The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
N. Balasubramanian - One of the best experts on this subject based on the ideXlab platform.
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Spectrophotometric determination of Hydrazine
Talanta, 2007Co-Authors: Mary George, K. S. Nagaraja, N. BalasubramanianAbstract:Abstract Hydrazine is determined spectrophotometrically by forming the derivative 2,4-dinitrophenylHydrazine from 2,4-dinitrochlorobenzene. The formed dinitro derivative undergoes condensation reaction to form the hydrazone with p-dimethylaminobenzaldehyde (p-DAB). The resulting yellow colored product is stable in acidic medium and has a maximum absorption at 458 nm. The colour system obeys Beer's law in the range 0–7 μg of Hydrazine in an overall volume of 25 mL. The molar absorptivity is calculated to be 8.1 × 104 L mol−1 cm−1 with a correlation coefficient of 0.998. The relative standard deviation is 1.7% (n = 10) at 6 μg of Hydrazine. Interferences due to foreign ions have been studied and the method has been applied for the determination of Hydrazine in boiler feed water.
G.j. Van Esch - One of the best experts on this subject based on the ideXlab platform.
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Maleic hydrazide, carcinogenicity study in rats.
Toxicology, 2002Co-Authors: C.a. Van Der Heijden, Johanna M. Garbis-berkvens, Engelina M. Den Tonkelaar, G.j. Van EschAbstract:Abstract The carcinogenicity of maleic hydrazide is discussed by several national and international organizations because of contradictory results of a number of carcinogenecity studies carried out in the past. Because maleic hydrazide is used in agriculture on edible crops, an oral carcinogenicity study with rats was carried out for 28 months at dietary levels of 0, 1.0 and 2.0% maleic hydrazide which contained less than 1.5 mg Hydrazine/kg product as impurity. In this study as well as in an experiment with mice carried out with the same batch of maleic hydrazide at the International Agency for Research on Cancer (IARC) in Lyon, France, treatment did not affect tumour incidence and it was concluded that maleic hydrazide itself is not a carcinogen. Most likely the presence of relatively high levels of Hydrazine as an impurity was responsible for the contradictory results in studies as reported previously. Furthermore the results of this study showed that 1.0 and 2.0% maleic hydrazide in the diet caused proteinuria and increased protein/creatinine ratio's in the urine in both sexes without detectable histopathological changes in kidney or urinary tract. From this study, based on the effects of kidney function the “no-toxic” effect level is considered to be lower than 1.0% maleic hydrazide in the diet of rats.
Shigeru Nagase - One of the best experts on this subject based on the ideXlab platform.
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Hydrazine and thermal reduction of graphene oxide reaction mechanisms product structures and reaction design
Journal of Physical Chemistry C, 2010Co-Authors: Joonkyung Jang, Shigeru NagaseAbstract:The density functional theory method (M05-2X/6-31G(d)) was used to investigate reaction mechanisms for deoxygenation of graphene oxides (GOs) with Hydrazine or heat treatment. Three mechanisms were identified as reducing epoxide groups of GO with Hydrazine as a reducing agent. No reaction path was found for the Hydrazine-mediated reductions of the hydroxyl, carbonyl, and carboxyl groups of GO. We instead discovered the mechanisms for dehydroxylation, decarbonylation, and decarboxylation using heat treatment. The Hydrazine de-epoxidation and thermal dehydroxylation of GO have opposite dependencies on the reaction temperature. In both reduction types, the oxygen functionalities attached to the interior of an aromatic domain in GO are removed more easily, both kinetically and thermodynamically, than those attached at the edges of an aromatic domain. The Hydrazine-mediated reductions of epoxide groups at the edges are suspended by forming hydrazino alcohols. We provide atomic-level elucidation for the deoxyge...
Mary George - One of the best experts on this subject based on the ideXlab platform.
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Spectrophotometric determination of Hydrazine
Talanta, 2007Co-Authors: Mary George, K. S. Nagaraja, N. BalasubramanianAbstract:Abstract Hydrazine is determined spectrophotometrically by forming the derivative 2,4-dinitrophenylHydrazine from 2,4-dinitrochlorobenzene. The formed dinitro derivative undergoes condensation reaction to form the hydrazone with p-dimethylaminobenzaldehyde (p-DAB). The resulting yellow colored product is stable in acidic medium and has a maximum absorption at 458 nm. The colour system obeys Beer's law in the range 0–7 μg of Hydrazine in an overall volume of 25 mL. The molar absorptivity is calculated to be 8.1 × 104 L mol−1 cm−1 with a correlation coefficient of 0.998. The relative standard deviation is 1.7% (n = 10) at 6 μg of Hydrazine. Interferences due to foreign ions have been studied and the method has been applied for the determination of Hydrazine in boiler feed water.
Herbert Mayr - One of the best experts on this subject based on the ideXlab platform.
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Nucleophilic Reactivities of Hydrazines and Amines: The Futile Search for the α-Effect in Hydrazine Reactivities
The Journal of organic chemistry, 2012Co-Authors: Tobias A. Nigst, Anna Antipova, Herbert MayrAbstract:The kinetics of the reactions of amines, Hydrazines, hydrazides, and hydroxylamines with benzhydrylium ions and quinone methides were studied in acetonitrile and water by UV–vis spectroscopy, using conventional spectrometers and stopped-flow and laser-flash techniques. From the second-order rate constants k2 of these reactions, the nucleophilicity parameters N and sN were determined according to the linear free energy relationship log k2 = sN(N + E). While methyl groups increase the reactivities of the α-position of Hydrazines, they decrease the reactivities of the β-position. Despite the 102 times lower reactivities of amines and Hydrazines in water than in acetonitrile, the relative reactivities of differently substituted amines and Hydrazines are almost identical in the two solvents. In both solvents Hydrazine has a reactivity similar to that of methylamine. This observation implies that replacement of one hydrogen in ammonia by Me increases the nucleophilicity more than introduction of an amino group,...
