Dimethyl tetrachloroterephthalate

Last updated
Dimethyl tetrachloroterephthalate
Dimethyl tetrachloroterephthalate.svg
Names
Preferred IUPAC name
Dimethyl 2,3,5,6-tetrachlorobenzene-1,4-dicarboxylate
Other names
Chlorthal-dimethyl; Dimethyl 2,3,5,6-tetrachloroterephthalate
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.015.877 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 217-464-7
KEGG
PubChem CID
UNII
  • InChI=1S/C10H6Cl4O4/c1-17-9(15)3-5(11)7(13)4(10(16)18-2)8(14)6(3)12/h1-2H3
    Key: NPOJQCVWMSKXDN-UHFFFAOYSA-N
  • Clc1c(C(=O)OC)c(Cl)c(Cl)c(C(=O)OC)c1Cl
Properties [1]
C10H6Cl4O4
Molar mass 331.95 g·mol−1
AppearanceColourless to grey crystalline powder
Density 1.56
Melting point 156 °C (313 °F; 429 K)
Boiling point 345 °C (653 °F; 618 K)
0.21 mg/L (20 °C)
log P 4.28
Vapor pressure 0.21 mPa (2.5 x 10−6 Torr)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
toxic with long-lasting effects
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
1
0
Flash point Nonflammable
N/A
Lethal dose or concentration (LD, LC):
>10000 mg/kg [2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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. [3] [1] [4] It kills annual grasses and many common weeds without killing sensitive plants such as turf grasses, flowers, fruits, vegetables, and cotton. [5]

Contents

DCPA was first registered for use in the United States in 1958, for use on turf grasses, for the control of annual grasses such as crabgrass, and certain annual broad-leaved weeds. [5] [6] Production of DCPA was eventually discontinued by ISK Biosciences in 1998, but the large manufacturing company AMVAC (American Vanguard Corporation) began producing the product in 2001 for use in America. [7] In Australia, DCPA is the active ingredient in agchem company Farmalinx's herbicide called Dynamo 750. [8]

EPA registration for use on vegetable crops was voluntarily terminated by the manufacturer in 2005 in response to EPA concerns regarding the contamination of groundwater. [5] [9] In 2009, DCPA was banned for use on crops in the European Union. [10] On August 6, 2024 the United States Environmental Protection Agency announced the emergency suspension of all registrations of the pesticide in the United States due to concerns regarding embryo-fetal toxicity [11] According to the EPA, when pregnant mothers are exposed to DCPA their babies could experience changes to fetal thyroid hormone levels, and these changes are generally linked to symptoms such as low birth weight, impaired brain development, decreased IQ, and impaired motor skills later in life, some of which may be irreversible. [11]

Synthesis

The use of DCPA as a herbicide was first described in a patent filed in 1958. [12] The material was prepared as had been described in a 1948 research paper by treating terephthaloyl chloride with chlorine to give tetrachloroterephthaloyl chloride which was then esterified with methanol. [13]

C6H4(COCl)2 + 4 Cl2 + Fe (cat.) → C6Cl4(COCl)2
C6Cl4(COCl)2 + 2 CH3OH → C6Cl4(CO2CH3)2

Contamination

DCPA is released directly into the environment during its use as a herbicide. DCPA exists in both the vapor and particulate phases when exposed to the air. In the vapor phase, DCPA should react slowly with hydroxyl radicals with an estimated half-life of 36 days. Particulate-phase DCPA may be physically removed from air by wet and dry deposition. With a high Koc of 3900, DCPA is presumably immobile in soil, and thus may strongly attach to inorganic material in soil and other environments. [9]

In addition, its breakdown products, TPA (Tetrachloroterephthalic acid) and MTP (Monomethyl tetrachloroterephthalic acid), enter the environment after being formed through various processes. Studies have shown that DCPA can partially degrade through volatilization, as well as via photodegradation, but biodegradation is the primary route of DCPA degradation leading to MTP and TPA. Environmental Protection Agency testing in New York showed "measurable residues of DCPA and degradates" on land that had endured five years of treatment with DCPA, followed by three years of no treatment. DCPA is also prevalent in water and bioconcentration is seen in aquatic animals. DCPA accumulation was shown in fish at "several locations" in the United States. [9] Some of these locations included the Apalachicola, Colorado, Mobile, Savannah, and Pee Dee River Basins in both bass and carp. In the study done on these river basin locations, roughly 39% of the fish tested had stored DCPA concentrations that exceeded their limit of detection, and the male fish had higher stored concentrations of DCPA than their female counterparts. [14] Fish collected from different locations throughout the United States are often contaminated by DCPA if they are near agricultural areas that use or have used it as an herbicide. [15]

Humans are exposed to DCPA through drinking well water, eating fish, and eating leafy and root vegetables. In some areas where agriculture is prominent, inhalation of air can be a means of exposure.

