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Methylene Chloride (methylene + chloride)
Selected AbstractsChemInform Abstract: A New Entry to 1,5-Keto Esters and Their 4,4-Dideuterio Derivatives via Methylene Chloride as "Methylene Dianion" Equivalents.CHEMINFORM, Issue 42 2008Kuo-Wei Lin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A rapid and simple method for determination of halothane, iso,urane and sevo,urane in blood using gas chromatographyBIOMEDICAL CHROMATOGRAPHY, Issue 9 2004Richard J. Atherley Abstract We have developed a technique to determine the concentration of volatile anesthetics (halothane, iso,urane and sevo,urane) in blood that is a modi,cation of a method used for volatile anesthetics in Krebs solution. Methylene chloride was the internal standard and chloroform was used to extract the volatile anesthetic from blood. The congealed blood proteins were separated from the chloroform solvent (containing anesthetic) using a two-compartment vial that ,ltered out the proteinaceous material during centrifuging. Recovery averaged 102%. Linearity was excellent (r = 0.992,0.999) in the 50,600, 50,300 and 50,300 µg/mL range for halothane, iso,urane and sevo,urane, respectively. Intra-day and inter-day precisions were likewise excellent, with relative standard deviations <5.3 and <7.1%, respectively. Accuracy ranged from 0.8 to 9.5% of the estimated theoretical value. Extracted anesthetic in chloroform solvent was stable over 4,5 days, with <3% variability. The time from obtaining the blood sample to determination of the concentration from the chromatographic peak was 15 min or less. Copyright © 2004 John Wiley & Sons, Ltd. [source] Crystal growth, morphology, spectrographic characterization and thermal properties of 4,5-bis(benzoylthio)-1,3-dithiole-2-thioneCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2008Xinqiang Wang Abstract Single crystals of 4,5-bis(benzoylthio)-1,3-dithiole-2-thione (BBDT), were grown from methylene chloride and the growth morphology was deduced by the Bravais,Friedel Donnay,Harker (BFDH) model. The grown crystals were characterized by optical absorption, infrared, Raman and X-ray powder diffraction spectroscopy. The thermal behavior of BBDT has been investigated by means of thermogravimetric analysis and differential thermal analysis measurements in air. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Characterization and uncertainty analysis of VOCs emissions from industrial wastewater treatment plantsENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2010Kaishan Zhang Abstract Air toxics from the industrial wastewater treatment plants (IWTPs) impose serious health concerns on its surrounding residential neighborhoods. To address such health concerns, one of the key challenges is to quantify the air emissions from the IWTPs. The objective here is to characterize the air emissions from the IWTPs and quantify its associated uncertainty. An IWTP receiving the wastewaters from an airplane maintenance facility is used for illustration with focus on the quantification of air emissions for benzyl alcohol, phenol, methylene chloride, 2-butanone, and acetone. Two general fate models, i.e., WATER9 and TOXCHEM+V3.0 were used to model the IWTP and quantify the air emissions. Monte Carlo and Bootstrap simulation were used for uncertainty analysis. On average, air emissions from the IWTP were estimated to range from 0.003 lb/d to approximately 16 lb/d with phenol being the highest and benzyl alcohol being the least. However, emissions are associated with large uncertainty. The ratio of the 97.5th percentile to the 2.5th percentile air emissions ranged from 5 to 50 depending on pollutants. This indicates point estimates of air emissions might fail to capture the worst scenarios, leading to inaccurate conclusion when used for health risk assessment. © 2009 American Institute of Chemical Engineers Environ Prog, 2010 [source] Effect of thermal treatment of incubated potato juice on the formation of Maillard volatilesINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2003Stephen J. Davids Summary Potato juice samples, obtained from potatoes stored at different temperatures (0,24 °C) and times (8,20 weeks), were incubated (45,57 °C for 42 h) with or without commercial proteases. The samples were then used for thermal browning experiments by placing in either a heated oven at 125 °C overnight or in an autoclave at 132 or 121 °C for 1 h, these experiments promoted the occurrence of the Maillard reaction. After the heat treatment step, all samples were extracted with methylene chloride and analysed by gas chromatography/mass spectrometry. The data indicated that, by subjecting the potato juice to thermal treatments, a wide variety of volatiles generated by the Maillard were produced and these are known to be associated with specific flavour notes, examples are alkyl and acetyl pyrazines, piperazinediones, furans and pyrroles. These findings suggest that the study of potato juice extract as a new medium for flavour development, in particular in those applications which presently use malt, coffee, soybean, meat and yeast extracts, is a worthwhile endeavour. [source] Cuticular hydrocarbons on elytra of the Diaprepes root weevil Diaprepes abbreviatus (L.) (Coleoptera: Curculionidae)AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 4 2004Stephen L. Lapointe Abstract 1,External gland openings and associated structures on the elytra of teneral and mature Diaprepes root weevils, Diaprepes abbreviatus (L.), were elucidated by scanning electron microscopy (SEM). 