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

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

with the

chemical formula In chemistry, 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, ...

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

herbicide Herbicides (, ), also commonly known as weedkillers, 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 fo ...

.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 grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...

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, t ...

species. DCBN interferes with cellulose synthesis. DCBN adapted cell walls use minimal amounts of cellulose, instead relying on Ca²⁺-bridge pectates.

Safety

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." 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).

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." The

U.S. Department of Energy 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 manages the research and development of nuclear power and nuclear weapons in the United States. ...

- Bonneville Power Administration has reported "high potential" for dichlobenil to enter groundwater.

Residue

Inland Fisheries Ireland has reported, "The dichlobenil residue in water almost completely dissipates in 5 to 6 months." U.S. FDA reports on pesticide residue.

Toxicity and environment

Since 1995, the

U.S. National Institutes of Health The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late 1 ...

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.

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.

The report quotes a European Union regulatory effective date of 2009. 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.

The London underground found itself in violation by using dichlobenil in September 2011. 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 Chloracne is an acne-like 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 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.

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.

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. The U.S.

Centers for Disease Control and Prevention The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...

(CDC) follows and cites the ICPS.

Consumer products

United States

This partial list of consumer products with "dichlobenil" as an active ingredient: * Oblitiroot * Root Reach * Foaming Root Killer * RootX

Synthesis

Dichlobenil is produced from 2,6-dichlorotoluene via the

aldoxime In organic chemistry, an oxime is a 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-substitute ...

References

{{DEFAULTSORT:Dichlorobenzonitrile, 2, 6- Herbicides Benzonitriles Chlorobenzenes