In organic chemistry, thioesters are organosulfur compounds with the molecular structure .mw-parser-output .template-chem2-su{display:inline-block;font-size:80%;line-height:1;vertical-align:-0.35em}.mw-parser-output .template-chem2-su>span{display:block;text-align:left}.mw-parser-output sub.template-chem2-sub{font-size:80%;vertical-align:-0.35em}.mw-parser-output sup.template-chem2-sup{font-size:80%;vertical-align:0.65em}R−C −S−R'. They are analogous to carboxylate esters −O−R') with the sulfur in the thioester replacing oxygen in the carboxylate ester, as implied by the thio- prefix. They are the product of esterification of a carboxylic acid −O−H) with a thiol . In biochemistry, the best-known thioesters are derivatives of coenzyme A, e.g., acetyl-CoA. The R and R' represent organyl groups, or H in the case of R.