Names | |
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Preferred IUPAC name 2,6-Dichlorobenzonitrile | |
Other names Dichlobanil, Dichlobenil | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChemSpider | |
ECHA InfoCard | 100.013.443 |
KEGG | |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C7H3Cl2N | |
Molar mass | 172.01 g/mol |
Appearance | white crystalline powder |
Density | 1.623 g/cm3 |
Melting point | 144.5 °C (292.1 °F; 417.6 K) |
Boiling point | 279 °C (534 °F; 552 K) |
insoluble | |
Hazards | |
Flash point | 126 °C (259 °F; 399 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
2,6-Dichlorobenzonitrile (DCBN or dichlobenil) is an organic compound with the chemical formula C6H3Cl2CN. It is a white solid that is soluble in organic solvents. It is widely used as a herbicide and organic chemistry building block. [1]
It has herbicidal properties killing young seedlings of both monocot and dicot species. [2] DCBN interferes with cellulose synthesis. DCBN adapted cell walls use minimal amounts of cellulose, instead relying on Ca2+-bridge pectates. [3]
In 1971 in the U.S. State of California, their department of agriculture reported, "Dichlobenil kills the roots of many species, but not all; further, the killing does not extend much beyond the portion actually soaked." [4]
In 1996, the University of California's Statewide Integrated Pest Management Project reported:
Dosages were difficult to control... and as a result soaking or spraying methods are no longer used.
The current application method involves applying metam-sodium products in foam carriers (similar to shaving cream). [5]
The U.S. Food & Drug Administration (FDA, a major operational division of the U.S. Department of Health & Human Services) mentions "dichlobenil" in a report entitled "Herbicidal suppression of bracken and effects on forage production." [6]
The U.S. Department of Energy - Bonneville Power Administration has reported "high potential" for dichlobenil to enter groundwater. [7]
According to the US Environmental Protection Agency, [8]
On an acute basis, dichlobenil is practically nontoxic to birds, mammals, honey bees; slightly to moderately toxic to aquatic invertebrates and estuarine organisms; and moderately toxic to fish. Dichlobenil is practically nontoxic to birds on a subacute dietary basis, but insufficient data are available to assess chronic avian toxicity. Dichlobenil is toxic to non-target terrestrial and aquatic plants. Dichlobenil may chronically affect fish at levels as low as 0.33 ppm and may chronically affect aquatic invertebrates at levels as low as 0.75 ppm. The dichlobenil degradate, BAM is slightly toxic to mammals and practically nontoxic to fish and aquatic invertebrates on an acute basis.
Inland Fisheries Ireland has reported, "The dichlobenil residue in water almost completely dissipates in 5 to 6 months." [9]
U.S. FDA reports on pesticide residue. [10]
Since 1995, the U.S. National Institutes of Health has warned about potential damage to humans during indoor usage (see products listed, below):
Leave all windows open and fans operating... Put all pets outdoors, and take yourself any your family away from treated areas for at least the length of time prescribed on the label. [11]
In 2006, the University of Hertfordshire reported on "dichlobenil":
It is no longer approved for use within the EU. It has low solubility, is not highly volatile and has potential to leach into groundwater. It is moderately persistent in soils and very persistent in water. It is moderately toxic to mammals, aquatic organisms, honeybees and earthworms. [12]
The report quotes a European Union regulatory effective date of 2009. [12] The Inland Fisheries Ireland has reported:
The registration of all dichlobenil products (including Casoron G) was revoked in Ireland from 18th March 2009, under Commission Decision 2008/754/EC of 18th September 2008. A period of grace for the disposal, storage, placing on the market and use of existing stocks expired on 18th March 2010. [9]
The London underground found itself in violation by using dichlobenil in September 2011. [13] As of 2012, the United Nations' International Programme on Chemical Safety (IPCS) has advised that "the substance can be absorbed into the body by inhalation, through the skin and by ingestion... A harmful concentration of airborne particles can be reached quickly when dispersed... The substance may have effects on the skin. This may result in chloracne." [14] Further, it has advised
The substance is toxic to aquatic organisms. This substance does enter the environment under normal use. Great care, however, should be taken to avoid any additional release, for example through inappropriate disposal. [14]
For personal protection during usage, the IPCS advises:
Particulate filter respirator adapted to the airborne concentration of the substance... Sweep spilled substance into covered sealable containers. If appropriate, moisten first to prevent dusting. Carefully collect remainder. Then store and dispose of according to local regulations. [14]
While the ICPS warns strongly, "Do NOT let this chemical enter the environment," it does not note the contradiction that dichlobenil's usage is on the environment. [14]
The U.S. Centers for Disease Control and Prevention (CDC) follows and cites the ICPS. [15]
This partial list of consumer products with "dichlobenil" as an active ingredient:
Dichlobenil is produced from 2,6-dichlorotoluene via the aldoxime. [1]
Herbicides, also commonly known as weed killers, are substances used to control undesired plants, also known as weeds. Selective herbicides control specific weed species while leaving the desired crop relatively unharmed, while non-selective herbicides kill plants indiscriminately. The combined effects of herbicides, nitrogen fertilizer, and improved cultivars has increased yields of major crops by 3x to 6x from 1900 to 2000.
Glyphosate is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphorus compound, specifically a phosphonate, which acts by inhibiting the plant enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSP). It is used to kill weeds, especially annual broadleaf weeds and grasses that compete with crops. Its herbicidal effectiveness was discovered by Monsanto chemist John E. Franz in 1970. Monsanto brought it to market for agricultural use in 1974 under the trade name Roundup. Monsanto's last commercially relevant United States patent expired in 2000.
