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Ch. 20 - The Organic Chemistry of Carbohydrates
Bruice - Organic Chemistry 8th Edition
Bruice8th EditionOrganic ChemistryISBN: 9780135213711Not the one you use?Change textbook
Chapter 21, Problem 6b

What are the systematic names of the following compounds? Indicate the configuration (R or S) of each asymmetric center.
b. D-mannose

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1
Identify the structure of d-mannose. d-Mannose is an aldohexose, meaning it is a six-carbon sugar with an aldehyde functional group at the first carbon. Its structure includes four chiral centers at carbons 2, 3, 4, and 5.
Draw the Fischer projection of d-mannose. In the Fischer projection, the aldehyde group (-CHO) is at the top, and the hydroxymethyl group (-CH2OH) is at the bottom. The hydroxyl groups (-OH) on carbons 2, 3, 4, and 5 are arranged as follows: -OH on the left at C2, -OH on the right at C3, -OH on the left at C4, and -OH on the right at C5.
Assign priorities to the substituents at each chiral center using the Cahn-Ingold-Prelog (CIP) priority rules. For each chiral center, assign priorities based on atomic number: the -OH group has the highest priority, followed by the -CH(OH) group, then the -CH2OH group, and finally the hydrogen atom.
Determine the configuration (R or S) for each chiral center. For each chiral center, orient the molecule so that the lowest-priority group (hydrogen) is pointing away from you. Trace the path from the highest-priority group to the second-highest and then to the third-highest. If the path is clockwise, the configuration is R; if counterclockwise, it is S.
Combine the systematic name of the sugar with the configurations of the chiral centers. The systematic name of d-mannose will include the prefix 'D-' (indicating the configuration at the highest-numbered chiral center, C5) and the configurations (R or S) of the other chiral centers in parentheses.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Systematic Naming of Organic Compounds

Systematic naming, or IUPAC nomenclature, is a standardized method for naming organic compounds based on their structure. It involves identifying the longest carbon chain, naming substituents, and applying specific rules for functional groups and stereochemistry. Understanding this system is essential for accurately conveying the identity of a compound.
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Stereochemistry and Chiral Centers

Stereochemistry is the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. Chiral centers, or asymmetric centers, are carbon atoms bonded to four different groups, leading to non-superimposable mirror images known as enantiomers. Identifying the configuration of these centers as R (rectus) or S (sinister) is crucial for understanding the compound's properties.
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D-Mannose and Its Configuration

D-Mannose is a naturally occurring sugar and an epimer of glucose, differing in the configuration around one specific carbon atom. It is important to recognize its structure and stereochemistry to determine its systematic name and the configuration of its chiral centers. The 'D' designation indicates the orientation of the hydroxyl group on the highest-numbered chiral carbon, which is vital for its classification.
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