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Methomyl Structural Formulae .V.1.svg
CAS number 16752-77-5 YesY
PubChem 5353758
Jmol-3D images Image 1
Molecular formula C5H10N2O2S
Molar mass 162.21 g mol−1
Appearance Crystals
Odor Slight, sulfur-like[2]
Density 1.2946 g/cm3
Melting point 78 to 79 °C (172 to 174 °F; 351 to 352 K)
Solubility in water 58 g/L
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Methomyl is a carbamate insecticide introduced in 1966. It is highly toxic to humans.[3] The EU and UK imposed a pesticide residue limit of 0.02 mg/kg for apples and oranges.[citation needed]

Methomyl is the active ingredient in commercial fly bait granules which are mixed with a cola drink to kill bothersome raccoon, skunk and opossum. Using methomyl in this "off-label" way may be against the law in some of the United States. [4][5]


Methomyl can be produced by reaction of methyl isocyanate and methylthioacetaldoxime (also known as methomyl oxime).

First prepare ester

{{\text{H}}_{\text{3}}}\text{C-}\underset{\underset{\text{O}}{\mathop{\text{ }\!\!|\!\!\text{  }\!\!|\!\!\text{ }}}\,}{\mathop{\text{C}}}\,\text{-OH+HS-C}{{\text{H}}_{\text{3}}}\xrightarrow{\text{30--50 }\!\!~\!\!\text{  }\!\!{}^\circ\!\!\text{ C}\text{,-}{{\text{H}}_{2}}O}{{\text{H}}_{\text{3}}}\text{C-}\underset{\underset{\text{O}}{\mathop{\text{ }\!\!|\!\!\text{  }\!\!|\!\!\text{ }}}\,}{\mathop{\text{C}}}\,\text{-S-C}{{\text{H}}_{\text{3}}}

Second prepare oxime from ester {{\text{H}}_{\text{3}}}\text{C-}\underset{\underset{\text{O}}{\mathop{\text{ }\!\!|\!\!\text{  }\!\!|\!\!\text{ }}}\,}{\mathop{\text{C}}}\,\text{-S-C}{{\text{H}}_{\text{3}}}\text{+}{{\text{H}}_{\text{2}}}\text{NOH}\xrightarrow{-{{H}_{2}}O}\text{HO-N=}\underset{\text{C}{{\text{H}}_{\text{3}}}}{\mathop{\underset{\text{ }\!\!|\!\!\text{ }}{\mathop{\text{C}}}\,}}\,\text{-S-C}{{\text{H}}_{\text{3}}}

Third prepare product from isocyanate and oxime. {{\text{H}}_{\text{3}}}\text{C-N=C=O+HO-N=}\underset{\text{C}{{\text{H}}_{\text{3}}}}{\mathop{\underset{\text{ }\!\!|\!\!\text{ }}{\mathop{\text{C}}}\,}}\,\text{-S-C}{{\text{H}}_{\text{3}}}\xrightarrow{\text{C}{{\text{H}}_{\text{2}}}\text{C}{{\text{l}}_{\text{2}}}\text{,30--50 }\!\!~\!\!\text{  }\!\!{}^\circ\!\!\text{ C}}\text{Methomyl}


  1. ^ Merck Index, 11th Edition, 5905
  2. ^ CDC - NIOSH Pocket Guide to Chemical Hazards
  3. ^ Methomyl at Extension Toxicology Network
  4. ^ Conservation Warden Warns: Fly bait to control wild animals – illegal and a bad idea (Wisconsin Department of Natural Resources)
  5. ^ Farm stores promoted poisoning raccoons, state chemist says

External Links[edit]