Ethylene → 7-Ethenylbicyclo[4.2.0]octa-1,3,5-triene

Participants

Reaction Conditions

Reaction Steps

The monomer is prepared by heating a mixture of 4-bromobenzocyclobutene with 4-vinylbenzocyclobutene at reflux. Vinylbenzocyclobutene is prepared by adding 0.98 g of 4-bromobenzocyclobutene, 0.04 g palladium (II) acetate, and 0.17 g of tri-o-tolylphosphine to a mixture of 100 ml acetonitrile and 0.6 g of triethylamine in a 450 ml Parr pressure reactor. The reactor is pressurized with 250 psig ethylene. The mixture is heated to 125° C. and stirred for 16 hours. The apparatus is cooled and the remaining ethylene is vented. The product is washed with water and 5 percent hydrochloric acid and dried over MgSO4. The solvent is removed to provide 4-vinylbenzocyclobutene. A 2.4 g sample of 4-bromobenzocyclobutene, 1.7 g of 4-vinylbenzocyclobutene, 2.4 g of tri-n-butylamine, 100 mg of tri-o-tolylphosphine, 29 mg palladium (II) acetate and 10 ml acetonitrile are added to a flask equipped with a reflux condenser, nitrogen inlet, and magnetic stirrer. The reaction mixture is heated to reflux under nitrogen for 4 hours. The solution is cooled to room temperature and stirred into 60 ml of 10 percent hydrochloric acid solution. The precipitate is collected by filtration, washed with water and air dried. The product is recrystallized from ethylacetate and has a melting point of 132° to 133° C.

Provenance & Evidence