Dithiocarbamate

Last updated
General chemical structure of dithiocarbamate esters. R and R" is any group (typically hydrogen or organyl), and R' is organyl. Dithiocarbamate.svg
General chemical structure of dithiocarbamate esters. R and R" is any group (typically hydrogen or organyl), and R' is organyl.

In organic chemistry, a dithiocarbamate is a functional group with the general formula R2N−C(=S)−S−R and structure >N−C(=S)−S−. It is the analog of a carbamate in which both oxygen atoms are replaced by sulfur atoms (when only one oxygen is replaced the result is thiocarbamate).

Contents

Dithiocarbamate also refers to the dithiocarbamate ion R2N−CS−2 and its salts. A common example is sodium diethyldithiocarbamate. Dithiocarbamates and their derivatives are widely used in the vulcanization of rubber. [1]

Formation

Many secondary amines react with carbon disulfide and sodium hydroxide to form dithiocarbamate salts: [2]

R2NH + CS2 + NaOH → R2NCS−2Na+ + H2O

Ammonia reacts with CS2 similarly:

2 NH3 + CS2 → H2NCS2−NH4+

Dithiocarbamate salts are pale colored solids that are soluble in water and polar organic solvents.

Dithiocarbamic acid

A primary amine and carbon disulfide react to give a dithiocarbamic acid:

RNH2 + CS2 → R(H)NCS2H

In the presence of diimides or pyridine, these acids convert to isothiocyanates: [3]

R(H)NCS2H + C(=NR')2 → RN=C=S + S=C(NHR')2

Reactions

Dithiocarbamates are readily S-alkylated. Thus, methyl dimethyldithiocarbamate can be prepared by methylation of the dithiocarbamate: [4]

(CH3)2NCS2Na + (CH3O)2SO2 → (CH3)2NC(S)SCH3 + Na[CH3OSO3]

Oxidation of dithiocarbamates gives the thiuram disulfide:

2 R2NCS2− → [R2NC(S)S]2 + 2e−

Thiuram disulfides react with Grignard reagents to give esters of dithiocarbamic acid: [5]

[R2NC(S)S]2 + R'MgX → R2NC(S)SR' + R2NCS2MgX

Dithiocarbamates react with transition metal salts to give a wide variety of transition metal dithiocarbamate complexes.

Structure and bonding

Dithiocarbamates are described by invoking resonance structures that emphasize the pi-donor properties of the amine group. This bonding arrangement is indicated by a short C–N distance and the coplanarity of the NCS2 core as well as the atoms attached to N. [6]

Main resonance structures of a dithiocarbamate anion. DTCresSt's.png
Main resonance structures of a dithiocarbamate anion.

Because of the pi-donation from nitrogen, dithiocarbamates are more basic than structurally related anions such as dithiocarboxylates and xanthates. Consequently, they tend to bind as bidentate ligands. Another consequence of the C–N multiple bonding is that rotation about that bond is subject to a high barrier.

Applications

Several transition metal dithiocarbamate complexes are useful in industry. Zinc dithiocarbamates are used to modify the crosslinking of certain polyolefins with sulfur, a process called vulcanization. They are used as ligands for chelating metals. [7]

Structure of the dimethyldithiocarbamate of zinc. Zn(Me2dtc)2Improved.png
Structure of the dimethyldithiocarbamate of zinc.

Some dithiocarbamates, specifically ethylene bisdithiocarbamates (EBDCs), in the form of complexes with manganese (maneb), zinc (zineb) or a combination of manganese and zinc (mancozeb), have been used extensively as fungicides in agriculture since the 1940s. [8] In the United States they began to be registered for use in the late 1950s and early 1960s and were quickly put to work on sooty blotch and flyspeck. [9] Many growers switched from captan to EBDCs for the longer residual period. [9] Both captan and EBDCs were the primary treatments for SBFS in that country until the early 1990s when the US Environmental Protection Agency banned EBDCs within 77 days to harvest. [9] This effectively made summer use impossible, reduced EBDC use overall, and radically increased SBFS. [9]

Methylenebis(dibutyldithiocarbamate) is an additive in some extreme pressure gear oils, serving as an antioxidant and protecting metal surfaces. CH2 dtc 2.svg
Methylenebis(dibutyldithiocarbamate) is an additive in some extreme pressure gear oils, serving as an antioxidant and protecting metal surfaces.

See also

Related Research Articles

<span class="mw-page-title-main">Carbamate</span> Chemical group (>N–C(=O)–O–)

In organic chemistry, a carbamate is a category of organic compounds with the general formula R2NC(O)OR and structure >N−C(=O)−O−, which are formally derived from carbamic acid. The term includes organic compounds, formally obtained by replacing one or more of the hydrogen atoms by other organic functional groups; as well as salts with the carbamate anion H2NCOO−.

