0 votes
15 views
ago in Organic Chemistry by (139k points)
What is the chemical reaction mechanism for the conversion of an alkene to an alcohol using acidic potassium permanganate as the oxidizing agent, and how does the functional group of the alkene change during the reaction?

1 Answer

0 votes
ago by (170 points)
The conversion of an alkene to an alcohol using acidic potassium permanganate  KMnO4  as the oxidizing agent is an example of an oxidative cleavage reaction. The mechanism for this reaction can be broken down into the following steps:1. Formation of the cyclic intermediate: The alkene reacts with the acidic potassium permanganate  KMnO4  to form a cyclic intermediate. This occurs through the transfer of one electron from the alkene double bond to the permanganate ion  MnO4-  and the formation of a bond between the manganese atom and one of the carbon atoms of the alkene. Simultaneously, one of the oxygen atoms from the permanganate ion forms a bond with the other carbon atom of the alkene. This results in the formation of a cyclic intermediate with a five-membered ring containing manganese.2. Cleavage of the cyclic intermediate: The cyclic intermediate is unstable and undergoes cleavage, breaking the carbon-carbon double bond. This is facilitated by the transfer of a proton from the acidic solution to one of the oxygen atoms in the intermediate. The cleavage results in the formation of two carbonyl groups  C=O  on the two carbon atoms that were initially part of the alkene.3. Reduction of the carbonyl groups: The carbonyl groups formed in the previous step are then reduced to hydroxyl groups  OH  by the reduced manganese species  Mn2+ . This is achieved through the transfer of a hydride ion  H-  from the manganese species to the carbonyl carbon, followed by the addition of a proton  H+  from the acidic solution to the oxygen atom. This results in the formation of two alcohol functional groups.In summary, the functional group of the alkene  C=C  changes to two alcohol functional groups  OH  during the reaction. The overall reaction can be represented as:R-CH=CH-R' + KMnO4 + H2O + H+  R-CH OH -CH OH -R' + Mn2+ + K+ + 2OH-
Welcome to Sarvan Science Q&A, where you can ask questions and receive answers from other members of the community.
...