Lithium diisopropylamide

Structural formula
General
Surname	Lithium diisopropylamide
other names	Diisopropylamine lithium salt LDA
Molecular formula	C 6 H 14 LiN
Brief description	self-igniting, moisture-sensitive solid
External identifiers / databases
CAS number 4111-54-0 EC number 223-893-0 ECHA InfoCard 100,021,721 PubChem 2724682 Wikidata Q413164
properties
Molar mass	107.12 g mol −1
Physical state	solid (but mostly in solution)
density	0.86 g cm −3 (25 ° C)
solubility	soluble in hexane
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 250-260-314-361 P: 222-223-231 + 232-280-305 + 351 + 338-310
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Lithium diisopropylamide (LDA) is the lithium salt of diisopropylamine . It is a strong base used in the organic chemistry often for deprotonation of CH-acid is used compounds. Because of the steric hindrance caused by the space-filling isopropyl radicals, LDA is not very nucleophilic . The pK _S value of the conjugate acid is 40. It is thus possible, weakly acidic CH compounds, such as carbonyl compounds in α-position to deprotonate and this characterized in enolates to transfer. LDA is usually commercially available as a solution in diethyl ether or THF . In these solutions it forms dimeric structures. In non-polar solvents such as. B. toluene , however, it is a mixture of trimers, tetramers, pentamers and higher oligomers.

LDA dimer with 2 THF molecules

Manufacturing

LDA can be made from diisopropylamine with organo-lithium compounds such as phenyllithium or butyllithium . A cheaper way is to react elemental lithium with diisopropylamine in the presence of styrene .

Individual evidence

1. ↑ Entry on lithium diisopropylamide. In: Römpp Online . Georg Thieme Verlag, accessed on August 16, 2015.
2. ↑ ^{a b c d} data sheet lithium diisopropylamide from Sigma-Aldrich , accessed on August 16, 2015 ( PDF ).
3. ↑ KPC Vollhardt, NE Schore: Organic Chemistry. 3. Edition. Wiley-VCH, Weinheim 2000, ISBN 3-527-29819-3 .
4. ↑ PG Williard, JM Salvino: Synthesis, Isolation, and Structure of an LDA-THF Complex. In: J. Org. Chem. 58 (1), 1993, pp. 1-3, doi: 10.1021 / jo00053a001 .
5. ^ R. Neufeld, M. John, D. Stalke: Elucidation of the donor base-free aggregation of lithium diisopropylamide in hydrocarbons using a DOSY method. In: Angew. Chem. 127 (1), 2015, pp. 7100-7104, doi: 10.1002 / anie.201502576 .
6. ↑ R. Neufeld: DOSY External Calibration Curve Molecular Weight Determination as a Valuable Methodology in Characterizing Reactive Intermediates in Solution. Dissertation. Georg August University, Göttingen 2016.
7. ↑ AP Smith, JJS Lamba, CL Fraser: Efficient Synthesis of Halomethyl-2,2'-Bipyridines: 4,4'-Bis (chloromethyl) -2,2'-Bipyridine In: Organic Syntheses . 78, 2002, p. 82, doi : 10.15227 / orgsyn.078.0082 ; Coll. Vol. 10, 2004, p. 107 ( PDF ).
8. ↑ MT Reetz, WF Maier: Simple representation of lithium diisopropylamide on a molar scale. In: Liebig's annals . 10, 1980, pp. 1471-1473, doi: 10.1002 / jlac.198019801002 .