Conductometric determination of the Soret coefficients of a ternary mixed electrolyte. Reversed thermal diffusion of sodium chloride in aqueous sodium hydroxide solutions

1990 ◽  
Vol 94 (1) ◽  
pp. 447-451 ◽  
Author(s):  
Derek G. Leaist ◽  
Lu. Hui
Keyword(s):  
Sodium Chloride ◽  
Sodium Hydroxide ◽  
Thermal Diffusion ◽  
Aqueous Sodium Hydroxide ◽  
Mixed Electrolyte ◽  
Aqueous Sodium

The retroaldol reaction of 3-methyl-2-butenal

1983 ◽  
Vol 61 (1) ◽  
pp. 171-178 ◽  
Author(s):  
J. Peter Guthrie ◽  
Brian A. Dawson
Keyword(s):  
Sodium Hydroxide ◽  
Equilibrium Constant ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Aqueous Sodium Hydroxide ◽  
Initial Increase ◽  
Aqueous Sodium ◽  
Rate Determining Step ◽  
Kinetics Of

In aqueous sodium hydroxide solutions at 25 °C, 3-methyl-2-butenal, 1c, undergoes retroaldol cleavage to acetone and acetaldehyde. The kinetics of the retroaldol reaction were followed spectrophotometrically at 242 nm and showed simple first order behavior. When 3-methyl-3-hydroxybutanal, 2c, was added to aqueous sodium hydroxide solutions at 25 °C, there was an initial increase in absorbance at 242 nm, attributed to formation of 1c, followed by a 20-fold slower decrease; the rate of the slow decrease matches the rate of disappearance of 1c under the same conditions. Analysis of the kinetics allows determination of the three rate constants needed to describe the system: khyd = 0.00342; kdehyd = 0.00832; kretro = 0.0564; all M−1 s−1. The equilibrium constant for enone hydration is 0.41. Rate constants for the analogous reactions for acrolein and crotonaldehyde could be obtained from the literature. There is a reasonable rate–equilibrium correlation for the retroaldol step. For the enone hydration step, rate and equilibrium constants respond differently to replacement of hydrogen by methyl. It is proposed that this results from release of strain after the rate-determining step by rotation about a single bond; this decrease in strain is reflected in the equilibrium constant but not in the rate constant.

THE DETERMINATION OF OESTROGENS IN BODY FLUIDS

1954 ◽  
Vol 11 (2) ◽  
pp. 189-196 ◽  
Author(s):  
HANNELORE BRAUNSBERG ◽  
MARGARET I. STERN ◽  
G. I. M. SWYER
Keyword(s):  
Stationary Phase ◽  
Sodium Hydroxide ◽  
Chromatographic Separation ◽  
Aqueous Sodium Hydroxide ◽  
Body Fluids ◽  
Aqueous Sodium ◽  
Elution Pattern ◽  
Phenolic Extract

SUMMARY A micro-method is described for the chromatographic separation of oestrone, oestradiol and oestriol from a phenolic extract of body fluids. The stationary phase is 3·1n aqueous sodium hydroxide held by Celite 535 as the supporting medium. Oestrone and oestradiol are eluted with benzene:petroleum ether, b.p. 60–80° C, 4:1 (v/v), and oestriol with a 17:3-chloroform:butanol mixture. A diagram of the apparatus used is shown. The elution pattern, and data showing how it changes with temperature, are included.

Ion association of dilute aqueous sodium hydroxide solutions to 600�C and 300 MPa by conductance measurements

1996 ◽  
Vol 25 (8) ◽  
pp. 711-729 ◽  
Author(s):  
Patience C. Ho ◽  
Donald A. Palmer
Keyword(s):  
Sodium Hydroxide ◽  
Ion Association ◽  
Aqueous Sodium Hydroxide ◽  
Aqueous Sodium

DETERMINATION OF TRACE AMOUNTS OF SILVER IN GALENA ORES

1960 ◽  
Vol 38 (9) ◽  
pp. 1488-1494 ◽  
Author(s):  
E. J. Bounsall ◽  
W. A. E. McBryde
Keyword(s):  
Aqueous Solution ◽  
Nitric Acid ◽  
Sodium Chloride ◽  
Hydrochloric Acid ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Silver Content ◽  
Aqueous Sodium Chloride Solution ◽  
Aqueous Sodium

An analytical method is described for the determination of microgram amounts of silver in galena ores, based on the "reversion" of silver dithizonate. Silver is separated from relatively large amounts of lead by extraction as dithizonate into chloroform from an aqueous 1:99 nitric acid solution. Separation from mercury, which is also extracted under these conditions and would, if present, interfere in the analysis, is achieved by reverting the dithizonate solution with a 5% aqueous sodium chloride solution which is also 0.015 molar in hydrochloric acid. Following dilution of this aqueous solution and adjustment of pH, silver is again extracted into chloroform as the dithizonate, and determined absorptiometrically. Analyses of a number of galena ore samples showed a precision of within 3% for a silver content ranging from 0.03 to 0.4%.Some other methods for isolating silver from these samples, which were tried but found unsatisfactory, are discussed.

scholarly journals Triple Helix of Scleroglucan in Dilute Aqueous Sodium Hydroxide

1981 ◽  
Vol 13 (12) ◽  
pp. 1135-1143 ◽  
Author(s):  
Toshio Yanaki ◽  
Takemasa Kojima ◽  
Takashi Norisuye
Keyword(s):  
Sodium Hydroxide ◽  
Triple Helix ◽  
Aqueous Sodium Hydroxide ◽  
Aqueous Sodium
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