Degradation and metabolism

Dimethyl tetrachloroterephthalate.svg
DCPA
Monomethyl tetrachloroterephthalate.svg
MTP
Tetrachloroterephthalic acid.svg
TPA
Dimethyl tetrachloroterephthalate and two stages of degradation

DCPA degrades via successive hydrolysis of the two ester linkages, first forming monomethyl tetrachloroterephthalate (MTP) then further to tetrachloroterephthalic acid (TPA). Following ingestion, TPA is formed in tissues during the metabolism of DCPA. [16] [17]

In the presence of sunlight, the half-life for DCPA floating on the surface of water is less than three days. In soil, the half-life in the presence of sunlight ranges from 14 to 100 days. [5]

Properties of Degradates

TPA and MTP are both more water-soluble than DCPA, and readily leach into groundwater wherever DCPA is used, regardless of soil composition. TPA has been observed to cause weight loss and diarrhea in laboratory rats, the same symptoms caused by DCPA, but at lower doses than necessary for DCPA. [9] TPA does not degrade, and infiltrates soil and nearby water sources. The accumulation of TPA and its salts in areas where DCPA is widely used has prompted research on TPA, although no carcinogenicity studies have been conducted yet. [18] There have been no standard toxicity studies identified for MTP. [19]

Toxicology

DCPA is listed as a Group C Possible Human Carcinogen by the National Library of Medicine. [20]

Studies show that DCPA and TPA may cause detrimental health effects in laboratory animals, mainly weight loss and diarrhea occurring at doses near 2000 mg/kg/day. There were also effects on the lungs, liver, kidney, and thyroid glands of male and female rats. The LD50, or 50% lethal dose of DCPA, is greater than 10,000 mg/kg in beagle dogs. In humans, it seems that DCPA is poorly absorbed, as 6% of a 25-mg dose and 12% of a 50-mg dose were absorbed according to metabolites in urine. Decreased motor activity and poor sight reflexes were also observed in a study on New Zealand white rabbits that were exposed to DCPA. Exposure from DCPA to pregnant rats resulted in reduced body weight in both mother and pup, as well as changes to the thyroid in pups. [9] Additionally, rats whose mothers were exposed to DCPA during pregnancy had impaired higher-level learning test scores than those whose mothers were not exposed. [20] Studies regarding the carcinogenicity of DCPA have produced mixed results. A study by ISK Biotech Corp. in 1993 showed DCPA leading to thyroid tumors in male and female rats, and liver tumors in female rats. Alternatively, a 1963 study using pure DCPA did not produce any negative results when administered to albino rats. [9]

Studies have demonstrated that DCPA acts as a chemical disruptor by interfering with microtubule formation in exposed cells. This interference results in abnormal cell division. The abnormal microtubules affect cell wall formation as well as chromosome replication and division. [21] The key difference between DCPA and other mitotic inhibitors is that it often produces multinucleate cells. [22] It essentially kills plants by inhibiting cell division in this manner. [21]

Exposure to DCPA has shown damaging effects in the adrenal glands, kidneys, livers, thyroids, and spleens of laboratory animals. [21] The effects on the rabbits included decreased motor activity and poor reflexes. [9]

According to the US EPA, when pregnant mothers are exposed to DCPA their babies could experience changes to fetal thyroid hormone levels, and these changes are generally linked to symptoms like low birth weight, impaired brain development, decreased IQ, and impaired motor skills, which may be irreversible and lifelong. [11]

Regulation

Europe

DCPA has been prohibited for use on crops in the European Union since 2009. [10]

