Executive Summary : | Aldehydes have been widely used in various industries, including polymers, medicinal preparations, fragrances, colors, pesticides, explosives, oximes, hydrazones, carboxylic acids, amines, alcohols, and diols. However, their sulphur counterpart, thioaldehydes (TA), was often overlooked due to their instability. Thioaldehydes are crucial for biological, combustion, and atmospheric reactions. They were once thought to be produced by the nucleophilic assault of carbonyl compounds by the bisulfide anion. When the oxygen atom in carbonyl groups is replaced with a sulphur atom, a range of compounds with thiocarbonyl groups are produced, such as thioaldehydes and thioketones. However, thioaldehydes are more labile under the air than naturally occurring aldehydes, making them challenging to work with at ambient temperature. The most striking differences between thiocarbonyl and carbonyl chemistry can be seen in reactions involving nucleophiles, olefins, and conjugated dienes. Nucleophilic attack on carbonyl compounds often occurs at the carbonyl carbon, while it can occur at either the carbon or sulphur in thiocarbonyls. To eliminate the use of hazardous chemicals, researchers are attempting to isolate thiobenzaldehyde in its monomeric form and use it for other processes, such as benzoin condensation, using N-heterocyclic carbenes and organocatalysts based on thiourea. |