We said that regardless of the length of the R group, it's always going to turn into benzoic acid unless you're missing hydrogens. Essentially, 3 of these have a benzylic hydrogen. One doesn't. A has a hydrogen. C has a hydrogen, and D actually has 2 hydrogens. But B has none. So B is the answer. B would actually display no reaction when reacted with KMnO4 because it does not have a benzylic hydrogen available to oxidize. So it's not going to be able to respond to the oxidizing agent. Awesome, guys. Like I said, pretty easy concept. Not much to know. Let's move on to the next one.
- 1. A Review of General Chemistry5h 5m
- Summary23m
- Intro to Organic Chemistry5m
- Atomic Structure16m
- Wave Function9m
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- Sigma and Pi Bonds9m
- Octet Rule12m
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- Formal Charges6m
- Skeletal Structure14m
- Lewis Structure20m
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- Hybridization23m
- Molecular Geometry16m
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- 2. Molecular Representations1h 14m
- 3. Acids and Bases2h 46m
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- Test 3:Disubstituted Cycloalkanes13m
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- 18. Aromaticity2h 31m
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- Blocking Groups - Sulfonic Acid12m
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- Side-Chain Halogenation6m
- Side-Chain Oxidation4m
- Reactions at Benzylic Positions31m
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- Diazo Replacement Reactions6m
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- Nucleophilic Aromatic Substitution28m
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- 20. Phenols55m
- 21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
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- 23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
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- Acetoacetic Ester Synthesis13m
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- 27. Heterocycles2h 0m
- Nomenclature of Heterocycles15m
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- Reactions of Pyrrole, Furan, and Thiophene13m
- Directing Effects in Substituted Pyrroles, Furans, and Thiophenes16m
- Addition Reactions of Furan8m
- EAS Reactions of Pyridine17m
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- Side-Chain Reactions of Substituted Pyridines20m
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- Glycoside6m
- Monosaccharides - N-Glycosides18m
- Monosaccharides - Reduction (Alditols)12m
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- Monosaccharides - Oxidative Cleavage27m
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- Monosaccharides - Kiliani-Fischer23m
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- 29. Amino Acids3h 20m
- Proteins and Amino Acids19m
- L and D Amino Acids14m
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- Acid-Base Properties of Amino Acids33m
- Isoelectric Point14m
- Amino Acid Synthesis: HVZ Method12m
- Synthesis of Amino Acids: Acetamidomalonic Ester Synthesis16m
- Synthesis of Amino Acids: N-Phthalimidomalonic Ester Synthesis13m
- Synthesis of Amino Acids: Strecker Synthesis13m
- Reactions of Amino Acids: Esterification7m
- Reactions of Amino Acids: Acylation3m
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- Reactions of Amino Acids: Ninhydrin Test11m
- 30. Peptides and Proteins2h 42m
- Peptides12m
- Primary Protein Structure4m
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- Quaternary Protein Structure10m
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- Intro to Peptide Sequencing2m
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- Peptide Sequencing: Partial Hydrolysis with Cyanogen Bromide7m
- Peptide Sequencing: Edman Degradation28m
- Merrifield Solid-Phase Peptide Synthesis18m
- 32. Lipids 2h 50m
- 34. Nucleic Acids1h 32m
- 35. Transition Metals5h 33m
- Electron Configuration of Elements45m
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- Ligands24m
- Electron Counting10m
- The 18 and 16 Electron Rule13m
- Cross-Coupling General Reactions40m
- Heck Reaction40m
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- Suzuki Reaction25m
- Sonogashira Coupling Reaction17m
- Fukuyama Coupling Reaction15m
- Kumada Coupling Reaction13m
- Negishi Coupling Reaction16m
- Buchwald-Hartwig Amination Reaction19m
- Eglinton Reaction17m
Side-Chain Oxidation - Online Tutor, Practice Problems & Exam Prep
Side chain oxidation involves the transformation of an alkyl side chain attached to a benzene ring into benzoic acid using hot potassium permanganate (KMnO4). Regardless of the alkyl chain length, the reaction cleaves the chain, replacing it with a carboxylic acid. For oxidation to occur, at least one benzylic hydrogen must be present. The reaction conditions typically include KMnO4, base, heat, and an acidic workup. Understanding these conditions and the requirement for a benzylic hydrogen is crucial for predicting the outcome of the reaction.
We know that the alkyl group directly attached to benzene is known as an alkyl side-chain. Now, regardless of the length of that side-chain, it can be oxidized to benzoic acid using hot KMnO4. What's the kicker? There must be at least one benzylic hydrogen.
Benzylic Oxidation
Which alkylbenzene would NOT yield benzoic acid, treated with KMnO4
Video transcript
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More setsHere’s what students ask on this topic:
What is side chain oxidation in organic chemistry?
Side chain oxidation in organic chemistry refers to the process where an alkyl side chain attached to a benzene ring is transformed into a carboxylic acid, specifically benzoic acid, using a strong oxidizing agent like hot potassium permanganate (KMnO4). This reaction cleaves the entire alkyl chain, regardless of its length, and replaces it with a carboxylic acid group. The reaction conditions typically include KMnO4, a base, heat, and an acidic workup.
What reagents are required for the side chain oxidation of alkylbenzenes?
The reagents required for the side chain oxidation of alkylbenzenes include hot potassium permanganate (KMnO4), a base (such as NaOH), heat, and an acidic workup (such as H3O+). These conditions are necessary to ensure the complete oxidation of the alkyl side chain to a carboxylic acid, specifically benzoic acid.
Why is a benzylic hydrogen necessary for side chain oxidation to occur?
A benzylic hydrogen is necessary for side chain oxidation to occur because it is required for the initial step of the oxidation process. The presence of at least one hydrogen atom on the carbon directly attached to the benzene ring (the benzylic position) allows the oxidizing agent to abstract this hydrogen, initiating the oxidation reaction. Without a benzylic hydrogen, the oxidation cannot proceed, and the alkyl side chain will not be converted to a carboxylic acid.
What is the product of side chain oxidation of toluene using hot KMnO4?
The product of the side chain oxidation of toluene (methylbenzene) using hot potassium permanganate (KMnO4) is benzoic acid. The methyl group (CH3) attached to the benzene ring is oxidized to a carboxylic acid group (COOH), resulting in the formation of benzoic acid (C6H5COOH).
How does the length of the alkyl side chain affect the outcome of side chain oxidation?
The length of the alkyl side chain does not affect the outcome of side chain oxidation. Regardless of how long the alkyl chain is, the entire chain will be cleaved and replaced with a carboxylic acid group when treated with hot potassium permanganate (KMnO4). The final product will always be benzoic acid (C6H5COOH), as long as there is at least one benzylic hydrogen present.
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