United States

In the U.S. The Safe Drinking Water Act of 1996 has the U.S. EPA publish a list of contaminants referred to as the Contaminant Candidate List to assist in research efforts. The Safe Drinking Water Act also calls for the EPA to choose five contaminants from the list and determine whether regulation is necessary. In July 2008, the EPA determined that no regulatory action is necessary for DCPA mono-acid (MTP) degradate and DCPA di-acid (TPA) degradate. After multiple studies, it was determined that degradates of DCPA appear too infrequently to pose a serious health risk so the government does not regulate DCPA or its degradates in drinking water. [23] Public water systems are also not required to monitor DCPA, MTP, or TPA. There are standards set by some states ranging from 0.17 µg/L to 2 µg/L. [19]

Some uses of DCPA, particularly on vegetable crops, were voluntarily terminated by the chemical's registrant in 2005, in response to the EPA's concerns regarding DCPA and TPA contamination of groundwater. [9]

In California, DCPA products are required to be labeled with the information that states that products with DCPA also contain trace amounts of Hexachlorobenzene (HCB) which is a chemical known to the State of California to cause cancer or birth defects. [24]

On August 6, 2024 the United States Environmental Protection Agency announced the emergency suspension of all registrations of this pesticide in the United States due to embryo-fetal toxicity concerns. [11] This was the first time in almost 40 years that the EPA had taken this type of emergency action. “DCPA is so dangerous that it needs to be removed from the market immediately,” said Assistant Administrator for the Office of Chemical Safety and Pollution Prevention Michal Freedhoff. [11] [25]

Related Research Articles

<span class="mw-page-title-main">Glyphosate</span> Systemic herbicide and crop desiccant

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.

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

Bifenthrin is a pyrethroid insecticide. It is widely used against ant infestations.

<span class="mw-page-title-main">Perfluorooctanesulfonic acid</span> Fluorosurfactant and persistent organic pollutant

Perfluorooctanesulfonic acid (PFOS) is a chemical compound having an eight-carbon fluorocarbon chain and a sulfonic acid functional group, and thus it is a perfluorosulfonic acid and a perfluoroalkyl substance (PFAS). It is an anthropogenic (man-made) fluorosurfactant, now regarded as a global pollutant. PFOS was the key ingredient in Scotchgard, a fabric protector made by 3M, and related stain repellents. The acronym "PFOS" refers to the parent sulfonic acid and to various salts of perfluorooctanesulfonate. These are all colorless or white, water-soluble solids. Although of low acute toxicity, PFOS has attracted much attention for its pervasiveness and environmental impact. It was added to Annex B of the Stockholm Convention on Persistent Organic Pollutants in May 2009.

<span class="mw-page-title-main">Alachlor</span> Chemical compound; herbicide

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.

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

Atrazine is a chlorinated herbicide of the triazine class. It is used to prevent pre-emergence broadleaf weeds in crops such as maize (corn), soybean and sugarcane and on turf, such as golf courses and residential lawns. Atrazine's primary manufacturer is Syngenta and it is one of the most widely used herbicides in the United States, Canadian, and Australian agriculture. Its use was banned in the European Union in 2004, when the EU found groundwater levels exceeding the limits set by regulators, and Syngenta could not show that this could be prevented nor that these levels were safe.

<span class="mw-page-title-main">Vinclozolin</span> Fungicide used on fruits and vegetables

Vinclozolin is a common dicarboximide fungicide used to control diseases, such as blights, rots and molds in vineyards, and on fruits and vegetables such as raspberries, lettuce, kiwi, snap beans, and onions. It is also used on turf on golf courses. Two common fungi that vinclozolin is used to protect crops against are Botrytis cinerea and Sclerotinia sclerotiorum. First registered in 1981, vinclozolin is widely used but its overall application has declined. As a pesticide, vinclozolin is regulated by the United States Environmental Protection Agency. In addition to these restrictions within the United States, as of 2006 the use of this pesticide was banned in several countries, including Denmark, Finland, Norway, and Sweden. It has gone through a series of tests and regulations in order to evaluate the risks and hazards to the environment and animals. Among the research, a main finding is that vinclozolin has been shown to be an endocrine disruptor with antiandrogenic effects.

Iodomethane, also called methyl iodide, and commonly abbreviated "MeI", is the chemical compound with the formula CH3I. It is a dense, colorless, volatile liquid. In terms of chemical structure, it is related to methane by replacement of one hydrogen atom by an atom of iodine. It is naturally emitted by rice plantations in small amounts. It is also produced in vast quantities estimated to be greater than 214,000 tons annually by algae and kelp in the world's temperate oceans, and in lesser amounts on land by terrestrial fungi and bacteria. It is used in organic synthesis as a source of methyl groups.

