Karboxylsyragrupp

Karboxylsyragrupp is not a standard term in mainstream chemical nomenclature. In most contexts, a carboxyl group linked to a sulfur-containing moiety is described as a thioester, with the general structure R-CO-S-R'. The carboxyl carbon is attached to sulfur, forming a carbonyl adjacent to a thioester linkage.

The thioester motif has distinctive chemical properties. The carbonyl carbon of a thioester is highly activated toward nucleophilic attack, making thioesters more reactive than corresponding ordinary esters. This increased reactivity is largely due to the lower pπ–pπ overlap between carbon and sulfur compared with oxygen, which lowers resonance stabilization of the carbonyl and enhances susceptibility to hydrolysis and transesterification.

Biological relevance is notable. Many acyl transfers in metabolism involve thioesters, most famously acetyl-CoA and other acyl-CoA derivatives, where the acyl group is transported and transferred via the thioester linkage to coenzyme A or enzyme active sites. In biochemistry, thioesters participate in fatty acid synthesis, the citric acid cycle, and various post-translational modification processes.

Synthesis and reactions commonly involve forming a thioester by reacting a carboxylic acid with a thiol under activating conditions (e.g., coupling agents or acid chlorides) or via trans-thioesterification. Hydrolysis of thioesters yields the corresponding carboxylic acid and a thiol. They also participate in acyl-transfer reactions, contributing to both synthetic organic chemistry and biological pathways.

In summary, while karboxylsyragrupp is not a widely used term, the functional motif it likely denotes is the thioester linkage, a carboxyl group bonded to sulfur with important chemical and biological roles. See also thioesters, carboxylic acids, and acyl transfer chemistry.