Thioester
| Thioester |
|---|
 Thiolic acid ester , a monothioester |
 Thionic acid ester , a monothioester |
| R 1 , R 2 = organyl group such as e.g. B. alkyl group or aryl group .
The functional groups are marked in blue . |
In organic chemistry, thioesters (also known as thiolesters) are two groups of isomeric compounds in which one oxygen atom in the ester group is replaced by sulfur . Since the ester group contains two oxygen atoms, there are also two possibilities of substitution .
If both oxygen atoms of a carboxylic acid ester are replaced by sulfur atoms, dithioesters (dithiocarboxylic acid esters) are present.
Thiolester
Of utmost importance which are by replacing the acyl group with the radical R 2 bonded oxygen resulting thiol ester in metabolism . This thiolester bond is energetically quite unfavorable; H. their dissolution z. B. by hydrolysis provides a relatively large amount of energy. Therefore they play a central role in the metabolism of all living organisms as energy and acyl group transmitters. Important thiolesters of the metabolism are z. B. acetyl-CoA or malonyl-CoA . The photochemistry of thiolesters is described in the literature, and disulfides are formed in the process . During the photolysis of the aryl esters of ortho -chlorodithiobenzoic acid , the formation of thioxanthone derivatives is observed. Analogous photosyntheses of azathioxanthones have also been described.
Thionester
The thione esters, on the other hand, result from the replacement of the carbonyl oxygen of an ester group with sulfur. This is possible e.g. B. by reaction of an ester with Lawesson's reagent . The thionester compound class is of no great importance.
Individual evidence
- ^ Albert Gossauer: Structure and reactivity of biomolecules , Verlag Helvetica Chimica Acta AG, 2006, p. 415. ISBN 978-3-906390-29-1 .
- ↑ Jürgen Martens and Klaus Praefcke : Organic sulfur compounds VII: Photochemical α-cleavage of thiobenzoic acid-Sp-tolylesters in solution , Chemical Reports 107 (1974) 2319-2325, doi : 10.1002 / cber.19741070716 .
- ↑ Gerd Buchholz, Jürgen Martens, Klaus Praefcke: Photochemical Thioxanthone Synthesis from Halogenthiobenzoic acid S-aryl esters , Synthesis 1974, 666-667, doi : 10.1055 / s-1974-23399 .
- ↑ Gerd Buchholz, Jürgen Martens, Klaus Praefcke: 2- and 4-azathioxanthones by photo rearrangement of thionicotinic acid S-aryl esters , Angew. Chem. 1974, 86 , 562-563; Angew. Chem. Int. Ed. Engl. 1974, 13 , 550-551, doi : 10.1002 / anie.197405501 .