Metalaxyl is an acylalanine

fungicide Fungicides are pesticides used to kill parasitic fungi or their spores. Fungi can cause serious damage in agriculture, resulting in losses of yield and quality. Fungicides are used both in agriculture and to fight fungal infections in animals, ...

with systemic function. Its chemical name is methyl N-(methoxyacetyl)-N-(2,6-xylyl)-DL-alaninate. It can be used to control ''

Pythium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but '' Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are fre ...

'' in a number of

vegetable Vegetables are edible parts of plants that are consumed by humans or other animals as food. This original meaning is still commonly used, and is applied to plants collectively to refer to all edible plant matter, including edible flower, flo ...

crops, and ''

Phytophthora ''Phytophthora'' (from Greek (''phytón''), "plant" and (), "destruction"; "the plant-destroyer") is a genus of plant-damaging oomycetes (water molds), whose member species cause economic losses on crops worldwide, as well as environmental dam ...

'' in

pea Pea (''pisum'' in Latin) is a pulse or fodder crop, but the word often refers to the seed or sometimes the pod of this flowering plant species. Peas are eaten as a vegetable. Carl Linnaeus gave the species the scientific name ''Pisum sativum' ...

s. Metalaxyl-M is the ISO common name and Ridomil Gold is the trade name for the optically pure (-) / D / R active stereoisomer, which is also known as mefenoxam. It is the active ingredient in the seed treatment agent Apron XL LS. The fungicide has suffered severe problems. The fungicide was

marketed Marketing is the act of acquiring, satisfying and retaining customers. It is one of the primary components of business management and commerce. Marketing is usually conducted by the seller, typically a retailer or manufacturer. Products can ...

for use against ''

Phytophthora infestans ''Phytophthora infestans'' is an oomycete or Oomycete, water mold, a fungus-like microorganism that causes the serious potato and tomato disease known as late blight or potato blight. Early blight, caused by ''Alternaria solani'', is also often c ...

''. However, in the summer of 1980, in the

Republic of Ireland Ireland ( ), also known as the Republic of Ireland (), is a country in Northwestern Europe, north-western Europe consisting of 26 of the 32 Counties of Ireland, counties of the island of Ireland, with a population of about 5.4 million. ...

, the crop was devastated by a potato blight epidemic after a resistant race of the

oomycete The Oomycetes (), or Oomycota, form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms within the Stramenopiles. They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction o ...

appeared. Irish

farmer A farmer is a person engaged in agriculture, raising living organisms for food or raw materials. The term usually applies to people who do some combination of raising field crops, orchards, vineyards, poultry, or other livestock. A farmer ...

s later successfully

sued A lawsuit is a proceeding by one or more parties (the plaintiff or claimant) against one or more parties (the defendant) in a civil court of law. The archaic term "suit in law" is found in only a small number of laws still in effect today. T ...

the company for their losses. Maximum pesticide residue limits for the EU/UK are set at 0.5 mg/kg for oranges and 1.0 mg/kg for apples. As early as 1998

was known to be widely developing resistance to metalaxyl which was the most effective control at the time. Various ''Pythium'' populations have been known to have resistance to mefenoxam since the 1980s and metalaxyl since 1984. There is wide variability in resistance/sensitivity between ''Pythium'' species, with some populations showing complete ineffectiveness.

Synthesis

The first synthesis of metalaxyl was disclosed in patents filed by

Ciba Geigy Novartis AG is a Swiss multinational pharmaceutical corporation based in Basel, Switzerland. Novartis is one of the largest pharmaceutical companies in the world and was the eighth largest by revenue in 2024. Novartis manufactures the drugs c ...

. : 2,6-Xylidine is

alkylated Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting al ...

with methyl 2-bromopropionate to give an

alanine Alanine (symbol Ala or A), or α-alanine, is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group sid ...

derivative. This is further reacted with the

acid chloride In organic chemistry, an acyl chloride (or acid chloride) is an organic compound with the functional group . Their formula is usually written , where R is a side chain. They are reactive derivatives of carboxylic acids (). A specific example o ...

methoxyacetic acid Methoxyacetic acid is the organic compound with the formula . It can be viewed as a derivative of acetic acid in which a hydrogen atom of the methyl group is replaced by a methoxy group. As indicated by the synonym methyl glycolic acid, and as the ...

to yield

racemic In chemistry, a racemic mixture or racemate () is a mixture that has equal amounts (50:50) of left- and right-handed enantiomers of a chiral molecule or salt. Racemic mixtures are rare in nature, but many compounds are produced industrially as r ...

metalaxyl. The homochiral, single-isomer version of the chemical, which retains all its fungicidal activity, has been manufactured.

References

External links

* * Fungicides Alkyl-substituted benzenes {{mycology-stub