1

I am confused in following reaction: $\ce{(CH3)2CH-CHO}$ when reacts with conc. $\ce{NaOH}$, will it undergo cannizaro reaction?

According to our professor, It can undergo both Cannizzaro as well as aldol condensation reaction.

If we consider aldol condensation, we get tertiary carbanion as intermediate, which is unstable and can be formed in thermodynamically controlled reaction, but the aldol is kinetically controlled .

Therefore, it undergoes Cannizzaro reaction also which is a thermodynamically controlled reaction.

Now, I know a thermodynamically controlled reaction means getting product that is stable and kinetically controlled means getting product which forms fast.

I am not able to understand how the Cannizzaro reaction being thermodynamically controlled helps.

Safdar Faisal
  • 7,010
  • 4
  • 26
  • 53
Hannah .
  • 445
  • 2
  • 11
  • 2
    The cannizaro reaction is only possible for molecules without an H-atom at the alpha position so an enol form is not possible.

    Your molecule has a alpha-H atom so it should not undergo carnizzaro and instead it will form the enol tautomer and undergo aldol condensation.

     – Inselino Apr 22 '21 at 07:20
  • @Waylander : see this , https://chemistry.stackexchange.com/q/65089/108706 it undergoes cannizaro, but what is role of thermodynamic and kinetic control has in it ? – Hannah . Apr 22 '21 at 07:43
  • Ok I see. So what exactly is your question? Two reaction pathes are avaible according to the link you provided (even thought it is more cannizaro-like because definition of cannizaro is explictly without a-hydrogen). Usally when you have two reaction paths, one is thermodynamicaly controlled, one is kinetic controlled. You can influence which way the reaction takes by changing things like temperature, reaction time, concentration etc. – Inselino Apr 22 '21 at 07:59
  • @Inselino : My question is how can we say a reaction for eg. Cannizaro reaction is thermodynamically controlled ?and how it being thermodynamically controlled makes its product major. – Hannah . Apr 22 '21 at 11:12
  • There is few good explanation given in here. Specially mechanism given by @user55119's answer. – Mathew Mahindaratne Apr 22 '21 at 13:17

0 Answers0