Skip to main content
Ch. 23 - Carbohydrates and Nucleic Acids
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Non è quello che usi tu?Cambia libro di testo
Capitolo 23, Problema 48a,b,c

Use Figure 23-3 (the D family of aldoses) to name the following aldoses.
(a) the C2 epimer of D-arabinose
(b) the C3 epimer of D-mannose
(c) the C3 epimer of D-threose
Diagram of aldoses showing D-glyceraldehyde and its enantiomers, including D-galactose and C5 epimer of D-glucose.

Guida verificata passo dopo passo
1
Step 1: Understand the concept of epimers. Epimers are stereoisomers that differ in configuration at only one specific carbon atom, while the rest of the molecule remains identical. For aldoses, this means identifying the carbon atom where the configuration changes.
Step 2: For part (a), identify the C2 epimer of D-arabinose. Locate D-arabinose in Figure 23-3 (the D family of aldoses). D-arabinose is a five-carbon aldose (aldopentose). To find its C2 epimer, invert the stereochemistry at the second carbon (C2) while keeping the rest of the molecule unchanged.
Step 3: For part (b), identify the C3 epimer of D-mannose. Locate D-mannose in Figure 23-3. D-mannose is a six-carbon aldose (aldohexose). To find its C3 epimer, invert the stereochemistry at the third carbon (C3) while keeping the rest of the molecule unchanged.
Step 4: For part (c), identify the C3 epimer of D-threose. Locate D-threose in Figure 23-3. D-threose is a four-carbon aldose (aldotetrose). To find its C3 epimer, invert the stereochemistry at the third carbon (C3) while keeping the rest of the molecule unchanged.
Step 5: After identifying the epimers for each part, use the names provided in Figure 23-3 to assign the correct name to each epimer. Ensure that the D-configuration is maintained for all the aldoses.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
2m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Aldoses

Aldoses are a type of monosaccharide characterized by the presence of an aldehyde group (-CHO) at one end of the molecule. They can vary in the number of carbon atoms, and their structure influences their reactivity and biological function. Understanding aldoses is crucial for identifying their epimers, which are stereoisomers differing at one specific carbon atom.
Video consigliato:
03:21
General Reaction

Epimers

Epimers are a specific type of diastereomer that differ in configuration at only one stereogenic center. In the context of aldoses, identifying epimers involves recognizing how the orientation of hydroxyl (-OH) groups changes at specific carbon atoms. This concept is essential for naming aldoses based on their structural variations, such as the C2 or C3 epimers mentioned in the question.
Video consigliato:
03:42
Identifying Types of Stereoisomers

D and L Configuration

The D and L configuration refers to the stereochemical designation of sugars based on the orientation of the hydroxyl group on the chiral carbon farthest from the aldehyde group. D-sugars have the hydroxyl group on the right in a Fischer projection, while L-sugars have it on the left. This classification is fundamental for naming aldoses and understanding their relationships, including the identification of epimers.
Video consigliato:
05:09
Representations of L-Configuration
Pratica correlata
Domanda del libro di testo

Without referring to the chapter, draw the chair conformations of

(d) N-acetylglucosamine, glucose with the C2 oxygen atom replaced by an acetylated amino group.

810
views
Domanda del libro di testo

Without referring to the chapter, draw the chair conformations of

(b) α-D-allopyranose (the C3 epimer of glucose).

850
views
Domanda del libro di testo

Without referring to the chapter, draw the chair conformations of

(c) β-D-galactopyranose (the C4 epimer of glucose).

882
views
Domanda del libro di testo

Classify the following monosaccharides. (Examples: D-aldohexose, L-ketotetrose.)

1904
views
Domanda del libro di testo

(a) Give the products expected when (+)-glyceraldehyde reacts with HCN.

(b) What is the relationship between the products? How might they be separated?

(c) Are the products optically active? Explain.

922
views
Domanda del libro di testo

The relative configurations of the stereoisomers of tartaric acid were established by the following syntheses:

(1) D-(+)-glyceraldehyde →HCN\(\xrightarrow{HCN}\) diastereomers A and B (separated)

(2) Hydrolysis of A and B using aqueous Ba(OH)2 gave C and D, respectively.

(3) HNO3 oxidation of C and D gave (-)-tartaric acid and meso-tartaric acid, respectively.

(a) You know the absolute configuration of D-(+)-glyceraldehyde. Use Fischer projections to show the absolute configurations of products A, B, C, and D.

(b) Show the absolute configurations of the three stereoisomers of tartaric acid: (+)-tartaric acid, (-)-tartaric acid, and meso-tartaric acid.

1152
views