Synthesis of some substituted carbamates, their nematicidal activity and dissipation of thiodicarb in soils
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Date
2012
Authors
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Publisher
CCSHAU
Abstract
Pesticides are a vital facet of farming because they enable us to produce sufficient high quality wholesome food for a growing population. They also allow efficient and economic pest control and often there is no alternative control option. We all benefit from these chemicals and therefore have a
responsibility to ensure that these benefits are maximized and adverse effects are minimized. Keeping this
in mind, the synthesis and characterization of 2H-1-benzopyran-2-ones (7-14), 3-(substitutedphenyl)-1-(2/3-hydroxyphenyl)-2-propen-1-ones (60-75), 2/3-[5-(substituted phenyl) isoxazol-3-yl phenols (142-157)
and 2/3-[5-(substitutedphenyl)-4, 5-dihydro-1H-pyrazol-3-yl] phenols (207-222) and their carbamate
derivatives were synthesized. The chemical structure of newly synthesized compounds was elucidated by
1 H NMR, IR and other physical and analytical data. The structure activity relation in the above evaluation
studies was also investigated. The bioactive assay showed that compounds 1-{3-[5-(substituted phenyl) isoxazole-3-yl] phenoxy}-3-(4-chlorophenoxy) propane-2-oxo-phenylcarbamtes (198-205) were found highly active at all concentrations. Compounds 2/3-[5-(substitutedphenyl)-4,5-dihydro-1H-pyrazol-3-yl]phenyl phenyl carbamates(223-238)showed moderate activity. All other compounds werealso active at
tested highest concentration. The compounds showed spectacular prospects for further research and use in this field. The findings suggested that the isoxazoles and pyrazoles framework is an attractive template for
synthesis of nematicides. These compounds needs further exploration for their possible use as nematicides
and deserve further investigation. A lab experimentwas conducted to study the dissipation of thiodicarb in
soils. It was concluded that thiodicarb residues reached below detectable level of 0.005 mg kg-1 within 15
days and 30 days in sandy loam and clay loam soils,respectively following first order kinetics and half life
period between 4-9 days. Complete dissipation of methomyl took place after 15 days in both the soils with
half life period between 6-9 days. Thiodicarb with its metabolite, methomyl persisted upto 30 days with per
cent dissipation of 85.71 and 82.69 in sandy loam and clay loam soils, respectively. Its dissipation followed
first order kinetics with half life period between 6-8 days. The persistence was more at higher dose and
methomyl persisted more than thiodicarb in both thedoses of clay loam and sandy loam soils. Thiodicarb
along with its metabolite, methomyl persisted beyond 30 days in both the soils.
Description
Keywords
Carbamates, Coumarins, Chalcones, Isoxaxoles, Pyrazoles, Nematicidal Activity, Persistence, Thiodicarb.