<span class="mw-page-title-main">Xanthate</span> Salt that is a metal-thioate/O-esters of dithiocarbonate

A xanthate is a salt or ester of a xanthic acid. The formula of the salt of xanthic acid is [R−O−CS2]−M+. Xanthate also refers to the anion [R−O−CS2]−. The formula of a xanthic acid is R−O−C(=S)−S−H, such as ethyl xanthic acid, while the formula of an ester of a xanthic acid is R−O−C(=S)−S−R', where R and R' are organyl groups. The salts of xanthates are also called O-organyl dithioates. The esters of xanthic acid are also called O,S-diorganyl esters of dithiocarbonic acid. The name xanthate is derived from Ancient Greek ξανθός (xanthos) meaning 'yellowish' or 'golden', and indeed most xanthate salts are yellow. They were discovered and named in 1823 by Danish chemist William Christopher Zeise. These organosulfur compounds are important in two areas: the production of cellophane and related polymers from cellulose and for extraction of certain sulphide bearing ores. They are also versatile intermediates in organic synthesis.

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

Dimethylamine is an organic compound with the formula (CH3)2NH. This secondary amine is a colorless, flammable gas with an ammonia-like odor. Dimethylamine is commonly encountered commercially as a solution in water at concentrations up to around 40%. An estimated 270,000 tons were produced in 2005.

<span class="mw-page-title-main">Extreme pressure additive</span>

Extreme pressure additives, or EP additives, are additives for lubricants with a role to decrease wear of the parts of the gears exposed to very high pressures. They are also added to cutting fluids for machining of metals.

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

Methacrylic acid, abbreviated MAA, is an organic compound with the formula CH2=C(CH3)CO2H. This colorless, viscous liquid is a carboxylic acid with an acrid unpleasant odor. It is soluble in warm water and miscible with most organic solvents. Methacrylic acid is produced industrially on a large scale as a precursor to its esters, especially methyl methacrylate (MMA), and to poly(methyl methacrylate) (PMMA).

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

Methyl isothiocyanate is the organosulfur compound with the formula CH3N=C=S. This low melting colorless solid is a powerful lachrymator. As a precursor to a variety of valuable bioactive compounds, it is the most important organic isothiocyanate in industry.

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

Sodium diethyldithiocarbamate is the organosulfur compound with the formula NaS2CN(C2H5)2. It is a pale yellow, water soluble salt.

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

Sodium dimethyldithiocarbamate is the organosulfur compound with the formula NaS2NN(CH3)2. It is one of the simplest organic dithiocarbamates. It is a white or pale yellow, water soluble solid. The compound is a precursor to fungicides and rubber chemicals.

<span class="mw-page-title-main">Thiuram disulfide</span> Class of chemical compounds

Thiuram disulfides are a class of organosulfur compounds with the formula (R2NCSS)2. Many examples are known, but popular ones include R = Me and R = Et. They are disulfides obtained by oxidation of the dithiocarbamates. These compounds are used in sulfur vulcanization of rubber as well as in the manufacture of pesticides and drugs. They are typically white or pale yellow solids that are soluble in organic solvents.

<span class="mw-page-title-main">Thiocarbamate</span> Organosulfur compounds of the forms ROC(S)NR2 or RSC(O)NR2

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, ROC(=S)NR2 (esters), and S-thiocarbamates, RSC(=O)NR2 (thioesters).

<span class="mw-page-title-main">Potassium ethyl xanthate</span> Chemical compound

Potassium ethyl xanthate (KEX) is an organosulfur compound with the chemical formula CH3CH2OCS2K. It is a pale yellow powder that is used in the mining industry for the separation of ores. It is a potassium salt of ethyl xanthic acid.

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

Ethylene thiourea (ETU) is an organosulfur compound with the formula C3H6N2S. It is an example of an N,N-disubstituted thiourea. It is a white solid. It is synthesized by treating ethylenediamine with carbon disulfide.

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

Perchloromethyl mercaptan is the organosulfur compound with the formula CCl3SCl. It is mainly used as an intermediate for the synthesis of dyes and fungicides (captan, folpet). It is a colorless oil, although commercial samples are yellowish. It is insoluble in water but soluble in organic solvents. It has a foul, unbearable, acrid odor. Perchloromethyl mercaptan is the original name. The systematic name is trichloromethanesulfenyl chloride, because the compound is a sulfenyl chloride, not a mercaptan.

<span class="mw-page-title-main">Zinc bis(dimethyldithiocarbamate)</span> Chemical compound

Zinc dimethyldithiocarbamate is a coordination complex of zinc with dimethyldithiocarbamate. It is a pale yellow solid that is used as a fungicide, the sulfur vulcanization of rubber, and other industrial applications.

