Editing Disulfide (section)

===Synthesis===
Disulfide bonds are usually formed from the [[oxidation]] of [[thiol]] ({{chem2|\sSH}}) groups, especially in biological contexts.<ref name=Witt>{{cite journal | last = Witt | first = D. | title = Recent developments in disulfide bond formation | journal = [[Synthesis (journal)|Synthesis]] | volume = 2008 | year = 2008 | issue = 16 | pages = 2491–2509 | doi = 10.1055/s-2008-1067188}}</ref> The transformation is depicted as follows:
:<chem>2 RSH <=> RS-SR + 2 H+ + 2 e-</chem>
A variety of oxidants participate in this reaction including oxygen and [[hydrogen peroxide]]. Such reactions are thought to proceed via [[sulfenic acid]] intermediates. In the laboratory, [[iodine]] in the presence of base is commonly employed to oxidize thiols to disulfides. Several metals, such as copper(II) and iron(III) [[metal complex|complex]]es affect this reaction.<ref>{{cite journal |last1=Kreitman |first1=Gal Y. |title=Copper(II)-Mediated Hydrogen Sulfide and Thiol Oxidation to Disulfides and Organic Polysulfanes and Their Reductive Cleavage in Wine: Mechanistic Elucidation and Potential Applications |journal=Journal of Agricultural and Food Chemistry |date=March 5, 2017 |volume=65 |issue=12 |pages=2564–2571 |doi=10.1021/acs.jafc.6b05418 |pmid=28260381 |bibcode=2017JAFC...65.2564K |url=https://pubs.acs.org/doi/10.1021/acs.jafc.6b05418 |access-date=31 May 2021}}</ref> Alternatively, disulfide bonds in proteins often formed by [[thiol-disulfide exchange]]:
: <chem>RS-SR + R'SH <=> R'S-SR + RSH</chem>
Such reactions are mediated by enzymes in some cases and in other cases are under equilibrium control, especially in the presence of a catalytic amount of base.

The [[alkylation]] of alkali metal di- and [[polysulfide]]s gives disulfides. "Thiokol" polymers arise when [[sodium polysulfide]] is treated with an alkyl dihalide. In the converse reaction, carbanionic reagents react with elemental sulfur to afford mixtures of the thioether, disulfide, and higher polysulfides. These reactions are often unselective but can be optimized for specific applications.