Cyproconazole

Structural formula
Structure without stereochemistry
General
Surname	Cyproconazole
other names	2- (4-chlorophenyl) -3-cyclopropyl-1- (1 H -1,2,4-triazol-1-yl) butan-2-ol ( IUPAC )
Molecular formula	C 15 H 18 ClN 3 O
Brief description	beige solid
External identifiers / databases
CAS number 94361-06-5 113096-99-4 (undefined stereochemistry) EC number 619-020-1 ECHA InfoCard 100.130.443 PubChem 86132 ChemSpider 77706 Wikidata Q1148372
properties
Molar mass	291.78 g mol −1
Physical state	firmly
density	1.26 g cm −3
Melting point	106.5 ° C
Vapor pressure	0.026 mPa (25 ° C)
solubility	practically insoluble in water Easily soluble in ethanol , xylene , acetone and dimethyl sulfoxide
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 301-360D-373-410 P: 201-264-280-301 + 310-308 + 313
Toxicological data	1020 mg kg −1 ( LD 50 ,  rat ,  oral )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Cyproconazole is used as an active ingredient in crop protection products and is a mixture of four stereoisomeric chemical compounds from the group of triazoles .

Extraction and presentation

Cyproconazole, like tebuconazole and hexaconazole , can be obtained by reacting the corresponding epoxide with triazole .

In the overall reaction, 1- (4-chlorophenyl) -2-cyclopropylethanone reacts with methyl iodide in the presence of sodium hydride followed by treatment with dodecyldimethylsulfonium methyl sulfate , the epoxide being formed as an intermediate product, which is reacted with triazole in the presence of a base.

properties

As a technical product, cyproconazole is a beige solid. The pure substance is colorless and practically insoluble in water.

Stereochemistry

Cyproconazole is a chiral compound that contains two stereocenters. The compound is therefore usually in the form of a mixture of stereoisomeric molecules which differ in certain physical properties and physiological effects. Using suitable synthesis strategies (“ asymmetric synthesis ”) or separation processes ( racemate resolution ), individual stereoisomers can be specifically prepared or isolated.

The technical cyproconazole is a mixture of all four isomers in a ratio of about 1: 1: 1: 1 with increasing fungicidal activity in the order ( S , S ) ≤ ( S , R ) ≪ ( R , S ) <( R , R ). In contrast to other triazole fungicides, none of the individual isomers is more effective than a mixture of all four, which indicates that the enantiomers work together.

use

Cyproconazole is a broad spectrum fungicide announced in 1986 and introduced in 1989 against powdery mildew , rust and Monilinia , Cercospora , Veninria , Rhizoctonia and Sclerotium . It works by intervening in the sterol biosynthesis in the membranes.

In Switzerland, Austria and Germany, plant protection products that contain cyproconazole as an active ingredient are approved.

Residues in food

In Switzerland, there is a relatively high maximum residue level of 2.5 milligrams of cyproconazole per kilogram for nut lettuce .

Individual evidence

1. ↑ ^{a b} data sheet cyproconazole from Sigma-Aldrich , accessed on January 25, 2018 ( PDF ).
2. ↑ ^{a b c} 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 .
3. ↑ ^{a b c d e} Ullmann's Agrochemicals, Volume 1 . Viley, 2007, ISBN 978-3-527-31604-5 ( page 612 in the Google book search).
4. ↑ ^{a b c} Entry on cyproconazole in the GESTIS substance database of the IFA , accessed on January 15, 2020(JavaScript required) .
5. ↑ Entry on (2RS, 3RS; 2RS, 3SR) -2- (4-chlorophenyl) -3-cyclopropyl-1- (1H-1,2,4-triazol-1-yl) butan-2-ol in the Classification and Labeling inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
6. ↑ Thomas A. Unger: Pesticide synthesis handbook . 1996, ISBN 0-8155-1401-8 ( page 681 in the Google book search).
7. ↑ Horst Lyr: Modern selective fungicides, p. 229 . University of Minnesota, 1995, ISBN 3-334-60455-1 .
8. ^ Horst Börner: Plant diseases and plant protection . 2009, ISBN 978-3-540-49068-5 , pp. 496 ( limited preview in Google Book search).
9. ^ Directorate-General for Health and Food Safety of the European Commission: Entry on Cyproconazole in the EU pesticide database; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on March 12, 2016.
10. ↑ Ordinance of the EDI on the maximum levels for pesticide residues in or on products of plant and animal origin. In: admin.ch . Retrieved February 6, 2020 .