Dithiol

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In organic chemistry, a dithiol is a type of organosulfur compound with two thiol (−SH) functional groups. Their properties are generally similar to those of monothiols in terms of solubility, odor, and volatility. They can be classified according to the relative location of the two thiol groups on the organic backbone.

Contents

Geminal dithiols

Geminal dithiols have the formula RR'C(SH)2. They are derived from aldehydes and ketones by the action of hydrogen sulfide. Their stability contrasts with the rarity of geminal diols. Examples include methanedithiol, ethane-1,1-dithiol, and cyclohexane-1,1-dithiol. Upon heating, gem-dithiols often release hydrogen sulfide, giving the transient thioketone or thial, which typically convert to oligomers. [1]

1,2-Dithiols

Compounds containing thiol groups on adjacent carbon centers are common. Ethane-1,2-dithiol reacts with aldehydes (−CH=O) and ketones (>C=O) to give 1,3-dithiolanes:

Some dithiols are used in chelation therapy, i.e. the removal of heavy metal poisons. [2] Examples include dimercaptopropanesulfate (DMPS), dimercaprol ("BAL"), and meso-2,3-dimercaptosuccinic acid.

Enedithiols

Enedithiols, with the exception of aromatic examples, are rare. The parent aromatic example is benzenedithiol. The dithiol of 1,3-dithiole-2-thione-4,5-dithiolate 2- is also known.

1,3-Dithiols

Propane-1,3-dithiol is the parent member of this series. It is employed as a reagent in organic chemistry, since it forms 1,3-dithianes upon treatment with ketones and aldehydes. When derived from aldehydes, the methyne (=CH−) group is sufficiently acidic that it can be deprotonated and the resulting anion can be C-alkylated. The process is the foundation of the umpolung phenomenon. [3]

Like 1,2-ethanedithiol, propanedithiol forms complexes with metals, for example with triiron dodecacarbonyl:

Fe3(CO)12 + C3H6(SH)2 → Fe2(S2C3H6)(CO)6 + H2 + Fe(CO)5 + CO

A naturally occurring 1,3-dithiol is dihydrolipoic acid.

1,3-Dithiols oxidize to give 1,2-dithiolanes. [4]

1,4-Dithiols

A common 1,4-dithiol is dithiothreitol (DTT), HSCH2CH(OH)CH(OH)CH2SH, sometimes called Cleland's reagent, for to reduce protein disulfide bonds. Oxidation of DTT results a stable six-membered heterocyclic ring with an internal disulfide bond.

Reduction of a typical disulfide bond by DTT via two sequential thiol-disulfide exchange reactions. Disulfide reduction by DTT-2.png
Reduction of a typical disulfide bond by DTT via two sequential thiol-disulfide exchange reactions.

Related Research Articles

In chemistry, a disulfide is a compound containing a R−S−S−R′ functional group or the S2−
2 anion. The linkage is also called an SS-bond or sometimes a disulfide bridge and usually derived from two thiol groups.

<span class="mw-page-title-main">Thiol</span> Any organic compound having a sulfanyl group (–SH)

In organic chemistry, a thiol, or thiol derivative, is any organosulfur compound of the form R−SH, where R represents an alkyl or other organic substituent. The −SH functional group itself is referred to as either a thiol group or a sulfhydryl group, or a sulfanyl group. Thiols are the sulfur analogue of alcohols, and the word is a blend of "thio-" with "alcohol".

<span class="mw-page-title-main">Dicarbonyl</span> Molecule containing two adjacent C=O groups

In organic chemistry, a dicarbonyl is a molecule containing two carbonyl groups. Although this term could refer to any organic compound containing two carbonyl groups, it is used more specifically to describe molecules in which both carbonyls are in close enough proximity that their reactivity is changed, such as 1,2-, 1,3-, and 1,4-dicarbonyls. Their properties often differ from those of monocarbonyls, and so they are usually considered functional groups of their own. These compounds can have symmetrical or unsymmetrical substituents on each carbonyl, and may also be functionally symmetrical or unsymmetrical.

