page_title: Lithium diisopropylamide
section_title: Preparation and structure
hierarchical_section_title: Lithium diisopropylamide / Preparation and structure
caption_attribution_description: English: Deprotonation using LDA doi 10.15227/orgsyn.087.0137
context_page_description: Lithium diisopropylamide is a chemical compound with the molecular formula [(CH₃)₂CH]₂NLi. It is used as a strong base and has been widely accepted due to its good solubility in non-polar organic solvents and non-nucleophilic nature. It is a colorless solid, but is usually generated and observed only in solution. It was first prepared by Hamell and Levine in 1950 along with several other hindered lithium diorganylamides to effect the deprotonation of esters at the α position without attack of the carbonyl group.
context_section_description: LDA is commonly formed by treating a cooled (0 to −78 °C) tetrahydrofuran (THF) solution of diisopropylamine with n-butyllithium.
  When dissociated, the diisopropylamide anion can become protonated to form diisopropylamine. Diisopropylamine has a pKa value of 36. Therefore, its conjugate base is suitable for the deprotonation of compounds with greater acidity, importantly, such weakly acidic compounds (carbon acids) of the type R₂CHZ, where Z = C(O)R', CO₂R' or CN. Conventional protic functional groups such as alcohols and carboxylic acids are of course readily deprotonated.
  Like most organolithium reagents, LDA is not a salt, but is highly polar. It forms aggregates in solution, with the extent of aggregation depending on the nature of the solvent. In THF its structure is primarily that of a solvated dimer. In nonpolar solvents such as toluene, it forms a temperature-dependent oligomer equilibrium. At room temperature trimers and tetramers are the most likely structures. With decreasing temperature the aggregation extends to pentameric and higher oligomeric structures.
  Solid LDA is pyrophoric, but its solutions are generally not. As such it is commercially available as a solution in polar aprotic solvents such as THF and ether; however, for small scale use (less than 50 mmol), it is common and more cost effective to prepare LDA in situ.
caption: Deprotonation using LDA [8].
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