Chapter 21, Problem 78PP

Interpretation Introduction

Interpretation:

Reagents used for the synthesis of Rheosmin by crossed Aldol reaction need to be identified.

Concept introduction:

Aldol condensation reaction is where the aldol addition product undergoes dehydration to give a conjugated enone.  In organic chemistry condensation reaction means loss of small molecules.  For Aldol condensation reaction to take place the starting material should have two $\alpha$ hydrogens in the same carbon atom.  The driving force for Aldol condensation reaction is the formation of conjugated system.  The steps involved in Aldol condensation reaction are,

• Deprotonation of $\alpha$ carbon
• Attack of enolate ion with the carbonyl (nucleophilic attack)
• Protonation of the alkoxide ion to give aldol product
• Dehydration of the aldol addition product to form conjugated enone (aldol condensation product)

Please note that Aldol condensation product is formed at higher temperature.

If there is an more acidic group present in the carbonyl compound then the formation of enolate is not possible.  Hence the more acidic group has to be protected, for the carbonyl compound to take part in Aldol condensation reaction.

Reduction is the a reaction where hydrogen is added or it is loss of oxygen.  Few examples of reduction are conversion of unsaturated bond to saturated bond.  Reduction of carboxylic acid to alcohol etc.