Oxidation of bromide and iodide ions in acidic solutions in the presence of acetone forms the corresponding acetone derivatives. Iodate was reduced with thiosulfate prior to the determination. After extraction with benzene the bromo- and iodoacetone were measured by gas chromatography using electron capture detection. The bromide and iodide contents of rainwater, drinking water, river water, seawater, oil brine, common salt, cow milk, and human blood serum were determined. The relative standard deviations for bromide at 10(-7) M and for iodide at 10(-8) M concentration were 1.9% and 3.0%, respectively, using a 10-mL sample for the determination without preconcentration.
SynopsisThe rate of isomerization during the polyesterification of maleic acid or maleic anhydride depends on the structure of the glycol used: the longer the chain of the glycol, the lower the isomerization rate. The rate constants differ greatly from one case to another. Thus, the difference in the reaction rate constants depends mainly on the steric effects caused by the different types of glycols used in the polycondensation. The isomerization approaches a constant value, ;which after a certain time depends on the structure of the glycol and the temperature of the condensation. The activation energies calculated from the rate constants would fall at about 20 f 4 kcal./mole. This value for the activation energy corresponds to that reported in the literature for the transformation of maleic acid into fumaric acid. The reaction apparently follows secondorder kinetics due to the catalytic effect of the maleic acid on the isomerization.
The intermediates in the permanganate oxidation of maleic and fumaric acids have been studied in acidic solutions, The accumulation and decay of manganese(ti1) has been demonstrated by the stopped-flow technique. The concomitant four-electron oxidation of the substrates leads to the formation of forrnyl( hydroxy)acetic acid. The subsequent reactions reveal a complex pattern in which hydroxymalonic. glyoxylic, and oxalic acid are further intermediates. The product distribution has been determined as a function of the pH and the mole ratio of the reactants. A reaction scheme is suggested which rationalises the observed behaviour. Sciences,
The kinetics of the oxidation of glyoxylic and pyruvic acids by periodate have been studied at pH 0-9 and 273-303 K. The kinetics are second order, first order in each reactant and the rate has a maximum at pH 6. It is suggested that the dehydrated periodate monoanion lo4is the only reactive periodate species and the or-oxocarboxylic acids and their anions react in their dehydrated forms.
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