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Ch.23 - Organic and Biological Chemistry
Chapter 23, Problem 9

Spermaceti, a fragrant substance isolated from sperm whales, was a common ingredient in cosmetics until its use was banned in 1976 to protect the whales from extinction. Chemically, spermaceti is cetyl palmitate, the ester of palmitic acid with cetyl alcohol (the straight-chain C16 alcohol). Show the structure of spermaceti.

Verified step by step guidance
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Step 1: Understand the components of spermaceti. Spermaceti is chemically known as cetyl palmitate, which is an ester formed from palmitic acid and cetyl alcohol.
Step 2: Identify the structure of palmitic acid. Palmitic acid is a saturated fatty acid with the chemical formula C16H32O2, and its structure consists of a carboxylic acid group (COOH) attached to a 15-carbon alkyl chain.
Step 3: Identify the structure of cetyl alcohol. Cetyl alcohol is a straight-chain alcohol with the chemical formula C16H34O, consisting of a hydroxyl group (OH) attached to a 15-carbon alkyl chain.
Step 4: Form the ester linkage. In an esterification reaction, the hydroxyl group of the alcohol reacts with the carboxylic acid group of the acid, releasing a molecule of water and forming an ester bond (COO) between the two components.
Step 5: Draw the structure of cetyl palmitate. Combine the structures of palmitic acid and cetyl alcohol through the ester linkage to form cetyl palmitate, showing the long carbon chains connected by the ester functional group.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Ester Formation

Ester formation is a chemical reaction between an alcohol and a carboxylic acid, resulting in the production of an ester and water. In the case of spermaceti, cetyl palmitate is formed from cetyl alcohol (a long-chain alcohol) and palmitic acid (a saturated fatty acid). This reaction is typically catalyzed by an acid and is a key process in organic chemistry for creating various esters used in food, cosmetics, and pharmaceuticals.
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Chemical Structure of Fatty Acids

Fatty acids are carboxylic acids with long hydrocarbon chains, which can be saturated or unsaturated. Palmitic acid, specifically, is a saturated fatty acid with a 16-carbon chain, represented as C16H32O2. Understanding the structure of fatty acids is essential for grasping how they interact with alcohols to form esters, as well as their roles in biological systems and industrial applications.
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Structural Representation of Organic Compounds

The structural representation of organic compounds, such as spermaceti, involves depicting the arrangement of atoms and the bonds between them. For cetyl palmitate, this includes illustrating the long hydrocarbon chains of both cetyl alcohol and palmitic acid, as well as the ester functional group. Familiarity with drawing and interpreting structural formulas is crucial for understanding the properties and reactivity of organic molecules.
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