Description
Dithiocarbamates (DCs) are a well-known group of pesticides
which have been used to control a number of species belonging
to taxonomically different groups, e.g., bacteria, fungi, nematodes,
and molluscs for over 60 years. The first integrated
product containing sodium dimethyldithiocarbamate (SDMC)
was registered in 1949.
Chemical Properties
Sodium dimethyldithiocarbamate is a clear yellow liquid or yellow crystalline solid. The pure product is a scaly white crystal, which is easily soluble in water. The crystal obtained by the crystallization method contains 2.5 molecules of crystal water, which loses 2 molecules of crystal water when heated to 115 °C, and completely loses crystal water at 130 °C. The industrial intermediate is a 15% aqueous solution, a yellowish or grass-green transparent liquid, a relative density of 1.06, and a pH of 9 to 11. Used as soil disinfectant.
Uses
Sodium dimethyldithiocarbamate(SDMC) is used as a disinfectant, corrosion inhibitor, coagulant, vulcanizing agent, chelating agent, and fungicide. SDMC is used in water treatment, the rubber industry, and is a registered biocide for cutting oils and aqueous systems in industries such as leather tanning and paper manufacturing. It is also used as an antimicrobial agent in paints. generally SDMC are able to function as metal chelators and have been used in metal finishing operations and wastewater treatments to enhance the precipitation of metals. As a free radical inhibitor, it has been used in the rubber industry to rapidly stop the polymerization of synthesis. It is also used as a biocide for cutting oils and aqueous systems such as leather tanning and paper manufacturing.
Preparation
Sodium dimethyldithiocarbamate is prepared by combining dimethylamine with carbon disulfide in a solution of sodium hydroxide, forming the water-soluble dithiocarbamate salt.
Application
The methyl ester of dimethyldithiocarbamic acid is produced by the reaction of sodium dimethyldithiocarbamate with dimethyl sulfate in aqueous medium in the presence of a small amount of emulsifier at 40° to 50° C.
Dimethyldithiocarbamic Acid Sodium Salt was used in studies to develop removal of heavy metals from water by sulfide precipitation.
Sodium N,N-dimethylthithiocarbamate is use as a disinfectant, corrosion inhibitor, coagulant, vulcanizing agent, chelating agent, and fungicide may result in its release to the environment through various waste streams(SRC). It is also used as an antimicrobial agent in paints.
General Description
Crystals or liquid. Becomes anhydrous at 266°F.
Air & Water Reactions
Slowly decomposes in aqueous solution to form carbon disulfide and methylamine or other amines. Such decompositions are accelerated by acids.
Reactivity Profile
Flammable gases are generated by the combination with aldehydes, nitrides, and hydrides. Incompatible with acids, peroxides, and acid halides.
Health Hazard
ACUTE/CHRONIC HAZARDS: When heated to decomposition it emits very toxic fumes.
Fire Hazard
Flash point data for Sodium dimethyldithiocarbamate are not available. Sodium dimethyldithiocarbamate is probably not flammable.
Safety Profile
Moderately toxic by ingestion and intraperitoneal routes. Mutation data reported. When heated to decomposition it emits very toxic fumes of NOx, SOx, and Na2O. See also CARBAMATES.
Potential Exposure
The slow release of poisonous gases from hydrolysis of many thio and dithiocarbamates requires the use of respirators during handling. Used as an antimicrobial/fungicidal agent in paints, water treatment; a registered biocide for cutting oils and aqueous systems in industries such as leather tanning and paper manufacturing. Used in the rubber industry as a vulcanization accelerator for making synthetic and natural rubbers (i.e., butadiene rubber, latex). Used as a fungicide on melons (tolerance set as 25 ppm). Also used as an indirect food additive for use only as a component of adhesives.
Environmental Fate
Routes and Pathways and Relevant Physicochemical
Properties
The estimated pKa of SDMC is 5.4, indicating that this
compound will primarily exist in the dissociated form at environmentally
relevant pHs. If released to air, SDMC will exist
solely in the particulate phase in the ambient atmosphere, since
it is a salt and will be nonvolatile. Due to the short chemical
lifetime of SDMC in air, it is not expected to accumulate in air or
transported in the gaseous phase over long distances. Furthermore,
based on the estimated Henry’s law constant at
25°C ＝ 6.972 1015 atmm3 mol
-1at 20 °C for it and Log Pow
equal to 2.41, air will not be an environmental compartment
of concern and sodium N,N-dimethyldithiocarbamate can be
classified as a nonadsorbed substance.
Partition Behavior in Water, Sediment, and Soil
The Koc of SDMC is estimated as 2.2, suggesting that SDMC is
expected to have very high mobility in soil and is not adsorbed
to suspended solids or sediment.
Environmental Persistency
Particulate-phase SDMC will be removed from the atmosphere
by wet and dry depositions. Photolysis in aqueous solution and
soil was found to be an important degradation process for
SDMC. Depending on the geographical latitude (30–50 N)
and the climatic season, the calculated environmental half-lives
of SDMC range from 0.3 to 2.26 days. Hydrolysis of SDMC
occurs at neutral and acidic pHs. The hydrolysis half-life of
18 min, 25.9, and 433.3 h was reported for SDMC at pH 5, 7,
and 9, respectively. The products of degradation are less toxic
than the product itself. 14C-SDMC is rapidly photodegraded in
buffered solution at pH 9 with a calculated experimental halflife
of 0.79 days, corresponding to 19 h. Direct photolysis in
surface water and soil is an important degradation process for
SDMC.
Purification Methods
Crystallise it from a small volume of H2O, or dissolve it in the minimum volume of H2O and add cold Me2CO, collect it and dry it in air. The solubility in Me2CO is 50g/400mL. The dihydrate loses H2O on heating at 115o to give the hemi-hydrate which decomposes on further heating [Kulka Can J Chem 34 1096 1956]. [Beilstein 4 IV 233.]
Toxicity evaluation
sodium dimethyldithiocarbamate is toxic to aquatic life and can combine to form, or break down to, a number of other toxic chemicals, including thiram (an EPA registered fungicide) and other thiurams, other dithiocarbamates, carbon disulfide, and dimethylamine. The distal peripheral and peripheral neuropathies induced by DCs are postulated to arise via a common mechanism of toxicity, that is, the formation of carbon disulfide. Chronic exposure increases brain neurotransmitters and stimulates sex hormone cycle, especially in women.
Incompatibilities
Slowly decomposes in water, forming carbon disulfide, oxides of sulfur and nitrogen, hydrogen sulfide, ammonia, and amines, including methylamine; this decomposition is accelerated in the presence of acids. Flammable gases are generated by the combination with aldehydes, nitrides, and hydrides. Incompatible with acids, peroxides, and acid halides. Thiocarbamate esters are combustible. They react violently with powerful oxidizers such as calcium hypochlorite. Poisonous gases are generated by the thermal decomposition of thiocarbamate compounds, including carbon disulfide, oxides of sulfur, oxides of nitrogen, hydrogen sulfide, ammonia, and methylamine. Thio and dithiocarbamates slowly decompose in aqueous solution to form carbon disulfide and methylamine or other amines. Such decompositions are accelerated by acids. Flammable gases are generated by the combination of thiocarbamates with aldehydes, nitrides, and hydrides. Thiocarbamates are incompatible with carboxylic acid acids, peroxides, and acid halides.
Waste Disposal
Dispose of contents and container to an approved waste disposal plant. All federal, state, and local environmental regulations must be observed.
