Dichlorprop

Last updated
Dichlorprop
(RS)-Dichlorprop Structural Formula V.1a.svg
Names
IUPAC name
(R)-2-(2,4-dichlorophenoxy)propanoic acid
Other names
2,4-DP
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.991
EC Number
  • 204-390-5
KEGG
PubChem CID
RTECS number
  • UF1050000
UNII
UN number 3077 2765
Properties
C9H8Cl2O3
Molar mass 235.064 g/mol
Appearancewhite solid
Melting point 116 to 120 °C (241 to 248 °F; 389 to 393 K)R-isomer
Boiling point 215 °C
720 mg/L at 20 °C (R-isomer)
Hazards
GHS pictograms GHS-pictogram-acid.svg GHS-pictogram-exclam.svg
GHS Signal word Danger
H302, H312, H315, H318
P264, P270, P280, P301+312, P302+352, P305+351+338, P310, P312, P321, P322, P330, P332+313, P362, P363, P501
Flash point 204 °C (399 °F; 477 K)
Related compounds
Related compounds
2,4-D
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)
Infobox references

Dichlorprop is a chlorophenoxy herbicide similar in structure to 2,4-D that is used to kill annual and perennial broadleaf weeds. It is a component of many common weedkillers. About 4 million pounds of dichlorprop are used annually in the United States.

Contents

Chemistry

R-dichlorprop (dichlorprop-p) (R)-Dichlorprop Structural Formula V.1a.svg
R-dichlorprop (dichlorprop-p)

Dichlorprop possesses a single asymmetric carbon and is therefore a chiral molecule, however only the R-isomer is active as an herbicide. When dichlorprop was first marketed in the 1960s, it was sold as racemic mixture of stereoisomers, but since then advances in asymmetric synthesis have made possible the production of the enantiopure compound. Today, only R-dichlorprop (also called dichlorprop-p or 2,4-DP-p) and its derivatives are sold as pesticides in the United States.

Dichlorprop is a carboxylic acid, and like related herbicides with free acid groups, it is often sold as a salt or ester. Currently, the 2-ethylhexyl ester is used commercially. The butoxyethyl and isooctyl esters were once popular, but are no longer approved for agricultural use. For the salts, the dimethylamine salt is still available, while the diethanolamine salt is no longer used.

According to the United States Environmental Protection Agency (EPA), "2,4-DP-p is thought to increase cell wall plasticity, biosynthesis of proteins, and the production of ethylene. The abnormal increase in these processes result in abnormal and excessive cell division and growth, damaging vascular tissue. The most susceptible tissues are those that are undergoing active cell division and growth." [1]

Health effects

The EPA rates the oral acute toxicity of dichlorprop as "slight" based on a rat LD50 of 537 mg/kg, and its derivatives are even less toxic. It is, however, considered to be a severe eye irritant. [1] There has been concern that chlorophenoxy herbicides including dichlorprop may cause cancer, and in 1987 the International Agency for Research on Cancer (IARC) ranked this class of compounds as group 2B "possibly carcinogenic to humans". [2] The EPA classifies the R-isomer as “Not Likely to be Carcinogenic to Humans.” [1]

Related Research Articles

A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis, the formation of cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substances are considered carcinogens, but their carcinogenic activity is attributed to the radiation, for example gamma rays and alpha particles, which they emit. Common examples of non-radioactive carcinogens are inhaled asbestos, certain dioxins, and tobacco smoke. Although the public generally associates carcinogenicity with synthetic chemicals, it is equally likely to arise in both natural and synthetic substances. Carcinogens are not necessarily immediately toxic; thus, their effect can be insidious.

Roundup is the brand name of a systemic, broad-spectrum glyphosate-based herbicide originally produced by Monsanto, which Bayer acquired in 2018. Glyphosate is the most widely used herbicide in the United States. As of 2009, sales of Roundup herbicides still represented about 10 percent of Monsanto's revenue despite competition from Chinese producers of other glyphosate-based herbicides. The overall Roundup line of products, which includes genetically modified seeds, represented about half of Monsanto's yearly revenue. The product is marketed to consumers by Scotts Miracle-Gro Company.

1,4-Dichlorobenzene (1,4-DCB, p-DCB, or para-dichlorobenzene, sometimes abbreviated as PDB or para) is an organic compound with the formula C6H4Cl2. This colorless solid has a strong odor. The molecule consists of a benzene ring with two chlorine atoms (replacing hydrogen atoms) on opposing sites of the ring.

Glyphosate Broad-spectrum 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. It is used to kill weeds, especially annual broadleaf weeds and grasses that compete with crops. It was discovered to be an herbicide 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.

Acrylonitrile is an organic compound with the formula CH2CHCN. It is a colorless volatile liquid although commercial samples can be yellow due to impurities. It has a pungent odor of garlic or onions. In terms of its molecular structure, it consists of a vinyl group linked to a nitrile. It is an important monomer for the manufacture of useful plastics such as polyacrylonitrile. It is reactive and toxic at low doses. Acrylonitrile was first synthesized by the French chemist Charles Moureu (1863–1929) in 1893.

Nitrobenzene chemical compound

Nitrobenzene is an organic compound with the chemical formula C6H5NO2. It is a water-insoluble pale yellow oil with an almond-like odor. It freezes to give greenish-yellow crystals. It is produced on a large scale from benzene as a precursor to aniline. In the laboratory, it is occasionally used as a solvent, especially for electrophilic reagents.

