organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

, a dithiol is a type of

organosulfur compound Organosulfur chemistry is the study of the properties and synthesis of organosulfur compounds, which are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur der ...

with two

thiol In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl grou ...

()

functional group In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions r ...

s. Their properties are generally similar to those of monothiols in terms of

solubility In chemistry, solubility is the ability of a chemical substance, substance, the solute, to form a solution (chemistry), solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form su ...

, odor, and volatility. They can be classified according to the relative location of the two thiol groups on the organic backbone. File:C6H4(SH)2.svg, Benzene-1,2-dithiol, the

parent A parent is either the progenitor of a child or, in humans, it can refer to a caregiver or legal guardian, generally called an adoptive parent or step-parent. Parents who are progenitors are First-degree relative, first-degree relatives and have ...

aromatic dithiol File:1,3-Propandithiol Structural Formula V1.svg, Propane-1,3-dithiol File:Meso-2,3-dimercaptosuccinic-acid-2D-skeletal-A-configurations-labelled.png, The drug meso-2,3- dimercaptosuccinic acid File:Dimercaprol.svg, Dimercaprol ("British anti-Lewisite"), an early antidote for arsenic poisoning File:Dihydrolipoic-acid-2D-skeletal.png, Dihydrolipoic acid, a vitamin File:Dithiothreitol.png,

Dithiothreitol Dithiothreitol (DTT) is an organosulfur compound with the formula . 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 ...

, a reagent in protein biochemistry

Geminal dithiols

Geminal dithiols have the formula RR'C(SH)₂. They are formally derived from aldehydes and ketones by the action of

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist ...

. 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

oligomer In chemistry and biochemistry, an oligomer () is a molecule that consists of a few repeating units which could be derived, actually or conceptually, from smaller molecules, monomers.Quote: ''Oligomer molecule: A molecule of intermediate relativ ...

1,2-Dithiols

Compounds containing thiol groups on adjacent carbon centers are common. Ethane-1,2-dithiol reacts with aldehydes () and ketones () to give 1,3-dithiolanes: :(HS)2C2H4 + R-CHO -> R-CHS2C2H4 + H2O Some dithiols are used in

chelation therapy Chelation therapy is a medical procedure that involves the administration of chelating agents to remove heavy metals from the body. Chelation therapy has a long history of use in clinical toxicology and remains in use for some very specific medic ...

, i.e. the removal of heavy metal poisons. 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

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

s. When derived from aldehydes, the methyne () 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 In organic chemistry, umpolung () or polarity inversion is the chemical modification of a functional group with the aim of the reversal of Chemical polarity, polarity of that group. This modification allows secondary reactions of this functional g ...

phenomenon. Like 1,2-ethanedithiol, propanedithiol forms complexes with metals, for example with triiron dodecacarbonyl: : A naturally occurring 1,3-dithiol is dihydrolipoic acid. 1,3-Dithiols oxidize to give 1,2-dithiolanes.

1,4-Dithiols

A common 1,4-dithiol is

dithiothreitol Dithiothreitol (DTT) is an organosulfur compound with the formula . 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 ...

(DTT), HSCH₂CH(OH)CH(OH)CH₂SH, sometimes called Cleland's reagent, for to reduce protein

disulfide bond In chemistry, a disulfide (or disulphide in British English) is a compound containing a functional group or the anion. The linkage is also called an SS-bond or sometimes a disulfide bridge and usually derived from two thiol groups. In inor ...

s. Oxidation of DTT results a stable six-membered

heterocyclic A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, proper ...

ring with an internal

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References

Functional groups Organosulfur compounds