In chemistry, a fatty amine is loosely defined as any amine possessing a mostly linear hydrocarbon chain of eight or more carbon atoms. They are typically prepared from the more abundant fatty acids, with vegetable or seed-oils being the ultimate starting material. As such they are often mixtures of chain lengths, ranging up to about C22. They can be classified as oleochemicals. Commercially important members include coco amine, oleylamine, tallow amine, and soya amine. These compounds and their derivatives are used as fabric softeners, froth flotation agents, corrosion inhibitors, lubricants and friction modifiers. They are also the basis for a variety of cosmetic formulations.

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

2-Mercaptobenzothiazole is an organosulfur compound with the formula C6H4(NH)SC=S. A white solid, it is used in the sulfur vulcanization of rubber.

<span class="mw-page-title-main">Ureas</span>

In chemistry, ureas are a class of organic compounds with the formula (R2N)2CO where R = H, alkyl, aryl, etc. Thus, in addition to describing the specific chemical compound urea ((H2N)2CO), urea is the name of a functional group that is found in many compounds and materials of both practical and theoretical interest. Generally ureas are colorless crystalline solids, which, owing to the presence of fewer hydrogen bonds, exhibit melting points lower than that of urea itself.

<span class="mw-page-title-main">Nickel bis(dimethyldithiocarbamate)</span> Chemical compound

Nickel bis(dimethyldithiocarbamate) is the coordination complex on nickel and dimethyldithiocarbamate, with the formula Ni(S2CNMe2)2 (Me = methyl). It is the prototype for a large number of bis(dialkhyldithiocarbamate)s of nickel(II), which feature diverse organic substituents, most of which have feature square planar molecular geometry. Nickel bis(dimethyldithiocarbamate) has been marketed as a fungicide and related complexes are used as stabilizers in polymers.

Potassium amyl xanthate (/pəˈtæsiəm ˌæmɪl ˈzænθeɪt/) is an organosulfur compound with the chemical formula CH3(CH2)4OCS2K. It is a pale yellow powder with a pungent odor that is soluble in water. It is widely used in the mining industry for the separation of ores using the flotation process.

<span class="mw-page-title-main">Transition metal dithiocarbamate complexes</span>

Transition metal dithiocarbamate complexes are coordination complexes containing one or more dithiocarbamate ligand, which are typically abbreviated R2dtc−. Many complexes are known. Several homoleptic derivatives have the formula M(R2dtc)n where n = 2 and 3.

References

  1. ↑ Engels, Hans-Wilhelm; et al. "Rubber, 4. Chemicals and Additives". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a23_365.pub2. ISBN   978-3527306732.
  2. ↑ Rüdiger Schubart (2000). "Dithiocarbamic Acid and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a09_001. ISBN   3-527-30673-0.
  3. ↑ Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, p. 1297, ISBN   978-0-471-72091-1
  4. ↑ A. D. Ainley; W. H. Davies; H. Gudgeon; J. C. Harland; W. A. Sexton (1944). "The Constitution of the So-Called Carbothialdines and the Preparation of Some Homologous Compounds". J. Chem. Soc.: 147–152. doi:10.1039/JR9440000147.
  5. ↑ John R. Grunwell (1970). "Reaction of Grignard Reagents with Tetramethylthiuram Disulfide [yielding dithiocarbamates]". J. Org. Chem. 35 (5): 1500–1501. doi:10.1021/jo00830a052.
  6. ↑ Coucouvanis, Dimitri (1979). "The chemistry of the dithioacid and 1,1-dithiolate complexes, 1968–1977". Prog. Inorg. Chem. Progress in Inorganic Chemistry. 26: 301–469. doi:10.1002/9780470166277.ch5. ISBN   978-0-470-16627-7.
  7. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN   978-0-08-037941-8.
  8. ↑ "A Short History of Fungicides". The American Phytopathological Society. Archived from the original on 16 April 2016. Retrieved 10 May 2016.
  9. 1 2 3 4 Gleason, Mark L.; Zhang, Rong; Batzer, Jean C.; Sun, Guangyu (2019-08-25). "Stealth Pathogens: The Sooty Blotch and Flyspeck Fungal Complex". Annual Review of Phytopathology . 57 (1). Annual Reviews: 135–164. doi:10.1146/annurev-phyto-082718-100237. ISSN   0066-4286. PMID   31150591. S2CID   172137916.
  10. ↑ Theo Mang; Jürgen Braun; Wilfried Dresel; Jürgen Omeis (2011). "Lubricants, 2. Components". Ullmanns Encyclopedia of Industrial Chemistry. Wiley-VCH. doi:10.1002/14356007.o15_o04. ISBN   978-3-527-30673-2.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.