Dimethenamid

• 2-chloro- N-(2,4 - dimethyl-3 - thienyl) -N-( 2 - methoxy-1 - methylethyl) acetamide
• Frontier

• 87674-68-8
• 163515-14-8 dimethenamid -P [(S )-isomer ]

Yellow- brown liquid

Liquid

127 ° C.

0.7 MPa ( 20-25 ° C)

Soluble in water ( 37.5 g · l -1)

Risk

• 397 mg · kg -1 ( LD50, rat, oral)
• > 2000 mg · kg -1 ( LD50, rat, transdermal)

Template: Infobox chemical / molecular formula search available

Dimethenamid is one of the chemical compounds from the group of chloroacetamides. Today is used in Europe mainly dimethenamid -P, a mixture of two particularly effective dimethenamid isomers. It is corn and beet, but also used as a herbicide, above all in the legumes ( soybeans) and sunflower cultivation.

Production and representation

Dimethenamid can be prepared by a multi-stage reaction of methacrylic acid, 1- methoxy-2- propylamine, 1 -methoxy -2-aminopropane, thionyl chloride and chloroacetyl chloride. Methacrylic acid, and 1 -methoxy-2 -propylamine react and cyclize to give 2,4-dimethyl- tetrahydro-3 - thiophenone.

Isomerism

Dimethenamide is - similar to the related chloroacetamide Metachlor - four stereoisomers because it

• Axial chirality along the bond (restricted rotation ) between the 3-position of the thiophene ring and the nitrogen atom and
• A stereogenic center in the side chain

Possesses. Thus, there are the following stereoisomers: (1S, aS )-form, (1R, aR )-form, (1S, aR )-form and the (1R, aS )-form. The mixture of from (1S, aS) -form and the (1S, aR )-form - sometimes called the " ( S)- dimethenamide " - is more effective than herbicide and can be dosed lower than the mixture of the four stereoisomers.

Use

Admission

The European Commission decided in 2006 not to include dimethenamide in the list of permitted pesticide active ingredients. This was primarily the formation of non - identifiable degradation products in soil. In Switzerland dimethenamide could be used until recently in agriculture. The sell-out period of a product ended on 31 August 2010, the grace period has expired on 31 August 2013. In Germany and Austria no pesticide products containing this active ingredient are allowed.

The isomeric drug dimethenamide -P was recorded in 2003 in the list according to Directive 91/414/EEC. Dimethenamide -P is approved, among others in Germany, Austria and Switzerland.