scholarly journals Physicochemical Investigations of Scheelite Concentrate Decomposition

2015 ◽  
Vol 17 (3) ◽  
pp. 209 ◽  
Author(s):  
G. Yar-Mukhamedova ◽  
А. Darisheva ◽  
K. Kasimzhanov ◽  
D. Babazhanov ◽  
B. Barkitova
Keyword(s):  
Sodium Carbonate ◽  
Kinetic Studies ◽  
Adsorbed Water ◽  
Oxide Surface ◽  
Scheelite Concentrate ◽  
Carbonate Decomposition ◽  
Kinetic Mode ◽  
Oxide Ions ◽  
Hydrolysis Of ◽  
Carbonate Leaching

<p>In the article results of kinetic studies of autoclave-carbonate decomposition of scheelite concentrates are presented. Studies are carried out in temperature range of 368–523 K, at mixing with a speed of 100–400 revolutions per minute. Solutions of sodium carbonate, mol/ dm<sup>3</sup>: 0.5, 0.75, 1.0, 1.25, 1.5, 2.0 was used to determine the dependence of the degree of tungsten leaching from scheelite on concentration. It was established, that with increase of concentration of sodium carbonate leaching degree increases and at the concentration of 1.5–2.0 mol/dm<sup>3</sup> it is reached rapid, within 45–60 min, 80−90% of leaching, and the almost complete  leaching of tungsten (95.2–99.3%) achieved in 2 h. For interaction of WO<sub>3</sub> with Na<sub>2</sub>CO<sub>3</sub> solution it was obtained the kinetic mode. In this case there is practically no concentration gradient of sodium carbonate at an oxide surface. It is obvious, that increase of the hydrolysis takes place due to the fact that to oxides reaction with a reagent-solvent precedes hydration of their surface. In the adsorbed water molecules due to their interaction with the oxide surface intramolecular bonds are weakened, thereby hydrolysis of<br /> oxide ions coming to the hydrated surface flows more fully.</p>

Micellar catalysis of organic reactions. VIII. Kinetic studies of the hydrolysis of 2-acetyloxybenzoic acid (aspirin) in the presence of micelles

1982 ◽  
Vol 35 (7) ◽  
pp. 1357 ◽  
Author(s):  
TJ Broxton
Keyword(s):  
Aqueous Solution ◽  
Cetyltrimethylammonium Bromide ◽  
Cetylpyridinium Chloride ◽  
Kinetic Studies ◽  
Base Catalysis ◽  
Plateau Region ◽  
General Base ◽  
Mechanism Of Hydrolysis ◽  
Ph Range ◽  
Hydrolysis Of

The hydrolysis of 2-acetyloxybenzoic acid in the pH range 6-12 has been studied in the presence of micelles of cetyltrimethylammonium bromide (ctab) and cetylpyridinium chloride (cpc). In the plateau region (pH 6-8) the hydrolysis is inhibited by the presence of micelles, while in the region where the normal BAC2 hydrolysis (pH > 9) occurs the reaction is catalysed by micelles of ctab and cpc. The mechanism of hydrolysis in the plateau region is shown to involve general base catalysis by the adjacent ionized carboxy group both in the presence and absence of micelles. This reaction is inhibited in the presence of micelles because the substrate molecules are solubilized into the micelle and water is less available in this environment than in normal aqueous solution.

The synthesis of Cyclododecane-r-1,c-5,c-9-triamine and r-1,c-5,c-9-Tris(2,3-dimethoxybenzamido)cyclododecane

1975 ◽  
Vol 28 (3) ◽  
pp. 673 ◽  
Author(s):  
DJ Collins ◽  
C Lewis ◽  
JM Swan
Keyword(s):  
Aqueous Solution ◽  
Acid Hydrolysis ◽  
Sulphuric Acid ◽  
Sodium Carbonate ◽  
Sodium Azide ◽  
Room Temperature ◽  
Dimethyl Formamide ◽  
Lithium Aluminium Hydride ◽  
Lithium Aluminium ◽  
Hydrolysis Of

Treatment of cyclododecane-r-1,c-5,c-9-triyl tris(p-toluenesulphonate) with sodium azide in dimethyl-formamide at 100� for 6 h gave the corresponding cis,cis-triazide which upon hydrogenation or reduction with lithium aluminium hydride gave cyclododecane-r-1,c-5,c-9-triamine, isolated as the tris-salicylidene derivative. Acid hydrolysis of this, removal of the salicylaldehyde, and treatment of the aqueous solution with sodium carbonate and 2,3-dimethoxybenzoyl chloride gave r-1,c-5,c- 9-tris(2,3-dimethoxybenzamido)cyclododecane. ��� Treatment of (E,E,E)-cyclododeca-1,5,9-triene with an excess of acetonitrile and sulphuric acid at room temperature for three days gave 18% of (E,E)-1-acetamidocyclododeca-4,8-diene; no di- or tri-amides were isolated.

scholarly journals Stability of Indomethacin in Aqueous Solution. (1): Kinetic Studies and Effect of Solvents on the Hydrolysis of Indomethacin.

1992 ◽  
Vol 18 (1) ◽  
pp. 43-51 ◽  
Author(s):  
KAORU CHIBA ◽  
MASANAO TAKAHASHI ◽  
NOBUMASA HAYASE ◽  
SHIGETAKA AKUTSU ◽  
SHUNICHI INAGAKI
Keyword(s):  
Aqueous Solution ◽  
Kinetic Studies ◽  
Effect Of Solvents ◽  
Hydrolysis Of

scholarly journals Studies on the mechanism of sheep liver cytosolic aldehyde dehydrogenase

1985 ◽  
Vol 225 (1) ◽  
pp. 159-165 ◽  
Author(s):  
F M Dickinson
Keyword(s):  
Aldehyde Dehydrogenase ◽  
Kinetic Studies ◽  
Dissociation Reaction ◽  
Quenching Effect ◽  
Sheep Liver ◽  
Association Reaction ◽  
Hydrolysis Of

The dissociation of the aldehyde dehydrogenase X NADH complex was studied by displacement with NAD+. The association reaction of enzyme and NADH was also studied. These processes are biphasic, as shown by McGibbon, Buckley & Blackwell [(1977) Biochem. J. 165, 455-462], but the details of the dissociation reaction are significantly different from those given by those authors. Spectral and kinetic experiments provide evidence for the formation of abortive complexes of the type enzyme X NADH X aldehyde. Kinetic studies at different wavelengths with transcinnamaldehyde as substrate provide evidence for the formation of an enzyme X NADH X cinnamoyl complex. Hydrolysis of the thioester relieves a severe quenching effect on the fluorescence of enzyme-bound NADH.

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