Textbook Question
What alkyl halide is used in the acetamidomalonic ester synthesis to prepare
b. phenylalanine?
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Ch. 21 - Amino Acids, Peptides, and Proteins
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
Chapter 22, Problem 24b
What amino acid is formed when the aldehyde used in the Strecker synthesis is
b. 2-methylbutanal?
Verified step by step guidance1
The Strecker synthesis is a method for synthesizing α-amino acids by reacting an aldehyde with ammonium chloride (NH₄Cl) and potassium cyanide (KCN). The process involves the formation of an imine intermediate, followed by cyanide addition and hydrolysis.
Identify the aldehyde provided in the problem: 2-methylbutanal. Its structure consists of a four-carbon chain with a methyl group attached to the second carbon and an aldehyde functional group (-CHO) at the terminal carbon.
In the first step of the Strecker synthesis, the aldehyde (2-methylbutanal) reacts with ammonium chloride (NH₄Cl) and forms an imine intermediate through a condensation reaction. This imine has the general structure R-CH=NH, where R represents the 2-methylbutyl group.
Next, potassium cyanide (KCN) reacts with the imine intermediate. The cyanide ion (CN⁻) adds to the carbon atom of the imine, forming an α-aminonitrile intermediate. The structure of this intermediate will have the 2-methylbutyl group, an amino group (-NH₂), and a nitrile group (-C≡N) attached to the same carbon.
Finally, the α-aminonitrile undergoes hydrolysis under acidic conditions. The nitrile group (-C≡N) is converted into a carboxylic acid group (-COOH), resulting in the formation of the α-amino acid. The amino acid formed will have the 2-methylbutyl group as its side chain, making it isoleucine.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Strecker Synthesis
Strecker synthesis is a method for producing amino acids from aldehydes or ketones. It involves the reaction of an aldehyde with ammonia and hydrogen cyanide, leading to the formation of an α-amino nitrile intermediate, which can be hydrolyzed to yield the corresponding amino acid. Understanding this process is crucial for determining the specific amino acid produced from a given aldehyde.
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Synthesis of Amino Acids: Strecker Synthesis Concept 1
Amino Acid Structure
Amino acids are organic compounds characterized by the presence of both an amino group (-NH2) and a carboxyl group (-COOH), along with a unique side chain (R group) that determines the properties of the amino acid. The structure of the amino acid formed in the Strecker synthesis will depend on the aldehyde used, in this case, 2-methylbutanal, which influences the resulting side chain and overall identity of the amino acid.
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Aldehyde Reactivity
Aldehydes are reactive carbonyl compounds that can undergo various chemical reactions, including nucleophilic addition. In the context of Strecker synthesis, the aldehyde reacts with ammonia and cyanide to form an amino nitrile. The specific structure of the aldehyde, such as 2-methylbutanal, affects the final amino acid product, making it essential to understand how different aldehydes influence reactivity and product formation.
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Related Practice
Textbook Question
Esterase is an enzyme that catalyzes the hydrolysis of esters. It hydrolyzes esters of l-amino acids more rapidly than esters of D-amino acids. How can this enzyme be used to separate a racemic mixture of amino acids?
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Textbook Question
What alkyl halide is used in the acetamidomalonic ester synthesis to prepare
a. lysine?
1121
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Textbook Question
What amino acid is formed using the N-phthalimidomalonic ester synthesis when the following alkyl halides are used in the third step?
b. CH3SCH2CH2Br
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Textbook Question
Draw the tetrapeptide Ala-Thr-Asp-Asn and indicate the peptide bonds.
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Textbook Question
Draw the resonance contributors of the peptide bond in the less stable configuration.
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