Search results for "Dimethylamine"
showing 10 items of 34 documents
CCDC 907670: Experimental Crystal Structure Determination
2013
Related Article: Jochen Körber, Stefan Löffler, Dieter Schollmeyer, Udo Nubbemeyer|2013|Synthesis|45|2875|doi:10.1055/s-0033-1338519
Ion–Molecule Rate Constants for Reactions of Sulfuric Acid with Acetate and Nitrate Ions
2022
Atmospheric nucleation from precursor gases is a significant source of cloud condensation nuclei in the troposphere and thus can affect the Earth's radiative balance. Sulfuric acid, ammonia, and amines have been identified as key nucleation precursors in the atmosphere. Studies have also shown that atmospheric ions can react with sulfuric acid to form stable clusters in a process referred to as ion-induced nucleation (IIN). IIN follows similar reaction pathways as chemical ionization, which is used to detect and measure nucleation precursors via atmospheric pressure chemical ionization mass spectrometers. The rate at which ions form clusters depends on the ion-molecule rate constant. Howeve…
Determination of aliphatic amines in water by liquid chromatography using solid-phase extraction cartridges for preconcentration and derivatization
2001
Bond Elut C18 solid-phase extraction cartridges were used for preconcentration and pre-column derivatization with 3,5-dinitrobenzoyl chloride (DNB) of aliphatic amines in water. Conditions for analyte preconcentration and derivatization (including the volume of sample, concentration of reagent, time of reaction and pH) were investigated, using ethylamine, isopropylamine and dimethylamine as model compounds. On the basis of these studies, a rapid and sensitive method for the determination of aliphatic amines in water is presented. The analytes are retained and purified on the cartridges and then derivatized and desorbed by drawing in succession the DNB solution and acetonitrile. The collecte…
Effect of antibodies against cytochrome P-450 on demethylation and denitrosation of N-nitrosodimethylamine and N-nitrosomethylaniline.
1988
Rat liver microsomes which were induced either with ethanol or PB were incubated with NDMA or NMA. Formaldehyde generation and nitrite formation were measured as metabolic parameters for oxidative bioactivation and denitrosation, respectively. The influence of antiserum PB3a1 and PB22 containing antibodies against the corresponding cytochrome P-450 species on both metabolic functions was investigated. The results showed that the influence on formaldehyde production and denitrosation varied independently in that both parameters were either not affected, or influenced in an opposite way, or inhibited to a different degree. Especially remarkable was the 80% inhibition of formaldehyde generatio…
Enthalpies of transfer of pentanol from water to sodium dodecylsulfate-dodecyl-dimethylamine oxide-water mixtures
1994
At a given surfactant-surfactant ratio, the enthalpies of transfer ΔH (W→W+S) of pentanol 0.03m from water to sodium dodecylsulfate (NaDS)-dodecyldimethylamine oxide-water mixtures as functions of the surfactants mixture concentration (m t) were determined. ForX NaDS=0.9, ΔH (W→W+S) increases monotonically withm t such as observed for pure surfactants. ForX NaDS=0.12 and 0.3, ΔH (W→W+S) increases withm t up to 0.12m beyond which it decreases withm t. AtX NaDS=0.6, two monotonic curves can be distinguished in the ΔH (W→W+S)vs. m t trend. Experimental data were fitted through an equation previously reported for additives in pure surfactants derived by assuming the pseudo-phase transition mode…
A study on the fragmentation of sulfuric acid and dimethylamine clusters inside an atmospheric pressure interface time-of-flight mass spectrometer
2022
Abstract. Sulfuric acid and dimethylamine vapours in the atmosphere can form molecular clusters, which participate in new particle formation events. In this work, we have produced, measured, and identified clusters of sulfuric acid and dimethylamine using an electrospray ionizer coupled with a planar-differential mobility analyser, connected to an atmospheric pressure interface time-of-flight mass spectrometer (ESI–DMA–APi-TOF MS). This set-up is suitable for evaluating the extent of fragmentation of the charged clusters inside the instrument. We evaluated the fragmentation of 11 negatively charged clusters both experimentally and using a statistical model based on quantum chemical data. Th…
The effect of N-tetradecyl-N,N-dimethylamine oxide micelles on the kinetics of the electron transfer reaction of Ce(IV) with substituted malonic acids
2009
Abstract The kinetics of the oxidation of malonic acid and (its substituted compounds, methyl-, ethyl-, butyl- and benzyl-malonic acid) by ceric ions has been studied at 20.0 °C in the absence and the presence of the surfactant N-tetradecyl-N,N-dimethylamine oxide (C 14 DMAO). The addition of increasing amounts of C 14 DMAO influences the rate of the redox process to an extent that significantly depends on the hydrophobicity of the reducing species. The reactivity data together with the estimated binding constants and the standard transfer free energies of the malonic acids from water to the micelles suggest that the malonic acid is confined to the aqueous pseudo-phase while for the other s…
Synthesis and inhibitory activity of dimethylamino-chalcone derivatives on the induction of nitric oxide synthase.
2002
A series of nine dimethylamino-chalcone derivatives (1,3-diaryl-propenones) was synthesized and screened as potential inhibitors of NO and PGE(2) production in the RAW 264.7 macrophage cell line. 4-Dimethylamino-2',5'-dimethoxychalcone (6) was found to be the most potent and dual inhibitor (IC(50s) in the submicromolar range) of NO and PGE(2) production. 2',6'-Dimethoxylation appeared to be an effective requirement for selective and potent inhibition of nitric oxide synthase induction as it was confirmed by Western blot analysis. Chalcone (6) at 25 mg kg(-1) by oral route, inhibited significantly the formation of oedema in the carrageenan-induced model of inflammation in mice.
Liquid chromatographic determination of aliphatic amines in water using solid support assisted derivatization with 9-fluorenylmethyl chloroformate
2002
A simple and sensitive method has been developed for the liquid chromatographic determination of short-chain aliphatic amines in water. Analytes are retained in solid-phase extraction (SPE) cartridges, and then derivatized by drawing an aliquot of the fluorogeneic reagent 9-fluorenylmethyl chloroformate (FMOC) through the cartridges. After a certain reaction time the derivatives formed are desorbed with acetonitrile. The collected extracts are then chromatographed on a LiChrospher 100 RP18 125 mm×4 mm i.d., 5 μm, column using an acetonitrile-water gradient. The influence of experimental conditions (SPE material, volume of sample, concentration of FMOC, time of reaction and pH) has been inve…
Determination of DNA single strand breaks and selective DNA amplification by N-nitrodimethylamine and analogs, and estimation of the indicator cells'…
1986
N-nitrodimethylamine is metabolized oxidatively to N-nitrohydroxymethylmethylamine, which decomposes to yield formaldehyde and N-nitromethylamine. All four compounds and N-nitromethylamine were tested for their ability to induce DNA single strand breaks in hepatocytes and in SV 40-transformed Chinese hamster embryo cell lines. Only the two monoalkylnitramines were positive. They induced single strand breaks in hepatocytes, but were not effective in the other cells. Formaldehyde and N-nitrohydroxymethylmethylamine were toxic to the cells. None of the compounds tested was able to induce selective DNA amplification in the two transformed cell lines. Enzymes involved in drug metabolism were ass…