A diol is a chemical compound containing two hydroxyl groups. An aliphatic diol may also be called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified. They are used as protecting groups of carbonyl groups, making them essential in synthesis of organic chemistry.

<span class="mw-page-title-main">Dithiothreitol</span> Chemical compound

Dithiothreitol (DTT) is an organosulfur compound with the formula (CH CH2SH)2. A colorless compound, it is classified as a dithiol and a diol. DTT is redox reagent also known as Cleland's reagent, after W. Wallace Cleland. The reagent is commonly used in its racemic form. Its name derives from the four-carbon sugar, threose. DTT has an epimeric ('sister') compound, dithioerythritol (DTE).

<span class="mw-page-title-main">Thiophenol</span> Chemical compound

Thiophenol is an organosulfur compound with the formula C6H5SH, sometimes abbreviated as PhSH. This foul-smelling colorless liquid is the simplest aromatic thiol. The chemical structures of thiophenol and its derivatives are analogous to phenols, where the oxygen atom in the hydroxyl group (-OH) bonded to the aromatic ring in phenol is replaced by a sulfur atom. The prefix thio- implies a sulfur-containing compound and when used before a root word name for a compound which would normally contain an oxygen atom, in the case of 'thiol' that the alcohol oxygen atom is replaced by a sulfur atom.

<span class="mw-page-title-main">2-Mercaptoethanol</span> Chemical compound

2-Mercaptoethanol (also β-mercaptoethanol, BME, 2BME, 2-ME or β-met) is the chemical compound with the formula HOCH2CH2SH. ME or βME, as it is commonly abbreviated, is used to reduce disulfide bonds and can act as a biological antioxidant by scavenging hydroxyl radicals (amongst others). It is widely used because the hydroxyl group confers solubility in water and lowers the volatility. Due to its diminished vapor pressure, its odor, while unpleasant, is less objectionable than related thiols.

<span class="mw-page-title-main">Ethane-1,2-dithiol</span> Chemical compound

Ethane-1,2-dithiol, also known as EDT, is a colorless liquid with the formula C2H4(SH)2. It has a very characteristic odor which is compared by many people to rotten cabbage. It is a common building block in organic synthesis and an excellent ligand for metal ions.

A diamine is an amine with exactly two amino groups. Diamines are used as monomers to prepare polyamides, polyimides, and polyureas. The term diamine refers mostly to primary diamines, as those are the most reactive.

<span class="mw-page-title-main">2,3-Dimercapto-1-propanesulfonic acid</span> Chemical compound

2,3-Dimercapto-1-propanesulfonic acid and its sodium salt are chelating agents that form complexes with various heavy metals. They are related to dimercaprol, which is another chelating agent.

<span class="mw-page-title-main">Dithiane</span> Chemical compound

A dithiane is a heterocyclic compound composed of a cyclohexane core structure wherein two methylene bridges are replaced by sulfur. The three isomeric parent heterocycles are 1,2-dithiane, 1,3-dithiane and 1,4-dithiane. They are all colorless solids.

<span class="mw-page-title-main">1,2-Propanedithiol</span> Chemical compound

1,2-Propanedithiol, sometimes called 1,2-dimercaptopropane, is a thiol with the formula HSCH2CH(SH)CH3. This colorless, intensely odorous liquid is the simplest chiral dithiol. Related dithiols include 1,2-ethanedithiol, 2,3-dimercapto-1-propanesulfonic acid, and 1,3-propanedithiol. It is generated by the addition of H2S to the related episulfide, CH3CHCH2S.

<span class="mw-page-title-main">Propane-1,3-dithiol</span> Chemical compound

1,3-Propanedithiol is the chemical compound with the formula HSCH2CH2CH2SH. This dithiol is a useful reagent in organic synthesis. This liquid, which is readily available commercially, has an intense stench.

