Names | |
---|---|
Preferred IUPAC name 2,4,5,6-Tetrachlorobenzene-1,3-dicarbonitrile | |
Other names 2,4,5,6-Tetrachloroisophthalonitrile Bravo Daconil Tetrachloroisophthalonitrile Celeste Bronco Agronil Aminil | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.015.990 |
EC Number |
|
KEGG | |
PubChem CID | |
RTECS number |
|
UNII | |
UN number | 3276, 2588 |
CompTox Dashboard (EPA) | |
| |
| |
Properties | |
C8Cl4N2 | |
Molar mass | 265.90 g·mol−1 |
Appearance | white crystalline solid |
Density | 1.8 g cm−3, solid |
Melting point | 250 °C (482 °F; 523 K) |
Boiling point | 350 °C (662 °F; 623 K) (760 mmHg) |
10 mg/100 mL [1] | |
log P | 2.88–3.86 |
Hazards | |
GHS labelling: | |
Danger | |
H317, H318, H330, H335, H351, H410 | |
P201, P202, P260, P261, P271, P272, P273, P280, P281, P284, P302+P352, P304+P340, P305+P351+P338, P308+P313, P310, P312, P320, P321, P333+P313, P363, P391, P403+P233, P405, P501 | |
Related compounds | |
Related nitriles; organochlorides | benzonitrile; hexachlorobenzene, dichlorobenzene, chlorobenzene |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) is an organic compound mainly used as a broad spectrum, nonsystemic fungicide, with other uses as a wood protectant, pesticide, acaricide, and to control mold, mildew, bacteria, algae. [2] Chlorothalonil-containing products are sold under the names Bravo, Echo, and Daconil. It was first registered for use in the US in 1966. In 1997, it was the third most used fungicide in the US, behind only sulfur and copper, with 12 million pounds (5.4 million kilograms) used in agriculture that year. [3] Including nonagricultural uses, the United States Environmental Protection Agency (EPA) estimates, on average, almost 15 million lb (6.8 million kg) were used annually from 1990 to 1996. [2]
In the US, chlorothalonil is used predominantly on peanuts (about 34% of usage), potatoes (about 12%), and tomatoes (about 7%), although the EPA recognizes its use on many other crops. [2] It is also used on golf courses and lawns (about 10%) and as a preservative additive in some paints (about 13%), resins, emulsions, and coatings. [2]
Chlorothalonil is commercially available in many different formulations and delivery methods. It is applied as a dust, dry or water-soluble grains, a wettable powder, a liquid spray, a fog, and a dip. It may be applied by hand, by ground sprayer, or by aircraft. [2]
Chlorothalonil reacts with glutathione giving an glutathione adduct with elimination of HCl. Its mechanism of action is similar to that of trichloromethyl sulfenyl fungicides [4] such as captan and folpet. [5]
According to the EPS, chlorothalonil is a toxicity category I eye irritant, producing severe eye irritation. It is in toxicity category II, "moderately toxic", if inhaled (inhaled LD50 0.094 mg/L in rats.) For skin contact and ingestion, chlorothalonil is rated toxicity category IV, "practically nontoxic", meaning the oral and dermal LD50 is greater than 10,000 mg/kg. [2]
Long-term exposure to chlorothalonil resulted in kidney damage and tumors in animal tests. [2]
International Agency for Research on Cancer IARC has assessed chlorothalonil as a Group 2B "possible human carcinogen", based on observations of cancers and tumors of the kidneys and forestomachs in laboratory animals fed diets containing chlorothalonil. [2]
Chlorothalonil was found to be an important factor in the decline of the honey bee population, by making the bees more vulnerable to the gut parasite Nosema ceranae . [6]
Chlorothalonil is highly toxic to fish and aquatic invertebrates, but not toxic to birds. [7]
At a concentration of 164 μg/L, chlorothalonil was found to kill a species of frog within a 24-hour exposure. [8]
Common chlorothalonil synthesis procedures frequently result in contamination of it with small amounts of hexachlorobenzene (HCB), which is toxic. US regulations limit HCB in commercial production to 0.05% of chlorothalonil. According to the EPA report, "post-application exposure to HCB from chlorothalonil is not expected to be a concern based on the low level of HCB in chlorothalonil. 2,3,7,8-Tetrachlorodibenzodioxin being one of the most potent carcinogens known is also a known contaminant". [2]
Chlorothalonil has been detected in ambient air Prince Edward Island, [9] as well as in groundwater in Long Island, New York [2] and Florida. [2] In the first three cases, the contamination is presumed to have come from potato farms. It has also been detected in several fish kills in Prince Edward Island. [10]
The main breakdown product of chlorothalonil is hydroxy-2,5,6-trichloro-1,3-dicyanobenzene (SDS-3701). It has been shown to be 30 times more acutely toxic than chlorothalonil and more persistent in the environment. [11] [12] Laboratory experiments have shown it can thin the eggshells of birds, but no evidence supports this happening in the environment. [2]
In 2019, a review of the evidence found that "a high risk to amphibians and fish was identified for all representative uses", and that chlorothalonil breakdown products may cause DNA damage. [13] [14] Chlorothalonil and other fungicides are claimed to be the strongest factor in bumblebee population decline. [13]
Syngenta sued to stop communication by Swiss health authorities with the Swiss public regarding the "relevance" of specific metabolites of chlorothalonil that Swiss authorities detected in high concentrations in the groundwater from which hundreds of thousands of Swiss people obtain drinking water. The court banned Swiss health authorities from communicating with the public about the dangers posed by some of the metabolites. [15]
In March 2019, as a result of the previously mentioned research, the European Union banned the use of chlorothalonil [13] dated to take effect May 20, 2020. [16] Switzerland followed in December 2019. [17]
Chlorothalonil can be produced by the direct chlorination of isophthalonitrile or by dehydration of tetrachloroisophthaloyl amide with phosphoryl chloride. [18] It is a white solid. It breaks down under basic conditions, but is stable in neutral and acidic media. [7] Technical grade chlorothalonil contains traces of dioxins and hexachlorobenzene, [2] a persistent organic pollutant banned under the Stockholm Convention.
