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A process for preparing pyraclostrobin

IP.com Disclosure Number: IPCOM000240710D
Publication Date: 2015-Feb-19

Publishing Venue

The IP.com Prior Art Database

Abstract

Pyraclostrobin is a strobilurin fungicide, which has a wide fungicidal spectrum and can control most of the diseases including ascomycetes, basidiomycetes, deuteromycetes and oomycetes or the like. It has been widely used in controlling diseases on wheat, rice, peanut, grape, vegetables,potato, banana, lemon, coffee, fruit trees, walnut, tea tree, tobacco and ornamental plants, lawn, and other field crops.

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A process for preparing pyraclostrobin

Pyraclostrobin is a strobilurin fungicide, which has a wide fungicidal spectrum and can control most of the diseases including ascomycetes, basidiomycetes, deuteromycetes and oomycetes or the like. It has been widely used in controlling diseases on wheat, rice, peanut, grape, vege-

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tables, potato, banana, lemon, coffee, fruit trees, walnut, tea tree, tobacco and ornamental plants, lawn, and other field crops.

One possible route for producing pyraclostrobin is extensively described in the literature includ- ing further detailed disclosure how to perform various steps, see for example Modern Crop Pro- tection Compounds, Vol 2, ©2007, US6040458, Wang Zheng, Sun Ke, Zhang Minheng, Agro-

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chemicals, 2014, 53(6): 463-465, CN102399190A, CN104211641A, US 5,922,886, WO09/906373, WO09/906339, US5831093, WO 09/912911.

The route described therein can be summarized in scheme 1 below.

step 1

step 2

N

H NH2

O

X

N N

O2

N N

Cl

Cl OH

Cl OH


(I)


(II)


(III)

NO2

Base

R1

step 5

step 3


(IV)

H2 Catalyst

Me2SO4

Base

O

O

Cl N N

Cl N N

NO2

N

H OH

step 4

O


(V)

Cl OMe

O

O

MeO N OMe

Cl N N

Cl N N

MeO N OH

O

O


(VII)

(VI)

Pyraclostrobin

step 6

Sche

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me 1

[AE-Nr.] REF/... Datum

[ggf. Fig/Seq]


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The present publication focuses on some aspects of this route describing several steps in a more detailed manner starting with the oxidation from II to III.

Step 1

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How to produce compound II is prior art and for example described in Wang Zheng et al (A Review of Synthetic Methods of Pyraclostrobin [J]. Agrochemicals, 2014, 53(6): 463-465)). In- stead of acrylamide (X=NH2) used therein, also other leaving groups, for example other acryla- mides or acryloylhalogenids, such as acryloylchlorid, fluoride or bromide or methlyacrylate can

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be used.

Step 2

The oxidation from II to III is customarily performed with oxygen between 0 °C and the boiling point of the reaction mixture. It is possible to perform the reaction between 20 °C and 100 °C

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under specific reaction conditions. When the process is carried out under pressure, even higher temperatures are possible.

The oxidation can be carried out with at a pressure from 1 to 200 bar. The pressure can be built up by compressing air or pure oxygen or mixtures of these. Pressures of 1 to 50 bar are advan-

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tageous. In general, pressures of from 1 to 20 bar are suitable.

The oxidation from II to III can be done in water in the presence of a base using oxygen as the oxidizing agent, wherein an aqueous basic solution of II is treated with air or pure oxygen gas, wherein the pH of the reaction medium is below 7.

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Thus, an equimolar amount of base is added to II.

Examples are inorganic bases, such as hydroxides or carbonates of the alkali or alkaline earth metals. Examples include sodium hydroxide, potassium hydroxide, magnesium hydroxide, po-

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tassium carbonate or sodium carbonate.

Organic bases are equally suitable in principle. In this case, bases which are non...