2,There were clear differences between teneral, callow adults and fully mature adults. In the field, teneral adults remain in the pupal chamber in the soil until sclerotization of the cuticle is complete or nearly so. 3,Phenotypic variation of the elytra in this species consists of varying patterns and coloration of scaled intervals between a variable number of raised ridges devoid of scales. In addition to being thinner and lighter in colour than fully mature adults, the elytra of teneral adults were devoid of waxy hydrocarbon secretions. 4,External gland openings at the base of each scale were observed on teneral elytra and mature elytra washed with methylene chloride. 5,SEM evidence to document the production of waxy filaments by these glands and partial characterization of these by gas chromatography and mass spectrometry are presented. [source] Development of a Simple and Low-Cost Enzymatic Methodology for Quantitative Analysis of Carbamates in Meat Samples of Forensic InterestJOURNAL OF FORENSIC SCIENCES, Issue 3 2010Bruno Duarte Sabino Ph.D. Abstract:, Foods contaminated with a granulated material similar to Temik (a commercial pesticide formulation containing the carbamate insecticide aldicarb) are often involved in accidental ingestion, suicides, and homicides in Brazil. We developed a simple technique to detect aldicarb. This technique is based on the inhibition of a stable preparation of the enzyme acetylcholinesterase, and it is specially adapted for forensic purposes. It comprises an initial extraction step with the solvent methylene chloride followed by a colorimetric acetylcholinesterase assay. We propose that results of testing contaminated forensic samples be expressed in aldicarb equivalents because, even though all other carbamates are also potent enzyme inhibitors, aldicarb is the contaminant most frequently found in forensic samples. This method is rapid (several samples can be run in a period of 2 h) and low cost. This method also proved to be precise and accurate, detecting concentrations as low as 40 ,g/kg of aldicarb in meat samples. [source] Synthesis of new proton-ionizable crown ether compounds containing substituted lh-pyridin-4-one subcyclic unitsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2001Peter Huszthy Five novel pyridono-18-crown-6 (10-14) and two new benzyloxy-substituted pyridino-18-crown-6 (15 and 16) ligands have been prepared. By the catalytic hydrogenative removal of the benzyl group from the benzyloxy moiety at position 4 of the pyridine ring of 15 and 16, pyridono-18-crown-6 ethers 5 and 12 were obtained. These ligands were transformed to their 3,5-dibromo (10 and 13) and 3,5-dinitro derivatives (11 and 14) by treatment with bromine in methylene chloride and nitric acid in acetic anhydride, respectively. The latter proton-ionizable crown ethers have pKavalues of about 7.5 for 10 and 13 and 4.5 for 11 and 14. Thus, they are good candidates for complexation and proton-coupled transport of selected cations. [source] Encapsulation and Stabilization of Photo-Sensitive Antioxidants by Using Polymer Microcapsules with Controlled Phase HeterogeneityMACROMOLECULAR RAPID COMMUNICATIONS, Issue 6 2008Bo-Mi Koo Abstract We describe a robust method for both encapsulating and stabilizing photo-sensitive antioxidants in polymer microcapsules prepared by a water-in-oil-in-water double emulsification and evaporation technique, in which a volatile solvent from the oil layer consisting of poly(methyl methacrylate) and methylene chloride is gradually removed. Using poly(ethylene glycol) (PEG) in this study, we demonstrate that control over its molecular weight allows to tune the phase property of the capsule wall; introducing PEG with high molecular weight results in increased heterogeneity. The heterogeneity of the capsule walls displays an ability to effectively block sunlight, which is essential for improving the molecular stability of photo-sensitive antioxidants. In this study, we experimentally confirm this by observing natural sunlight-driven molecular decomposition of a model antioxidant, riboflavin-5,-phosphate, in poly (methyl methacrylate) microcapsules. [source] Synthesis of 5-fluoroalkyl lsoxazolidines via 1,3-dipolar cycloaddition of ethyl 2-hydropolyfluoroalk-2-enoates with nitrones,CHINESE JOURNAL OF CHEMISTRY, Issue 9 2004Jin-Tao Liu Abstract 1,3-Dipolar cycloaddition reactions of ethyl 2-hydropolyfluoroalk-2-enoates (1) with some nitrones were described. The reaction of 3,4-dihydroisoquinoline N-oxide (2) with 1 took place readily in methylene chloride at room temperature to give the corresponding 5-fluoroalkylisoxazolidines regioselectively as a mixture of two diastereoisomers (trans and cis) in high yields, while longer reaction time and higher temperature were needed in the case of non-cyclic nitrones. Under similar conditions the reaction of quinoline N-oxide (14) with 1 did not give the expected adducts and a ring-opening product was obtained. [source] Synthesis of some new fused coumarin derivativesCHINESE JOURNAL OF CHEMISTRY, Issue 4 2000El-Deen Ibrahim Mohey Abstract 2-Hydrazino-4-hydroxy-5H -[1]-benzopyrano-[4,3-d]-pyrimidin-5-one (3) was prepared via condensation of 2 with hydrazine hydrate. Treatment of 3 with methylene chloride, ethyl chloroformate, ethyl chloroacetate and benzaldehyde yielded the corresponding 2 - ( substituted ) hydrazino - 4 -hydro-xy-5H -[1]-benzopyrano-[4,3-d]-pyrimidin-5-one (4, 5, 6, and 10), followed by cyclization of 4, 5 and 6 with dimethyl formamide and fused sodium acetate under reflux, while compound 10 was cyclized with bromine and sodium acetate in acetic acid. Compound 3 reacted with ,-(toloyl) acrylic acid, ethyl ,-cyano- p -methoxycinnamate, diethyl malonate and acetyl chloride affording the corresponding 2-(substituted) hydrazino-4-hydroxy-5H -[1]-benzopyrano-[4,3-d]-pyrimidin-5-one (12, 13, 14, 15 and 16). [source] | ||||||||||