Sulfines and sulfenes

These are respectively the 5-oxides and 5-dioxides of thiocarbonyl compounds. The lachrymatory factor of onions was shown to be (Z)-propanethial 5-oxide (R1 = Et, R2 = H), and a good deal of the chemistry of sulfines was carried out in connection with the study of the organosulfur chemistry of alliaceous plants [186]. 

Sulfines are commonly prepared by oxidation of the corresponding thiocarbonyl compounds [187, 188]. Monosubstituted sulfines are not available by such a process, and an indirect route has been proposed [189], 

Both sulfines and sulfenes are readily involved in cycloaddition reactions [176,187]. 

Thioketone S-sulfides [190-192] and 5-imides 1193] are also attractive molecules that have been evidenced or isolated. 

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The trapping of both sulfines and sulfenes with dienes is probably the method of choice for the preparation of 3-thiene oxides and dioxides, respectively143,337. 

Bilayer carboxylate membranes can be produced by surface modification of Nafion-type membranes. In a process used by Asahi Chemical the sulfonate on a Nafion-type surface is reduced to sulfinic and sulfenic acids, then oxidized to a carboxylate layer of 2-10 pm thickness ... 

The chemical reactivity of the cumulenes under discussion ranges from highly reactive species to almost inert compounds. While some cumulenes can only be generated in a matrix at low temperatures, others are indefinitely stable at room temperature. For example, sulfines and sulfenes are only generated in situ, but some cumulenes with bulky substituents are sometimes isolated at room temperature for example, C=C=S was detected in interstellar space by microwave spectroscopy, and its spectrum was later verified by matrix isolation spectroscopy. In contrast, some cumulenes, such as carbon dioxide and carbon disulfide, are often used as solvents in organic reactions or in the extraction of natural products. The reactivity of some center carbon heterocumulenes in nucleophilic reactions is as follows isocyanates > ketenes > carbodiimides > isothiocyanates. However these reactivities do not relate to the reactivities in cycloaddition reactions. Often reactive cumulenes are isolated as their cyclodimers. Aromatic diisocyanates are more reactive than aliphatic diisocyanates in nucleophilic as well as cycloaddition reactions. 

All NHases are either Fe- or Co-dependent, with mechanistic evidence pointing toward a direct activation of the nitrile by the metal ion [9,10]. The metal binding site requires two cysteine residues in higher oxidation states (sulfinic and sulfenic acid) by posttranslational modification, and the smallest functional quarternary structure is a a [3 dimer that often forms larger multimers in solution [ 11 ]. Hence, most applications on laboratory and production scale use wild-type strains or recombinant hosts, as isolated enzyme formulations usually suffer from low activity and operational instability. 

Thioaldehydes and thioketones oxidized at sulfur are additively named as thioaldehyde oxides, dioxides and thioketone oxides, dioxides, respectively. Besides, the traditional names sulfine and sulfene are still used for these species. 

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