A Quantitative Analysis of the Effects of Head Group Bulk on SN2 and E2 Reactions in Cationic Micelles

Langmuir ◽  
1997 ◽  
Vol 13 (17) ◽  
pp. 4583-4587 ◽  
Author(s):  
Lucia Brinchi ◽  
Pietro Di Profio ◽  
Raimondo Germani ◽  
Gianfranco Savelli ◽  
Clifford A. Bunton
Keyword(s):  
Quantitative Analysis ◽  
Head Group ◽  
Cationic Micelles

scholarly journals SN2 Mechanism of Cationic Micelles on the Hydrolysis of Bis-p-Methoxyphenyl Phosphate Ester

2015 ◽  
Vol 58 (3) ◽  
pp. 117-121
Author(s):  
Abanish Kumar
Keyword(s):  
Head Group ◽  
Phosphate Ester ◽  
Polar Head Group ◽  
Polar Groups ◽  
First Order Kinetics ◽  
Cationic Micelles ◽  
Pseudophase Model ◽  
Group Form ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Hydrolysis of bis-p-methoxyphenyl phosphate ester (bis-p-MPPE) was studied in micellar solutions of cityltrimethylammoniumbromide n-C16H33N+(CH3)3Br- (CTABr) at pH-9.0. The hydrolysis followed first order kinetics with respect to bis-p-MPPE concentration. At the concentration of critical micelle concentration (CMC) the rate of hydrolysis increased with increasing CTABr concentration. Surfactant with cationic or polar head group form micelles in water with hydrocarbon like interior or polar groups at the surface and bind cationic solute. The binding constant of micelle for bis-p-MPPE and the rate constant in micellar pseudo phase were determined from kinetic data using the pseudophase model. 

Decarboxylation of 6-nitrobenzisoxazole-3-carboxylate ion in cationic micelles: Effect of head group size

1989 ◽  
Vol 2 (7) ◽  
pp. 553-558 ◽  
Author(s):  
Raimondo Germani ◽  
Pier Paolo Ponti ◽  
Tiziana Romeo ◽  
Gianfranco Savelli ◽  
Nicoletta Spreti ◽  
...  
Keyword(s):  
Group Size ◽  
Head Group ◽  
Cationic Micelles

Cleavage of 4-Nitrophenyl Diphenyl Phosphate by Isomeric Quaternary Pyridinium Ketoximes - How Can Structure and Lipophilicity of Functional Surfactants Influence Their Reactivity in Micelles and Microemulsions?

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1642-1658 ◽  
Author(s):  
Milan Kivala ◽  
Radek Cibulka ◽  
František Hampl
Keyword(s):  
Model Reaction ◽  
Head Group ◽  
Hexadecyltrimethylammonium Bromide ◽  
Polar Head Group ◽  
Cationic Micelles ◽  
Brij 35 ◽  
Ionic Micelles ◽  
Diphenyl Phosphate ◽  
Functional Surfactants ◽  
Triton X

Amphiphilic pyridinium ketoximes 4-[1-(hydroxyimino)alkyl]-1-methylpyridinium bromides (1) and 1-alkyl-4-[1-(hydroxyimino)ethyl]pyridinium bromides (2) are isomeric cationic surfactants bearing the nucleophilic hydroxyimino group. They differ in the position of the nucleophilic function relative to polar head group and hydrophobic alkyl chain. The 4-nitrophenyl diphenyl phosphate (PNPDPP) cleavage by the oximate anions generated from 1 and 2 was used as a model reaction for the investigation of the influence of the structure and lipophilicity of functional surfactants on their reactivity in micelles and microemulsions. The investigation of the model reaction in cationic micelles of hexadecyltrimethylammonium bromide (CTAB), in non-ionic micelles (Triton X-100 and Brij 35) and in o/w microemulsion (isooctane/phosphate buffer/CTAB and butan-1-ol) has revealed that it is the lipophilicity which is the most important factor influencing the localization and reactivity of functional surfactants in nanoaggregates.

Influence of surface micellar head group neutralized in hexadecyltrimethylammonium bromide (CTAB) and hydroxide (CTAOH) on the dehydrochlorination of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD)

1985 ◽  
Vol 63 (11) ◽  
pp. 2892-2898 ◽  
Author(s):  
C. Otero ◽  
E. Rodenas
Keyword(s):  
Experimental Results ◽  
Head Group ◽  
Hexadecyltrimethylammonium Bromide ◽  
Empirical Expressions ◽  
Theoretical Approaches ◽  
Cationic Micelles

The basic dehydrohalogenation reactions of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) have been studied in cationic micelles of hexadecyltrimethylammonium bromide (CTAB) and hexadecyltrimethylammonium hydroxide (CTAOH). Different theoretical approaches are discussed, considering the fraction of micellar head group neutralized, β, as a constant, or supposing different kinds of variation in its value. The following two empirical expressions for β have been found: β = 0.8 + 0.5 ([NaOH] + [KBr]) for DDT, and β = 0.8 + 1 ([NaOH] + [KBr]) for DDD, and this is the best way to explain the experimental results.

