Bromuconazole

Structural formula
Simplified structural formula of the mixture of four stereoisomers
General
Surname	Bromuconazole
other names	1 - [((2 RS , 4 RS ; 2 RS , 4 SR ) -4-bromo-2- (2,4-dichlorophenyl) tetrahydro-2-furanyl) methyl] -1 H -1,2,4-triazole ( IUPAC ) 1 - ((4-bromo-2- (2,4-dichlorophenyl) tetrahydro-2-furanyl) methyl) -1 H -1,2,4-triazole
Molecular formula	C 13 H 12 BrCl 2 N 3 O
Brief description	colorless solid with a slightly alcoholic odor
External identifiers / databases
CAS number 116255-48-2 (mixture of isomers) EC number 601-417-6 ECHA InfoCard 100.133.137 PubChem 3444 Wikidata Q2152394
properties
Molar mass	377.06 g mol −1
Physical state	firmly
density	1.72 g cm −3
Melting point	84 ° C
solubility	practically insoluble in water (60 mg l −1 at 20 ° C) soluble in dichloromethane and acetone
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 302-400 P: 273
Toxicological data	365 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 .

Bromuconazole is a mixture of four stereoisomeric chemical compounds from the group of the triazoles and conazoles .

Extraction and presentation

Bromuconazole can be produced in a five-step synthetic sequence. In the first step takes place Umgrignardierung of 1-Brommethoxyacetylen with ethyl magnesium bromide . The resulting acetylene Grignard compound is added to 2,4-dichlorobenzoylmethyl chloride in the second step . After hydrogenation of the triple bond and a ring closure reaction with 4-methylphenylsulfonic acid , the last step is a nucleophilic exchange of the chlorine substitution by 1,2,4-triazole in the presence of potassium carbonate . In an alternative synthesis route, allyl magnesium bromide , which is obtained by reacting allyl bromide with magnesium , is added to 2,4-dichlorobenzoylmethyl chloride. This is followed by the nucleophilic substitution of the chloride function by 1,2,4-triazole. After bromination of the double bond, the target compound (more precisely, a mixture of four stereoisomers) is obtained by a basic ring closure with dehydrohalogenation.

properties

Bromuconazole is a colorless solid with a slightly alcoholic odor that is practically insoluble in water. Bromuconazole is stable to hydrolysis .

Isomers

Bromuconazole contains two stereogenic centers . The technical product is a mixture of four stereoisomers, it consists of two racemic diastereomer pairs, the ratio between the (2 RS , 4 SR ) isomers on the one hand and the (2 RS , 4 RS ) isomers on the other hand between 1.04 : 1 and 1.33: 1.

Isomers of bromuconazole
Surname	(2 R , 4 R ) -Bromuconazole	(2 S , 4 S ) -Bromuconazole	(2 R , 4 S ) -Bromuconazole	(2 S , 4 R ) -Bromuconazole
Structural formula
CAS number	114544-81-9 [(2 RS , 4 RS ) - = (±) - (2 R * , 4 R * ) isomers]		114544-80-8 [(2 RS , 4 SR ) - = (±) - (2 R * , 4 S * ) isomers]
	116255-48-2 (mixture of isomers)
PubChem	3444 (mixture of isomers)

use

Bromuconazole is used as a fungicide and was launched in 1990 by Rhône-Poulenc under the name Granit .

Admission

Bromuconazole was approved in Germany between 1994 and 2007.

Due to concerns about ecotoxicology , the EU Commission decided in 2008 not to include the substance mixture in Annex I of Directive 91/414 / EEC. On the basis of a renewed application for approval and further information, the EU Commission came to the conclusion that bromuconazole does not pose a major risk to groundwater and that the risk to aquatic organisms is within acceptable limits. The substance was therefore included in Annex I of Directive 91/414 / EEC for use as a fungicide with effect from February 1, 2011.

In many EU countries, including Germany and Austria, pesticides with this active ingredient are approved, but not in Switzerland.

Individual evidence

1. ↑ ^{a b c d e f} EPA Pesticide Fact Sheet: Bromuconazole (PDF; 27 kB), 2002.
2. ↑ ^{a b c d e} data sheet bromuconazole from Sigma-Aldrich , accessed on May 20, 2017 ( PDF ).
3. ↑ Müller, F .; Ackermann, P .; Margot, P .: Fungicides, Agricultural, 2. Individual Fungicides in Ullmanns Enzyklopädie der Technischen Chemie , 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, doi : 10.1002 / 14356007.o12_o06 .
4. ↑ Patent EP0258161 : 2,5-dihydrofuran derivatives with a triazole or imidazo radical, process for production, use as a fungicide. Applied on August 18, 1987 , published on March 2, 1988 , applicant: Rhône-Poulenc , inventor: Alfred Greiner, Régis Pepin. ‌
5. ↑ entry to bromuconazole in the Hazardous Substances Data Bank , accessed on April 15, 2013.
6. ↑ Thomas A. Unger: Pesticide Synthesis Handbook . William Andrew, 1996, ISBN 0-8155-1853-6 , pp. 686 ( limited preview in Google Book Search).
7. ↑ U. Schirmer, P. Jeschke, M. Witschel: Modern Crop Protection Compounds: Herbicides, Volume 1 . Wiley-VCH Verlag GmbH & Co. KGaA, 2011, ISBN 978-3-527-32965-6 , p. 784 ( limited preview in Google Book search).
8. ^ ^{A b} Terence Robert Roberts, David Herd Hutson: Metabolic Pathways of Agrochemicals: Part 2, Insecticides and fungicides . Royal Society of Chemistry, 1999, ISBN 0-85404-499-X , pp. 1025 ( limited preview in Google Book search).
9. ↑ EU: Review report for the active substance bromuconazole (PDF; 164 kB), 23 November 2010.
10. ↑ Ulrich Schirmer, Peter Jeschke, Matthias Witschel: Modern Crop Protection Compounds: Herbicides . John Wiley & Sons, 2012, ISBN 978-3-527-32965-6 , pp. 783 ( limited preview in Google Book search).
11. ↑ Peter Brandt: Reports on Plant Protection Products 2009: Active Ingredients in Plant Protection Products ; Approval history and regulations of the Plant Protection Application Ordinance . Springer DE, 2010, ISBN 3-0348-0028-2 , pp. 25 ( limited preview in Google Book search).
12. ↑ EU: Commission decision of November 3, 2008 on the non-inclusion of bromuconazole in Annex I of Council Directive 91/414 / EEC and the revocation of authorizations for plant protection products containing this substance (PDF)
13. ↑ EU: Commission Directive 2010/92 / EU of December 21, 2010 amending Council Directive 91/414 / EEC to include the active substance bromuconazole (PDF)
14. ↑ General Directorate Health and Food Safety of the European Commission: Entry on bromuconazole in the EU pesticide database ; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on February 23, 2016.