Question

The carbonyl group of an aldehyde or ketone may be reduced via several different methods. Select all viable methods for aldehyde/ketone reduction. 1) LiAIH 4, 2) H 2O NH 3, H 2. and Raney Ni Na 2Cr 2O 7 and H 2SO 4 Wolff-Kishner method Clemmensen method Baeyer-Villiger method KMnO 4 and H 2SO 4 Of the reduction methods, which one would be best performed under acidic conditions? KMnO 4 and H2 SO 4 NH 3, H 2, and Raney Ni Wolff-Kishner method Na 2Cr 2O 7 and H 2SO 4 Clemmensen method Baeyer-Villiger method 1) LiAIH 4, 2) H 2O

Answer 1

The reduction of aldehyde or ketone with LiAlH4 gives alcohol он formaldehyde н.с CH acetaldehyde CH propan-2-one Propan-2-ol The reduction of aldehydes and ketones with hydrazine NH,NH NH + H,O Aldehyde or ketone Propan-2-ylidcnchydrazinc

Aldehyde or ketone Propan-2-ylidcnchydrazinc NH2 KOH Heat + N propane It is called as Wolff-Kishner reduction. In this reaction, a base and heat converts hydrazine into a alkane. Reduction of aldehyde or ketone by Clemmensen reduction method Zn(Hg), HCI propane-2-one propane This reduction of aldehyde or ketone is done with the zinc amalgam in concentrated hydrochloric acid. This reduces the aldehyde or ke to a hydrocarbon

The reduction of aldehyde or ketone in the presence of Raney N NH,.H Rancy Ni cyclohexanone 1.1-dimethylcyclohexane This reduction of aldehyde or ketone is done in the presence of NH3.H2 with Raney Ni Hence, the variables used for the reduction of aldehyde and ketones are given as follows. (1) LiAlH4, H20 (2) Wolf-Kishner method (3) Clemmensen reduction (4) NH,.H, with Raney N Clemmensen reduction works best in a highly acidic environment due to unreactive nature of substance (zinc amalgam in concentrated hydrochloric acid) with environment Wolff-kishner reduction works best in a highly basic environment Hence, Clemmensen reduction works best in a highly acidic environment.