Chapter 17.SE, Problem 45AP

Interpretation Introduction

a)

Interpretation:

Starting with benzene and using other alcohols of six or fewer carbons as the organic reagents how 1-ethylcyclohexanol can be prepared is to be stated.

Concept introduction:

An alicyclic 3⁰ alcohol is to be prepared from benzene. For this purpose benzene has to be converted into an alicyclic ketone and then treated with Grignard reagent. Benzene can be converted into phenol, first by halogenation followed by treatment with NaOH. Phenol can be converted into cyclohexanol by reducing with H₂, Rh/C in ethanol. Cyclohexanol when oxidized with pyridiniumchlorochromate is converted in to the alicyclic ketone, cyclohexanone, required.

To state:

Starting with benzene and using other alcohols of six or fewer carbons as the organic reagents how to prepare 1-ethylcyclohexanol.

Interpretation Introduction

b)

Interpretation:

Starting with benzene and using other alcohols of six or fewer carbons as the organic reagents how 3-methylhexan-1-ol can be prepared is to be given.

Concept introduction:

A six carbon straight chain alcohol with a methyl group on C₃ is to be prepared from benzene. By ozonolysis, the benzene ring is broken to get the open chain dialdehyde glyoxal. To one of the aldehydic group in glyoxal, an isopentyl group can be introduced by treating with a suitable Grignard reagent. Upon heating the alcohol will eliminate water to yield an unsaturated aldehyde. The unsaturated aldehyde can be reduced to a saturated aldehyde which on NaBH₄ reduction will lead to the formation of the product required.

To give:

Starting with benzene and using other alcohols of six or fewer carbons as the organic reagents how to prepare 3-methylhexan-1-ol.

Interpretation Introduction

c)

Interpretation:

Starting with benzene and using other alcohols of six or fewer carbons as the organic reagents how 2-methyl-2-phenyl-2 butanol can be prepared is to be given.

Concept introduction:

An aromatic 3⁰ alcohol is required. Friedal-Crafts acylation of benzene with suitable acyl halide will produce an alkylphenyl ketone. The ketone when treated with a Grignard reagent will yield the 3⁰ alcohol required.

To give:

Starting with benzene and using other alcohols of six or fewer carbons as the organic reagents how to prepare .

Interpretation Introduction

d)

Interpretation:

Starting with benzene and using other alcohols of six or fewer carbons as the organic reagents how 5-methylhexan-3-ol can be prepared is to be given.

Concept introduction:

A six carbon straight chain aldehyde with a methyl group on C₄ is to be prepared from benzene. By ozonolysis, the benzene ring is broken to get the open chain dialdehyde, maloaldehyde with three carbon atoms. To one of the aldehydic group in the dialdehyde, an isobutyl group can be introduced by treating with a suitable Grignard reagent to get an aldol. The aldehyde group in the aldol is reduced to an alkyl group to get the alcohol requireds.

To give:

Starting with benzene and using other alcohols of six or fewer carbons as the organic reagents how to prepare 3-methylhexan-1-ol.