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)
1970
views
Ch.5 - Stereochemistry
Wade9th EditionOrganic ChemistryISBN: 9780135213728
Not the one you use?Change textbookSelect a different textbook
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 7
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.
Verified step by step guidance1
Identify the structure of octa-2,4,6-triene, which contains three double bonds at positions 2, 4, and 6.
Recognize that each double bond can exist in either a cis or trans configuration, which would typically suggest 2^3 = 8 possible stereoisomers.
Consider the concept of conjugation in octa-2,4,6-triene, where the double bonds are in a continuous sequence, allowing for overlap of p-orbitals across the entire chain.
Understand that due to conjugation, the molecule can adopt a planar conformation, which imposes restrictions on the possible stereoisomers, reducing the number from eight to six.
Draw the six stereoisomers by considering the possible cis/trans configurations for each double bond, while ensuring that the overall molecule remains planar due to conjugation.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
4mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Stereoisomerism
Stereoisomerism refers to the phenomenon where compounds have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of their atoms. In the case of octa-2,4,6-triene, the presence of double bonds introduces the possibility of cis and trans configurations, leading to different stereoisomers. Understanding stereoisomerism is crucial for determining the number of unique isomers a compound can have.
Recommended video:
Guided course
01:58
Determining when molecules are stereoisomers.
Stereogenic Centers
Stereogenic centers are atoms in a molecule that can create stereoisomers due to their ability to form different spatial arrangements. In octa-2,4,6-triene, the double bonds act as stereogenic centers, but not all double bonds contribute to the total count of stereoisomers. The specific arrangement of substituents around these centers determines the actual number of distinct stereoisomers.
Recommended video:
Guided course
02:38The difference between chiral and trigonal centers.
E/Z Nomenclature
E/Z nomenclature is a system used to describe the configuration of double bonds in alkenes based on the priority of substituents attached to the carbon atoms involved in the double bond. For octa-2,4,6-triene, the presence of three double bonds allows for E and Z configurations, but due to symmetry and the arrangement of substituents, only six unique stereoisomers can be formed instead of the expected eight. This concept is essential for understanding the limitations in the number of stereoisomers.
Recommended video:
Guided course
03:48E/Z Diastereoisomerism
Related Practice
Textbook Question
Star (*) each asymmetric carbon atom in the following examples, and determine whether it has the (R) or (S) configuration.
(i)
878
views
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).
(c)
(d) 1-bromo-2-methylbutane
1682
views
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
1552
views
Textbook Question
Star (*) each asymmetric carbon atom in the following examples, and determine whether it has the (R) or (S) configuration.
(a)
(b)
1404
views
Textbook Question
A solution of pure (S)-2-iodobutane ([α] = +15.90° ) in acetone is allowed to react with radioactive iodide, 131I-, until 1.0% of the iodobutane contains radioactive iodine. The specific rotation of this recovered iodobutane is found to be +15.58°. a. Determine the percentages of (R)- and (S)-2-iodobutane in the product mixture.
1861
views