Search results for "Chlorin"
showing 10 items of 374 documents
Prenatal exposure to organochlorine compounds and lung function during childhood
2019
Introduction: Prenatal exposure to organochlorine compounds (OCs) can increase the risk of reported respiratory symptoms in children. It remains unclear whether these compounds can also impact on lung function. We assessed the association between prenatal exposure to OCs and lung function during childhood. Methods: We included 1308 mother-child pairs enrolled in a prospective cohort study. Prenatal concentrations of p,p′-dichlorodiphenyltrichloroethane [p,p′-DDT], p,p′-dichlorodiphenyldichloroethylene [p,p′-DDE], hexachlorobenzene [HCB], and seven polychlorinated biphenyls [PCBs] were measured in cord blood. Spirometry was performed in the offspring at ages 4 (n = 636) and 7 years (n = 1192…
New potentially cytotoxic thiolatogold(I) complexes of 1,1′-bis(diphenylphosphino)ferrocene
1996
Abstract 1,1′-Bis[chlorogold(I) diphenylphosphino] ferrocene (1) was chosen as the starting material to synthesize new thiolato gold(I) complexes. This has been achieved by substituting the chlorine atoms by monofunctional and bifunctional thiolates affording ‘open’ thiolatogold complexes and trimetallic ferrocenophane-type structures, respectively. The new 1,1′-bis(2,6-dithia-1-phosphanyl)ferrocene (7) containing directly linked P and S atoms was also prepared but no gold complex was obtained. Compound 2 crystallizes in the monoclinic space group P21/n with a=10.2632), b=21.064(4), c=16.259(3) A , β=97.06(2)° and V=3.488(1) A 3 . The distance between the two gold atoms (3.06 A) indicates a…
Mass spectra of halogenated esters. Part IX—methyl esters of 2-butenoic acids containing chlorine and/or bromine atom(s)
1990
The electron impact mass spectra of methyl esters of chloro-, bromo-, dichloro-, bromochloro- and dibromo-2-butenoic acids (13 esters at all) have been investigated. Generally, the peaks due to the following fragments are abundant: M+·, [M OCH3]+, [M CH3OH]+·, [M X]+, [M OCH3 CO]+ or [M COOCH3]+, [M X CH3OH]+ or [M OCH3 HX]+, [M OCH3 CO HX]+, [M OCH3 X X]+ and [M OCH3 CO X X]+. Characteristic for the 2- and 4-halo isomers are the primary losses of a methyl radical and methanol, and for the 3-halo isomers the loss of X· from M+·. Disparities between the spectra of the E and Z isomers are shown, the effect of position of halogen substitution being much more pronounced, as reported previously …
Isomer Distribution and Interconversion in Cationic Allylpalladium(II) Complexes with 2-(Iminomethyl)pyridine Ligands
1997
The complexes [Pd(η3-allyl)(N-N‘)]ClO4 [allyl = 2-butenyl or 3-methyl-2-butenyl, N-N‘ = C5H3(6-R)N-2-CHNR‘ (R = H, R‘ = Me, CMe3, C6H4OMe-4; R = Me, R‘ = C6H4OMe-4) and C5H4N-2-CH2NMe2] are present in solution with different isomers, the structures of which may be assigned by an 1H NMR criterion based on chemical shift changes of the pyridine H(6) and/or of the allylic methyl protons, as confirmed also by 2D 1H NMR spectra. The isomer distribution depends mainly on the steric requirements of both the allyl and N-N‘ ligands: for [Pd(η3-3-methyl-2-butenyl)(N-N‘)]ClO4 the predominant isomer (ca. 100%) has a structure with the allylic methyl groups cis to the coordinated pyridine nitrogen when…
Gas chromatography of homologous esters
1984
Abstract The gas chromatographic retention behaviour of the propanoyl and monochloropropanoyl esters of saturated C3C5 branched-chain and unsaturated C3C6 alcohols on SE-30 and OV-351 capillary columns at several temperatures is reported. Retention index increments at 80 and 120°C show the effect of branching in the alkyl chain and also the effect of unsaturation and of its position in the chain with chlorination at the two possible positions in the acyl chain. The various incremental effects are discussed and compared with the behaviour of the corresponding n-alkyl esters.
