Difenacoum

• Diphenacoum
• 3 - (3 -biphenyl -4-yl -1 ,2,3,4- tetrahydro-1 -naphthyl) -4-hydroxy -coumarin
• 3 - (3 - (1,1 '-biphenyl )-4- yl -1 ,2,3,4- 1- naphthalenyl) -4-hydroxy -2H-1 -benzopyran -2-one

• 56073-07-5
• 151986-16-2 (trans- isomer)
• 151986-15-1 (cis- isomer)

White solid

Fixed

1.25 g · cm -3

215-217 ° C ( decomposition)

• Practically insoluble in water (2.5 mg · l-1 at 20 ° C)
• Soluble in acetone and chloroform

Risk

• 0.68 mg · kg -1 ( LD50, Rat, oral, mixture of isomers )
• 2.5-5.0 mg · kg -1 ( LD50, Mouse, oral, 1R3R isomer)
• 0.8-1.5 mg · kg -1 ( LD50, Mouse, oral, 1S3S - isomer)
• 2.5-5.0 mg · kg -1 ( LD50, Mouse, oral, 1S3R isomer)
• 0.3-0.9 mg · kg -1 ( LD50, Mouse, oral, 1R3S isomer)

Template: Infobox chemical / molecular formula search available

Difenacoum is a mixture of several isomeric chemical compounds from the group of 4- hydroxycoumarins.

• 4.1 As a biocidal product
• 4.2 As plant protection agents

Production and representation

Difenacoum, by a Kondensationsreraktion of 4 -hydroxycoumarin and 3 - ( biphenyl-4- yl) -1,2,3,4- obtained tetrahydro-1 -naphthol. Laboratory synthesis of the individual isomers run using stereoisomeric starting materials and intermediates.

Properties

Difenacoum is a flammable solid that is practically insoluble in water. It decomposes above a temperature above 215-217 ° C. It is present as a mixture of more toxicologically active isomers, in which the technical product exists the cis- isomer to 50 to 80 %.

Stereochemistry

Difenacoum is a chiral compound, which contains two asymmetrically substituted carbon atoms. Thus, there are four stereoisomers, the (1S, 3S) - and (1R, 3R) -isomer and the (1S, 3R ) - and ( 1R, 3S)- isomers form corresponding pairs of enantiomers. Melting points for the amount of (1R, 3S) - (1S, 3R)- isomeric 216 ° C and the (1R, 3R) - (1S, 3S)- isomeric 213 ° C.

Use

Difenacoum is an anticoagulant ( prevents blood clotting, so that after the inclusion of the animal dies from internal bleeding ) of the second generation and is used as a rodenticide in various forms against rats and mice. Because of the identified risks of the drug (potentially persistent, bioaccumulative and toxic) Difenacoum was recorded for only five years in the Appendix of the Biocides Directive. Resistance to Difenacoum are documented in Denmark, Germany and the UK. However, they are lower than for anticoagulants warfarin, coumatetralyl, Chlorphacinon and bromadiolone.

Admission

As a biocidal product

Accordance with European legislation (Directive 98/8/EC concerning the placing of biocidal products ) and with decision on 29 July 2008 is a decision before the active ingredient Difenacoum from 1 April 2010 to the appropriate list (Annex I to Directive 98 / 8/EC ) for product type 14 ( rodenticides ) record. The release of biocidal products containing the active ingredient Difenacoum is therefore in the EU ( Switzerland has adopted this provision ) will still be allowed. This exemption was subject to certain conditions:

• The nominal concentration of the active substance in the products shall not exceed 75 mg / kg, and it may only use products are allowed.
• The Products shall contain an aversive agent and, where appropriate, a dye. Products must not be used as tracking powder.
• To reduce risk to humans, non-target animals and the environment are appropriate measures to implement. Thus the restriction to professional use only, setting a package size and the obligations to use tamper resistant and secured bait boxes.
• The grant will be initially limited to 31 March 2015 to extend this period is subject to a new risk assessment.

As plant protection agents

Accordance with European legislation (Directive 91/414/EEC of 15 July 1991 concerning the placing of plant protection products ) and Directive 2009/70/EC of 25 June 2009, the EU Commission has decided to refer the drug Difenacoum in Annex I to Directive 91/414/EEC ( positive list of permitted substances in plant protection products ) record. The sale of plant protection products containing the active ingredient Difenacoum is therefore still allowed in the EU. This exemption was subject to certain conditions:

• The nominal concentration of the active substance in the products shall not exceed 50 mg / kg.
• The applications are allowed only in the form of prepared baits that are located in protected and secured bait boxes.
• Admission will be limited to professional users.
• The grant will be initially limited to 30 December 2019.

In Germany Difenacoum is included in preparations from rats. In Switzerland and Austria no pesticide is approved, containing the active substance.

Safety

Difenacoum is very toxic in absorption, in contact with skin or inhalation.