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

Endrin is an organochlorine compound with the chemical formula C12H8Cl6O that was first produced in 1950 by Shell and Velsicol Chemical Corporation. It was primarily used as an insecticide, as well as a rodenticide and piscicide. It is a colourless, odorless solid, although commercial samples are often off-white. Endrin was manufactured as an emulsifiable solution known commercially as Endrex. The compound became infamous as a persistent organic pollutant and for this reason it is banned in many countries.

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

Acetochlor is an herbicide developed by Monsanto Company and Zeneca. It is a member of the class of herbicides known as chloroacetanilides. Its mode of action is elongase inhibition, and inhibition of geranylgeranyl pyrophosphate (GGPP) cyclization enzymes, part of the gibberellin pathway. It carries high risks of environmental contamination.

<span class="mw-page-title-main">Methoxychlor</span> Synthetic organochloride insecticide, now obsolete.

Methoxychlor is a synthetic organochloride insecticide, now obsolete. Tradenames for methoxychlor include Chemform, Maralate, Methoxo, Methoxcide, Metox, and Moxie.

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

Dimethyl phthalate (DMP) is an organic compound and phthalate ester. it is a colourless and oily liquid that is soluble in organic solvents, but which is only poorly soluble in water.

<span class="mw-page-title-main">Dinoseb</span> Chemical compound used as a herbicide

Dinoseb is a common industry name for 6-sec-butyl-2,4-dinitrophenol, a herbicide in the dinitrophenol family. It is a crystalline orange solid which does not readily dissolve in water. Dinoseb is banned as an herbicide in the European Union (EU) and the United States because of its toxicity.

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

Diethyl phthalate (DEP) is a phthalate ester. It occurs as a colourless liquid without significant odour but has a bitter, disagreeable taste. It is more dense than water and insoluble in water; hence, it sinks in water.

<span class="mw-page-title-main">2,4-Dichlorophenoxyacetic acid</span> Herbicide

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.

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

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.

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

Bentazon is a chemical manufactured by BASF Chemicals for use in herbicides. It is categorized under the thiadiazine group of chemicals. Sodium bentazon is available commercially and appears slightly brown in colour.

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.

American Vanguard Corporation, through its subsidiary AMVAC Chemical Corporation, is an American producer of agrochemicals and pesticide delivery systems. The company was cofounded by Glenn Wintemute, who stepped down as president in 1994. His son, Eric Wintemute, became chairman and chief executive officer in 1994.

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

Cyanazine is a herbicide that belongs to the group of triazines. Cyanazine inhibits photosynthesis and is therefore used as a herbicide.

<span class="mw-page-title-main">Ohio River Park</span> Contaminated site in Pennsylvania, U.S.

Ohio River Park is a Superfund Site located in Neville Island, Pennsylvania. Between the 1920s-1970s, the Site was used for municipal waste, pesticide manufacturing, coke sludge disposal, cement manufacturing disposal, and pesticide waste. In 1977, Neville Land Company donated the Site to Allegheny County who started developing the Site as a community park. In 1979, Allegheny County found various hazardous contaminants on the Site. On August 30, 1990, the Site was determined to be a Superfund Site due to VOCs, SVOCs, inorganics, and pesticides being present in the surface soil, subsurface soil, surface water, river sediment, and groundwater. Soil remediation began in February 1998 and ended in September 1999. Today, Ohio River Park has the Robert Morris University Island Sports Center and Coraopolis Bridge on top of it. Additionally, benzene continues to be monitored because it is still present in the Site's groundwater.

