2,6-Dichlorobenzonitrile (DCBN or dichlobenil) is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

C₆H₃Cl₂CN. It is a white solid soluble in organic solvents. It is widely used as a

herbicide Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...

and organic chemistry building block.Franz Müller and Arnold P. Applebyki "Weed Control, 2. Individual Herbicides" in Ullmann's Encyclopedia of Industrial Chemistry 2010

Mechanism of action

It has herbicidal properties killing young seedlings of both

monocot Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are flowering plants whose seeds contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. A monocot taxon has been in use for several decades, but ...

and

dicot The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, ...

species. DCBN interferes with cellulose synthesis. DCBN adapted cell walls use minimal amounts of cellulose, instead relying on Ca²⁺-bridge pectates. Dichlobenil kills the roots of many species, but not all; further, the killing does not extend much beyond the portion actually soaked, according to the Californian department of agriculture in 1971.

Application

In 1996, the

University of California The University of California (UC) is a public university, public Land-grant university, land-grant research university, research university system in the U.S. state of California. Headquartered in Oakland, California, Oakland, the system is co ...

reported that "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)."

Environmental behavior

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. Dichlobenil residue in water almost completely dissipates in 5 to 6 months. The

USDOE The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and energy production, the research and development of nuclear power, the military's nuclear weap ...

Bonneville Power Administration The Bonneville Power Administration (BPA) is an American federal agency operating in the Pacific Northwest. BPA was created by an act of United States Congress, Congress in 1937 to market electric power from the Bonneville Dam located on the Col ...

reported "high potential" for dichlobenil to enter groundwater.

Regulatory status

It is no longer approved for use within the EU, as of 2009. The Inland Fisheries Ireland has reported "the registration of all dichlobenil products ... was revoked in Ireland from 18th March 2009, under Commission Decision 2008/754/EC of 18th September 2008. A period of grace for ... existing stocks expired on 18th March 2010." The London underground found itself in violation by using dichlobenil in September 2011.

Environmental toxicity

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.

Safety

Since 1995, the

U.S. National Institutes of Health The National Institutes of Health (NIH) is the primary agency of the United States government responsible for biomedical and public health research. It was founded in 1887 and is part of the United States Department of Health and Human Service ...

has warned about indoor usage: "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." The UN

IPCS ipcs is a Unix and Linux command to list System V InterProcess Communication System's API kernel entities to ''stdout''. System V IPC kernel entities are: * Shared memory segments *Message queues *Semaphore arrays Implementations On Linux, the ...

reports dichlobenil can be absorbed into the body by inhalation, through skin and by ingestion, and that dispersion can create harmful concentrations in air quickly; dichlobenil may affect skin, possbily causing

chloracne Chloracne is an acneiform eruption of blackheads, cysts, and pustules associated with exposure to certain halogenated aromatic compounds, such as chlorinated dioxins and dibenzofurans. The lesions are most frequently found on the cheeks, behind ...

. Further, it warns dichlobenil is toxic to aquatic organisms, and does enter the environment under normal use, but great care should be taken to avoid release, e.g. through inappropriate disposal. The IPCS advises particulate filter respirators as PPE adapted to the air concentration of dichlobenil; spilled substance should be swept into covered sealable containers, moistened if needed to prevent dusting, and disposed of according to local regulations. The U.S.

Centers for Disease Control and Prevention The Centers for Disease Control and Prevention (CDC) is the National public health institutes, national public health agency of the United States. It is a Federal agencies of the United States, United States federal agency under the United S ...

(CDC) follows and cites the ICPS.

Products

United States

These consumer products use dichlobenil as an active ingredient: "Oblitiroot", "Root Reach", "Foaming Root Killer" and "RootX". This is not an exhaustive list. "Casoron" is dichlobenil sold agriculturally as a 50%

wettable powder A wettable powder (WP) is an insecticide or other pesticide formulation consisting of the active ingredient An active ingredient is any ingredient that provides biologically active or other direct effect in the diagnosis, cure, mitigation, trea ...

and as 4% granules.

Synthesis

Dichlobenil is produced from 2,6-

dichlorotoluene Dichlorotoluenes are organochlorine compounds, in particular aryl chlorides, with the formula . Six constitutional isomers exist, differing in the relative position of the two chlorine substituents around the ring. They are all colorless and lipop ...

via the

aldoxime In organic chemistry, an oxime is an organic compound belonging to the imines, with the general formula , where R is an organic side-chain and R' may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substituted ...

References

{{DEFAULTSORT:Dichlorobenzonitrile, 2, 6- Herbicides Benzonitriles Chlorobenzene derivatives Group 29 herbicides