Substituent effects of1H NMR parameters of chlorinated diphenyl ethers. A statistical approach
1994
The 1H NMR spectra of 64 polychlorinated diphenyl ethers (PCDEs) were measured and assigned. Multiple linear regression analysis was used to estimate the effects of chlorine atoms on the 1H NMR chemical shifts and coupling constants. The ‘simple sum rules’ were found to be inadequate for the prediction of 1H NMR chemical shifts of PCDEs. Therefore, corrective terms of two chlorine atoms were taken into account. The most important effects on chemical shifts were shown to be the steric interactions of two adjacent chlorine atoms and the intramolecular ring current effect observed in the ortho-proton of tri-ortho-substituted PCDEs. The substituent effects on J(HH) coupling constants were found…
Substituent effects on13C NMR parameters of chlorinated diphenyl ethers. A multiple linear regression analysis
1995
13C NMR chemical shifts and nJ(C,H) coupling constants of polychlorinated diphenyl ethers (PCDEs) were measured and analysed. The chlorine substituent effects on the chemical shifts and the coupling constants were determined by a multiple linear regression analysis. The 13C NMR chemical shifts depend on the conformational preferences in PCDEs. In addition to single substituent effects, corrective terms reflecting the conformational state of the molecule and the mutual steric interactions of two chlorine atoms had to be taken into account for the reliable prediction of the 13C chemical shifts. In contrast to chemical shifts, conformational effects play a minor role in the substituent effects…
Occurrence of priority pollutants in WWTP effluents and Mediterranean coastal waters of Spain
2011
A comprehensive study aimed at evaluating the occurrence, significance of concentrations and spatial distribution of priority pollutants (PPs) along the Comunidad Valenciana coastal waters (Spain) was carried out in order to fulfil the European Water Framework Directive (WFD). Additionally, PP concentrations were also analysed in the effluent of 28 WWTPs distributed along the studied area. In coastal waters 36 organic pollutants of the 71 analysed, including 26 PPs were detected although many of them with low frequency of occurrence. Only 13 compounds, which belong to four different classes (VOCs, organochlorinated pesticides, phthalates and tributyltin compounds (TBT)) showed a frequency o…
Confirmation of in situ exposure of fish to secondary treated bleached-kraft mill effluent using a laboratory simulation
1998
To corroborate the responses in whitefish (Coregonus Iavaretus L.) exposed to elemental chlorine free (ECF) bleached-kraft pulp mill effluent (BKME) in situ, a 30-d laboratory exposure was carried out at concentrations simulating the field conditions. The flow-through exposures were conducted at four secondary (activated sludge) treated effluent (STE) concentrations: 1.3, 2.3, 3.5, and 7%. To evaluate the role of the secondary treatment, fish were also exposed to one concentration (3.5%) of pretreated effluent (PTE) from the mill. Compared to the control, whitefish liver 7-ethoxyresorufin-O-deethylase (EROD) activity was twofold in fish exposed to 3.5% STE, which was similar to monooxygenas…
A time course investigation of vitamin A level and lipid composition of the liver endoplasmic reticulum in rats following treatment with congeneric p…
1990
Abstract The drug metabolizing enzyme activities, the vitamin A content and the fatty acid composition in the endoplasmic reticulum membrane were studied in rat liver after a single injection of the polychlorobiphenyls (PCBs) 3,3′,4,4′-tetrachlorobiphenyl [(3,4)2Cl] or 2,2′,4,4′,5,5′-hexachlorobiphenyl [(2,4,5)2Cl], 300 μ mol/kg each. The microsomal vitamin A level was markedly lowered 3 days after treatment with (3,4)2Cl, a coplanar type inducer of cytochrome P-450. A marked increase in microsomal AHH and UDPGT activities occurred within 3 days after injection of (3,4)2Cl whereas (2,4,5,)2Cl treatment enhanced APDM activity only. Arachidonic, stearic and linoleic acid microsomal contents w…