Textbook Question
Give equations for the formation and hydrogenolysis of glutamine benzyl ester.
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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 16
Give equations for the formation and hydrogenolysis of N-benzyloxycarbonyl methionine.
Verified step by step guidance1
Identify the structure of N-benzyloxycarbonyl methionine. This compound is a derivative of methionine where the amino group (-NH2) is protected by a benzyloxycarbonyl (Cbz) group. The general structure of the Cbz group is C6H5CH2OCO-.
Write the reaction for the formation of N-benzyloxycarbonyl methionine. This typically involves reacting methionine with benzyl chloroformate (C6H5CH2OCOCl) in the presence of a base (e.g., NaOH or NaHCO3) to neutralize the HCl byproduct. The reaction can be represented as: \( \text{H2N-CH(CH2CH2SCH3)-COOH} + \text{C6H5CH2OCOCl} \rightarrow \text{C6H5CH2OCO-NH-CH(CH2CH2SCH3)-COOH} + \text{HCl} \).
Explain the purpose of the benzyloxycarbonyl (Cbz) group. It is a protecting group used to temporarily block the amino group (-NH2) during chemical reactions to prevent unwanted side reactions. This is particularly useful in peptide synthesis.
Write the reaction for the hydrogenolysis of N-benzyloxycarbonyl methionine. Hydrogenolysis involves the removal of the Cbz group using hydrogen gas (H2) in the presence of a palladium catalyst (e.g., Pd/C). The reaction can be represented as: \( \text{C6H5CH2OCO-NH-CH(CH2CH2SCH3)-COOH} + \text{H2} \xrightarrow{\text{Pd/C}} \text{H2N-CH(CH2CH2SCH3)-COOH} + \text{C6H5CH3} + \text{CO2} \).
Summarize the overall process. The formation of N-benzyloxycarbonyl methionine involves protecting the amino group of methionine with a Cbz group using benzyl chloroformate. The hydrogenolysis step removes the Cbz group, regenerating the free amino group and producing toluene (C6H5CH3) and carbon dioxide (CO2) as byproducts.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
N-benzyloxycarbonyl (Z) Group
The N-benzyloxycarbonyl (Z) group is a protective group used in organic synthesis, particularly in peptide chemistry. It protects the amine group of amino acids during reactions, preventing unwanted side reactions. The Z group can be removed under specific conditions, allowing for the subsequent functionalization of the amino acid.
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E/Z Diastereoisomerism
Hydrogenolysis
Hydrogenolysis is a chemical reaction that involves the cleavage of a bond by hydrogen in the presence of a catalyst, typically resulting in the removal of a protecting group. In the context of N-benzyloxycarbonyl methionine, hydrogenolysis would involve the reduction of the Z group to yield the free amino acid. This reaction is crucial for the synthesis of peptides and proteins.
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Formation of N-benzyloxycarbonyl Methionine
The formation of N-benzyloxycarbonyl methionine involves the reaction of methionine with benzyloxycarbonyl chloride (Z-Cl) in the presence of a base. This reaction results in the attachment of the Z group to the amino group of methionine, creating a protected amino acid that can be used in peptide synthesis without interference from the amine.
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Related Practice
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Suggest how you would separate the free L-amino acid from its acylated D enantiomer in Figure 24-5.
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