Thioester

The functional groups are highlighted in blue.

Under thioester (also thiol ) is understood in the organic chemistry, two groups of isomeric compounds in which an oxygen atom of the ester group is replaced by sulfur. Since the ester group contains two oxygen atoms, there are two possibilities of substitution.

If both oxygen atoms of a carboxylic acid ester is replaced by sulfur atoms, are dithioester before ( dithio ).

Thiol ester

Of paramount importance are the ones to be joined by the replacement of the acyl group to the rest of R2 resulting thiol ester oxygen in metabolism. This thiolester bond is energetically quite unfavorable, that is, their resolution, for example by hydrolysis provides relatively much energy. Therefore, they play a central role as an energy - and acyl group donor in the metabolism of all living organisms. Important Thiol esters of metabolism are, for example, acetyl -CoA or malonyl -CoA. The photochemistry of the thiol ester is described in the literature, thereby forming disulfides, among others. In the photolysis of aryl esters of ortho- Chlordithiobenzoesäure the formation of Thioxanthone derivatives is observed. Analog Photosynthesen of Azathioxanthonen have also been described.

Thionester

The Thionester arise on the other hand by the replacement of the carbonyl oxygen of an ester group by sulfur. This is possible, for example, by reaction of an ester with Lawesson's reagent. The class of compounds Thionester has no greater significance.