| |||
| Names | |||
|---|---|---|---|
| Preferred IUPAC name Naphthalen-1-yl methylcarbamate | |||
| Other names | |||
| Identifiers | |||
| |||
3D model (JSmol) | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
| ||
| ECHA InfoCard | 100.000.505 | ||
| EC Number |
| ||
| KEGG |
| ||
| RTECS number |
| ||
| UNII | |||
| UN number | 2757 | ||
| |||
| |||
| Properties | |||
| C12H11NO2 | |||
| Molar mass | 201.225 g·mol−1 | ||
| Appearance | Colorless crystalline solid | ||
| Density | 1.2 g/cm3 | ||
| Melting point | 142 °C (288 °F; 415 K) | ||
| Boiling point | decomposes | ||
| very low (0.01% at 20°C)[1] | |||
| Pharmacology | |||
| QP53AE01 (WHO) | |||
| Hazards | |||
| GHS labelling: | |||
    | |||
| Danger | |||
| H301,H302,H332,H351,H410 | |||
| P201,P202,P261,P264,P270,P271,P273,P281,P301+P310,P301+P312,P304+P312,P304+P340,P308+P313,P312,P321,P330,P391,P405,P501 | |||
| Flash point | 193-202[1] | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) | 710 mg/kg (rabbit, oral) 250 mg/kg (guinea pig, oral) 850 mg/kg (rat, oral) 759 mg/kg (dog, oral) 500 mg/kg (rat, oral) 150 mg/kg (cat, oral) 128 mg/kg (mouse, oral) 230 mg/kg (rat, oral)[2] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 5 mg/m3[1] | ||
REL (Recommended) | TWA 5 mg/m3[1] | ||
IDLH (Immediate danger) | 100 mg/m3[1] | ||
| Safety data sheet (SDS) | ICSC 0121 | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
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Carbaryl (1-naphthyl methylcarbamate) is a chemical in thecarbamate family used chiefly as aninsecticide. It is a white crystalline solid previously sold under the brand nameSevin, which was a trademark of theBayer Company.The Sevin trademark has since been acquired byGardenTech, which has eliminated carbaryl from most Sevin formulations.[needs update][3][4]Union Carbide discovered carbaryl and introduced it commercially in 1958. Bayer purchased Aventis CropScience in 2002, a company that included Union Carbide pesticide operations. Carbaryl was the third-most-used insecticide in the United States for homegardens, commercial agriculture, and forestry and rangeland protection. As aveterinary drug, it is known ascarbaril (INN).
Carbaryl is often inexpensively produced by direct reaction ofmethyl isocyanate with1-naphthol.[5]
Alternatively, 1-naphthol can be treated with excessphosgene to produce 1-naphthylchloroformate, which is then converted to carbaryl by reaction withmethylamine.[5] The former process was used in the chemical plant that caused theBhopal disaster. In comparison, the latter synthesis uses exactly the same reagents required for the synthesis of methyl isocyanate. This route avoids the potential hazards of methyl isocyanate, allbeit at a higher cost.
Carbamate insecticides are reversible inhibitors of the enzymeacetylcholinesterase and are considered less toxic thanorganophosphate insecticides, which inhibit the enzyme irreversibly.[6] They resembleacetylcholine, but the carbamoylated enzyme undergoes the final hydrolysis step very slowly (minutes) compared with the acetylated enzyme generated by acetylcholine (microseconds). They interfere with the cholinergic nervous system and cause death because the effects of the neurotransmitter acetylcholine cannot be terminated by carbamoylated acetylcholinesterase.
The development of the carbamate insecticides has been called a major breakthrough inpesticides. The carbamates do not have the persistence of chlorinated pesticides. Although toxic to insects, carbaryl is detoxified and eliminated rapidly in vertebrates. It is neither concentrated in fat nor secreted in milk, so is favored for food crops, at least in the US.[7] It is the active ingredient in Carylderm shampoo used to combat head lice until infestation is eliminated.[8]
Carbaryl kills both targeted (e.g., malaria-carrying mosquitos) and beneficial insects (e.g.,honeybees), as well as crustaceans.[9] Because it is highly toxic tozooplankton, the algae they feed onexperience blooms. Boone & Bridges 2003 find that largeralgae eaters such asBufo woodhousii benefit from this effect.[10]
Although it can increase survival rates for organisms that benefit from consequential algae blooms, the long term effects of these changes in competition levels and predation can be detrimental to many aquatic ecosystems, particularly those dominated by Anurans.[11]
It is approved for more than 100 crops in the US. Carbaryl has been illegal in the EU since 21 November 2007[12] and Angola.[13]
Carbaryl is acholinesterase inhibitor and is toxic to humans. It is classified as a likely humancarcinogen by theUnited States Environmental Protection Agency (EPA.)[14] The oralLD50 is 250 to 850 mg/kg for rats and 100 to 650 mg/kg for mice.[9]
Carbaryl can be produced usingmethyl isocyanate (MIC) as an intermediary.[5] A leak of MIC used in the production of carbaryl caused theBhopal disaster, the most lethal industrial accident in history.[15]
