Metalaxyl
| Names | |
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| IUPAC name
Methyl 2-[N-(2,6-dimethylphenyl)(methoxy)acetamido]propanoate
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| Other names
Methyl N-(2,6-dimethylphenyl)-N-(2-methoxyacetyl)alaninate
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3D model (JSmol)
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| C15H21NO4 | |
| Molar mass | 279.33 g/mol |
| Appearance | Fine white powder |
| Density | 1.20g/cm3 at 20 °C |
| Melting point | 71 to 72 °C (160 to 162 °F; 344 to 345 K)[2] |
| Boiling point | 295.9 °C (564.6 °F; 569.0 K) at 760 mm Hg |
| 8,400 mg/L at 22 °C | |
| log P | 1.65 (octanol/water)[1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Metalaxyl is an acylalanine fungicide with systemic function.[3] Its chemical name is methyl N-(methoxyacetyl)-N-(2,6-xylyl)-DL-alaninate. It can be used to control Pythium in a number of vegetable crops, and Phytophthora in peas. Metalaxyl-M is the ISO common name[4] and Ridomil Gold is the trade name for the optically pure (-) / D / R active stereoisomer, which is also known as mefenoxam.[5]
It is the active ingredient in the seed treatment agent Apron XL LS.[6]
The fungicide has suffered severe resistance problems. The fungicide was marketed for use against Phytophthora infestans. However, in the summer of 1980, in the Republic of Ireland, the crop was devastated by a potato blight epidemic after a resistant race of the oomycete appeared.[7] Irish farmers later successfully sued the company for their losses.[citation needed] Maximum pesticide residue limits for the EU/UK are set at 0.5 mg/kg for oranges and 1.0 mg/kg for apples.[citation needed] As early as 1998 Pythium was known to be widely developing resistance to metalaxyl[8] which was the most effective control at the time.[8] Various Pythium populations have been known to have resistance to mefenoxam since the 1980s[9] and metalaxyl since 1984.[10] There is wide variability in resistance/sensitivity between Pythium species, with some populations showing complete ineffectiveness.[9]
Synthesis
[edit | edit source]The first synthesis of metalaxyl was disclosed in patents filed by Ciba Geigy.[11]
2,6-Xylidine is alkylated with methyl 2-bromopropionate to give an alanine derivative. This is further reacted with the acid chloride of methoxyacetic acid to yield racemic metalaxyl.[11][12] The homochiral, single-isomer version of the chemical, which retains all its fungicidal activity, has been manufactured.[13]
References
[edit | edit source]- ^ Hansch, C., Leo, A., D. Hoekman. Exploring QSAR - Hydrophobic, Electronic, and Steric Constants. Washington, DC: American Chemical Society., 1995., p. 134
- ^ O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. 13th Edition, Whitehouse Station, NJ: Merck and Co., Inc., 2001., p. 1058
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- ^ Working on potato blight in Northern Ireland
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- ^ a b GB patent 1500581, "Substituted amides and their use as fungicides", issued Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value)., assigned to Ciba-Geigy AG
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External links
[edit | edit source]- Metalaxyl in the Pesticide Properties DataBase (PPDB)
- Metalaxyl-M in the Pesticide Properties DataBase (PPDB)
