Textbook Question
What product or products are obtained when D-galactose reacts with each of the following?
e. Br2 in water
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Ch. 20 - The Organic Chemistry of Carbohydrates
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 21, Problem 34c
What product or products are obtained when D-galactose reacts with each of the following?
c. NaBH4, followed by H3O+
Verified step by step guidance1
Identify the functional groups present in d-galactose. D-galactose is an aldose sugar, meaning it contains an aldehyde group (-CHO) at the anomeric carbon and multiple hydroxyl (-OH) groups.
Understand the role of NaBH4 (sodium borohydride). NaBH4 is a reducing agent that specifically reduces aldehydes and ketones to their corresponding alcohols. In this case, the aldehyde group in d-galactose will be reduced to a primary alcohol (-CH2OH).
Write the reaction mechanism for the reduction. NaBH4 donates a hydride ion (H⁻) to the carbonyl carbon of the aldehyde group, converting it into an alkoxide intermediate. This intermediate is then protonated by H3O+ (acidic workup) to form the primary alcohol.
Determine the structure of the product. After the reduction, the aldehyde group at the anomeric carbon of d-galactose is replaced by a primary alcohol group (-CH2OH), while the rest of the molecule (the hydroxyl groups on the other carbons) remains unchanged.
Conclude the reaction outcome. The product of this reaction is d-galactitol (also known as dulcitol), a sugar alcohol derived from d-galactose. No other products are formed in this reaction.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Reduction Reactions
Reduction reactions involve the gain of electrons or hydrogen, or the loss of oxygen. In organic chemistry, this often refers to the conversion of carbonyl groups (like aldehydes and ketones) into alcohols. In the case of d-galactose, the reaction with NaBH4, a strong reducing agent, will reduce the aldehyde group to a primary alcohol.
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Reductive Amination
Hydrolysis
Hydrolysis is a chemical reaction that involves the breaking of a bond in a molecule using water. In the context of the reaction with H3O+, hydrolysis can help in converting any intermediate formed during the reduction into a stable product. This step is crucial for ensuring that the final product is in its desired alcohol form after reduction.
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Stereochemistry of Sugars
Stereochemistry refers to the spatial arrangement of atoms in molecules and how this affects their chemical behavior. d-Galactose is a stereoisomer of glucose, and its specific configuration influences the outcome of reactions. Understanding the stereochemistry of d-galactose is essential for predicting the structure of the final product after reduction and hydrolysis.
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Related Practice
Textbook Question
What product or products are obtained when D-galactose reacts with each of the following?
f. ethanol + HCl
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Textbook Question
Refer to Figure 20.5 to answer the following questions: b. People with type AB blood can receive blood from anyone, but they cannot give blood to everyone. To whom can they not give blood?
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Textbook Question
What product or products are obtained when D-galactose reacts with each of the following?
b. Ag+, NH3, HO-
569
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Textbook Question
Refer to Figure 20.5 to answer the following questions: a. People with type O blood can donate blood to anyone, but they cannot receive blood from everyone. From whom can they not receive blood?
1109
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Textbook Question
What product or products are obtained when d-galactose reacts with each of the following?
d. excess CH3I + Ag2O
803
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