Polymers of ortho‐vinylbenzaldehyde

Abstract

Ortho‐vinylbenzaldehyde has been prepared in a three‐step synthesis. Vacuum‐degassed monomer was polymerized with azodiisobutyronitrile initiator in bulk and in solution in 2‐butanone. The kp/kt1/2 value at 60°C is 4.7 × 10−2 L1/2 mol−1/2s−1/2. This is about twice the ratio for styrene. Chain transfer to monomer appears to be significant. Insoluble, crosslinked products were produced at high conversions, because of chain transfer to polymer. Tg of poly(ortho‐vinylbenzaldehyde) was found to be 142°C. Polymers made under N2 atmosphere often contained acetal groups. These can be produced by acid catalysis in the presence of small concentrations of ortho‐vinylbenzyl alcohol. A laddertype structure is produced. The monomer is capable of photoinitiation. Insoluble gels were produced in bulk monomer at all conversions. The initiation rate was very high and crosslinking resulted from combination of radicals produced from photolysis of the pendant 0‐benzaldehyde groups in the macromolecules.

Unexpectedly Facile Rh(I) Catalyzed Polymerization of Ethynylbenzaldehyde Type Monomers: Synthesis of Polyacetylenes Bearing Reactive and Easy Transformable Pendant Carbaldehyde Groups

“…To the best of our knowledge a direct polymerization of (ethynylarene)carbaldehydes has not been described. The reasons may be the following: (i) The monomers containing unprotected carbaldehyde groups like vinylbenzaldehydes can be polymerized smoothly by radical polymerization . This type of polymerization, however, is not applicable for arylacetylenes because of delocalization of the charge of the active species along the growing conjugated polyacetylene chains.…”

“…The reasons may be the following: (i) The monomers containing unprotected carbaldehyde groups like vinylbenzaldehydes can be polymerized smoothly by radical polymerization. [21][22][23] This type of polymerization, however, is not applicable for arylacetylenes because of delocalization of the charge of the active species along the growing conjugated polyacetylene chains. (ii) The coordination polymerization of (ethynylarene)carbaldehydes for which the Rh-based catalysts might be suitable for their tolerance to heteroatom groups seemed to be disqualified by the experiments from Ogawa in 1995.…”