Carbaryl

Carbaryl
Names
	IUPAC name 1-naphthyl methylcarbamate
	Other names Sevin; α-Naphthyl N-methylcarbamate
Identifiers
CAS Number	63-25-2 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:3390 ;
ChEMBL	ChEMBL46917 ;
ChemSpider	5899 ;
ECHA InfoCard	100.000.505
EC Number	200-555-0;
KEGG	D07613 ;
PubChem CID	6129;
RTECS number	FC5950000;
UNII	R890C8J3N1 ;
UN number	2757
CompTox Dashboard (EPA)	DTXSID9020247 ;
	InChI InChI=1S/C12H11NO2/c1-13-12(14)15-11-8-4-6-9-5-2-3-7-10(9)11/h2-8H,1H3,(H,13,14) Key: CVXBEEMKQHEXEN-UHFFFAOYSA-N ; InChI=1/C12H11NO2/c1-13-12(14)15-11-8-4-6-9-5-2-3-7-10(9)11/h2-8H,1H3,(H,13,14) Key: CVXBEEMKQHEXEN-UHFFFAOYAZ;
	SMILES CNC(=O)Oc1c2ccccc2ccc1;
Properties
Chemical formula	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
Solubility in water	very low (0.01% at 20°C)
Pharmacology
ATCvet code	QP53AE01 (WHO)
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H302, H332, H351, H410
Precautionary statements	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
	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)
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 5 mg/m3
REL (Recommended)	TWA 5 mg/m3
IDLH (Immediate danger)	100 mg/m3
Safety data sheet (SDS)	ICSC 0121
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Carbaryl (1-naphthyl methylcarbamate) is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid commonly sold under the brand name Sevin, a trademark of the Bayer Company. Union Carbide discovered carbaryl and introduced it commercially in 1958. Bayer purchased Aventis CropScience in 2002, a company that included Union Carbide pesticide operations. It remains the third-most-used insecticide in the United States for home gardens, commercial agriculture, and forestry and rangeland protection. About 11 million kilograms were applied to U.S. farm crops in 1976.^[3] As a veterinary drug, it is known as carbaril (INN).

Production

Carbaryl is produced by treating methyl isocyanate with 1-naphthol.^[4]

C₁₀H₇OH + CH₃NCO → C₁₀H₇OC(O)NHCH₃

Alternatively, 1-naphthol can be treated with excess phosgene to produce 1-naphthyl chloroformate, which is then converted to carbaryl by reaction with methyl amine.^[4] The former process was carried out in Bhopal. In comparison, the latter synthesis uses exactly the same reagents, but in a different sequence. This synthesis avoids the preparation of methyl isocyanate.

Biochemistry

Carbamate insecticides are slowly reversible inhibitors of the enzyme acetylcholinesterase. They resemble acetylcholine, 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.

Applications

The development of the carbamate insecticides has been called a major breakthrough in pesticides. 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.^[3] It is the active ingredient in Carylderm shampoo used to combat head lice until infestation is eliminated.

Risk

Carbaryl kills both targeted (e.g. malaria-carrying mosquitos) and beneficial insects (e.g. honeybees), as well as crustaceans.^[5]

Although approved for more than 100 crops in the US, carbaryl is illegal in several countries, including the United Kingdom, Austria, Denmark, Sweden, Iran, Germany, and Angola.^[6]

Carbaryl is often produced using methyl isocyanate (MIC) as an intermediary.^[4] A leak of MIC used in the production of carbaryl caused the Bhopal disaster, the most lethal industrial accident in history.^[7]

Safety

Carbaryl is a cholinesterase inhibitor and is toxic to humans. It is classified as a likely human carcinogen by the United States Environmental Protection Agency (EPA.)^[8] The oral LD₅₀ is 250 to 850 mg/kg for rats and 100 to 650 mg/kg for mice.^{[citation needed]} A recent study reports that carbaryl is a structural mimic of the neurohormone melatonin and directly binds to MT2 melatonin receptor (Ki = 70 nM).^[9] This could significantly impact circadian rhythms and increase risk for diabetes and metabolic disorders.^[10]

References

^ ^a ^b ^c ^d ^e NIOSH Pocket Guide to Chemical Hazards. "#0100". National Institute for Occupational Safety and Health (NIOSH).
^ "Carbaryl". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
^ ^a ^b Robert L. Metcalf “Insect Control” in Ullmann’s Encyclopedia of Industrial Chemistry” Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a14_263
^ ^a ^b ^c Thomas A. Unger (1996). Pesticide Synthesis Handbook (Google Books excerpt). William Andrew. pp. 67–68. ISBN 0-8155-1401-8.
^ [1]
^ Carbaryl Insecticide Hazard Data Archived May 11, 2010, at the Wayback Machine
^ Eckerman, Ingrid (2005). The Bhopal Saga—Causes and Consequences of the World's Largest Industrial Disaster. India: Universities Press. doi:10.13140/2.1.3457.5364. ISBN 81-7371-515-7.
^ Interim Reregistration Eligibility Decision for Carbaryl Archived July 25, 2008, at the Wayback Machine, U.S. EPA, June 2003.
^ Popovska-Gorevski, Marina; Dubocovich, Margarita L.; Rajnarayanan, Rajendram V. (2017-02-20). "Carbamate Insecticides Target Human Melatonin Receptors". Chemical Research in Toxicology. 30 (2): 574–582. doi:10.1021/acs.chemrestox.6b00301. ISSN 0893-228X. PMC 5318275. PMID 28027439.
^ "Insecticide Exposure: Creating Higher Risk for Diabetes". Chronobiology.com. 2017-01-27. Retrieved 2017-04-26.

External links

[PGCH-1] NIOSH Pocket Guide to Chemical Hazards. "#0100". National Institute for Occupational Safety and Health (NIOSH).

[2] "Carbaryl". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).

[Ullmann-3] Robert L. Metcalf “Insect Control” in Ullmann’s Encyclopedia of Industrial Chemistry” Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a14_263

[unger-4] Thomas A. Unger (1996). Pesticide Synthesis Handbook (Google Books excerpt). William Andrew. pp. 67–68. ISBN 0-8155-1401-8.

[Carbaryl_Fact_Sheet-5] [1]

[Carbaryl_Insecticide_Hazard_Data-6] Carbaryl Insecticide Hazard Data Archived May 11, 2010, at the Wayback Machine

[Eckerman2005-7] Eckerman, Ingrid (2005). The Bhopal Saga—Causes and Consequences of the World's Largest Industrial Disaster. India: Universities Press. doi:10.13140/2.1.3457.5364. ISBN 81-7371-515-7.

[8] Interim Reregistration Eligibility Decision for Carbaryl Archived July 25, 2008, at the Wayback Machine, U.S. EPA, June 2003.

[9] Popovska-Gorevski, Marina; Dubocovich, Margarita L.; Rajnarayanan, Rajendram V. (2017-02-20). "Carbamate Insecticides Target Human Melatonin Receptors". Chemical Research in Toxicology. 30 (2): 574–582. doi:10.1021/acs.chemrestox.6b00301. ISSN 0893-228X. PMC 5318275. PMID 28027439.

[10] "Insecticide Exposure: Creating Higher Risk for Diabetes". Chronobiology.com. 2017-01-27. Retrieved 2017-04-26.

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