GB796135A - Improvements in or relating to polymers of unsaturated bicyclic compounds - Google Patents

Abstract

Compounds of the formula (1): <FORM:0796135/IV (b)/1> where X is -H or -CH3 are prepared by the removal of two molecules of H2 from a compound of formula (2): <FORM:0796135/IV (b)/2> where Z is Cl, Br, I, OH, or OCOR, where R is alkyl, preferably methyl. When Z is OH, dehydration may be carried out by heating in the presence of alumina, aluminium silicate, phosphoric acid on silica gel, or silica-alumina at 65-150 DEG C. When Z is halogen dehydrohalogenation may be accomplished by refluxing with alcoholic caustic alkali. When Z is acyloxy the compound is pyrolized at 450-550 DEG C. The compounds of formula (2) may themselves be prepared by hydrogenation, e.g. catalytic reduction with hydrogen over nickel or platinum oxide, of the corresponding 5,6-ethylenically unsaturated compounds. Such unsaturated compounds can be formed by a Dials-Alder condensation between cyclopentadiene-1,3 or 1-methyl cyclopentadiene-1,3 and maleic anhydride, a maleic diester or maleic or fumaric acid; the anhydride or diacid grouping can then be reduced with LiAlH4 to a 2,3-dimethylol grouping or esterified; the diester grouping can be transformed to dimethylol with hydrogen and chromite or with sodium and alcohol. The hydroxyl groups can then, if desired, be transformed to halide (e.g. with phosphorus triiodide or red phosphorus and iodine) or to ester groups by acylation (e.g. with acetic anhydride). Reduction of the 5,6-unsaturation can, if desired be accomplished prior to the formation of the methylol groups. Compounds having 5,6-unsaturation may also be conveniently prepared by a Dials-Alder condensation between cyclopentadiene-1,3 or 1-methyl cyclopentadiene-1,3 and a butane-2 derivative selected from: HOCH2.CH = CH.CH2OH, ClCH2.CH = CH.CH2Cl and RCOOCH2.CH = CH.CH2OCOR, where R is alkyl, preferably methyl. The compound of formula (2) in which Z is OH can also be prepared by the reduction of a 2,3-dimethylol - bicyclo - [2 : 2 : 1] - 2,5 - heptadiene, itself prepared by a Dials-Alder condensation between cyclopentadiene-1,3 or 1-methyl cyclopentadiene - 1,3 and 1,4 - dihydroxybutyne - 2. Dicyclopentadiene may be substituted for cyclopentadiene. In an example, dicyclopentadiene and 1,4-dihydroxybutene-2 are heated at 200 DEG C. for 8 hours to give 2,3-dimethylol-bicyclo-[2 : 2 : 1]-heptane-5 which was acetylated with acetic anhydride to the corresponding diacetate and the 5,6-unsaturation removed by hydrogenation using Adams' platinum oxide catalyst. The product was pyrolized by dropping into an atmosphere of nitrogen in an externally heated tube containing glass helices at 530 DEG C. The 2,3-dimethylenebicyclo-[2 : 2 : 1]-heptane was characterized by a Dials-Alder maleic anhydride adduct of melting-point 116-119 DEG C. The compounds of formula (1) may be polymerized (see Group IV (a)).ALSO:The two compounds represented by the formula <FORM:0796135/IV (a)/1> where X is -H or -CH3 (see Group IV (b)) may be polymerized in the presence of a free radical-yielding catalyst. They may also be copolymerized with 1,3-butadiene, isoprene, styrene, a -methyl styrene or chlorostyrene. They may for example be polymerized in aqueous emulsion at 40-60 DEG C. in the presence of potassium persulphate, or in bulk at 90-110 DEG C. in the presence of benzoyl peroxide. They may also be polymerized suspended in water with a monomer-soluble catalyst to give granules of polymer. In an example, 2,3-dimethylenebicyclo - [2 : 2 : 1] - heptane was polymerized at 50 DEG C. in aqueous emulsion, using sodium oleate as emulsifying agent and potassium persulphate and n-dodecyl mercaptan as catalyst system.