Chapter 8, Problem 55P

(a)

Interpretation Introduction

Interpretation:Synthesis of $\text{3-octanol}$ from ketone should be devised.

Concept introduction: The carbonyl bond is polar with the partial positive charge on carbon and partial negative charge on oxygen as illustrated below.

  

Thus it can undergo hydride addition at carbon and proton addition at oxygen. Certain reagents that are useful for such hydride addition at carbonyl carbon include sodium borohydride, lithium aluminum hydride. The boron and lithium in these reagents tend to push the electron of $\text{B-H}$ bond towards carbonyl carbon as illustrated below:

  

(b)

Interpretation Introduction

Interpretation:Synthesis of $\text{3-octanol}$ from aldehyde should be devised.

Concept introduction:The alcohols are best synthesized from on the basis of retrosynthetic analysis with the aid of Grignard reagents.

The carbonyl bond is polar with partial positive charge on carbon and partial negative charge on oxygen as illustrated below.

  

Grignard reagents are alkyl magnesium halides obtained from treatment of haloalkane with magnesium in presence of dried ether conditions. Theses reagent are useful precursor for quick synthesis of variety of organic compounds For example, the reaction of Grignard reagent with aldehyde or ketone generates alcohols as illustrated below.

  

Methyl bromide reacts with magnesium ether to give Grignard reagent. This Grignard methylmagnsium bromide on treatment with formaldehyde gives corresponding alcohol. The mechanistic pathway for the latter reaction is as follows:

  

The polar carbonyl bond breaks and the polar Grignard reagent attack at electron-deficient carbon. Finally with the hydrolysis and work up the alcohol is formed.

(c)

Interpretation Introduction

Interpretation: Synthesis of $\text{3-octanol}$ from different aldehyde should be devised.

Concept introduction: The alcohols are best synthesized from on the basis of retrosynthetic analysis with the aid of Grignard reagents.

The carbonyl bond is polar with the partial positive charge on carbon and partial negative charge on oxygen as illustrated below.

  

Grignard reagents are alkyl magnesium halides obtained from the treatment of haloalkane with magnesium in the presence of dried ether conditions. Theses reagent are a useful precursor for the quick synthesis of a variety of organic compounds For example, the reaction of Grignard reagent with aldehyde or ketone generates alcohols as illustrated below.

  

Methyl bromide reacts with magnesium ether to give Grignard reagent. This Grignard methylmagnsium bromide on treatment with formaldehyde gives corresponding alcohol. The mechanistic pathway for the latter reaction is as follows:

  

The polar carbonyl bond breaks and the polar Grignard reagent attack at electron-deficient carbon. Finally with the hydrolysis and work up the alcohol is formed.