Organometallic compounds of Group II. Part VI. 1,2-Acenaphthenylenecalcium

Abstract

Mercury-activated calcium readily forms an adduct with acenaphthylene in tetrahydrofuran at –35°. Rapid carboxylation gives acenaphthene-trans-1,2-dicarboxylic acid as the only acidic product, whereas slow carboxylation produces two further isomeric diacenaphthyl dicarboxylic acids. One of these isomers has been obtained in dimorphic forms, the dimethyl esters of which are thermally interconvertible. An adduct of sodium with acenaphthylene has also been prepared and carboxylated to give acenaphthene-trans-1,2-dicarboxylic acid.

Excess of methanolic sodium methoxide converts acenaphthene-trans-1,2-dicarboxylic acid into a salt of the cis-isomer, whereas the same reagent catalyses the cis→trans epimerisation of the corresponding dimethyl esters.