No abstract

Acetylene is a key building block for organic chemistry and potentially can be involved in a diverse range of synthetic transformations. However, critical analysis of practical considerations showed that application of gaseous acetylene in regular synthetic labs encounters a number of difficulties. Safety limitations due to flammable and explosive nature of gaseous acetylene and requirements for specialized high‐pressure equipment impose serious drawbacks. Typical reaction conditions involve excess of gaseous reactant, which is simply released to the atmosphere at the end of the reaction, thus generating waste and causing contamination. Calcium carbide brings a new green and sustainable wave into powerful alkyne transformations and significantly expands the repertoire of traditional acetylene chemistry. The novel trend of using calcium carbide instead of gaseous acetylene is synthetically beneficial and opens a novel reactivity for the C≡C unit. This review highlights recent advances in carbide chemistry, demonstrates its advantages and prospects in term of green synthetic approach.

An electric current promotes copper electrode dissolution in ionic liquids and creates an active catalyst. The catalyst formed was successfully tested in synthetic transformations. Reversing the polarity allows regeneration of ILs and catalyst.

A vinylation/devinylation looping system for acetaldehyde manufacturing was evaluated. Vinylation of iso‐butanol with calcium carbide under solvent‐free conditions was combined with hydrolysis of the resulting iso‐butyl vinyl ether under slightly acidic conditions. Acetaldehyde produced by hydrolysis was collected from the reaction mixture by simple distillation, and the remaining alcohol was redirected to the vinylation step. All the inorganic co‐reagents can be looped as well, and the full sequence is totally sustainable. A complete acetaldehyde manufacturing cycle was proposed on the basis of the developed procedure. The cycle was fed with calcium carbide and produced the aldehyde as a single product in a total preparative yield of 97 %. No solvents, hydrocarbons, or metal catalysts were needed to maintain the cycle. As calcium carbide in principle can be synthesized from virtually any source of carbon, the developed technology represents an excellent example of biomass and waste conversion into a valuable industrial product.

A series of biomass-derived alcohols were successfully vinylated with calcium carbide followed by the polymerization. The polymers were tested as materials and disassembled back to monomers through pyrolysis.