Textbook Question
In Problem 5-3, you drew the enantiomers for a number of chiral compounds. Now go back and designate each asymmetric carbon atom as either (R) or (S).
(a)
(b)
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Ch.5 - Stereochemistry
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 5, Problem 7c,d
In Problem 5-3, you drew the enantiomers for a number of chiral compounds. Now go back and designate each asymmetric carbon atom as either (R) or (S).
(c) 
(d) 1-bromo-2-methylbutane
Verified step by step guidance1
Step 1: Identify the chiral center in alanine (c). The chiral center is the carbon atom bonded to four different groups: NH₂, CH₃, H, and COOH.
Step 2: Assign priorities to the substituents around the chiral center in alanine based on the Cahn-Ingold-Prelog priority rules. The highest priority is given to the group with the atom of highest atomic number directly attached to the chiral center.
Step 3: Orient the molecule so that the lowest priority group (H) is pointing away from you. Then, determine the order of the remaining groups (1 → 2 → 3) and decide if the rotation is clockwise (R) or counterclockwise (S).
Step 4: For 1-bromo-2-methylbutane (d), identify the chiral center, which is the carbon atom bonded to four different groups: Br, CH₃, H, and CH₂CH₃.
Step 5: Repeat the process of assigning priorities, orienting the molecule, and determining the configuration (R or S) for 1-bromo-2-methylbutane using the Cahn-Ingold-Prelog rules.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Chirality
Chirality refers to the geometric property of a molecule that makes it non-superimposable on its mirror image. Molecules that possess chirality typically have one or more asymmetric carbon atoms, which are carbon atoms bonded to four different substituents. This property is crucial in organic chemistry as it affects the behavior of molecules in biological systems, influencing how they interact with enzymes and receptors.
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R and S Nomenclature
The R and S nomenclature system is used to assign configurations to chiral centers in molecules. The Cahn-Ingold-Prelog priority rules are applied to determine the order of substituents attached to the chiral carbon. If the priority of the substituents decreases in a clockwise direction, the configuration is designated as (R); if it decreases counterclockwise, it is designated as (S). This system is essential for accurately describing the stereochemistry of chiral compounds.
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Asymmetric Carbon Atom
An asymmetric carbon atom, also known as a chiral center, is a carbon atom that is bonded to four different groups or atoms. The presence of an asymmetric carbon is what gives rise to enantiomers, which are pairs of molecules that are mirror images of each other. Identifying and designating these carbon atoms is fundamental in understanding the stereochemistry of organic compounds, particularly in the context of biological activity and drug design.
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Related Practice
Textbook Question
b. Draw the six stereoisomers of octa-2,4,6-triene. Explain why there are only six stereoisomers, rather than the eight we might expect for a compound with three stereogenic double bonds.
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Textbook Question
Star (*) each asymmetric carbon atom in the following examples, and determine whether it has the (R) or (S) configuration.
(i)
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Textbook Question
Write structural formulas for the following compounds (includes both old- and new-style names).(j) vinylacetylene(k) (S)-3-methyl-1-penten-4-yne
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Textbook Question
In Problem 5-3, you drew the enantiomers for a number of chiral compounds. Now go back and designate each asymmetric carbon atom as either (R) or (S).
(e) chlorocyclohexane
(f) cis-1,2-dichlorocyclobutane
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Textbook Question
A solution of 2.0 g of (+)-glyceraldehyde, HOCH2CHOHCHO, in 10.0 mL of water was placed in a 100-mm cell. Using the sodium D line, a rotation of +1.74° was found at 25 °C. Determine the specific rotation of (+)-glyceraldehyde