Maleic hydrazide
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| General | ||||||||||||||||
| Surname | Maleic hydrazide | |||||||||||||||
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| Molecular formula | C 4 H 4 N 2 O 2 | |||||||||||||||
| Brief description |
White, crystalline solid |
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| properties | ||||||||||||||||
| Molar mass | 112.09 g mol −1 | |||||||||||||||
| Physical state |
firmly |
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| density |
1.61 g cm −3 (25 ° C) |
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| Melting point |
299-301 ° C |
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| pK s value |
5.67 |
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| solubility |
heavy in water (4.51 g l −1 at 25 ° C) |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | ||||||||||||||||
Maleic hydrazide belongs to the group of growth regulators and chemically to the group of heterocycles and hydrazides . Under normal conditions, maleic hydrazide is a white, crystalline solid. The substance is odorless and difficult to dissolve.
effect
Maleic hydrazide has been used in crop production since 1952 . The substance has a systemic effect and is transported in the pathways of the plants ( phloem and xylem ) to the root vegetation points . There, maleic acid hydrazide prevents cell division ( mitosis ) in the formation tissues ( meristems ) and thus prevents budding and root growth for weeks.
presentation
Maleic hydrazide can be prepared from the hydrazinolysis of maleic anhydride or maleic acid .
properties
The heat of decomposition determined by DSC is −66 kJ mol −1 or −590 kJ kg −1 .
use
The growth regulator maleic hydrazide is used in plant cultivation as a growth-inhibiting agent. It is mainly used in the production of food (potatoes, onions). Maleic hydrazide is also used as a growth regulator in weed control .
Active ingredients in pesticides are subject to strict guidelines. Their toxicology is intensively investigated in order to prevent hazards for the user / consumer. As part of these continuous investigations, a complete ban on the use of maleic acid hydrazide and certain of its salts with a content of> 1 mg / kg hydrazine was issued in 1979 ( EU Directive 79/117 / EEC amended by Directive 90/533 / EEC). The reason for the ban on use at that time was the contamination of maleic acid hydrazide with hydrazine, which had arisen during the manufacture of maleic acid hydrazide. Maleic hydrazide itself was and is toxicologically harmless. In the meantime, the manufacturing process for maleic hydrazide has been modified and optimized. Since January 1, 2004, maleic hydrazide has been included in Appendix I of the EU pesticide directive 91/414 / EEC as a positive substance that has been tested and is therefore permitted in the EU . It can therefore be used in pesticides. The active ingredient maleic hydrazide has been classified as non- mutagenic and non- carcinogenic in the Annex 1 listing at EU level according to the uniform, strict assessment principles (Annex VI) 91/414 / EL .
The World Health Organization has maleic as so-called "Table 5 substance " classified , under proper use poses no danger to users and the environment from the.
Preparations with this active ingredient are approved as growth regulators (germ-inhibiting effect) in potatoes and onion plants in Germany and Switzerland (there also to inhibit lateral growth in tobacco). In combination with the active ingredient pelargonic acid , herbicide products are approved in Germany, Austria and Switzerland for use in ornamental plant cultivation as well as on non-cultivated land and paths.
literature
- British Crop Protection Council 2000, Editor CDS Tomlin: The Pesticide Manual, Farnham, Surry, GB; ISBN 0-948404-79-5
- PSM Registration Report ITCAN 006526-00 / 00 Active substance (s): Maleic acid hydrazide (as) potassium salt Federal Office for Consumer Protection and Food Safety, from October 26, 2009 (PDF file)
Individual evidence
- ↑ a b c d e Entry on maleic hydrazide in the GESTIS substance database of the IFA , accessed on January 8, 2018(JavaScript required) .
- ↑ Data sheet Maleic hydrazide from Sigma-Aldrich , accessed on April 9, 2011 ( PDF ).
- ↑ a b Entry on maleic acid hydrazide in the ChemIDplus database of the United States National Library of Medicine (NLM) .
- ↑ Th. Curtius , HA Försterling: Hydrazides and azides of organic acids. VI. Treatise. 28. On the action of hydrazine hydrate on phthalic and maleic anhydride , in: J. Prakt. Chem. 1895 , 51 , 371-398; doi : 10.1002 / prac.18950510131 .
- ↑ H. Feuer, EH White, JE Wyman: The Reactions of Maleic Anhydride with Hydrazine Hydrate , in: J. Am. Chem. Soc. 1958 , 80 , 3790-3792; doi : 10.1021 / ja01547a081 .
- ↑ Grewer, T .; Klais, O .: Exothermic decomposition - investigations of the characteristic material properties , VDI-Verlag, series "Humanisierung des Arbeitsleben", Volume 84, Düsseldorf 1988, ISBN 3-18-400855-X , p. 9.
- ↑ Directive 2003/31 / EC of the Commission of April 11, 2003 amending Council Directive 91/414 / EEC to include the active substances 2,4-DB, beta-cyfluthrin, cyfluthrin, iprodione, linuron, maleic hydrazide and pendimethalin (PDF )
- ^ Directorate-General for Health and Food Safety of the European Commission: Entry on Maleic hydrazide in the EU pesticide database ; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on March 13, 2016.