Editing Lithium diisopropylamide (section)

==Preparation and structure==
[[File:dimerliamide.jpg|thumb|left|LDA dimer with THF coordinated to Li centers]]
LDA is commonly formed by treating a cooled (0 to −78&nbsp;°C) mixture of [[tetrahydrofuran]] and [[diisopropylamine]] with [[N-Butyllithium|''n''-butyllithium]].<ref>{{OrgSynth |author=Smith, A. P. |author2=Lamba, J. J. S. |author3=Fraser, C. L. |title=Efficient Synthesis of Halomethyl-2,2'-Bipyridines: 4,4'-Bis(chloromethyl)-2,2'-Bipyridine |collvol=10 |collvolpages=107 |year=2004 |prep=v78p0082}}</ref>

When dissociated, the diisopropylamide anion can become [[protonation|protonated]] to form diisopropylamine. Diisopropylamine has a [[Acid dissociation constant|p''K''<sub>a</sub>]] 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 {{chem2|HC(Z)R2}}, where Z = C(O)R', C(O)OR' or CN. Conventional protic functional groups such as alcohols and carboxylic acids are readily deprotonated.

Like most [[organolithium reagent]]s, 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 (chemistry)|dimer]].<ref>{{cite journal |author1=Williard, P. G. |author2=Salvino, J. M. |journal=[[Journal of Organic Chemistry]] |year=1993 |volume=58 |issue=1 |pages=1–3 |title=Synthesis, isolation, and structure of an LDA-THF complex |doi=10.1021/jo00053a001}}</ref><ref>{{cite journal |journal=[[Journal of the American Chemical Society]] |year=1991 |volume=113 |issue=21 |title=Crystal structure of lithium diisopropylamide (LDA): an infinite helical arrangement composed of near-linear nitrogen-lithium-nitrogen units with four units per turn of helix |author1=N.D.R. Barnett |author2=R.E. Mulvey |author3=W. Clegg |author4=P.A. O'Neil |pages=8187 |doi=10.1021/ja00021a066|bibcode=1991JAChS.113.8187B }}</ref> 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.<ref>{{cite journal |author=Neufeld, R. |author2=John, M. |author3=Stalke, D. |name-list-style=amp |journal=[[Angewandte Chemie International Edition]] |year=2015 |volume=54 |issue=24 |pages=6994–6998 |title=The Donor-Base-Free Aggregation of Lithium Diisopropyl Amide in Hydrocarbons Revealed by a DOSY Method |doi=10.1002/anie.201502576 |pmid=26014367}}</ref>

Solid LDA is [[pyrophoricity|pyrophoric]],<ref>[https://www.sigmaaldrich.com/US/en/sds/ALDRICH/246611 SDS] at [[Sigma-Aldrich]]</ref> 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&nbsp;mmol), it is common and more cost effective to prepare LDA [[in situ#Chemistry and chemical engineering|''in situ'']].
[[File:LDArxn.png|thumb|left|Deprotonation using LDA.<ref>{{cite journal |title=Preparation of Ethyl 1-Benzyl-4-Fluoropiperidine-4-Carboxylate |journal=Organic Syntheses |year=2010 |volume=87 |pages=137 |author=Jianshe Kong |author2=Tao Meng |author3=Pauline Ting |author4=Jesse Wong |name-list-style=amp |doi=10.15227/orgsyn.087.0137 |doi-access=free}}</ref>]]