Optimization of Micellar Catalysis of Nucleophilic Substitutions in Buffered Cetyltrimethylammonium Salt Solutions. 1. Buffers for the 9−10 pH Range†

Langmuir ◽  
2000 ◽  
Vol 16 (5) ◽  
pp. 2157-2163 ◽  
Author(s):  
Nadia Ouarti ◽  
Antonio Marques ◽  
Iva Blagoeva ◽  
Marie-Françoise Ruasse
Keyword(s):  
Micellar Catalysis ◽  
Salt Solutions ◽  
Nucleophilic Substitutions ◽  
Ph Range

scholarly journals Surface-active ionic liquids in micellar catalysis: impact of anion selection on reaction rates in nucleophilic substitutions

2016 ◽  
Vol 18 (19) ◽  
pp. 13375-13384 ◽  
Author(s):  
Alice Cognigni ◽  
Peter Gaertner ◽  
Ronald Zirbs ◽  
Herwig Peterlik ◽  
Katharina Prochazka ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Reaction Rates ◽  
Micellar Catalysis ◽  
Nucleophilic Substitutions ◽  
Surface Active

A series of surface-active ionic liquids based on the 1-dodecyl-3-methylimidazolium cation and different anions was synthesized and applied for micellar catalysis of nucleophilic substitutions.

Studies in bile salt solutions. IV. Rile salt catalysis and inhibition of ester hydrolysis

1984 ◽  
Vol 37 (9) ◽  
pp. 1881 ◽  
Author(s):  
CJ O'Conner ◽  
RG Wallace
Keyword(s):  
Acetylsalicylic Acid ◽  
Bile Salt ◽  
Bile Salts ◽  
Ester Hydrolysis ◽  
Diethyl Acetal ◽  
Salt Solutions ◽  
Phenyl Salicylate ◽  
The Stability ◽  
Ph Range

The reactivity of 4-nitrophenyl acetate has been examined in solutions of mono-, di-, and tri-hydroxy- cholanates and their taurine and glycine conjugates. The effect of cholate solutions on the stability of acetylsalicylic acid, phenyl salicylate and benzaldehyde diethyl acetal has also been determined. At the bile salt concentrations and in the pH range of the duodenum, bile salts do not significantly influence the stability of these compounds.

THE NUMBER OF SUBUNITS IN THE MOLECULE OF HORSE HEMOGLOBIN

1956 ◽  
Vol 34 (4) ◽  
pp. 411-425 ◽  
Author(s):  
M. E. Reichmann ◽  
J. Ross Colvin
Keyword(s):  
Light Scattering ◽  
Osmotic Pressure ◽  
Performic Acid ◽  
Approach To Equilibrium ◽  
Salt Solutions ◽  
Covalent Bonds ◽  
Molecular Weights ◽  
Equilibrium Sedimentation ◽  
Hemoglobin Molecule ◽  
Ph Range

The molecular weights of horse hemoglobin, horse globin, and performic acid oxidized horse globin were determined by osmotic pressure, by an approach to equilibrium sedimentation, and by light scattering (except hemoglobin) at pH 1.5 to 2.5 in 0.05 M NaCl. Sedimentation coefficients were determined for these materials over the same pH range and electrophoretic analyses were made from pH 1.5 to 4.0. The results show that in dilute salt solutions below pH 2.5 horse hemoglobin dissociates to four subunits all approximately equal in mass but at least two of which differ electrokinetically and therefore in composition. The subunits are probably held together in the native hemoglobin molecule only by non-covalent bonds.

A Stable Biomimetic Superhydrophobic CuO Surface Prepared by a Facile and Inexpensive Environmental-Friendly Method

2011 ◽  
Vol 239-242 ◽  
pp. 1190-1194 ◽  
Author(s):  
Zhi Qing Yuan ◽  
Xi Hai Hao ◽  
Pu Shi ◽  
Yue Jun Liu ◽  
Guang Sheng Zeng
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
High Stability ◽  
Salt Solutions ◽  
Environmental Friendly ◽  
Coating Method ◽  
Wide Ph Range ◽  
Basic Solutions ◽  
Ph Range ◽  
Simple Solid State Reaction

A facile and inexpensive environmental-friendly method was developed to prepare a biomimetic superhydrophobic CuO surface with hierarchical micro- and nanostructures by the combination of a simple solid state reaction and a convenient dipping-coating method. The biomimetic CuO surface showed superhydrophobicity even for some corrosive liquids including salt solutions and acidic and basic solutions at a wide pH range from 2 to 13. Moreover, the superhydrophobic CuO surface showed high stability in ambient environment even exposed to ultraviolet light for 10 h.

Hydrolysis of 4-Nitro-2-(trifluoroacetylamino)benzoic acid: Buffer catalysis, micellar catalysis and intramolecular general acid catalysis

1984 ◽  
Vol 37 (5) ◽  
pp. 977
Author(s):  
TJ Broxton
Keyword(s):  
Benzoic Acid ◽  
Acid Catalysis ◽  
Acidic Solution ◽  
Micellar Catalysis ◽  
Bond Breaking ◽  
Solution Rate ◽  
Solution Ph ◽  
General Acid ◽  
Ph Range ◽  
Hydrolysis Of

The hydrolysis of 4-nitro-2-(trifluoroacetylamino)benzoic acid was studied over the pH range 0-13. In strongly acidic solution (pH 0-3), intramolecular general acid catalysis was observed. In alkaline solution, rate determining protonation of the nitrogen atom of the intermediate complex formed by attack of hydroxide ion on the substrate, was observed. The alkaline hydrolysis was subject to significant micellar catalysis and this was accompanied by a change of mechanism to solvent assisted C-N bond breaking. At intermediate pH (4-8), the reaction was subject to significant buffer catalysis, and deprotonation of the intermediate formed by the attack of water on the substrate was proposed.

Isomorphous replacement in electron diffraction of wet crystals of rat hemoglobin

1983 ◽  
Vol 41 ◽  
pp. 446-447
Author(s):  
William F. Tivol ◽  
Murray Vernon King ◽  
D. F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Heavy Atom ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
Salt Solutions ◽  
X Ray ◽  
Isomorphous Replacement ◽  
Structure Factors ◽  
Diffraction Structure ◽  
The Mean

Feasibility of isomorphous substitution in electron diffraction is supported by a calculation of the mean alteration of the electron-diffraction structure factors for hemoglobin crystals caused by substituting two mercury atoms per molecule, following Green, Ingram & Perutz, but with allowance for the proportionality of f to Z3/4 for electron diffraction. This yields a mean net change in F of 12.5%, as contrasted with 22.8% for x-ray diffraction.Use of the hydration chamber in electron diffraction opens prospects for examining many proteins that yield only very thin crystals not suitable for x-ray diffraction. Examination in the wet state avoids treatments that could cause translocation of the heavy-atom labels or distortion of the crystal. Combined with low-fluence techniques, it enables study of the protein in a state as close to native as possible.We have undertaken a study of crystals of rat hemoglobin by electron diffraction in the wet state. Rat hemoglobin offers a certain advantage for hydration-chamber work over other hemoglobins in that it can be crystallized from distilled water instead of salt solutions.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

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