Dimethenamid

Structural formula
Simplified structural formula without taking stereoisomerism into account
General
Surname	Dimethenamid
other names	2-chloro- N - (2,4-dimethyl-3-thienyl) - N - (2-methoxy-1-methylethyl) acetamide Frontier
Molecular formula	C 12 H 18 ClNO 2 S
Brief description	yellow-brown liquid
External identifiers / databases
CAS number 87674-68-8 EC number 618-045-5 ECHA InfoCard 100.121.887 PubChem 91744 Wikidata Q3028201
properties
Molar mass	275.79 g mol −1
Physical state	liquid
boiling point	127 ° C
Vapor pressure	0.7 mPa (20-25 ° C)
solubility	soluble in water (37.5 g l −1 )
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 302-411 P: 273
Toxicological data	397 mg kg −1 ( LD 50 ,  rat ,  oral ) > 2000 mg kg −1 ( LD 50 ,  rat ,  transdermal )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Dimethenamid is one of the chemical compounds from the group of chloroacetamides. Today, in Europe, Dimethenamid-P , a mixture of two particularly effective dimethenamid isomers, is mainly used as a herbicide .

Extraction and presentation

Dimethenamid can be produced by a multistage reaction from 2-mercaptopropionic acid , methacrylic acid , 1-methoxy-2-propylamine , thionyl chloride and chloroacetic acid chloride . Methacrylic acid and 2-mercaptopropionic acid react with one another and cyclize to 2,4-dimethyl-tetrahydro-3-thiophenone.

Isomerism

Dimethenamid consists - similar to the related chloroacetamides alachlor and metolachlor - of four stereoisomers because it

• axial chirality along the bond (limited rotatability) between the 3-position of the thiophene ring and the nitrogen atom and
• a stereogenic center in the side chain

owns. The following stereoisomers thus exist: (1 S , a S ) form, (1 R , a R ) form, (1 S , a R ) form and the (1 R , a S ) form. The mixture of the (1 S , a S ) form and the (1 S , a R ) form - sometimes also called "( S ) -dimethenamid" - is more effective as a herbicide and can be dosed lower than the mixture of the four Stereoisomers.

use

Estimated application rate of Dimethenamid 2011 in the USA

Dimethenamid is used as a herbicide primarily in corn and beet , but also in legumes (soybeans) and sunflower cultivation.

Admission

In 2006 the EU Commission decided not to include dimethenamid in the list of permitted active ingredients in pesticides. The main reason was the formation of unidentifiable degradation products in the soil. In Switzerland, dimethenamid could be used in agriculture until recently. The sell-out period for the product ended on August 31, 2010; the use-by period expired on August 31, 2013. In Germany and Austria no pesticide products with this active ingredient are permitted.

Individual evidence

1. ↑ ^{a b c d} Entry on Dimethenamid in the Pesticide Properties DataBase (PPDB) of the University of Hertfordshire , accessed on February 15, 2014.
2. ↑ ^{a b} Entry of Dimethenamid in the GSI Chemical Database, accessed on August 8, 2013.
3. ↑ ^{a b} Datasheet Dimethenamid, PESTANAL at Sigma-Aldrich , accessed on May 19, 2017 ( PDF ).
4. ↑ Thomas A. Unger: Pesticide Synthesis Handbook . William Andrew, 1996, ISBN 0-8155-1853-6 , pp. 740 .
5. ↑ ^{a b} patent application US5457085 : Optical isomer of dimethenamid. Registered on September 21, 1994 , published October 10, 1995 , applicant: Sandoz , inventor: Stefan Blarer, Reynold Chollet, Karl Seckinger, Thomas Vettiger. ‌
6. ↑ Decision of the Commission of December 22, 2006 (PDF) on the non-inclusion of dimethenamid in Annex I of the Council Directive 91/414 / EEC and the revocation of the authorizations for plant protection products with this active substance (announced under file number K (2006) 6895) (2006/1009 / EC).
7. ↑ General Directorate Health and Food Safety of the European Commission: Entry on Dimethenamid in the EU pesticide database; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; Retrieved February 19, 2016.