Triclopyr is an organic compound in the pyridine group that is used as a systemic foliar herbicide and fungicide.
Imidacloprid is a systemic insecticide belonging to a class of chemicals called the neonicotinoids which act on the central nervous system of insects. The chemical works by interfering with the transmission of stimuli in the insect nervous system. Specifically, it causes a blockage of the nicotinergic neuronal pathway. By blocking nicotinic acetylcholine receptors, imidacloprid prevents acetylcholine from transmitting impulses between nerves, resulting in the insect's paralysis and eventual death. It is effective on contact and via stomach action. Because imidacloprid binds much more strongly to insect neuron receptors than to mammal neuron receptors, this insecticide is more toxic to insects than to mammals.
Chlorfenvinphos is an organophosphorus compound that was widely used as an insecticide and an acaricide. The molecule itself can be described as an enol ester derived from dichloroacetophenone and diethylphosphonic acid. Chlorfenvinphos has been included in many products since its first use in 1963. However, because of its toxic effect as a cholinesterase inhibitor it has been banned in several countries, including the United States and the European Union. Its use in the United States was discontinued in 1991.
Pesticides vary in their effects on bees. Contact pesticides are usually sprayed on plants and can kill bees when they crawl over sprayed surfaces of plants or other areas around it. Systemic pesticides, on the other hand, are usually incorporated into the soil or onto seeds and move up into the stem, leaves, nectar, and pollen of plants.
Aldicarb is a carbamate insecticide which is the active substance in the pesticide Temik. It is effective against thrips, aphids, spider mites, lygus, fleahoppers, and leafminers, but is primarily used as a nematicide. Aldicarb is a cholinesterase inhibitor which prevents the breakdown of acetylcholine in the synapse. Aldicarb is considered "extremely hazardous" by the EPA and World Health Organization and has been banned in more than 100 countries. In case of severe poisoning, the victim dies of respiratory failure.
Fipronil is a broad-spectrum insecticide that belongs to the phenylpyrazole chemical family. Fipronil disrupts the insect central nervous system by blocking the ligand-gated ion channel of the GABAA receptor and glutamate-gated chloride (GluCl) channels. This causes hyperexcitation of contaminated insects' nerves and muscles. Fipronil's specificity towards insects is believed to be due to its greater binding affinity for the GABAA receptors of insects than to those of mammals, and for its action on GluCl channels, which do not exist in mammals. As of 2017, there does not appear to be significant resistance among fleas to fipronil.
Hexachlorobenzene, or perchlorobenzene, is an aryl chloride and a six-substituted chlorobenzene with the molecular formula C6Cl6. It is a fungicide formerly used as a seed treatment, especially on wheat to control the fungal disease bunt. It has been banned globally under the Stockholm Convention on Persistent Organic Pollutants.
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.
Acibenzolar-S-methyl is the ISO common name for an organic compound that is used as a fungicide. Unusually, it is not directly toxic to fungi but works by inducing systemic acquired resistance, the natural defence system of plants.
Azoxystrobin is a broad spectrum systemic fungicide widely used in agriculture to protect crops from fungal diseases. It was first marketed in 1996 using the brand name Amistar and by 1999 it had been registered in 48 countries on more than 50 crops. In the year 2000 it was announced that it had been granted UK Millennium product status.
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.
Colony collapse disorder (CCD) is an abnormal phenomenon that occurs when the majority of worker bees in a honey bee colony disappear, leaving behind a queen, plenty of food, and a few nurse bees to care for the remaining immature bees. While such disappearances have occurred sporadically throughout the history of apiculture, and have been known by various names, the syndrome was renamed colony collapse disorder in early 2007 in conjunction with a drastic rise in reports of disappearances of western honey bee colonies in North America. Beekeepers in most European countries had observed a similar phenomenon since 1998, especially in Southern and Western Europe; the Northern Ireland Assembly received reports of a decline greater than 50%. The phenomenon became more global when it affected some Asian and African countries as well. From 1990 to 2021, the United Nation’s FAO calculated that the worldwide number of honeybee colonies increased 47%, reaching 102 million.
Pentachloronitrobenzene, typically abbreviated PCNB, is a registered fungicide formally derived from nitrobenzene. It is a off-white to yellow crystalline solid with a musty odor.
This is an index of articles relating to pesticides.
Thiamethoxam is the ISO common name for a mixture of cis-trans isomers used as a systemic insecticide of the neonicotinoid class. It has a broad spectrum of activity against many types of insects and can be used as a seed dressing.
Dimethyl tetrachloroterephthalate (DCPA, with the main trade name Dacthal) is an organic compound with the formula C6Cl4(CO2CH3)2. It is the dimethyl ester of tetrachloroterephthalic acid, used as a preemergent herbicide with the ISO common name chlorthal-dimethyl. It kills annual grasses and many common weeds without killing sensitive plants such as turf grasses, flowers, fruits, vegetables, and cotton.
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.
Cyanazine is a herbicide that belongs to the group of triazines. Cyanazine inhibits photosynthesis and is therefore used as a herbicide.
Pydiflumetofen is a broad spectrum fungicide used in agriculture to protect crops from fungal diseases. It was first marketed by Syngenta in 2016 using their brand name Miravis. The compound is an amide which combines a pyrazole acid with a substituted phenethylamine to give an inhibitor of succinate dehydrogenase, an enzyme that inhibits cellular respiration in almost all living organisms.