I know that oxidation reactions involve the loss of hydrogen. But is the mechanism the same


closed as too broad by Waylander, aventurin, Mithoron, airhuff, Avnish Kabaj Jun 2 '18 at 15:45

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  • $\begingroup$ That rather depends on what oxidation or reduction conditions you are considering $\endgroup$ – Waylander May 31 '18 at 13:17
  • $\begingroup$ sorry, I'm not sure what you mean $\endgroup$ – Y-MinG Jun 1 '18 at 1:12

Whether the oxidation of an alochol or the reduction of a carbonyl group follows a certain mechanism depends on the reagents/conditions.

For example: The sodium borohydride reduction of a ketone follows a nucleophilic addition mechanism:

$$\ce{R2C=O ->[1)\ \ce{NaBH4},\ \ce{CH3OH}][2)\ \ce{H3O+}] R2CHOH}$$ enter image description here

However, some metal catalyzed hydrogenation reactions are considered to be (nearly) concerted additions. For example, here is the transition state of the key step of the mechanism of the Noyori reduction.

$$\ce{R2C=O ->[\ce{H2}][\ce{RuCl2en2/BINAP}] R2CHOH}$$ enter image description here

Many oxidations of alcohols follow something of an elimination mechanism. For example, the key step of the Swern oxidation looks like an elimination. $$\ce{R2C=O ->[1)\ \ce{DMSO, (COCl)2}][2) \ce{Et3N}] R2CHOH}$$

enter image description here

There is a second important mechanism: hydride transfer oxidation. This is the prevailing mechanism biochemically, where the alochol is used as a hydride source to simultaneously reduce another compounds.

$$\ce{R2C=O ->[\ce{NAD+}][\ce{base}] R2CHOH}$$

enter image description here


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