Table of contents |
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Organic Named Reactions |
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Acyloin Condensation |
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Mechanisms |
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Pinacol Coupling Reactions |
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The McMurry Reaction |
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The Aldol Reaction |
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A name reaction is a chemical reaction named after its discoverers or developers. Among the tens of thousands of organic reactions that are known, hundreds of such reactions are well-known enough to be named after people.
The Organic Reactions discussed in this part are:
Acyloin condensation is a reductive coupling of two carboxylic esters using metallic sodium to yield an α-hydroxyketone, also known as an acyloin.
Mechanism for intramolecular acyloin ester condensation reaction:
Mechanism for intermolecular acyloin ester condensation reaction:
The inter-and intramolecular coupling of two carbonyl groups of aldehydes or ketones in the presence of a low-valent titanium species produces a C-C bond with two adjacent stereocenters, a 1,2-diol (a pinacol).
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Test: Aldol Condensation
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The McMurry reaction is an organic reaction in which two ketone or aldehyde groups are coupled to form an alkene using a titanium chloride compound such as titanium (III) chloride and a reducing agent. The reaction is named after its co-discoverer, John E. McMurry.
McMurry Reaction of Benzophenone
The general features of this coupling reaction are:
The mechanism of the McMurry coupling is not entirely clear, but it is composed of two distinct steps: 1) pinacol formation and 2) deoxygenation to the alkene.
Finely divided Ti(0) metal particles produced by reduction of TiC13, with potassium or Synthesis of Alkene lithium metal or with a zinc-copper couple reductive1 couple aldehydes and ketones at elevated temperature to produce alkenes.
The aldol reaction is one of the most useful methods for the construction of C—C bonds. The products of aldol reactions are either β-hydroxy carbonyl compounds or, after dehydration, α, β-unsaturated carbonyl compounds.
The base-catalyzed aldol reaction for aldehydes is slightly exothermic while the reaction for ketones is somewhat endothermic
The enol content of simple ketones is quite low under standard acid-catalyzed conditions (for acetone Keq = 10–7; cyclohexanone Keq = 10–6).
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Organic Reactions with Mechanism (Part-1)
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The β-hydroxy aldehydes and β-hydroxy ketones formed in aldol reactions are readily dehydrated to yield conjugated systems. This is called Aldol Condensation.
These elimination reactions can be affected by either acid or base while heating during the condensation.
Removal of H2O from the reaction mixture drives the equilibrium toward product formation. Even though the initial aldol step itself may be unfavorable (as it usually is for ketones), the subsequent dehydration step allows most aldol reactions to be carried out in good yield.
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1. What is the mechanism of the Aldol Reaction? | ![]() |
2. How does the Acyloin Condensation reaction proceed? | ![]() |
3. What is the significance of Pinacol Coupling Reactions in organic chemistry? | ![]() |
4. Can you explain the mechanism of the McMurry Reaction? | ![]() |
5. How do Organic Named Reactions with mechanisms contribute to the field of organic chemistry? | ![]() |