Temefos

Temefos
Names
Preferred IUPAC name
O-[4-({4-[(Dimethoxyphosphorothioyl)oxy]phenyl}sulfanyl)phenyl] O,O-dimethyl phosphorothioate
Other names
[4-(4-dimethoxyphosphinothioyloxyphenyl)sulfanylphenoxy]-
dimethoxy-sulfanylidene-phosphorane
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.020.175 Edit this at Wikidata
KEGG
MeSH Temefos
UNII
  • InChI=1S/C16H20O6P2S3/c1-17-23(25,18-2)21-13-5-9-15(10-6-13)27-16-11-7-14(8-12-16)22-24(26,19-3)20-4/h5-12H,1-4H3 checkY
    Key: WWJZWCUNLNYYAU-UHFFFAOYSA-N checkY
  • InChI=1/C16H20O6P2S3/c1-17-23(25,18-2)21-13-5-9-15(10-6-13)27-16-11-7-14(8-12-16)22-24(26,19-3)20-4/h5-12H,1-4H3
    Key: WWJZWCUNLNYYAU-UHFFFAOYAC
  • S=P(OC)(OC)Oc2ccc(Sc1ccc(OP(=S)(OC)OC)cc1)cc2
Properties
C16H20O6P2S3
Molar mass 466.46 g·mol−1
Appearance white, crystalline solid
Density 1.32 g cm−3
Melting point 30 °C (86 °F; 303 K)
Boiling point 120–125 °C (248–257 °F; 393–398 K) (decomposes)
insoluble
Vapor pressure 0.00000007 mmHg (20°C)
Hazards
NIOSH (US health exposure limits):
PEL (Permissible)
 15 mg/m3
REL (Recommended)
 TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp)
IDLH (Immediate danger)
 N.D.
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X markN verify (what is checkYX markN ?)

Temefos or temephos (trade name Abate) is an organophosphate larvicide used to treat water infested with disease-carrying insects (including mosquitoes, midges, and black fly larvae) and crustaceans (copepods).

Synthesis and Preparation

Temephos can be synthesized by reacting 4,4′-thiodiphenol with dimethoxythiophosphonyl chloride.

Properties

Temephos is a flammable, colorless (white) solid that is practically insoluble in water. It undergoes hydrolysis in strongly acidic and alkaline conditions.

Mode of action

Its mode of action involves the inhibition of acetylcholinesterase. As with other organophosphates, temephos affects the central nervous system through inhibition of cholinesterase. In larvae, this results in death before reaching the adult stage.

Uses

Temephos is used as an insecticide. It is used to control mosquito and sand fly larvae in bodies of water not used for drinking water production. Approximately 25,000 to 40,000 pounds are used annually in the United States.

In the developing world where the vector-borne disease dengue fever is endemic, temephos is widely used and applied by both private and public pest control in areas of standing water where the Aedes aegypti mosquito breeds, in order to reduce the population of this disease-carrying insect. Temephos is also used in the Guinea Worm Eradication Program to kill the copepods that carry guinea worm larvae.

Resistance to temephos by A. aegypti has been seen in Brazil. The Brazilian Aedes aegypti resistance monitoring program detected temephos resistance in A. aegypti populations from several localities in the country in 1999 (Funasa 2000, Lima et al. 2003). In 1999, mosquitoes from the city of Rio de Janeiro were observed to be resistant to temephos.

Registration

Temephos is not approved as an active ingredient in pesticides in the European Union; consequently, no pesticides containing this active ingredient are commercially available in Germany, Austria, or Switzerland.

References

  1. 1 2 3 4 5 6 7 "#0589". NIOSH Pocket Guide to Chemical Hazards. National Institute for Occupational Safety and Health.
  2. ↑ Abate Product Information
  3. ↑ NLM Hazardous Substances Data Bank entry for [ ]
  4. ↑ Thomas A. Unger (1996), Pesticide Synthesis Handbook, William Andrew, p. 335, ISBN 0-8155-1853-6
  5. 1 2 Record of Temephos in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  6. 1 2 Terry R Roberts, David H Hutson, Philip W Lee, Peter H Nicholls (1999), Metabolic Pathways of Agrochemicals: Part 2: Insecticides and Fungicides, Royal Society of Chemistry, p. 491, ISBN 0-85404-499-X{{citation}}: CS1 maint: multiple names: authors list (link)
  7. ↑ EPA: Temephos Facts (PDF; 13 kB), Juli 2001.
  8. ↑ New York Times article covering its application in Africa
  9. ↑ "Clinical Guidance for Guinea Worm". U.S. Centers for Disease Control and Prevention. 15 March 2024. Retrieved 25 April 2025.
  10. ↑ Lima JB, Da-Cunha MP, Da Silva RC, et al. (2003). "Resistance of Aedes aegypti to organophosphates in several municipalities in the State of Rio de Janeiro and Espírito Santo, Brazil". Am. J. Trop. Med. Hyg. 68 (3): 329–33. doi:10.4269/ajtmh.2003.68.329. PMID 12685640.
  11. ↑ "Commission Regulation (EC) No 2076/2002 of 20 November 2002 extending the time period referred to in Article 8(2) of Council Directive 91/414/EEC and concerning the non-inclusion of certain active substances in Annex I to that Directive and the withdrawal of authorisations for plant protection products containing these substances (Text with EEA relevance)". 2002..
  12. ↑ "EU Pesticides Database". ec.europa.eu. Retrieved 2026-10-18.

Bibliography