Demonstration of cyclopentane derived from adipic acid

Chemicals needed

adipic acidGSGESUND.gif (476 Byte) Xi    R36    S (2)

barium hydroxide (or octa-hydrate) GSATZEND.gif (935 Byte) C    R 20/22-34    S 26-36/37/38-45

Equipment needed

two test tubes (one big, one small)
rubber plug with hole and bent glass tube
stand with sleeve and clamp
alcohol burner

Test procedure



As can be seen from the above formula row, 2-cyclopentancarboxylic acid is produced from adipic acid via ester condensation. This is, as is typical for -keto acids, very susceptible to the loss of carbon dioxide. To be precise, it is the respective barium salt which, of course, reacts under the chosen reaction conditions. That the ester condensation does not lead to polymers is easily explained by the fact that on the one hand a particularly stable five-membered ring is formed by the intramolecular reaction and on the other that the involved atoms necessarily (favorably) lie close to one another in the intramolecular reaction. One compares this with the behavior of other dicarboxylic acids.


Experimental apparatus before begin of the reaction.


Adaptation of a macro synthesis from Houben-Weyl (exact description momentarily not available).