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

thiocarbamates In organic chemistry, thiocarbamates (thiourethanes) are a family of organosulfur compounds. As the prefix ''thio-'' suggests, they are sulfur analogues of carbamates. There are two isomeric forms of thiocarbamates: ''O''-thiocarbamates, (este ...

(thiourethanes) are a family of

organosulfur compound Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature abounds with organosulfur compounds—sulfu ...

s. As the prefix ''

thio- The prefix thio-, when applied to a chemical, such as an ion, means that an oxygen atom in the compound has been replaced by a sulfur atom. This term is often used in organic chemistry. For example, from the word ''ether,'' referring to an oxyg ...

'' suggests, they are

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

analogues of

carbamate In organic chemistry, a carbamate is a category of organic compounds with the general formula and structure , which are formally derived from carbamic acid (). The term includes organic compounds (e.g., the ester ethyl carbamate), formally o ...

s. There are two isomeric forms of thiocarbamates: ''O''-thiocarbamates, (

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...

s), and ''S''-thiocarbamates, (

thioester In organic chemistry, thioesters are organosulfur compounds with the functional group . They are analogous to carboxylate esters () with the sulfur in the thioester playing the role of the linking oxygen in the carboxylate ester, as implied by t ...

s).

Synthesis

Thiocarbamates can be synthesised by the reaction of water or alcohols upon

thiocyanate Thiocyanate (also known as rhodanide) is the anion . It is the conjugate base of thiocyanic acid. Common derivatives include the colourless salts potassium thiocyanate and sodium thiocyanate. Mercury(II) thiocyanate was formerly used in pyrot ...

s (

Riemschneider thiocarbamate synthesis The Riemschneider thiocarbamate synthesis converts alkyl or aryl thiocyanates to thiocarbamates under acidic conditions, followed by hydrolysis with ice water. The reaction was discovered by the German chemist in 1951 as a more efficient method to ...

): :RSCN + H₂O → RSC(=O)NH₂ :RSCN + R'OH → RSC(=O)NR'H Similar reactions are seen between alcohols and thiocarbamoyl chlorides such as

dimethylthiocarbamoyl chloride Dimethylthiocarbamoyl chloride is an organosulfur compound with the formula (CH3)2NC(S)Cl. A yellow solid, it is often encountered as a yellow syrup. It is a key reagent in the synthesis of arylthiols via the Newman-Kwart rearrangement. Synthes ...

; as well as between

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 gro ...

s and

cyanate Cyanate is an anion with the structural formula , usually written . It also refers to any salt containing it, such as ammonium cyanate. It is an isomer of the much less stable fulminate anion .William R. Martin and David W. Ball (2019): "Small ...

s. Alternatively, they arise by the reaction of amines with

carbonyl sulfide Carbonyl sulfide is the chemical compound with the linear formula OCS. It is a colorless flammable gas with an unpleasant odor. It is a linear molecule consisting of a carbonyl group double bonded to a sulfur atom. Carbonyl sulfide can be consi ...

. :2 R₂NH + COS → ₂NH₂⁺R₂NCOS⁻]

Reactions

In the Newman-Kwart rearrangement ''O''-thiocarbamates can isomerise to ''S''-thiocarbamates. This reaction, which generally requires high temperatures, is an important method for the synthesis of

thiophenols 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 phenol ...

Dithiocarbamates

Dithiocarbamates are related to thiocarbamates by the replacement of O by S. Despite this structural similarity their synthesis and chemistry is quite different. Dithiocarbamates and their derivatives are widely used in the vulcanization of rubber. Borate, Molybdenum, or Zinc thiocarbamates are also used in metal-to-metal lubrication proposes, mainly as an anti-oxidation or anti-extreme pressure (EP) additive. 1-2% of such compounds can be added to internal combustion engine lubricant to increase extreme pressure performance in high operational temperatures.

References

Functional groups {{Organic-chem-stub

Synthesis

Reactions

Dithiocarbamates

See also

References