Textbook Question
Predict the major products of the following reactions, including stereochemistry.
a. cyclohexene + KMnO4/H2O (cold, dilute)
b. cyclohexene + peroxyacetic acid in water
10. Addition Reactions
Dihydroxylation
4:29 minutesProblem 65c
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.
Verified step by step guidance1
Step 1: Recognize that maleic acid is the cis isomer of butenedioic acid, and tartaric acid is a dihydroxy derivative of butanedioic acid. The conversion involves adding hydroxyl groups to the double bond of maleic acid.
Step 2: Use a reagent capable of hydroxylation, such as cold, dilute potassium permanganate (KMnO₄) or osmium tetroxide (OsO₄). These reagents add hydroxyl groups to the double bond in a syn addition manner.
Step 3: Perform the hydroxylation reaction on maleic acid. The cis configuration of maleic acid ensures that the hydroxyl groups are added to the same side of the molecule, resulting in the formation of (+/-)-tartaric acid.
Step 4: Neutralize the reaction mixture if necessary, and isolate the product by purification techniques such as recrystallization or extraction.
Step 5: Confirm the structure of the product as (+/-)-tartaric acid using spectroscopic methods like NMR or IR, which will show characteristic signals for hydroxyl and carboxylic acid groups.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Geometric Isomerism
Geometric isomerism occurs when compounds have the same molecular formula but differ in the spatial arrangement of atoms. In the case of maleic acid (cis) and fumaric acid (trans), the positioning of the carboxylic acid groups around the double bond leads to distinct physical and chemical properties. Understanding this concept is crucial for recognizing how these isomers can interconvert and their implications in reactions.
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Hydroxylation Reactions
Hydroxylation reactions involve the addition of hydroxyl (-OH) groups to a compound, which can significantly alter its reactivity and properties. In the conversion of maleic acid to tartaric acid, hydroxylation is key, as it introduces two hydroxyl groups to the carbon chain, transforming the structure from a diene to a diol. This process is essential for synthesizing tartaric acid from maleic acid.
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Stereochemistry
Stereochemistry is the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. Tartaric acid has two chiral centers, leading to the formation of enantiomers. Understanding stereochemistry is vital for predicting the outcomes of reactions and the properties of the resulting compounds, especially when converting maleic acid to (±)-tartaric acid, which is a racemic mixture.
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