Acetylide

What is an Acetylide?

Acetylide is a type of chemical compound in which a metal and an alkyne are joined together. RC≡CM is the generic formula for acetylide, where R represents an organic side chain. A well-known reagent used in the synthesis of organic molecules is acetylide. They are also generated as a coupling reaction intermediate.

Structure and Bonding of Acetylide

• Acetylide exhibits ionic characteristics when linked to an alkali metal or an alkaline earth metal. Evidence for the ionic characteristics of acetylide can be confirmed by hydrolyzing these molecules.
• The hydrolysis of acetylide produces acetylene and metal oxide.
• When linked to transition metals, acetylide shows covalent characteristics.
• Similar features are shared by acetylide and its double-substituted counterparts.
• Metal acetylide has a polymeric structure when it doesn’t have a ligand, and the acetylide group is a bridging ligand.

Preparation of Acetylide

From Alkyne

• To synthesize acetylide from alkynes, organometallic or inorganic superbases are used.
• Using liquid ammonia, acetylide is synthesized from alkenes.
• Additionally, ethereal solvents are utilized to create acetylide from alkenes.

RC≡CH + R-M ⇌ R-H + RC≡CM

• To synthesize lithium acetylide, lithium amide, LiHMDS, and organolithium reagents such as ethyl lithium are often used.

• Sodium or potassium acetylide contributes to the formation at room temperature and atmospheric pressure using inorganic reagents such as sodium amide.
• Copper(I) acetylide is manufactured by passing copper chloride through acetylene.
• Typically, silver nitrate is used to synthesize silver acetylide.
• Lime, i.e. calcium oxide, is cooked with carbon at roughly 2,000°C to generate calcium carbide.
• Lithium carbide is produced by heating lithia, or lithium oxide, with carbon at roughly 2,000 degrees Celsius.
• Potassium acetylide is produced when a strong base, such as KOH, interacts with acetylene.

HC≡CH + KOH ⇌ HC≡CK + H2O

Further reaction with an alcohol or an aldehyde produces the favorski product, propargyl alcohol.

• N-butyllithium deprotonates ethyl propiolate in order to produce the equivalent acetylide.
• In addition to serving as an intermediate in coupling reactions, acetylide is also produced.

What is a Favorski Reaction?

The Favorski reaction is a strongly basic chemical reaction between an alkyne and a carbonyl molecule that produces alkynol.

It was discovered by the Russian scientist Alexei Favorski in the early 1900s.

What is a Coupling Reaction?

Coupling Reaction refers to a chemical reaction involving the union of two chemical species.

Organic halide and organometallic compound reaction is an example of a coupling reaction

Applications of Acetylide

• Due to their sensitivity to water, acetylides are used as explosives.
• Copper acetylide is passed through a solution of copper (I) chloride to detect the presence of acetylene.
• Copper acetylide is used in of petroleum chemistry.
• In industries, copper acetylide is used to produce the interior of pipes.
• In chemical synthesis, acetylide is often used to detect the presence of terminal alkynes.

Reactions of Acetylide

• Organic chemistry uses acetylide in alkynylation processes.
• In many electrophilic and unsaturated substrate reactions, acetylide functions as a nucleophile.

Hazards

Certain acetylides are notoriously flammable. When handling gaseous acetylene in the presence of metals such as mercury, silver, copper, or alloys with significant concentrations of these elements, the formation of acetylides poses a risk (brass, bronze, silver solder).

Frequently Asked Questions – FAQs on Acetylide