Textbook Question
Which of the following are optically active?
2
views
Ch. 4 - Isomers: The Arrangement of Atoms in Space
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 5, Problem 75
For many centuries, the Chinese have used extracts from a group of herbs known as ephedra to treat asthma. A compound named ephedrine has been isolated from these herbs and found to be a potent dilator of air passages in the lungs.
a. How many stereoisomers does ephedrine have?
b. The stereoisomer shown here is the one that is pharmacologically active. What is the configuration of each of the asymmetric centers?
Verified step by step guidance1
Step 1: Identify the asymmetric centers in the structure of ephedrine. An asymmetric center is a carbon atom bonded to four different groups. In the given structure, there are two asymmetric centers: one is the carbon attached to the hydroxyl group (-OH), the phenyl group, a hydrogen atom, and the rest of the chain; the other is the carbon attached to the amino group (-NH2), a methyl group (-CH3), a hydrogen atom, and the rest of the chain.
Step 2: Determine the number of stereoisomers possible for ephedrine. The formula for calculating the number of stereoisomers is 2^n, where n is the number of asymmetric centers. Since ephedrine has two asymmetric centers, the number of stereoisomers is 2^2 = 4.
Step 3: Analyze the configuration of each asymmetric center in the given stereoisomer. To assign the configuration (R or S), use the Cahn-Ingold-Prelog priority rules: assign priorities to the groups attached to the asymmetric center based on atomic number, and determine the spatial arrangement of these groups.
Step 4: For the first asymmetric center (carbon attached to -OH), assign priorities to the groups: phenyl group > hydroxyl group (-OH) > the rest of the chain > hydrogen. Determine the configuration by observing the arrangement of these groups in the given structure.
Step 5: For the second asymmetric center (carbon attached to -NH2), assign priorities to the groups: amino group (-NH2) > methyl group (-CH3) > the rest of the chain > hydrogen. Determine the configuration by observing the arrangement of these groups in the given structure.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3mWas 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. This can lead to different physical and chemical properties. In the case of ephedrine, it has multiple stereocenters, resulting in several stereoisomers, which can have varying biological activities.
Recommended video:
Guided course
01:58
Determining when molecules are stereoisomers.
Chirality and Asymmetric Centers
Chirality is a property of a molecule that makes it non-superimposable on its mirror image, often due to the presence of asymmetric centers (chiral centers). Each asymmetric center in a molecule can have two configurations, typically designated as R (rectus) or S (sinister). Understanding the configuration of these centers is crucial for determining the pharmacological activity of compounds like ephedrine.
Recommended video:
Guided course
05:41Understanding Other Chiral Atoms
Pharmacologically Active Stereoisomers
Pharmacologically active stereoisomers are specific stereoisomers of a compound that exhibit the desired therapeutic effects in biological systems. In the case of ephedrine, only one stereoisomer is responsible for its effectiveness as a bronchodilator. Identifying and understanding the configuration of this active stereoisomer is essential for drug development and therapeutic applications.
Recommended video:
Guided course
01:58Determining when molecules are stereoisomers.
Related Practice
Textbook Question
Draw the structure for a compound with molecular formula C2H2I2F2
c. that is optically active.
Textbook Question
Which of the following has an achiral stereoisomer?
e. 1,3-dibromocyclobutane
f. 2,4-dibromopentane
1
views
Textbook Question
Draw the structure for a compound with molecular formula C2H2I2F2
a. that is optically inactive because it does not have an asymmetric center.
b. that is optically inactive because it is a meso compound.
1
views
Textbook Question
Name the following:
c.
1
views
Textbook Question
Which of the following has an achiral stereoisomer?
a. 2,3-dichlorobutane
b. 2,3-dichloropentane
2
views