Search results for "hexane"

Über Arsen‐haltige Heterocyclen, I. Molekül‐ und Kristallstruktur von 2‐Chlor‐1,3,6,2‐trithiarsaocan

1974

Die Struktur der Titelsubstanz (2) wurde rontgenographisch aus Diffraktometer-Einkristalldaten bestimmt und bis zu einem konventionellen R von 0.037 verfeinert. Der 8-Ring hat eine deformierte Wannenform mit transannularer 1,5-AsS-Annaherung. 2 ist dissymmetrisch, der wechselseitige Ubergang zwischen den beiden Spiegelbildisomeren wird besprochen. Die Koordination am As-Atom ist ψ-trigonal-bipyramidal mit axialen Abstanden AsCl 2.36 A, AsS 2.72 A und aquatorialen Abstanden AsS 2.25 und 2.26 A. Bekannte AsS-Abstande und Koordinationen werden diskutiert und Standardwerte fur AsS- und SbS-Abstande verschiedenen Bindungstyps ermittelt. 2 bildet ein Modell fur die Blockierung von Enzym-Proteinen…

The Interplay of Hydrogen Bonding and Multiple Metal Binding – A New Cyclic Polyaminopolyalcohol Ligand as Building Block for the Construction of Mic…

2011

Cyclohexane-based polyaminopolyalcohols (PAPAs) such as 1,3-diamino-1,2,3-trideoxy-cis-inositol (daci) have been prepared by hydrogenation of suitable aromatic precursors. The pentanuclear complex [Cu5(daci)4(H–2daci)2](SO4)3·18H2O (C3) revealed antiferromagnetic and ferromagnetic interactions between the CuII centers with an S = 3/2 ground state. The microporous structure of C3 exhibited a dehydration/rehydration reaction with an entirely amorphous dehydrated phase at 150 °C and a completely reversible rehydration process at 30 °C. The potential of PAPA ligands for forming polynuclear complexes and supramolecular, hydrogen-bonded networks is discussed.

First Crystallographic Investigation of Complexes of cis-VO2+, cis-MoO22+, and trans-UO22+ Species with Schiff-Base Molecules Derived from 4,6-O-Ethy…

2001

The interaction of Schiff-base ligands derived from 4,6-O-ethylidene-β-D-glucopyranosylamine with cis-VO 2 + , cis-MoO 2 2+ , and trans-UO 2 2+ species have been studied by isolating and characterizing the corresponding products. The structures of one complex of each type of species have been established by single-crystal X-ray diffraction analysis. In all the complexes, the saccharide moiety adopts a chair conformation and has a β-anomeric form. A gradual increase in coordination number (5, 6, and 7) and a gradual variation in the geometry (distorted trigonal-bipyramidal, distorted octahedral, and pentagonal-bipyramidal) are observed on going from the complexes of cis-VO 2 + (mononuclear) …

Crystal structure of the layered inorganic-organic hybrid material bis(trans-cyclohexane-1,4-diammonium) hexabromidorhodate(III) bromide monohydrate,…

2014

C12H34Br7N4ORh, monoclinic, P21/c (no. 14), a = 11.3677(5) Å, b = 11.4644(5) Å, c = 19.0407(9) Å, β = 92.443(4)°, V = 2479.2 Å3, Z = 4, Rgt(F) = 0.0290, wRref(F2) = 0.0578, T = 295 K.

Synthesis and stereochemistry of some new derivatives of cis-dihydropinol

1999

Abstract The synthesis of four new derivatives of cis-hydroxy-cis-dihydropinol with allyl-, epoxyalkyl-, hydroxyalkyl- and ketoalkyl-groups substituted on the cyclohexane ring is presented. The cis-orientation of hydroxyl group at C-2 and the configuration of all stereogenic centers is confirmed by X-ray crystallography.

Sulphides of the platinum group elements—12. Bis(tetraphenylphosphonium) pentakaidekakissulphido platinates(IV)

1991

Abstract Synthetic routes to tetraphenylphosphonium salts of [PtSx]2− are outlined, where x = 15 or 18. Generally, (PPh4)2[Pt(S5)3] is formed most readily. The compound [(C6H5)4P]2[PtS15], always solvated, has been obtained by synthesis in acetonitrile (sulphur, triethylamine, H2S and [PPh4]2[PtCl6]) and by metathesis (in DMF) from the known hydrated ammonium compound (NH4)2[Pt(S5)3]2H2O+2[Ph4P]Br→(Ph4P)2[Pt(S5)3]· DMF+2NH4Br, and from the dismutation (in acetone) 3PtS172−→PtS152−+2PtS182−. X-ray diffraction shows that crystals obtained from DMF and acetone are the solvated salts [Ph4P]2· [Pt(S5)3]· S, with solvent molecules (S) uncoordinated. In both, the three platinopentathian rings rela…

PERSISTENCE OF SOME PESTICIDES IN THE AQUATIC ENVIRONMENT

1992

Toxicity of lindane, atrazine, and deltamethrin to early life stages of zebrafish (Brachydanio rerio).

1990

Fertilized eggs of zebrafish were exposed under flow-through conditions to several concentrations of the following pesticides: lindane 40, 80, 110, 130, and 150 micrograms/liter; atrazine 300, 1300, and 9100 micrograms/liter; deltamethrin 0.5, 0.8, and 1.2 micrograms/liter. Hatching, abnormalities in development (external deformations, edema, etc.), and mortality were recorded over a period of 35 days. At the end of the experiment, the body lengths of the fish were measured. Survival of juvenile fish after 35 days was reduced by increasing concentrations of all xenobiotics tested: lindane enhanced the mortality from 110 micrograms/liter and atrazine from 1300 micrograms/liter, and deltameth…

Chemical oxidation and reduction of hexachlorocyclohexanes: A review

2019

Abstract Lindane (γ-hexachlorocyclohexane) and its isomers (HCH) are some of the most common and most easily detected organochlorine pesticides in the environment. The widespread distribution of lindane is due to its use as an insecticide, accompanied by its persistence and bioaccumulation, whereas HCH were disposed of as waste in unmanaged landfills. Unfortunately, certain HCH (especially the most reactive ones: γ- and α-HCH) are harmful to the central nervous system and to reproductive and endocrine systems, therefore development of suitable remediation methods is needed to remove them from contaminated soil and water. This paper provides a short history of the use of lindane and a descri…

Assessment of Organochlorine Pesticide Residues in West African City Farms: Banjul and Dakar Case Study

2003

Validated analytical procedures for the determination of 21 organochlorine pesticides have been applied to 74 water samples, 76 soil samples, and 160 vegetable samples from nine Sene-Gambian farms. Mean pesticide residue levels found were compared to the results of other studies. The main contaminants were DDTs in water (231.9 ng/L), in soil (71.4 ng/g), and in vegetables (5.03 ng/g). The distribution of pesticide residues in water and neighboring soils and the soil-plant transfer of these pesticides is briefly discussed. Different bioconcentration factors for sum HCHs, sum DDTs, and sum endosulfans obtained in this study allow us to confirm the complex processes already reported in the lit…