrolysis of NaBH4 and NH4Cl in a highboiling glyme, by reduction of trichloroborazine, or by pyrolysis of
ammonia borane in diglyme.
A large body of literature exists on the preparation and chemistry of symmetrically and unsymmetrically substituted borazines. B-Substituted trihaloborazines, readily prepared
from BX3 and NH4Cl, react with Grignard reagents to give symmetrical trialkyl- or triarylborazines. Symmetrically substituted N-trialkylor N-triarylborazines are readily prepared from
LiBH4 and RNH3Cl, or by pyrolysis of
RNH2BH3.
Borazine is thermally stable at 0 C, but decomposes slowly at ambient temperature. Borazine hydrolyzes slowly, but trihaloborazines
hydrolyze quite rapidly. Hydrogen halides form
1 : 3 adducts with borazine, which decompose to
trihaloborazines on warming.