References

  1. 1 2 Pesticide Properties Database. "Chlorthal-dimethyl". University of Hertfordshire.
  2. ↑ "AMVAC MSDS No.: 291_9" (PDF). www.cdms.net. AMVAC Chemical Corporation. Archived from the original (PDF) on 2 April 2015. Retrieved 30 March 2015.
  3. ↑ "Compendium of Pesticide Common Names: chlorthal". BCPC.
  4. ↑ American Vanguard Dacthal Webpage Archived 2008-11-22 at the Wayback Machine
  5. 1 2 3 4 "Dimethyl Tetrachloroterephthalate (DCPA) Pesticide Management Plan" (PDF). Idaho State Department of Agriculture. June 2007. Archived from the original (PDF) on 2011-07-10. Retrieved 2022-09-24.
  6. ↑ Cox, Caroline. "DCPA (Dachtal)". Journal of Pesticide Reform. Archived from the original on 12 July 2010. Retrieved 29 March 2015.
  7. ↑ "Dacthal Returns to the Market; Crops, Use Patterns Remain the Same". SouthWestern Farm Press Staff. 8 February 2001. Retrieved 2015-03-22.
  8. ↑ Farmalinx. "DYNAMO 750 g/kg Chlorthal Dimethyl". Farmalinx. Retrieved 27 April 2015.
  9. 1 2 3 4 5 6 7 8 "Health Effects Support Document for Dacthal Degradates: Tetrachloroterephthalic Acid (TPA) and Monomethyl Tetrachloroterephthalic Acid (MTP)" (PDF). United States Environmental Protection Agency . May 2008. Retrieved 2022-09-24.
  10. 1 2 Tabuchi, Hiroko (2024-08-06). "E.P.A. Pulls From the Market a Weedkiller Harmful to Fetuses". The New York Times. ISSN   0362-4331 . Retrieved 2024-08-08.
  11. 1 2 3 4 5 US EPA, OA (2024-08-06). "EPA Issues Emergency Order to Stop Use of Pesticide Dacthal to Address Serious Health Risk". www.epa.gov. Retrieved 2024-08-06.
  12. ↑ USpatent 2923634,Lindemann R.F.,"Method of controlling undesirable plant growth",published 1960-02-02, assigned to Diamond Alkali Co.
  13. ↑ Rabjohn, Norman (1948). "The Chlorination of Isophthaloyl and Terephthaloyl Chloride". Journal of the American Chemical Society. 70 (10): 3518. doi:10.1021/ja01190a513. PMID   18891919.
  14. ↑ Hinck, Jo Ellen; Schmitt, Christopher J.; Ellersieck, Mark R.; Tillitt, Donald E. (2008). "Relations between and among contaminant concentrations and biomarkers in black bass (Micropterus spp.) and common carp (Cyprinus carpio) from large U.S. rivers, 1995–2004". Journal of Environmental Monitoring. 10 (12): 1499–518. doi:10.1039/B811011E. PMID   19037492.
  15. ↑ Cox, Caroline. "DCPA (Dacthal)". Archived from the original on 2010-07-12. Retrieved 2015-03-18.
  16. ↑ "Dimethyl Tetrachloroterephthalate". National Library of Medicine HSDB Database. National Library of Medicine. Retrieved 12 March 2015.
  17. ↑ Hurto KA, Turgeon AJ, Cole MA (1979). "Degradation of Benefin and DCPA in Thatch and Soil from a Kentucky Bluegrass (Poa pratensis) Turf". Weed Soil. 27 (1979): 154–7. doi:10.1017/S0043174500043721. JSTOR   4042994. S2CID   88297668.
  18. ↑ Klopman, Gilles; Fercu, Dan; Rosenkranz, Herbert S. (February 1996). "The carcinogenic potential of dacthal and its metabolites". Environmental Toxicology and Chemistry. 15 (2): 80–84. doi:10.1002/etc.5620150202.
  19. 1 2 "Summary from the Health Advisory (HA) for Dacthal and Dacthal Degradates (Tetrachloro terephthalic Acid and Monomethyl Tetrachloroterephthalic Acid)" (PDF). Health Advisory for Dacthal and Dacthal Degradates. Retrieved 31 March 2015.
  20. 1 2 "Dimethyl Tetrachloroterephthalate". Toxnet. National Library of Medicine. Retrieved 31 March 2015.
  21. 1 2 3 Cox, Caroline. "DCPA (Dacttal)". Archived from the original on 12 July 2010. Retrieved 18 March 2015.
  22. ↑ "Disruption of Mitosis" (PDF).
  23. ↑ The United States Environmental Protection Agency. "Regulatory Determination 2 for Contaminants on the Second Drinking Water Contaminant Candidate List".
  24. ↑ "Material Safety Data Sheet" (PDF). Archived from the original (PDF) on 2 April 2015. Retrieved 8 April 2015.
  25. ↑ Tabuchi, Hiroko (2024-08-06). "E.P.A. Pulls From the Market a Weedkiller Harmful to Fetuses". The New York Times. ISSN   0362-4331 . Retrieved 2024-08-06.
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.