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

10. Addition Reactions

Dihydroxylation

Organic Chemistry

10. Addition Reactions

Dihydroxylation

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2:48 minutes

Problem 35a

Textbook Question

Show how you would accomplish the following conversions.
a. cis-hex-3-ene to meso-hexane-3,4-diol

Verified step by step guidance

Identify the type of reaction needed for the conversion. The transformation from cis-hex-3-ene to meso-hexane-3,4-diol involves the addition of hydroxyl groups (-OH) to the double bond in a syn fashion. This suggests a syn-dihydroxylation reaction.

Choose an appropriate reagent for syn-dihydroxylation. A common reagent for this reaction is osmium tetroxide (OsO₄) in the presence of a co-oxidant like N-methylmorpholine N-oxide (NMO) or hydrogen peroxide (H₂O₂). Alternatively, potassium permanganate (KMnO₄) under cold, dilute conditions can also be used.

Write the reaction mechanism. The double bond in cis-hex-3-ene reacts with the OsO₄ or KMnO₄ to form a cyclic osmate ester or manganate intermediate. This intermediate ensures that the hydroxyl groups are added to the same face of the double bond (syn addition).

Hydrolyze the intermediate. The cyclic intermediate is then hydrolyzed with water to yield the diol product, meso-hexane-3,4-diol. The meso compound arises because the starting alkene is cis, and the syn addition leads to a product with internal symmetry.

Verify the stereochemistry of the product. The meso-hexane-3,4-diol has two chiral centers, but due to the symmetry of the molecule, it is optically inactive. This confirms the correct stereochemical outcome of the reaction.

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Key Concepts

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

Alkenes and Stereochemistry

Alkenes are hydrocarbons that contain at least one carbon-carbon double bond, which introduces geometric isomerism due to restricted rotation around the double bond. In this case, cis-hex-3-ene has substituents on the same side of the double bond, leading to specific stereochemical properties that are crucial for understanding the conversion to a diol.

Hydroxylation Reactions

Hydroxylation is the addition of hydroxyl groups (-OH) to a compound, often involving alkenes. In the conversion of cis-hex-3-ene to meso-hexane-3,4-diol, a common method is syn-dihydroxylation, where two hydroxyl groups are added to the same side of the double bond, resulting in a meso compound with internal symmetry.

Meso Compounds

Meso compounds are achiral molecules that contain multiple stereocenters but possess an internal plane of symmetry. In the case of meso-hexane-3,4-diol, the addition of hydroxyl groups to the cis-alkene leads to a compound that is superimposable on its mirror image, making it optically inactive despite having stereocenters.

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Related Practice

Textbook Question

Predict the major products of the following reactions, including stereochemistry.

c. cis-pent-2-ene + OsO₄/H₂O₂

d. cis-pent-2-ene + peroxyacetic acid in water

Textbook Question

Predict the major products of the following reactions, including stereochemistry.

a. cyclohexene + KMnO₄/H₂O (cold, dilute)

b. cyclohexene + peroxyacetic acid in water

Textbook Question

Show how you would make the following compounds from a suitable cyclic alkene.

(b)

Textbook Question

Show how you would accomplish the following conversions.

d. trans-hex-3-ene to (d,l)-hexane-3,4-diol

Textbook Question

The two butenedioic acids are called fumaric acid (trans) and maleic acid (cis). 2,3-Dihydroxybutanedioic acid is called tartaric acid.

Show how you would convert

c. maleic acid to (±)-tartaric acid.

Textbook Question

Show how you would make the following compounds from a suitable cyclic alkene.

(a)

Textbook Question

Predict the major products of the following reactions, and give the structures of any intermediates. Include stereochemistry where appropriate.

(j)

Textbook Question

Predict the product(s) of each of the following reactions, making sure to indicate the relative stereochemical outcome. Indicate any racemic mixtures by drawing both enantiomers.

(b)

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Show how you would accomplish the following conversions. a. cis-hex-3-ene to meso-hexane-3,4-diol

Key Concepts

Alkenes and Stereochemistry

Hydroxylation Reactions

Meso Compounds

Watch next

Show how you would accomplish the following conversions.
a. cis-hex-3-ene to meso-hexane-3,4-diol