STUDIES ON THE FORMATION OF HEXAMINE

1947 ◽  
Vol 25b (4) ◽  
pp. 387-396 ◽  
Author(s):  
Mary L. Boyd ◽  
C. A. Winkler
Keyword(s):  
Aqueous Solution ◽  
Mercuric Chloride ◽  
Initial Rate ◽  
Rapid Rate ◽  
Large Excess ◽  
Lower Yield ◽  
High Initial Rate

Rate curves have been determined for the reaction of ammonia and formaldehyde in aqueous solution at 0 °C. and 35 °C., over a range of initial mole ratios (formaldehyde: ammonia) of 0.25 to 2.0. For each set of conditions, three curves have been obtained on the basis of ammonia consumed, formaldehyde consumed, and material precipitated with mercuric chloride respectively.At 0 °C. the three rate curves tend to approximate one another in a large excess of ammonia but are widely separated in excess formaldehyde. The reverse is true at 35 °C. The reaction is characterized by a high initial rate of formation of hexamine, this rapid rate being maintained to a lower yield of hexamine the more dilute the solution. The existence of a stable by-product in excess formaldehyde is indicated by the variation in final yields of hexamine, when these are calculated on the basis of formaldehyde consumed, ammonia consumed, or material precipitated with mercuric chloride.A mechanism for the reaction has been suggested.

The mechanism of the oxidation of thiocyanate ion by peroxomonosulphate in aqueous solution. II. Kinetics of the reaction

1966 ◽  
Vol 19 (8) ◽  
pp. 1365 ◽  
Author(s):  
RH Smith ◽  
IR Wilson
Keyword(s):  
Aqueous Solution ◽  
Initial Rate ◽  
Stopped Flow ◽  
Thiocyanate Ion ◽  
First Order ◽  
Conductance Method ◽  
Rate Of Reaction ◽  
Kinetics Of

Initial rates of reaction for the above oxidation have been measured by a stopped-flow conductance method. Between pH 2 and 3.6, the initial rate of reaction, R, is given by the expression R{[HSO5-]+[SCN-]} = {kb+kc[H+]}[HSO5-]0[SCN-]20+ka[H+]-1[HSO5]20[SCN-]0 As pH increases, there is a transition to a pH-independent rate, first order in each thiocyanate and peroxomonosulphate concentrations.

Acute Mercury Poisoning After Polyvinyl Alcohol Preservative Ingestion

PEDIATRICS ◽  
1980 ◽  
Vol 66 (1) ◽  
pp. 132-134
Author(s):  
James Seidel
Keyword(s):  
Aqueous Solution ◽  
Acetic Acid ◽  
Polyvinyl Alcohol ◽  
Mercuric Chloride ◽  
Medical Center ◽  
Mercury Poisoning

Polyvinyl alcohol preservative (PVA) is used routinely in the laboratory for collection of specimens for examination for ova and parasites.1-4 PVA, presently used at Harbor-UCLA Medical Center, contains: 4.5% mercuric chloride, 5% polyvinyl alcohol, 30% denatured alcohol, 4.5% acetic acid, and 1.5% glycerin in an aqueous solution. The kit, as shown in the Figure, contains three bottles with 10-ml aliquots of PVA, wooden sticks for mixing the specimen, and written instructions for collection of the specimens. The bottles are clearly labeled as poison in English and Spanish, and specific verbal as well as written instructions are given to patients and their families when the ova and parasite kits are dispensed.

Iron(III) complexes of DL-methionine

1972 ◽  
Vol 25 (2) ◽  
pp. 421 ◽  
Author(s):  
EJ Halbert ◽  
MJ Rogerson
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Large Excess ◽  
Ph Titration ◽  
Oxidation Reduction ◽  
Infrared Studies ◽  
Rapid Hydrolysis ◽  
Iron Analysis ◽  
Hydrolysis Of ◽  
Made In

Few iron(111) complexes of amino acids have been isolated although attempts have been made to measure their stabilities in solution. Iron(111) in the presence of various amino acids showed no complex formation during pH titration in aqueous solution. Using oxidation-reduction and spectrophotometric techniques Perrin measured the stabilities of 1 : 1 complexes of iron(111) with different amino acids in solutions of low pH. Rapid hydrolysis of iron(111) occurred when the pH was increased even in the presence of a large excess of amino acids. Bielig and Bayer reported the isolation of a bis-complex of iron(111) and methionine prepared in aqueous solution. McAuliffe, Quagliano, and Vallarinoe reported a tris-complex made in ethanol, though their iron analysis was not consistent with the required structure. In both cases magnetic and infrared studies were used to characterize the products. Our attempts to repeat these preparations were unsuccessful. This paper describes the preparation of two 1 : 1 complexes of methionine and iron(111) and an investigation of their properties by analysis of infrared, magnetic, and N.M.R. measurements.

scholarly journals Mutating the dileucine motif of the human β2-adrenoceptor reduces the high initial rate of receptor phosphorylation by GRK without affecting postendocytic sorting

2010 ◽  
Vol 635 (1-3) ◽  
pp. 9-15 ◽  
Author(s):  
Hibah O. Awwad ◽  
Ellen E. Millman ◽  
Estrella Alpizar-Foster ◽  
Robert H. Moore ◽  
Brian J. Knoll
Keyword(s):  
Initial Rate ◽  
Receptor Phosphorylation ◽  
Dileucine Motif ◽  
High Initial Rate

scholarly journals Sensing Zn2+ in Aqueous Solution with a Fluorescent Scorpiand Macrocyclic Ligand Decorated with an Anthracene Bearing Tail

