Ch.23 Lipids

McMurry - Fundamentals of General, Organic, and Biological Chemistry 8th Edition

McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187Not the one you use?Change textbook

McMurry 8th Edition

Ch.23 Lipids

Problem 38

Chapter 23, Problem 38

Draw the structure of glyceryl trilaurate, which is made from glycerol and three lauric acid molecules.

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Understand the components: Glyceryl trilaurate is a triester formed from glycerol (a three-carbon molecule with three hydroxyl groups, \( \text{C}_3\text{H}_8\text{O}_3 \)) and three lauric acid molecules (a 12-carbon saturated fatty acid, \( \text{C}_{12}\text{H}_{24}\text{O}_2 \)).

Recognize the esterification process: Each hydroxyl group on glycerol reacts with the carboxylic acid group (\( \text{-COOH} \)) of lauric acid to form an ester bond (\( \text{-COO} \)) and release water (\( \text{H}_2\text{O} \)).

Draw the glycerol backbone: Start with a vertical chain of three carbon atoms, each bonded to a hydroxyl group (\( \text{-OH} \)) and sufficient hydrogens to satisfy the valency of carbon.

Attach the lauric acid chains: Replace each hydroxyl group on glycerol with an ester bond (\( \text{-COO} \)) connected to the 12-carbon chain of lauric acid. Ensure that each lauric acid chain is fully saturated (no double bonds) and ends with a methyl group (\( \text{-CH}_3 \)).

Verify the structure: Confirm that the final structure has three ester bonds, a glycerol backbone, and three lauric acid chains, each containing 12 carbons. The molecular formula of glyceryl trilaurate should be \( \text{C}_{39}\text{H}_{74}\text{O}_6 \).

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Key Concepts

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

Glycerol Structure

Glycerol, also known as glycerin, is a simple polyol compound with three hydroxyl (–OH) groups. Its structure consists of a three-carbon chain, where each carbon is attached to a hydroxyl group. This unique structure allows glycerol to act as a backbone for triglycerides, forming the basis for lipid molecules like glyceryl trilaurate.

Fatty Acids

Fatty acids are long hydrocarbon chains with a carboxylic acid group at one end. Lauric acid, specifically, is a saturated fatty acid with a 12-carbon chain. When fatty acids like lauric acid react with glycerol, they form esters, which are the building blocks of triglycerides, such as glyceryl trilaurate.

Esterification Reaction

Esterification is a chemical reaction between an alcohol and a carboxylic acid, resulting in the formation of an ester and water. In the case of glyceryl trilaurate, glycerol undergoes esterification with three lauric acid molecules, leading to the formation of a triglyceride. This reaction is crucial in the synthesis of fats and oils in biological systems.

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Ester Reactions: Esterification Example 1

Related Practice

Textbook Question

Which of these fatty acids has the lower melting point? Explain why.

a. Linoleic acid

b. Stearic acid

Textbook Question

Is the reaction shown here esterification, hydrogenation, hydrolysis, saponification, or substitution?

Textbook Question

Which of these fatty acids has the higher melting point? Explain why.

a. Linolenic acid

b. Stearic acid

Textbook Question

There are two isomeric triacylglycerol molecules whose components are glycerol, one palmitic acid unit, and two stearic acid units. Draw the structures of both, and explain how they differ.

Textbook Question

Draw the structures of all products you would obtain by saponification of the following lipid with aqueous KOH. What are the names of the products?

Textbook Question

Are the carbon–carbon double bonds in naturally occurring fatty acids primarily cis or trans?