To draw the structure of a wax formed from stearic acid [tex]\(\left[ CH_3\left( CH_2 \right)_{16} COOH \right]\)[/tex] and the alcohol, follow these general steps:
1. Identify the Components:
- Stearic Acid (Fatty Acid): This has the structure [tex]\(CH_3(CH_2)_{16}COOH\)[/tex]. The carboxyl group [tex]\(-COOH\)[/tex] is the functional group that participates in the esterification reaction.
- Alcohol: Typically, waxes are esters formed from long-chain fatty acids and long-chain alcohols. For simplicity, assume the alcohol is a long-chain alcohol with the formula [tex]\(C_nH_{2n+1}OH\)[/tex].
2. Form the Ester Bond:
- An ester is formed by the reaction between the carboxyl group of the fatty acid and the hydroxyl group of the alcohol. During this reaction, a molecule of water is released (condensation reaction).
3. Construct the Wax Molecule:
- Fatty Acid part: Start with the stearic acid minus the [tex]\(OH\)[/tex] from the carboxyl group, giving you a structure: [tex]\(CH_3(CH_2)_{16}C=O\)[/tex].
- Alcohol part: Consider a long-chain alcohol, for instance, cetyl alcohol [tex]\((CH_3(CH_2)_{14}CH_2OH )\)[/tex]. Removing the hydrogen from the hydroxyl group gives [tex]\(CH_3(CH_2)_{14}CH_2O\)[/tex].
4. Combine the Two Parts:
- The ester bond is formed between the carbonyl carbon of the fatty acid and the oxygen from the alcohol.
The structural formula for the wax, combining stearic acid and cetyl alcohol, would look like this:
[tex]\[
CH_3(CH_2)_{16}C(O)OCH_2(CH_2)_{14}CH_3
\][/tex]
To break it down further:
- The carboxyl group of stearic acid [tex]\(COOH\)[/tex] reacts with the hydroxyl group of the alcohol [tex]\(OH\)[/tex], releasing [tex]\(H_2O\)[/tex] and forming the ester bond.
- The resulting molecule is an ester with a long hydrocarbon chain on each side of the ester functional group.
This wax is a representative example formed from a specific alcohol (cetyl alcohol) and stearic acid, resulting in the compound called cetyl stearate.
