Chapter 19, Problem 58P

Interpretation Introduction

Interpretation:

For each of the following reaction the route that could reasonably be expected from the starting material to the product is to be provided.

Concept introduction:

Electrophiles are electron deficient species that have positive or partially positive charge. Lewis acids are electrophiles that accept electron pair.

Nucleophiles are electron rich species that have negative or partially negative charge. Lewis bases are nucleophiles that donate electron pair.

Free radical is an atom, molecule, or ion that has an unpaired electron, which makes it highly chemically reactive.

Substitution reaction: A reaction in which one of the hydrogen atoms of a hydrocarbon or a functional group is substituted by any other functional group is called substitution reaction.

Elimination reaction: A reaction in which two substituent groups are detached and a double bond is formed is called elimination reaction.

Addition reaction: It is the reaction in which unsaturated bonds are converted to saturated molecules by the addition of molecules.

The condensation reactions in carbonyl, the enolate or enol of a carbonyl group of one compound reacts with the carbonyl group of another compound. The two main types of condensation are Claisen and aldol condensation.

Claisen condensation entails the formation of keto esters through carbon–carbon bond formation.

The Claisen condensation is the carbon–carbon bond formation reaction and is important for the preparation of $\beta -\text{Keto ester}$.

In Claisen condensation, the ester of one molecule is added to the carbonyl carbon of another molecule and the formation of $\beta -\text{Keto ester}$ takes place.

When one ester molecule has no alpha hydrogen, crossed Claisen condensation occurs.

Aldol condensation involves the reaction of enolate of an aldehyde or ketone with the carbonyl carbon of another molecule under basic condition, forming hydroxyl ketone or aldehyde.

An aldol reaction takes place by acid catalysis, and direct dehydration of $\beta -$ hydroxy aldol intermediate forms $\alpha ,\beta -$ unsaturated product.

A chemical reaction that is catalyzed by an acid is called acid catalyzed reaction.

A chemical reaction that is catalyzed by an base is called base catalyzed reaction.

Aldol reaction is preferred in basic condition over acidic condition as after the aldol condensation, acid catalysis promotes the reaction further.

A carbon–carbon bond formation occurs through aldol condensation reaction.

An aldol reaction takes place in a protic solvent with a base.

Dehydration of aldol addition product leads to the formation of conjugated $\alpha ,\beta -$ unsaturated carbonyl compound and the overall reaction is aldol condensation.