Trans-1,3-Cyclopentanedicarboxylic acid

Ethyl l-cyano-l,2-cyclopentanedicarboxylate (15.0 g) was hydrolyzed by refluxing with 75 mL concentrated HCl for 30 h. The ester dissolved completely, giving a light brown solution that deposited, on cooling, 5 g crude fran -l,2-cyclopentanedicarboxylic acid with a melting point at 155-158°C. This was converted into the pure trans acid by being heated to 160°C with 1 mL concentrated HCl in a sealed tube for 1 h. The pure tram acid melted at lerc. 

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