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1355 ◽  
Author(s):  
Matteo Savastano ◽  
Matteo Fiaschi ◽  
Giovanni Ferraro ◽  
Paola Gratteri ◽  
Palma Mariani ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Complex Formation ◽  
Metal Ion ◽  
Equilibrium Constants ◽  
Macrocyclic Ligand ◽  
Fluorescence Emission ◽  
Zinc Complexes ◽  
Large Excess ◽  
Macrocyclic Ring ◽  
Ph Range

Synthesis of the new scorpiand ligand L composed of a [9]aneN3 macrocyclic ring bearing a CH2CH2NHCH2-anthracene tail is reported. L forms both cation (Zn2+) and anion (phosphate, benzoate) complexes. In addition, the zinc complexes of L bind these anions. The equilibrium constants for ligand protonation and complex formation were determined in 0.1 M NaCl aqueous solution at 298.1 ± 0.1 K by means of potentiometric (pH-metric) titrations. pH Controlled coordination/detachment of the ligand tail to Zn2+ switch on and off the fluorescence emission from the anthracene fluorophore. Accordingly, L is able to sense Zn2+ in the pH range 6–10 down to nM concentrations of the metal ion. L can efficiently sense Zn2+ even in the presence of large excess of coordinating anions, such as cyanide, sulphide, phosphate and benzoate, despite their ability to bind the metal ion.

Methods of preparation of sulfanes

1968 ◽  
Vol 46 (14) ◽  
pp. 2341-2346 ◽  
Author(s):  
E. Muller ◽  
J. B. Hyne
Keyword(s):  
Aqueous Solution ◽  
Proton Transfer ◽  
Sulfur Content ◽  
Reactive Intermediates ◽  
Molar Ratio ◽  
Crude Oils ◽  
Large Excess ◽  
Aqueous Sodium ◽  
Wide Range ◽  
Sodium Polysulfide

Sulfane crude oils obtained by acidification of aqueous sodium polysulfide solutions vary little in composition with varying sulfur content of the solution. Evidence presented suggests that the distribution of the sulfanes in such crude oils reflects the equilibrated distribution of the various polysulfide anions in the aqueous solution before acidification. The sulfane distribution in mixtures obtained by reaction of liquid H2S with Br2, SCl2, and S2Cl2 respectively varies over a wide range, depending on the molar ratio of the reactants. Liquid H2S reacts with Br2 or SCl2 to yield essentially the same products. These reactions, however, differ in the nature of their intermediates. By using a large excess of liquid H2S, H2S3 was directly synthesized in over 90% purity. Liquid H2S reacts with S2Cl2 to yield H2S4 in over 90% purity. Gaseous HCl catalyzes the reaction of H2S with the chlorosulfanes and a mechanism is suggested involving HCl as a proton transfer agent in the formation of the reactive intermediates.

Schiff base equilibria. VIII. Aqueous equilibria between salicylaldehyde and aliphatic diamines

1973 ◽  
Vol 26 (8) ◽  
pp. 1653 ◽  
Author(s):  
RW Green ◽  
PW Alexander ◽  
RJ Sleet
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Equilibrium Constants ◽  
Large Excess ◽  
Acid Base ◽  
Aliphatic Diamines

Equilibria between salicylaldehyde and three aliphatic diamines, ethylenediamine, trimethylenediamine, and 1,3-diaminopropan-2-ol, have been measured in aqueous solution containing a large excess of diamine to suppress hydrolysis. Equilibrium constants are reported for the formation and acid-base reactions of the mono-salicylideneimines formed from the three diamines. It is demonstrated that there are no conditions under which detectable concentrations of bis- salicylideneimines exist in aqueous solution.

scholarly journals STUDIES ON THE FORMATION OF HEXAMINE FROM FORMALDEHYDE AND AMMONIUM SALTS IN AQUEOUS SOLUTION

1947 ◽  
Vol 25b (6) ◽  
pp. 525-534 ◽  
Author(s):  
J. R. Polley ◽  
C. A. Winkler ◽  
R. V. V. Nicholls
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Ammonium Nitrate ◽  
Ammonium Salt ◽  
Mercuric Chloride ◽  
Product Formation ◽  
Ammonium Salts ◽  
Final Yield

It is shown that the reaction of formaldehyde with an ammonium salt to form hexamine is general. The rate of formation and the final yield of hexamine vary greatly with the different ammonium salts, being greater in the solutions of higher pH. When buffered at given pH, the various ammonium salts give approximately the same rates of formation and final yields of hexamine. Rate curves have been determined for the reaction of formaldehyde with ammonium nitrate in aqueous solutions buffered at pH 8.0, 6.0, and 4.0, at temperatures of 0°, 20°, and 40 °C. and over a range of initial mole ratios (formaldehyde: ammonium nitrate) of 0.75 to 3.0. For each set of conditions, three rate curves have been obtained on the basis of ammonia consumed, formaldehyde consumed, and material precipitated with mercuric chloride. In excess formaldehyde, it appears that a stable by-product is formed; its formation increases as the temperature is increased. In excess ammonium nitrate, by-product formation is decreased. A mechanism of hexamine formation is suggested in accordance with the data.

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