Propynyllithium is an

organolithium compound In organometallic chemistry, organolithium reagents are chemical compounds that contain carbon–lithium (C–Li) bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom ...

with the chemical formula . It is a white solid that is soluble in 1,2-dimethoxyethane, and

tetrahydrofuran Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water- miscible organic liquid with low viscosity. It is ...

. To preclude its degradation by oxygen and water, propynyllithium and its solutions are handled under inert gas (

argon Argon is a chemical element; it has symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

). Although commonly depicted as a monomer, propynyllithium adopts a more complicated cluster structure as seen for many other organolithium compounds.

Synthesis

Various preparations of propynyllithium are known, but the most expeditious route starts with 1-bromopropene: :CH₃CH=CHBr + 2 BuLi → CH₃C≡CLi + 2 BuH + LiBr

Historic routes

It can be prepared by passing

propyne Propyne (methylacetylene) is an alkyne with the chemical formula . It is a component of MAPD gas—along with its isomer propadiene (allene), which was commonly used in gas welding. Unlike acetylene, propyne can be safely condensed.Peter Pä ...

gas through a solution of ''n''-butyllithium or by direct metallization of propyne with lithium in liquid

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

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 Organic synthesis is a branch of chemical synthesis concerned with the construction of organic compounds. Organic compounds are molecules consisting of combinations of covalently-linked hydrogen, carbon, oxygen, and nitrogen atoms. Within the gen ...

as a reactant. It is a

nucleophile In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are ...

that adds to aldehydes to give

secondary alcohols In chemistry, an alcohol (), is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. Alcohols range from the simple, like methanol and ethanol, to complex, like sugar alcohols an ...

, with ketones to give

tertiary alcohols In chemistry, an alcohol (), is a type of organic compound that carries at least one hydroxyl () functional group bound to a Saturated and unsaturated compounds, saturated carbon atom. Alcohols range from the simple, like methanol and ethanol ...

, 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 Mifepristone, and also known by its developmental code name RU-486, is a drug typically used in combination with misoprostol to bring about a medical abortion during pregnancy. This combination is 97% effective during the first 63 days (9 wee ...

References

External links

Safety Data Sheet
{{Lithium compounds Alkyne derivatives Organolithium compounds