Effect of head group size, temperature and counterion specificity on cationic micelles

2011 ◽  
Vol 358 (1) ◽  
pp. 160-166 ◽  
Author(s):  
Alessandro Di Michele ◽  
Lucia Brinchi ◽  
Pietro Di Profio ◽  
Raimondo Germani ◽  
Gianfranco Savelli ◽  
...  
Keyword(s):  
Group Size ◽  
Head Group ◽  
Cationic Micelles

An Improved Quantitative Image Analyser

1977 ◽  
Vol 35 ◽  
pp. 226-227
Author(s):  
J.P. Fallon ◽  
P.J. Gregory ◽  
C.J. Taylor
Keyword(s):  
Feature Extraction ◽  
Quantitative Analysis ◽  
Frequency Content ◽  
General Sense ◽  
Physical Measurements ◽  
Quantitative Image ◽  
Image Analyser ◽  
Automatic Methods ◽  
Quantitative Results

Quantitative image analysis systems have been used for several years in research and quality control applications in various fields including metallurgy and medicine. The technique has been applied as an extension of subjective microscopy to problems requiring quantitative results and which are amenable to automatic methods of interpretation.Feature extraction. In the most general sense, a feature can be defined as a portion of the image which differs in some consistent way from the background. A feature may be characterized by the density difference between itself and the background, by an edge gradient, or by the spatial frequency content (texture) within its boundaries. The task of feature extraction includes recognition of features and encoding of the associated information for quantitative analysis.Quantitative Analysis. Quantitative analysis is the determination of one or more physical measurements of each feature. These measurements may be straightforward ones such as area, length, or perimeter, or more complex stereological measurements such as convex perimeter or Feret's diameter.

Quantification of Silica Uptake by Alveolar Macrophages - An Emperical Scanning Electron Microprobe Method

1982 ◽  
Vol 40 ◽  
pp. 332-333
Author(s):  
V. V. Damiano ◽  
R. P. Daniele ◽  
H. T. Tucker ◽  
J. H. Dauber
Keyword(s):  
Quantitative Analysis ◽  
Alveolar Macrophages ◽  
Bulk Sample ◽  
Silica Particles ◽  
Empirical Method ◽  
Phagocytic Cells ◽  
Calibration Standards ◽  
X Ray ◽  
Accurate Quantitative Analysis ◽  
Scanning Electron

An important example of intracellular particles is encountered in silicosis where alveolar macrophages ingest inspired silica particles. The quantitation of the silica uptake by these cells may be a potentially useful method for monitoring silica exposure. Accurate quantitative analysis of ingested silica by phagocytic cells is difficult because the particles are frequently small, irregularly shaped and cannot be visualized within the cells. Semiquantitative methods which make use of particles of known size, shape and composition as calibration standards may be the most direct and simplest approach to undertake. The present paper describes an empirical method in which glass microspheres were used as a model to show how the ratio of the silicon Kα peak X-ray intensity from the microspheres to that of a bulk sample of the same composition correlated to the mass of the microsphere contained within the cell. Irregular shaped silica particles were also analyzed and a calibration curve was generated from these data.

Lateral resolution of the electron microbeam analysis

1978 ◽  
Vol 36 (1) ◽  
pp. 542-543
Author(s):  
H.J. Dudek
Keyword(s):  
Quantitative Analysis ◽  
Depth Resolution ◽  
Lateral Resolution ◽  
Cylindrical Particle ◽  
Correction Procedure ◽  
X Ray ◽  
Element Concentrations ◽  
Microbeam Analysis ◽  
The Matrix

The chemical inhomogenities in modern materials such as fibers, phases and inclusions, often have diameters in the region of one micrometer. Using electron microbeam analysis for the determination of the element concentrations one has to know the smallest possible diameter of such regions for a given accuracy of the quantitative analysis.In th is paper the correction procedure for the quantitative electron microbeam analysis is extended to a spacial problem to determine the smallest possible measurements of a cylindrical particle P of high D (depth resolution) and diameter L (lateral resolution) embeded in a matrix M and which has to be analysed quantitative with the accuracy q. The mathematical accounts lead to the following form of the characteristic x-ray intens ity of the element i of a particle P embeded in the matrix M in relation to the intensity of a standard S

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