Polydithiocarbamate Resin on:
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Because of the pi-donation from nitrogen, dithiocarbamates are more basic than structurally related anions such as dithiocarboxylates and
Some dithiocarbamates, specifically ethylene bisdithiocarbamates (), in the form of complexes with 
In 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.; ...
, a dithiocarbamate is a functional group
In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest ...
with the general formula
In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...
and structure
A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...
. It is the analog of a 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 ...
in which both oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
atoms are replaced by 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 ...
atoms (when only 1 oxygen is replaced the result is thiocarbamate
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, (ester ...
).
A common example is sodium diethyldithiocarbamate
Sodium diethyldithiocarbamate is the organosulfur compound with the formula NaS2CN(C2H5)2. It is a pale yellow, water soluble salt.
Preparation
This salt is obtained by treating carbon disulfide with diethylamine in the presence of sodium hydrox ...
. Dithiocarbamates and their derivatives are widely used in the vulcanization
Vulcanization (British: Vulcanisation) is a range of processes for hardening rubbers. The term originally referred exclusively to the treatment of natural rubber with sulfur, which remains the most common practice. It has also grown to include ...
of rubber.
Formation
Many primary and secondaryamine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituen ...
s react with carbon disulfide
Carbon disulfide (also spelled as carbon disulphide) is a neurotoxic, colorless, volatile liquid with the formula and structure . The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical non ...
and sodium hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions .
Sodium hydroxide is a highly caustic base and alkali ...
to form dithiocarbamate salts:
:R2NH + CS2 + NaOH → R2NCS2−Na+ + 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.
Reactions
Dithiocarbamates are readily S-alkylated. Thus,methyl dimethyldithiocarbamate
Methyl dimethyldithiocarbamate is the organosulfur compound with the formula (CH3)2NC(S)SCH3. It is the one of simplest dithiocarbamic esters. It is a white volatile solid that is poorly soluble in water but soluble in many organic solvents. ...
can be prepared by methylation of the dithiocarbamate:
:(CH3)2NCS2Na + (CH3O)2SO2 → (CH3)2NC(S)SCH3 + Na H3OSO3
Oxidation of dithiocarbamates gives the thiuram disulfide
Thiuram disulfides are a class of organosulfur compounds with the formula (R2NCSS)2. Many examples are known, but popular ones include R = Me and Et. They are disulfides obtained by oxidation of the dithiocarbamates. These compounds are used i ...
:
:2 R2NCS2− → 2NC(S)Ssub>2 + 2e−
Thiuram disulfides react with Grignard reagents
A Grignard reagent or Grignard compound is a chemical compound with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromide . ...
to give esters of dithiocarbamic acid:
: 2NC(S)Ssub>2 + R'MgX → R2NC(S)SR' + R2NCS2MgX
Dithiocarbamates react with transition metal salts to give a wide variety of transition metal dithiocarbamate complexes 133px, Tris(dithiocarbamate) complexes have idealized D3 symmetry.
Transition metal dithiocarbamate complexes are coordination complexes containing one or more dithiocarbamate ligand, which are typically abbreviated R2dtc−. Many complexes are k ...
.
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.
Because of the pi-donation from nitrogen, dithiocarbamates are more basic than structurally related anions such as dithiocarboxylates and xanthate
150px, Sodium salt of ethyl xanthate
Xanthate usually refers to a salt with the formula (R = alkyl; M+ = Na+, K+), thus they are the metal-thioate/''O''-esters of dithiocarbonate. The name ''xanthates'' is derived from Ancient Greek ''xanthos'' ...
s. 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
Severaltransition metal dithiocarbamate complexes 133px, Tris(dithiocarbamate) complexes have idealized D3 symmetry.
Transition metal dithiocarbamate complexes are coordination complexes containing one or more dithiocarbamate ligand, which are typically abbreviated R2dtc−. Many complexes are k ...
are useful industry. Zinc dithiocarbamates are used to modify the crosslink
In chemistry and biology a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural ...
ing of certain polyolefin
A polyolefin is a type of polymer with the general formula (CH2CHR)n where R is an alkyl group. They are usually derived from a small set of simple olefins (alkenes). Dominant in a commercial sense are polyethylene and polypropylene. More speciali ...
s with sulfur, a process called vulcanization
Vulcanization (British: Vulcanisation) is a range of processes for hardening rubbers. The term originally referred exclusively to the treatment of natural rubber with sulfur, which remains the most common practice. It has also grown to include ...
. They are used as ligands for chelating metals.
Some dithiocarbamates, specifically ethylene bisdithiocarbamates (), in the form of complexes with manganese
Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...
(maneb
Maneb is a fungicide and a polymeric complex of manganese with the ethylene bis(dithiocarbamate) anionic ligand.Arno H. Reidies "Manganese Compounds" Ullmann's Encyclopedia of Chemical Technology 2007; Wiley-VCH, Weinheim.
Applications
It can be ...
), zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
(zineb
Zineb is the chemical compound with the formula n. Structurally, it is classified as a coordination polymer and a dithiocarbamate complex. This pale yellow solid is used as fungicide.
Production and applications
It is produced by treating ethyl ...
) or a combination of manganese and zinc (mancozeb
Mancozeb is a dithiocarbamate non-systemic agricultural fungicide with multi-site, protective action on contact. It is a combination of two other dithiocarbamates: maneb and zineb. The mixture controls many fungal diseases in a wide range of field ...
), have been used extensively as fungicides in agriculture since the 1940s. In the United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
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 Sooty blotch and flyspeck (SBFS) or apple summer disease is a plant disease caused by a complex of saprophytic fungi which colonize the epicuticular wax layer of apple (''Malus'' x ''domestica'' Borkh.). It is found worldwide in regions with moist g ...
. Many growers switched from captan
Captan is a general use pesticide (GUP) that belongs to the phthalimide class of fungicides. It is a white solid, although commercial samples appear yellow or brownish.
Applications
Although it can be applied on its own, Captan is often added ...
to EBDCs for the longer residual period. Both captan and EBDCs were the primary treatments for SBFS in that country until the early 1990s when the US Environmental Protection Agency
A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...
banned EBDCs within 77 days to harvest. This effectively made summer use impossible, reduced EBDC use overall, and radically increased SBFS.
See also
*Xanthate
150px, Sodium salt of ethyl xanthate
Xanthate usually refers to a salt with the formula (R = alkyl; M+ = Na+, K+), thus they are the metal-thioate/''O''-esters of dithiocarbonate. The name ''xanthates'' is derived from Ancient Greek ''xanthos'' ...
References