<span class="mw-page-title-main">Benzene-1,2-dithiol</span> Chemical compound

Benzene-1,2-dithiol is the organosulfur compound with the formula C6H4(SH)2. This colourless viscous liquid consists of a benzene ring with a pair of adjacent thiol groups. The conjugate base of this diprotic compound serves as chelating agent in coordination chemistry and a building block for the synthesis of other organosulfur compounds.

Alcohol oxidation is a collection of oxidation reactions in organic chemistry that convert alcohols to aldehydes, ketones, carboxylic acids, and esters. The reaction mainly applies to primary and secondary alcohols. Secondary alcohols form ketones, while primary alcohols form aldehydes or carboxylic acids.

<span class="mw-page-title-main">Thiol-yne reaction</span> Chemical addition of an –SH and –C≡CH molecule

In organic chemistry, the thiol-yne reaction is an organic reaction between a thiol and an alkyne. The reaction product is an alkenyl sulfide.

<span class="mw-page-title-main">Carbonyl reduction</span> Organic reduction of any carbonyl group by a reducing agent

In organic chemistry, carbonyl reduction is the conversion of any carbonyl group, usually to an alcohol. It is a common transformation that is practiced in many ways. Ketones, aldehydes, carboxylic acids, esters, amides, and acid halides - some of the most pervasive functional groups, -comprise carbonyl compounds. Carboxylic acids, esters, and acid halides can be reduced to either aldehydes or a step further to primary alcohols, depending on the strength of the reducing agent. Aldehydes and ketones can be reduced respectively to primary and secondary alcohols. In deoxygenation, the alcohol group can be further reduced and removed altogether by replacement with H.

<span class="mw-page-title-main">1,2-Dithiolane</span> Chemical compound

1,2-Dithiolane is an organosulfur compound with the formula S2(CH2)3. It is also classified as a heterocycle derived from cyclopentane by replacing two methylene bridges with a disulfide group. 1,3-Dithiolane is an isomer. The parent molecule is not important but substituted derivatives, especially lipoic acid and its derivatives, are important. Several occur in foods.

1,3-Dithiolane is the organosulfur compound with the formula CH2S2C2H4. Also classified as a heterocycle related cyclopentane by replacing two methylene bridges with thioether groups. It is an isomer of 1,2-dithiolane. 1,3-Dithiolanes are compounds where one or more H atoms of the parent 1,3-dithiolane are replaced by other groups. These species are more widely studied.

1,4-Butanedithiol is an organosulfur compound with the formula HSCH2CH2CH2CH2SH. It is a malodorous, colorless liquid that is highly soluble in organic solvents. The compound has found applications in biodegradable polymers.

References

  1. ↑ Cairns, T. L.; Evans, G. L.; Larchar, A. W.; McKusick, B. C. (1952). "gem-Dithiols". Journal of the American Chemical Society. 74 (16): 3982–9. doi:10.1021/ja01136a004.
  2. ↑ Rooney, James P.K. (2007). "The role of thiols, dithiols, nutritional factors and interacting ligands in the toxicology of mercury". Toxicology. 234 (3): 145–156. doi:10.1016/j.tox.2007.02.016. PMID   17408840.
  3. ↑ Conrow, R. E.; Le Huérou, Y. (2004). "1,3-Propanedithiol". In L. Paquette (ed.). Encyclopedia of Reagents for Organic Synthesis. J. Wiley & Sons, New York. doi:10.1002/047084289X. hdl: 10261/236866 . ISBN   9780471936237.
  4. ↑ Burns, John A.; Whitesides, George M. (1990). "Predicting the stability of cyclic disulfides by molecular modeling: Effective concentrations in thiol-disulfide interchange and the design of strongly reducing dithiols". Journal of the American Chemical Society. 112 (17): 6296–6303. Bibcode:1990JAChS.112.6296B. doi:10.1021/ja00173a017.
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