Textbook Question
(a) The isoelectric point (pI) of phenylalanine is pH 5.5. Draw the structure of the major form of phenylalanine at pH values of 1, 5.5, and 11.
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Ch. 24 - Amino Acids, Peptides, and Proteins
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 24, Problem 29c
Predict the products of the following reactions.
(c) 
Verified step by step guidance1
Step 1: Identify the reactants. Lys refers to lysine, an amino acid with an amine group (-NH2) and a carboxylic acid group (-COOH), along with an additional amine group in its side chain. (CH3CO)2O is acetic anhydride, a reagent commonly used for acetylation reactions.
Step 2: Understand the reaction conditions. The presence of excess acetic anhydride suggests that all nucleophilic groups in lysine will react with acetic anhydride to form acetylated products.
Step 3: Determine the reactive sites in lysine. The primary amine group (-NH2) in the side chain and the alpha-amino group (-NH2) attached to the alpha carbon are both nucleophilic and can react with acetic anhydride. Additionally, the hydroxyl group (-OH) of the carboxylic acid can also react.
Step 4: Predict the products. Each amine group will react with acetic anhydride to form an amide bond, resulting in acetylation. The hydroxyl group of the carboxylic acid will react to form an ester bond. The final product will be a fully acetylated lysine derivative.
Step 5: Write the general structure of the product. The alpha-amino group and the side chain amine group will each have an acetyl group (-COCH3) attached, and the carboxylic acid group will be converted into an ester (-COOCH3).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Reaction Mechanisms
Understanding reaction mechanisms is crucial in organic chemistry as they describe the step-by-step process by which reactants transform into products. This includes identifying intermediates, transition states, and the movement of electrons. Familiarity with mechanisms helps predict the outcome of reactions and the stability of products formed.
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Functional Groups
Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. Recognizing functional groups allows chemists to predict how different compounds will react under various conditions. This knowledge is essential for determining the products of organic reactions.
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Stereochemistry
Stereochemistry involves the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. It is important for predicting the products of reactions, especially in cases where chirality or geometric isomerism is involved. Understanding stereochemical principles helps in anticipating the specific isomers that may be formed in a reaction.
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Related Practice
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Predict the products of the following reactions.
(e)
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Textbook Question
Predict the products of the following reactions.
(b)
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Textbook Question
Predict the products of the following reactions.
(d)
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Predict the products of the following reactions.
(f)
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Textbook Question
The isoelectric point of glutamic acid is pH 3.2. Draw the structures of the major forms of glutamic acid at pH values of 1, 3.2, 7, and 11. Explain why the side-chain carboxylic acid is a weaker acid than the acid group next to the α-carbon atom.
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