Patent GB-973000-A (GB)
Title: Organic dimers and higher polymers containing boron-oxygen-boron linkages
Inventor: TURNER HAROLD SILAS
IPC: C08G79/08
Filed: 1961-09-15
Abstract: The invention comprises boron-containing dimers or higher polymers having a boron-oxygen-boron linkage obtainable by condensing under the influence of heat, one or more monomers of the general formula: <FORM:0973000/C1/1> where R is a tertiary alkyl group and each of X and Y, which may be the same or different, is an alkyl group, an aryl group or an aralkyl group or substituted alkyl, aryl or aralkyl group, or X when Y is an aryl group, is an alkoxy group, or X is an alkyl group, an aryl group or an aralkyl group and Y an alkyl group or an aryl group each of which contains a boron atom, e.g. (ButO)2B-C6H4-, and C6H5B(OBut)-C6H4-; or X and Y together with the group >B-O-R in which R is defined as above, form a fully or partly substituted borazole, e.g. a mono-, di- or tri-B-tert.-alkoxy borazole in which at least one alkoxy group is a tert.-alkoxy. The monomer may be refluxed at atmospheric pressure and boric acid may be used as a catalyst. For instance, (C6H5)2-B-O-But on heating gives the dimer (C6H5)2B-O-B(C6H5)2, and C6H5-B-(OBut)2 the dimer C6H5-B(OBut)-OB (OBut)-C6H5. A borazole <FORM:0973000/C1/2> gives <FORM:0973000/C1/3> where R is tert.-alkyl and the R1 groups are each substituted or unsubstituted alkyl, aryl or aralkyl. Continued heating gives rise to linear, branched or cross-linked polymers of formula: <FORM:0973000/C1/4> If intermediates are used containing on one boron atom a blocking group such as alkyl, aryl, substituted amino, alkoxy (other than tert.-alkoxy) or aryloxy, linear polymers are obtained. If two monomers are used which differ in respect of R1, a copolymer is obtained. In examples, (1) tri-B-tert.-butoxy-tri-N-methylborazole made from tri-B-chloro-tri-N-methylborazole and tert.-butanol using triethylamine as base, together with a dimer; (2) the monomer of (1) is heated to form a dimer and a polymer containing 7 borazole units; N-trimethyl-, N-tri-ethyl- and N-tri-n-propyl-B-tri-tert. butoxy borazole and made as in (1); (3) N-trimethyl -B-tri-tert.-butoxy borazole was refluxed with a few mgms of boric acid giving a dimer; (4) the N-triethyl and (5) the N-tri-propyl compounds are converted to the dimer; (9) di-t-butyl phenyl boronate is made from phenyl boron dichloride and tert.-butanol in the presence of triethylamine; the product is refluxed to form a linear dimer and trimer.ALSO:Polymers containing a boron-oxygen-boron linkage are obtainable by condensing under the influence of heat one or more monomers of the general formula <FORM:0973000/C3/1> where R is a tertiary alkyl group and the R1 groups are each a substituted or unsubstituted alkyl, aryl or aralkyl group and may be the same or different.  The first product is a dimer but continued heating gives linear, branched or cross-linked polymers fornulated from the units: <FORM:0973000/C3/2> If borazoles containing in place of one OR group a blocking group which may be alkyl, aryl, substituted amine, alkoxy (other than tert.-alkoxy) or aryloxy, linear polymers are obtained. The monomer is preferably heated at atmospheric pressure using boric acid as a catalyst.  In examples, N-trimethyl -b - tri-tert.-butoxy borazole is refluxed in the presence of boric acid, to form a cross-linked polymer. The N-triethyl and N-tri-n-propyl compounds give similar products.