The use of isotopes indetermination of mechanism.

Example: Hydrolysis of esters; mechanism study using isotopes.

• The hydrolysis of an ester may involve C-O bond cleavage with acyl carbon or with alkyl carbon.

• By using water with heavier oxygen isotope 18O, the cleavage a would give 18O enriched acid while cleavage b would result in 18O enriched alcohol and unlabelled acid.

Hydrolysis of esters; mechanism.

• In general esters are found to yield 18O enriched acid indicating the cleavage of acyl carbon-oxygen bond.

• After this it has to be ensured that after the cleavage either acid or alcohol does not undergo its oxygen exchange.

• It has been confirmed not to be happening.

In studying the reaction mechanism, it is required to know at which stage a particular bond is breaking. Whether a particular bond is before or during the rate determining step. 

• Just by studying the kinetics of a reaction it is not possible to conclude about it.

• Use of isotopic elements of the atoms attached through the bond in question can help in providing certain information about the breking of the bond in question for the reaction under study