Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

5. Chirality

Constitutional Isomers vs. Stereoisomers

Organic Chemistry

5. Chirality

Constitutional Isomers vs. Stereoisomers

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3:05 minutes

Problem 23a

Textbook Question

Which of the following pairs of compounds could be separated by recrystallization or distillation?
a. meso-tartaric acid and (±)-tartaric acid (HOOC—CHOH—CHOH—COOH)

Verified step by step guidance

Step 1: Understand the physical properties of the compounds in question. Meso-tartaric acid and (±)-tartaric acid are stereoisomers. Meso-tartaric acid is achiral due to internal symmetry, while (±)-tartaric acid is a racemic mixture of two enantiomers.

Step 2: Consider recrystallization as a separation method. Recrystallization relies on differences in solubility. Meso-tartaric acid and (±)-tartaric acid may have different solubility profiles in a given solvent, allowing for separation through selective crystallization.

Step 3: Evaluate distillation as a separation method. Distillation separates compounds based on differences in boiling points. Since both compounds are solid at room temperature and have similar functional groups, distillation is unlikely to be effective for their separation.

Step 4: Focus on recrystallization. To separate these compounds, dissolve the mixture in a solvent where one compound is more soluble than the other at a given temperature. Upon cooling, the less soluble compound will crystallize out first.

Step 5: Confirm the separation method. Analyze the crystallized product using techniques like melting point determination or spectroscopy to ensure successful separation of meso-tartaric acid and (±)-tartaric acid.

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Key Concepts

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

Recrystallization

Recrystallization is a purification technique used to separate compounds based on their solubility differences. In this process, a solid compound is dissolved in a hot solvent and then allowed to cool, leading to the formation of pure crystals. The impurities remain in the solution, allowing for the isolation of the desired compound. This method is particularly effective for compounds with different solubility profiles.

Distillation

Distillation is a separation technique that exploits differences in boiling points of compounds. In this process, a mixture is heated to vaporize the more volatile component, which is then condensed back into a liquid. This method is commonly used for separating liquids or volatile substances, making it useful for purifying solvents or separating liquid mixtures with distinct boiling points.

Stereoisomers

Stereoisomers are compounds that have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of their atoms. Meso compounds, like meso-tartaric acid, possess an internal plane of symmetry, making them achiral, while their enantiomers, such as (±)-tartaric acid, are chiral and exist as non-superimposable mirror images. Understanding the differences in chirality is crucial for determining the separation methods applicable to these compounds.

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