13 Questions
What is the molecular formula of Lithium diisopropylamide (LDA)?
LiN(CH(CH3)2)2
How is LDA commonly prepared?
Treating a cooled mixture of tetrahydrofuran and diisopropylamine with n-butyllithium
What is the pKa value of diisopropylamine?
36
Why is Lithium diisopropylamide (LDA) widely utilized?
Due to its good solubility in non-polar organic solvents and non-nucleophilic nature
What type of compounds can LDA deprotonate?
Compounds with greater acidity such as carbon acids
What happens when the diisopropylamide anion becomes protonated?
Forms diisopropylamine
What is the primary structure of LDA in THF?
Solvated dimer
In which solvent does LDA form temperature-dependent oligomer equilibriums?
Toluene
At room temperature, what are the most likely structures formed by LDA in toluene?
Trimers and tetramers
Why is solid LDA considered pyrophoric?
It ignites spontaneously in air
What is a common and more cost-effective way to prepare LDA for small-scale use (less than 50 mmol)?
Preparation of LDA in situ
What type of reaction control is required for kinetic deprotonation of carbon acids?
Sterically hindered base
Which group does LDA deprotonate in the case of phenylacetone, indicating the kinetic course of deprotonation?
Methyl group
Study Notes
Lithium Diisopropylamide (LDA)
- Molecular formula: L(NiPr2)
- Commonly prepared by reacting butyllithium with diisopropylamine
Properties of Diisopropylamine
- pKa value: 36
Utilization of LDA
- Widely utilized due to its strong basicity and ability to deprotonate a wide range of compounds
Deprotonation by LDA
- Can deprotonate carbon acids, including those with pKa values up to 30-40
- Deprotonation of diisopropylamide anion leads to the formation of diisopropylamine and lithium ions
Structure of LDA
- Primary structure in THF: a mixture of monomer, dimer, and tetramer
- Forms temperature-dependent oligomer equilibria in THF
Solvent Effects
- In toluene, the most likely structures formed by LDA at room temperature are dimers and trimers
Safety Considerations
- Solid LDA is considered pyrophoric due to its high reactivity with air and moisture
Preparation of LDA
- For small-scale use (less than 50 mmol), a common and more cost-effective way to prepare LDA is by reacting lithium metal with diisopropylamine
Reaction Control
- Kinetic deprotonation of carbon acids requires tight reaction control to ensure selective deprotonation
Deprotonation of Phenylacetone
- LDA deprotonates the alpha-methyl group of phenylacetone, indicating the kinetic course of deprotonation
Learn about the chemical compound Lithium diisopropylamide (LDA), its molecular formula, properties, and uses as a strong base in non-polar organic solvents. Explore its synthesis and applications.
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