Textbook Question
Name the epimers of D-glucose.
1815
views
Ch. 20 - The Organic Chemistry of Carbohydrates
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
Not the one you use?Change textbookSelect a different textbook
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 34g
What product or products are obtained when d-galactose reacts with each of the following?
g.
1. hydroxylamine/trace acid
2. acetic anhydride/∆
3. HO-/H2O
Verified step by step guidance1
Step 1: Understand the structure of D-galactose. D-galactose is an aldohexose, meaning it contains six carbons and an aldehyde functional group at the first carbon. The remaining carbons have hydroxyl (-OH) groups in specific stereochemical configurations.
Step 2: Analyze the reaction with hydroxylamine (NH2OH) in the presence of trace acid. Hydroxylamine reacts with the aldehyde group of D-galactose to form an oxime. This reaction involves nucleophilic attack by the hydroxylamine on the carbonyl carbon of the aldehyde, followed by the elimination of water.
Step 3: Examine the reaction with acetic anhydride under heat (∆). Acetic anhydride reacts with the hydroxyl groups of D-galactose to form acetylated derivatives. Each hydroxyl group is converted into an acetate ester (-OCOCH3). This reaction is typically carried out under heating to ensure complete acetylation.
Step 4: Consider the reaction with hydroxide ion (HO-) in water (H2O). In the presence of a strong base like hydroxide, D-galactose can undergo isomerization or epimerization. The base can abstract a proton from the alpha-hydrogen of the aldehyde, leading to the formation of an enolate intermediate. This intermediate can tautomerize to form different isomers, such as D-mannose or D-fructose.
Step 5: Summarize the products. The reactions yield the following: (1) an oxime from the reaction with hydroxylamine, (2) a fully acetylated D-galactose derivative from the reaction with acetic anhydride, and (3) potential isomers (D-mannose or D-fructose) from the reaction with hydroxide in water.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Monosaccharide Reactivity
Monosaccharides like d-galactose can undergo various chemical reactions due to their functional groups, primarily the aldehyde or ketone group. Understanding the reactivity of these groups is crucial for predicting the products formed during reactions with reagents such as hydroxylamine and acetic anhydride.
Recommended video:
Guided course
12:01
Monosaccharide
Formation of Oximes
When d-galactose reacts with hydroxylamine in the presence of trace acid, it forms an oxime. This reaction involves the nucleophilic attack of hydroxylamine on the carbonyl carbon of the sugar, leading to the formation of a stable oxime product, which is a key step in carbohydrate chemistry.
Recommended video:
Guided course
02:26Formation of Enolates
Acylation Reactions
Acetic anhydride reacts with d-galactose to perform acylation, where the hydroxyl groups of the sugar are converted into acetate esters. This reaction is significant for modifying the solubility and reactivity of sugars, and it can be used to protect hydroxyl groups in further synthetic applications.
Recommended video:
1:01Reactions of Amino Acids: Acylation Example 1
Related Practice
Textbook Question
What product or products are obtained when D-galactose reacts with each of the following?
e. Br2 in water
656
views
Textbook Question
What product or products are obtained when D-galactose reacts with each of the following?
f. ethanol + HCl
722
views
Textbook Question
Identify the sugar in each description.
a. An aldopentose that is not D-arabinose forms D-arabinitol when it is reduced with NaBH4.
1052
views
Textbook Question
Identify the sugar in each description.
b. A sugar that is not D-altrose forms D-altraric acid when it is oxidized with nitric acid.
720
views
Textbook Question
What product or products are obtained when d-galactose reacts with each of the following?
d. excess CH3I + Ag2O
803
views