I. SYNTHESIS AND POLYMERIZATION OF TWO NEW METHYLENECYCLOBUTENE ESTERS; II. MODEL COMPOUND SYNTHESIS FOR CARBON-13 NMR STRUCTURAL ELUCIDATION OF POLYBICYCLOBUTANE-1-CARBONITRILE.

Abstract

The two new compounds methyl 3-methylenecyclobutene-1- carboxylate and dimethyl 3-methylenecyclobute.ne-l,2- dicarboxylate were synthesized. The cycloadduct which forms between allene and acrylonitrile was used as the starting point for the synthesis of the former. This was chlorinated with phosphorus pentachloride, hydrolyzed with aqueous base, esterified with methanol and p-toluenesulfonic acid, and dehydrochlorinated with potassium hydride providing methyl 3-methylenecyclobutene-l-carboxylate. Chloromaleic anhydride was cycloadded to allene as the starting point for the synthesis of dimethyl 3-methylenecyclobutene-l,2-dicarboxylate. This cycloadduct was then hydrolyzed under basic conditions, esterified with diazomethane and dehydrochlorinated with 1,4-diazabicyclo[2.2.2]octane yielding dimethyl 3-methylenecyclobutene- l,2-dicarboxylate. Each of these new methylenecyclobutenes was then polymerized. Free radical homopolymerization proceeded in a 1,5 manner in each case yielding film forming polymers. Copolymers were also prepared from each using representative comonomers in free radical systems. Dimers of bicyclobutane-l-carbonitrile were prepared by the reaction of cyanocyclobutyl sodium with cyclobutane-l-carbonitrile and then chlorinated with phosphorus pentachloride. The ¹³C nmr spectra of the dimers and the chlorinated dimers were instrumental in showing that po1ybicyc1obutane-1-carbonitrile obtained either radically or anionically is formed primarily by trans 1,3 incorporation of the cyc10butane rings.