Propynyllithium

Propynyllithium is an organolithium compound with the chemical formula LiC
2CH
3. It is a white solid that quickly decomposes upon contact with air or water. It is soluble in 1,2-dimethoxyethane, and tetrahydrofuran. To preclude degradation by oxygen and water, propynyllithium and its solutions are handled under inert gas (Ar or N
2).[1]

Propynyllithium
Names
IUPAC name
1-Lithium-1-propyne
Other names
1-Propyn-1-yllithium
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.022.604
EC Number
  • 224-862-4
Properties
C3H3Li
Molar mass 46.00 g·mol−1
Appearance Whitish powder
Decomposition
Hazards
GHS pictograms
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Synthesis

Various preparations of propynyllithium are known, but the most expeditious route starts with 1-bromopropene:[2][3]

CH3CH=CHBr + 2 BuLi → CH3C2Li + 2 BuH + LiBr

Historic routes

It can be prepared by passing propyne gas through a solution of n-butyllithium[4] or by direct metallization of propyne with lithium in liquid ammonia or other solvent. Propyne, however, is an expensive gas, and, therefore, it is sometimes replaced by less expensive gas mixtures used for welding and containing a small percentage of propyne.

Applications

Propynyllithium is used in the organic synthesis as a reactant.[2][5] It is a nucleophile that adds to aldehydes to give secondary alcohols, with ketones to give tertiary alcohols, and with acid chlorides to give ketones containing the propynyl group. These reactions are used in the synthesis of complex natural and synthetic substances such as the drug mifepristone.[6]

References
  1. Greeves, Nicholas (15 April 2001). "Propynyllithium". Encyclopedia of Reagents for Organic Synthesis. onlinelibrary.wiley.com. doi:10.1002/047084289X.rp277. ISBN 978-0471936237.
  2. Samuel G. Bartko, James Deng, and Rick L. Danheiser (2016). "Synthesis of 1-Iodopropyne". Org. Synth. 93: 245. doi:10.15227/orgsyn.093.0245.CS1 maint: uses authors parameter (link)
  3. Toussaint, Dominique; Suffert, Jean (1999). "Generation of 1-Propynyllithium From (Z/E)-1-Bromo-1-propene: 6-Phenylhex-2-yn-5-en-4-ol". J. Org. Chem. vol. 60: 3550–3553.
  4. "Acetylenic lead compounds and gasoline compositions thereof US 3185553 A". Retrieved 17 May 2017.
  5. "Acetylenic lead compounds and gasoline compositions thereof US 3185553 A". Retrieved 17 May 2017.
  6. Hazra, B.G.; Pore, V.S. (2001). "Mifepristone (RU-486), the recently developed antiprogesterone drug and its analogues". Journal of the Indian Institute of Science. vol. 81: 287–298.
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