Textbook Question
Write the complete equation for the hydrolysis of a triacylglycerol in which the fatty acids are two molecules of stearic acid and one of oleic acid.
Ch.23 Lipids
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187
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Table of contents
- Ch.1 Matter and Measurements27
- Ch.2 Atoms and the Periodic Table20
- Ch.3 Ionic Compounds8
- Ch.4 Molecular Compounds23
- Ch.5 Classification & Balancing of Chemical Reactions12
- Ch.6 Chemical Reactions: Mole and Mass Relationships28
- Ch.7 Chemical Reactions: Energy, Rate and Equilibrium64
- Ch.8 Gases, Liquids and Solids24
- Ch.9 Solutions52
- Ch.10 Acids and Bases25
- Ch.11 Nuclear Chemistry22
- Ch.12 Introduction to Organic Chemistry: Alkanes57
- Ch.13 Alkenes, Alkynes, and Aromatic Compounds47
- Ch.14 Some Compounds with Oxygen, Sulfur, or a Halogen50
- Ch.15 Aldehydes and Ketones45
- Ch.16 Amines42
- Ch.17 Carboxylic Acids and Their Derivatives57
- Ch.18 Amino Acids and Proteins82
- Ch.19 Enzymes and Vitamins63
- Ch.20 Carbohydrates44
- Ch.21 The Generation of Biochemical Energy65
- Ch.22 Carbohydrate Metabolism45
- Ch.23 Lipids42
- Ch.24 Lipid Metabolism33
- Ch.25 Protein and Amino Acid Metabolism24
- Ch.26 Nucleic Acids and Protein Synthesis45
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187Not the one you use?Change textbook
Chapter 23, Problem 8
Write an equation for the complete hydrogenation of triolein, the triacylglycerol with three oleic acid acyl groups for which you drew the structure in Problem 23.3. Name the fatty acid from which the resulting acyl groups are derived.
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Identify the structure of triolein: Triolein is a triacylglycerol composed of glycerol esterified with three oleic acid molecules. Oleic acid is a monounsaturated fatty acid with the formula C₁₈H₃₄O₂, containing one double bond in its hydrocarbon chain.
Understand the process of hydrogenation: Complete hydrogenation involves the addition of hydrogen (H₂) across the double bonds in the unsaturated fatty acid chains, converting them into saturated fatty acid chains. This reaction is typically catalyzed by a metal catalyst such as nickel (Ni).
Write the chemical equation for the hydrogenation reaction: Represent triolein as C₅₇H₁₀₄O₆ (the molecular formula for a triacylglycerol with three oleic acid groups). Add three molecules of hydrogen (H₂) for each double bond present in the triolein molecule. The product will be a triacylglycerol with three stearic acid groups, as the double bonds are fully saturated.
Express the reaction in equation form:
Name the resulting fatty acid: The resulting acyl groups are derived from stearic acid, a saturated fatty acid with the formula C₁₈H₃₆O₂. Stearic acid is the fully hydrogenated form of oleic acid.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Triolein Structure
Triolein is a triacylglycerol composed of three oleic acid molecules. Each oleic acid contributes a long hydrocarbon chain with a double bond, making triolein unsaturated. Understanding its structure is crucial for predicting the products of hydrogenation, which involves the addition of hydrogen to the double bonds, converting them into single bonds.
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Hydrogenation Process
Hydrogenation is a chemical reaction that involves the addition of hydrogen (H2) to unsaturated fats, resulting in the conversion of double bonds to single bonds. This process typically occurs in the presence of a catalyst, such as nickel or platinum, and is used to solidify liquid oils. In the case of triolein, complete hydrogenation will yield a saturated fat, specifically tristearin.
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Fatty Acid Derivation
The fatty acids derived from the hydrogenation of triolein are saturated fatty acids. In this case, the resulting acyl groups after complete hydrogenation are derived from stearic acid, which has a straight-chain structure with no double bonds. Recognizing the relationship between the original unsaturated fatty acids and the resulting saturated fatty acids is essential for naming and understanding the products of the reaction.
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Related Practice
Textbook Question
Draw the complete structural formula of arachidonic acid (Table 23.1) in a way that shows the cis stereochemistry of its four double bonds.
Textbook Question
Identify the products formed by complete hydrolysis of all ester bonds in (a) the phosphatidylcholine on page 726.
Textbook Question
Identify the products formed by complete hydrolysis of all ester bonds in (b) the sphingomyelin in Figure 23.5.
Textbook Question
One of the constituents of the carnauba wax used in floor and furniture polish is an ester of a 32-carbon straight-chain alcohol with a C20:0 straight-chain carboxylic acid. Draw the structure of this ester. (Use subscripts to show the numbers of connected CH2 groups.)
Textbook Question
Can there be any chiral carbon atoms in triacylglycerols? If so, which ones can be chiral and what determines their chirality?