Organophosphate ester of phosphoric acid

Organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure O=P(OR)3. They can be considered as esters of phosphoric acid. Like most functional groups organophosphates occur in a diverse range of forms, with important examples including key biomolecules such as DNA, RNA and ATP, as well as many insecticides, herbicides, nerve agents and flame retardants.

Diethyl sulfate chemical compound

Diethyl sulfate is a highly toxic and likely carcinogenic chemical compound with formula (C2H5)2SO4. It occurs as a colorless, oily liquid with a faint peppermint odor and is corrosive.

Cacodylic acid chemical compound

Cacodylic acid is the organoarsenic compound with the formula (CH3)2AsO2H. With the formula R2As(O)OH, it is the simplest of the organoarsinic acids. It is a colorless solid that is soluble in water.

Caffeic acid chemical compound

Caffeic acid is an organic compound that is classified as a hydroxycinnamic acid. This yellow solid consists of both phenolic and acrylic functional groups. It is found in all plants because it is a key intermediate in the biosynthesis of lignin, one of the principal components of woody plant biomass and its residues.

2,4,5-Trichlorophenoxyacetic acid chemical compound

2,4,5-Trichlorophenoxyacetic acid, a synthetic auxin, is a chlorophenoxy acetic acid herbicide used to defoliate broad-leafed plants. It was developed in the late 1940s and was widely used in the agricultural industry until being phased out, starting in the late 1970s due to toxicity concerns. Agent Orange, a defoliant used by the British in the Malayan Emergency and the U.S. in the Vietnam War, was equal parts 2,4,5-T and 2,4-D. 2,4,5-T itself is toxic with a NOAEL of 3 mg/kg/day and a LOAEL of 10 mg/kg/day. Additionally, the manufacturing process for 2,4,5-T contaminates this chemical with trace amounts of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD is a carcinogenic persistent organic pollutant with long-term effects on the environment. With proper temperature control during production of 2,4,5-T, TCDD levels can be held to about .005 ppm. Before the TCDD risk was well understood, early production facilities lacked proper temperature controls and individual batches tested later were found to have as much as 60 ppm of TCDD.

<i>o</i>-Phenylenediamine chemical compound

o-Phenylenediamine (OPD) is an organic compound with the formula C6H4(NH2)2. This aromatic diamine is an important precursor to many heterocyclic compounds. It is isomeric with m-phenylenediamine and p-phenylenediamine.

Ethyl acrylate chemical compound

Ethyl acrylate is an organic compound with the formula CH2CHCO2CH2CH3. It is the ethyl ester of acrylic acid. It is a colourless liquid with a characteristic acrid odor. It is mainly produced for paints, textiles, and non-woven fibers. It is also a reagent in the synthesis of various pharmaceutical intermediates.

1,3-Dichloropropene chemical compound

1,3-Dichloropropene, sold under diverse trade names, is an organochlorine compound. It is colorless liquid with a sweet smell. It dissolves in water and evaporates easily. It is used mainly in farming as a pesticide, specifically as a preplant fumigant and nematicide. It is widely used in the US and other countries, but is in the process of being phased out in the European Union.

<i>o</i>-Toluidine chemical compound

o-Toluidine (ortho-toluidine) is an organic compound with the chemical formula CH3C6H4NH2. It is the most important of the three isomeric toluidines. It is a colorless liquid although commercial samples are often yellowish. It is a precursor to the herbicides metolachlor and acetochlor.

2,3,7,8-Tetrachlorodibenzodioxin chemical compound

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a polychlorinated dibenzo-p-dioxin with the chemical formula C
12
H
4
Cl
4
O
2
. Pure TCDD is a colorless solid with no distinguishable odor at room temperature. It is usually formed as an unwanted product in burning processes of organic materials or as a side product in organic synthesis.

Dimethyl tetrachloroterephthalate (DCPA, Dacthal) is an organic compound with the formula C6Cl4(CO2CH3)2. It is a colourless solid, although commercial samples can be off white. DCPA is the dimethyl ester of tetrachloroterephthalic acid. It is used as a preemergent herbicide. It kills grass and many common weeds without killing sensitive plants such as flowers, fruits, vegetables, turf, and cotton. DCPA was first registered for use in the United States in 1958. 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. In Australia, DCPA is the active ingredient in agchem company Farmalinx's herbicide called Dynamo 750. Currently, DCPA is only used for eggplant, kale, turnips, and sweet potatoes.

2,4-Dichlorophenoxyacetic acid Herbicide

2,4-Dichlorophenoxyacetic acid is an organic compound with the chemical formula C8H6Cl2O3 which is usually referred to by its ISO common name 2,4-D. It is a systemic herbicide which selectively kills most broadleaf weeds by causing uncontrolled growth in them but most grasses such as cereals, lawn turf, and grassland are relatively unaffected.

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.

Cyanazine chemical compound

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

References

  1. 1 2 3 Reregistration Eligibility Decision (RED) for Dichlorprop-p (2,4-DP-p), US EPA, August 29, 2007]
  2. CHLOROPHENOXY HERBICIDES (Group 2B), International Agency for Research on Cancer (IARC), 1987