Alachlor is an herbicide from the chloroacetanilide family. It is an odorless, white solid. The greatest use of alachlor is for control of annual grasses and broadleaf weeds in crops. Use of alachlor is illegal in the European Union and no products containing alachlor are currently registered in the United States.
Diquat is the ISO common name for an organic dication that, as a salt with counterions such as bromide or chloride is used as a contact herbicide that produces desiccation and defoliation. Diquat is no longer approved for use in the European Union, although its registration in many other countries including the USA is still valid.
Algaecide or algicide is a biocide used for killing and preventing the growth of algae, often defined in a loose sense that, beyond the biological definition, also includes cyanobacteria. An algaecide may be used for controlled bodies of water, but may also be used on land for locations such as turfgrass.
Toxicity class refers to a classification system for pesticides that has been created by a national or international government-related or -sponsored organization. It addresses the acute toxicity of agents such as soil fumigants, fungicides, herbicides, insecticides, miticides, molluscicides, nematicides, or rodenticides.
Dicamba is a selective systemic herbicide first registered in 1967. Brand names for formulations of this herbicide include Dianat, Banvel, Diablo, Oracle and Vanquish. This chemical compound is a chlorinated derivative of o-anisic acid. It has been described as a "widely used, low-cost, environmentally friendly herbicide that does not persist in soils and shows little or no toxicity to wildlife and humans."
Sulfentrazone is the ISO common name for an organic compound used as a broad-spectrum herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase. It was first marketed in the US in 1997 by FMC Corporation with the brand name Authority.
Clothianidin is an insecticide developed by Takeda Chemical Industries and Bayer AG. Similar to thiamethoxam and imidacloprid, it is a neonicotinoid. Neonicotinoids are a class of insecticides that are chemically similar to nicotine, which has been used as a pesticide since the late 1700s. Clothianidin and other neonicotinoids act on the central nervous system of insects as an agonist of nAChR, the same receptor as acetylcholine, the neurotransmitter that stimulates and activating post-synaptic acetylcholine receptors but not inhibiting AChE. Clothianidin and other neonicotinoids were developed to last longer than nicotine, which is more toxic and which breaks down too quickly in the environment.
Bromacil is an organic compound with the chemical formula C9H13BrN2O2, commercially available as a herbicide. Bromacil was first registered as a pesticide in the U.S. in 1961. It is used for brush control on non-cropland areas. It works by interfering with photosynthesis by entering the plant through the root zone and moving throughout the plant. Bromacil is one of a group of compounds called substituted uracils. These materials are broad spectrum herbicides used for nonselective weed and brush control on non-croplands, as well as for selective weed control on a limited number of crops, such as citrus fruit and pineapple. Bromacil is also found to be excellent at controlling perennial grasses.
Mesotrione is a selective herbicide used mainly in maize crops. It is a synthetic compound inspired by the natural substance leptospermone found in the bottlebrush tree Callistemon citrinus. It inhibits the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD) and is sold under brand names including Callisto and Tenacity. It was first marketed by Syngenta in 2001.
2,4-Dichlorophenoxyacetic acid is an organic compound with the chemical formula Cl2C6H3OCH2CO2H. It is usually referred to by its ISO common name 2,4-D. It is a systemic herbicide that kills most broadleaf weeds by causing uncontrolled growth, but most grasses such as cereals, lawn turf, and grassland are relatively unaffected.
Acifluorfen is the ISO common name for an organic compound used as an herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase which is necessary for chlorophyll synthesis. Soybeans naturally have a high tolerance to acifluorfen and its salts, via metabolic disposal by glutathione S-transferase. It is effective against broadleaf weeds and grasses and is used agriculturally on fields growing soybeans, peanuts, peas, and rice.
Imazaquin is an imidazolinone herbicide, so named because it contains an imidazolinone core. This organic compound is used to control a broad spectrum of weed species. It is a colorless or white solid, although commercial samples can appear brown or tan.
Bifenox is the ISO common name for an organic compound used as an herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase which is necessary for chlorophyll synthesis.
Cyproconazole is an agricultural fungicide of the class of azoles, used on cereal crops, coffee, sugar beet, fruit trees and grapes, and peanuts, on sod farms and golf course turf and on wood as a preservative. It has been used against powdery mildew, rust on cereals and apple scab, and applied by air or on the ground or by chemigation.
Glyphosate-based herbicides are usually made of a glyphosate salt that is combined with other ingredients that are needed to stabilize the herbicide formula and allow penetration into plants. The glyphosate-based herbicide Roundup was first developed by Monsanto in the 1970s. It is used most heavily on corn, soy, and cotton crops that have been genetically modified to be resistant to the herbicide. Some products include two active ingredients, such as Enlist Duo which includes 2,4-D as well as glyphosate. As of 2010, more than 750 glyphosate products were on the market. The names of inert ingredients used in glyphosate formulations are usually not listed on the product labels.
Fomesafen is the ISO common name for an organic compound used as an herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase (PPO) which is necessary for chlorophyll synthesis. Soybeans naturally have a high tolerance to fomesafen, via metabolic disposal by glutathione S-transferase. As a result, soy is the most common crop treated with fomesafen, followed by other beans and a few other crop types. It is not safe for maize/corn or other Poaceae.
Fluazifop is the common name used by the ISO for an organic compound that is used as a selective herbicide. The active ingredient is the 2R enantiomer at its chiral centre and this material is known as fluazifop-P when used in that form. More commonly, it is sold as its butyl ester, fluazifop-P butyl with the brand name Fusilade.
Butafenacil is the ISO common name for an organic compound of the pyrimidinedione chemical class used as an herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase to control broadleaf and some grass weeds in crops including cereals and canola.