نتایج جستجو برای: hexamethylenetetramine bromine
تعداد نتایج: 2569 فیلتر نتایج به سال:
Sudden depletions of tropospheric ozone during spring were reported from the Arctic and also from Antarctic coastal sites. Field studies showed that those depletion events are caused by reactive halogen species, especially bromine compounds. However the source and seasonal variation of reactive halogen species is still not completely understood. There are several indications that the halogen mo...
Very short-lived brominated substances (VSLBr) are an important source of stratospheric bromine, an effective ozone destruction catalyst. However, the accurate estimation of the organic and inorganic partitioning of bromine and the input to the stratosphere remains uncertain. Here, we report near-tropopause measurements of organic brominated substances found over the tropical Pacific during the...
A new, high yielding method for the preparation of vasicinone (7) is described. Reaction of 2-nitrobenzoic acid with N, N¢-carbonyldiimidazole followed by 2-pyrrolidinone gave 1-(2-nitrobenzoyl)pyrrolidine-2-one (3). Reduction of the latter with 10% Pd-C afforded deoxyvasicinone (4). Reaction of deoxyvasicinone (4) with bromine yielded monobromo-deoxyvasicinone (5). Exchange of bro...
Bromine may act as a catalyst for recombination of ozone and could be more efficient than either nitric oxide or chlorine. The lower atmosphere contains small concentrations of gaseous bromine produced in part by marine activity, in part by volatilization of particulate material released during the combustion of leaded gasoline, with an additional contribution due to the use of methyl bromide a...
The aim of the study was to establish influence a co-precipitation agent (i.e., NaOH–immediate precipitation; hexamethylenetetramine/urea–gradual precipitation and growth nanostructures) on properties catalytic activity as-synthesized Au-CeO2 nanocomposites. All catalysts were fully characterized with use XRD, nitrogen physisorption, ICP-OES, SEM, HR-TEM, UV-vis, XPS, tested in low-temperature ...
Hydroxy acid, oxidation, bromine The oxidation of glycollic, lactic, a-hydroxybutyric, and 2-phenyllactic acids by aque ous bromine has been studied. The reaction is of first order with respect to the oxidant and the anion of the hydroxy acid respectively. The active oxidising species is molecular bromine. The oxidation of ci,a-dideuterioglycollic acid indicated a kinetic isotope effect, ^h /^...
Lithium-air batteries have been considered as ultimate solutions for the power source of long-range electrified transportation, but state-of-the-art prototypes still suffer from short cycle life, low efficiency and poor power output. Here, a lithium-bromine rechargeable fuel cell using highly concentrated bromine catholytes is demonstrated with comparable specific energy, improved power density...
The metabolism of bromine in marine brown algae remains poorly understood. This contrasts with the recent finding that the accumulation of iodide in the brown alga Laminaria serves the provision of an inorganic antioxidant - the first case documented from a living system. The aim of this study was to use an interdisciplinary array of techniques to study the chemical speciation, transformation, ...
Due to its structure, hexamethylenetetramine (HMT) is a slowly biodegradable substance, hydrolysing in acid environment to ammonium and formaldehyde. Formaldehyde is toxic under normal conditions for biological treatment processes. Following an adaptation, a formaldehyde concentration of 1000 mg·l may become biodegradable both in aerobic and anaerobic conditions. Acidic conditions for hydrolysi...
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