Chapter 19, Problem 36P

Draw the structure of a wax formed from a 30-carbon straight chain alcohol and each carboxylic acid.
a. lauric acid
b. myristic acid
C. ${\text{CH}}_{\text{3}}{\left({\text{CH}}_{\text{2}}\right)}_{\text{22}}\text{COOH}$

Interpretation Introduction

(a)

Interpretation:

The structure of wax formed by the reaction of lauric acid, ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{10}\text{-COOH}$ and ${\text{CH}}_{\text{3}}\text{-(CH}\text{)}{}_{\text{29}}\text{-OH}$ should be drawn.

Concept Introduction:

The general reaction of wax formation of fatty acid and higher alcohols can be written as:

  ${\text{R-CH}}_{\text{2}}{\text{-COOH + HO-CH}}_{\text{2}}\text{-R }\stackrel{}{\to }{\text{R-CH}}_{\text{2}}{\text{-COO-CH}}_{\text{2}}{\text{-R + H}}_{\text{2}}\text{O}$

Answer to Problem 36P

The skeleton formula of wax is ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{10}\text{-COO-(CH}\text{)}{}_{\text{29}}{\text{-CH}}_{\text{3}}$.

Explanation of Solution

Fatty acids are long chain carboxylic acids, which consist of two parts, i.e., long hydrocarbon chains and polar −COOH group. Waxes are good example of hydrolyzable lipids, which are composed of fatty acid and higher alcohols. They have an ester functional group which is formed between $\text{–COOH and –OH}$ functional group of the fatty acid and alcohols respectively. The general reaction of wax formation of fatty acid and higher alcohols can be written as:

  ${\text{R-CH}}_{\text{2}}{\text{-COOH + HO-CH}}_{\text{2}}\text{-R }\stackrel{}{\to }{\text{R-CH}}_{\text{2}}{\text{-COO-CH}}_{\text{2}}{\text{-R + H}}_{\text{2}}\text{O}$

Hence, the reaction of ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{10}\text{-COOH}$ and ${\text{CH}}_{\text{3}}\text{-(CH}\text{)}{}_{\text{29}}\text{-OH}$ for the formation of wax must be written as:

  ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{10}{\text{-COOH + CH}}_{\text{3}}\text{-(CH}\text{)}{}_{\text{29}}\text{-OH}\stackrel{}{\to }{\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{10}\text{-COO-(CH}\text{)}{}_{\text{29}}{\text{-CH}}_{\text{3}}{\text{ + H}}_{\text{2}}\text{O}$

Interpretation Introduction

(b)

Interpretation:

The structure of wax formed by the reaction of myristic acid, ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{12}\text{-COOH}$ and ${\text{CH}}_{\text{3}}\text{-(CH}\text{)}{}_{\text{29}}\text{-OH}$ should be drawn.

Concept Introduction:

The general reaction of wax formation of fatty acid and higher alcohols can be written as:

  ${\text{R-CH}}_{\text{2}}{\text{-COOH + HO-CH}}_{\text{2}}\text{-R }\stackrel{}{\to }{\text{R-CH}}_{\text{2}}{\text{-COO-CH}}_{\text{2}}{\text{-R + H}}_{\text{2}}\text{O}$

Answer to Problem 36P

The skeleton formula of wax is ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{12}\text{-COO-(CH}\text{)}{}_{\text{29}}{\text{-CH}}_{\text{3}}$.

Explanation of Solution

Fatty acids are long chain carboxylic acids, which consist of two parts; long hydrocarbon chains and polar −COOH group. Waxes are good example of hydrolyzable lipids, which are composed of fatty acid and higher alcohols. They have an ester functional group which is formed between $\text{–COOH and –OH}$ functional group of the fatty acid and alcohols respectively. The general reaction of wax formation of fatty acid and higher alcohols can be written as:

  ${\text{R-CH}}_{\text{2}}{\text{-COOH + HO-CH}}_{\text{2}}\text{-R }\stackrel{}{\to }{\text{R-CH}}_{\text{2}}{\text{-COO-CH}}_{\text{2}}{\text{-R + H}}_{\text{2}}\text{O}$

Hence, the reaction of ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{12}\text{-COOH}$ and ${\text{CH}}_{\text{3}}\text{-(CH}\text{)}{}_{\text{29}}\text{-OH}$ for the formation of wax must be written as:

  ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{12}{\text{-COOH + CH}}_{\text{3}}\text{-(CH}\text{)}{}_{\text{29}}\text{-OH}\stackrel{}{\to }{\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{12}\text{-COO-(CH}\text{)}{}_{\text{29}}{\text{-CH}}_{\text{3}}{\text{ + H}}_{\text{2}}\text{O}$

Interpretation Introduction

(c)

Interpretation:

The structure of wax formed by the reaction of ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{22}\text{-COOH}$ and ${\text{CH}}_{\text{3}}\text{-(CH}\text{)}{}_{\text{29}}\text{-OH}$ should be drawn.

Concept Introduction:

The general reaction of wax formation of fatty acid and higher alcohols can be written as:

  ${\text{R-CH}}_{\text{2}}{\text{-COOH + HO-CH}}_{\text{2}}\text{-R }\stackrel{}{\to }{\text{R-CH}}_{\text{2}}{\text{-COO-CH}}_{\text{2}}{\text{-R + H}}_{\text{2}}\text{O}$

Answer to Problem 36P

The skeleton formula of wax is ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{22}\text{-COO-(CH}\text{)}{}_{\text{29}}{\text{-CH}}_{\text{3}}$.

Explanation of Solution

Fatty acids are long chain carboxylic acids, which consist of two parts, i.e., long hydrocarbon chains and polar −COOH group. Waxes are good example of hydrolyzable lipids, which are composed of fatty acid and higher alcohols. They have an ester functional group which is formed between $\text{–COOH and –OH}$ functional group of the fatty acid and alcohols respectively. The general reaction of wax formation of fatty acid and higher alcohols can be written as:

  ${\text{R-CH}}_{\text{2}}{\text{-COOH + HO-CH}}_{\text{2}}\text{-R }\stackrel{}{\to }{\text{R-CH}}_{\text{2}}{\text{-COO-CH}}_{\text{2}}{\text{-R + H}}_{\text{2}}\text{O}$

Hence, the reaction of ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{22}\text{-COOH}$ and ${\text{CH}}_{\text{3}}\text{-(CH}\text{)}{}_{\text{29}}\text{-OH}$ for the formation of wax must be written as:

  ${\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{22}{\text{-COOH + CH}}_{\text{3}}\text{-(CH}\text{)}{}_{\text{29}}\text{-OH}\stackrel{}{\to }{\text{CH}}_{\text{3}}\text{-}{(\text{CH})}_{22}\text{-COO-(CH}\text{)}{}_{\text{29}}{\text{-CH}}_{\text{3}}{\text{ + H}}_{\text{2}}\text{O}$