Search results for "Chlorin"

Synthesis, Characterisation and Reactivity towards PdII and PtII of ortho-, meta- and para-Xylyl-Based Phosphorus-Containing Macrocycles

2002

The new meta- and para-xylyl-based phosphadithiamacrocycles 6-phenyl-6-phospha-3,9-dithiabicyclo[9,3,1]pentadeca-1(15),12,14-triene (L2) and 6-phenyl-6-phospha-3,9-dithiabicyclo[9,2,2]pentadeca-1(13),12,14-triene (L3) have been synthesised and characterised. The reactivity of these ligands and the previously described ortho-xylyl macrocycle 6-phenyl-6-phospha-3,9-dithiabicyclo[9,4,0]pentadeca-1(11), 12,14-triene (L1) with [PdCl2(cod)] and K2[PtCl4] has been studied. [MCl2(L)] complexes have been obtained and characterised by NMR spectroscopy. X-ray structural analyses have been carried out in the case of [PdCl2L2]·CH3CN (2·CH3CN) and [PdCl2L3] (3). In both compounds the PdII ion adopts a sl…

Green synthesis of bromine by TiO2 heterogeneous photocatalysis and/or ozone: A kinetic study

2018

Abstract Elemental bromine is an industrially relevant compound traditionally produced from bromide ions by using chlorine as the oxidizing agent. Problems related to transportation and handling of the corrosive, expensive and toxic chlorine make green synthetic alternatives highly desirable. In this paper the green synthesis of bromine from bromide in aqueous solutions under mild conditions by means of TiO2 photocatalysis and/or ozonation has been investigated from a kinetic point of view. The ozonation in the absence of the photocatalyst follows a first order kinetic with respect to both ozone and bromide. The kinetics of the reactions in the presence of the photocatalyst has been describ…

Gas chromatographic determination of organochlorine pesticides; contamination of dicofol, fenson, and tetradifon in fish and natural waters of a wet …

1986

Accumulation of Tetradifon in an Algae ( Nannochloris oculata ) and the Cladoceran, Daphnia magna

1996

Dissipation and distribution of atrazine, simazine, chlorpyrifos, and tetradifon residues in citrus orchard soil.

1997

An environmental fate study was conducted in a citrus orchard plot in Valencia (Spain) in the fall of 1993. Dissipation and distribution of atrazine, simazine, chlorpyrifos and tetradifon residues following their controlled addition for agricultural purposes in a mediterranean red soil (Luvic Calcisol, Rhodoxeralf) were evaluated. During a two-month period, the amounts of applied pesticides in different soil layers (0-0.05, 0.05-0.22, 0.22-0.42, and 0.42-0.52 m) were monitored. In addition, information on soils, weather and agricultural practice were collected. Degradation half-lives were calculated, assuming zero-order kinetics: 11 days for atrazine, 12 days for simazine, 10 days for chlor…

Gas chromatographic determination of organochlorine pesticides in cow milk.

2004

A gas chromatographic method of use in determining the following organochlorine pesticides in cow milk has been adapted and validated: alpha-hexachlorocyclohexane (alpha-HCH), beta-HCH, lindane, delta-HCH, hexachlorobenzene, aldrin, heptachlor, heptachlor epoxide, mirex, 2,4-dichlorodiphenyltrichloroethane (2,4-DDT), 4,4-DDT, 2,4-dichlorodiphenyldichloroethane (2,4-DDD), 4,4-DDD, 2,4-dichlorodiphenylethane (2,4-DDE) and 4,4-DDE. The method studied consists of three steps: the extraction of fat by centrifugation, mixing with anhydrous sodium sulfate, and transfer to a glass column and elution with hexane; purification of the extract via concentrated sulfuric acid treatment; and determination…

Assessment of Pesticide Residues in Honey Samples from Portugal and Spain

2003

Fifty samples of honey collected from local markets of Portugal and Spain during year 2002 were analyzed for 42 organochlorine, carbamate, and organophosphorus pesticide residues. An analytical procedure based on solid-phase extraction with octadecyl sorbent followed by gas chromatography-mass spectrometry (GC-MS), for organochlorines, and by liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS), for organophosphorus and carbamates, has been developed. Recoveries of spiked samples ranged from 73 to 98%, except for dimethoate (40%), with relative standard deviations from 3 to16% in terms of repeatability, and from 6 to 19% in terms of reproducibility. …

Metals and Organochlorine Compounds in Fish from Latvian Lakes

1998

Organochlorines and metals have high toxicity and worldwide distribution in the aquatic environment. They are known to accumulate in sediments. In mollusks and fishes, they are bioconcentrated, even when released in minute quantities into the environment. This is important, as these chemicals have an adverse impact on species diversity, and accumulate in humans when seafood is consumed (Jaffar et al. 1988; Ruiter 1995). The nature and extent of accumulation and impact of persistent xenobiotics in water bodies depend on their sources; i.e. whether they are from industry, agricultural activities, transboundary transport with air masses (Sharif et al. 1993), geochemically determined elevated c…

Effect of an Acaricide on the Reproduction and Survival of Daphnia magna

1999

Daphnia magna feeding behavior after exposure to tetradifon and recovery from intoxication.

1999

Abstract The feeding behavior of the cladocera Daphnia magna subjected to a short-term exposure to the acaricide tetradifon (4-chlorophenyl 2,4,5-trichlorophenyl sulfone) was studied. The experiments were performed using the unicellular algae Nannochloris oculata at a density of 5×10 5 cells/ml as food for the organisms. In a first experiment, three generations (F0, F1, and F3) of the daphnids were exposed to sublethal levels of tetradifon (0.1, 0.18, 0.22, and 0.44 mg/l) and the effect of the toxicant on filtration and ingestion rates was determined. Rates of filtration and ingestion of D. magna declined in the three generations studied with increasing toxicant concentrations; however, tox…