Carbon Dioxide → 3-Isopropenyl-2-methylene-1-methyl-cyclopentanecarboxylic acid

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Reaction Conditions

Reaction Steps

75 ml of dry tetrahydrofuran and 23 g of magnesium shavings are added to a round flask which is fitted with a stirrer, thermometer, dropping funnel and reflux condenser. Without stirring there is added thereto slowly (within 4 hours) a solution of 112.4 g of 1-methyl-2-chloromethyl-3-(prop-1-en-2-yl)-cyclopent-1-ene in 100 ml of tetrahydrofuran. The mixture is brought to 60°-65° for 1 hour and then cooled to -10°. A carbon dioxide stream is conducted through the solution, which is cooled to -10° C. The amount of carbon dioxide introduced is weighed; it amounts to 29.5 g. The mixture is left to stand at room temperature overnight. The mixture is then cooled to 10° C. and decomposed with 300 ml of a 10% hydrochloric acid solution. The acid solution is extracted with ether, the organic acid formed is taken up as the sodium salt (treatment with 10% sodium hydroxide) from the ether into the aqueous phase, which is washed with ether. After acidifying with 10% orthophosphoric acid, the mixture is extracted with ether and the etherial solution is dried over sodium sulphate. The solvent is evaporated and there are obtained 78.2 g (yield: 66%) of crude 3-isopropenyl-2-methylene-1-methyl-cyclopentanecarboxylic acid, which are recrystallized with hexane.

Provenance & Evidence