L'oxydation chromique et les esters chromiques

1974 ◽  
Vol 52 (13) ◽  
pp. 2475-2484
Author(s):  
Jean-Claude Richer ◽  
Jean-Marie Hachey
Keyword(s):  
Anhydrous Benzene ◽  
Chromic Acid ◽  
Polar Solvents ◽  
Tertiary Alcohols ◽  
Acid Esters

Rates of decomposition of chromic acid esters derived from secondary alicyclic alcohols and rates of oxidation of these cyclanols by chromic esters derived from tertiary alcohols have been measured in anhydrous benzene. The results obtained are compared to those of other workers for reactions held in polar solvents. A mechanism is suggested to explain the observed results.

ChemInform Abstract: CHROMIC ACID ESTERS DERIVED FROM TERTIARY ALCOHOLS

1976 ◽  
Vol 7 (10) ◽  
pp. no-no
Author(s):  
JEAN-CLAUDE RICHER ◽  
JEAN-MARIE HACHEY
Keyword(s):  
Chromic Acid ◽  
Tertiary Alcohols ◽  
Acid Esters

Esters Chromiques Dérivés D'alcools Tertiaires

1975 ◽  
Vol 53 (20) ◽  
pp. 3087-3093 ◽  
Author(s):  
Jean-Claude Richer ◽  
Jean-Marie Hachey
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Chromic Acid ◽  
Resonance Spectroscopy ◽  
Tertiary Alcohols ◽  
Acid Esters

Chromic acid esters derived from tertiary alcohols have been synthesized and characterized via infrared, ultraviolet, and proton magnetic resonance spectroscopy.

Chromic acid oxidation of aromatic alcohols

1969 ◽  
Vol 47 (17) ◽  
pp. 3207-3212 ◽  
Author(s):  
Ross Stewart ◽  
Fariza Banoo
Keyword(s):  
Chromic Acid ◽  
Acid Oxidation ◽  
Secondary Alcohols ◽  
Tertiary Alcohols ◽  
Chromic Acid Oxidation ◽  
Hydride Shift ◽  
Rate Of Reaction ◽  
Aromatic Alcohols ◽  
Reaction Constant ◽  
Rate Controlling Step

The mechanism of the chromic acid oxidation of di- and tri-aryl carbinols has been studied in 80 wt% acetic acid containing sulfuric acid. The reactions are cleanly second-order and give benzophenones in the case of the secondary alcohols and benzophenones plus phenols in the case of the tertiary alcohols. Electron-donating substituents in the tertiary alcohol appear predominantly in the phenol component and the rate-controlling step is believed to be a 1,2-aryl shift. The reaction constant for the migration is ρ+ = −1.44 and that for the overall reaction is ρ+ = −0.879. The presence of manganous ions does not alter these values although it lowers the overall rate of reaction. Although an analogous 1,2-hydride shift mechanism can be written for the oxidation of the secondary alcohols, there are enough points of difference between the oxidations of the secondary and tertiary systems to make this appear unlikely.

Chromic Acid Esters as Corrosion Inhibitors

1975 ◽  
Vol 53 (24) ◽  
pp. 3702-3708
Author(s):  
Edward L. Ghali ◽  
Bertrand Girard ◽  
Jean-Marie Hachey
Keyword(s):  
Aqueous Solutions ◽  
Closed System ◽  
Corrosion Inhibitors ◽  
Chromic Acid ◽  
Side Reaction ◽  
Electrochemical Characteristics ◽  
Passive Region ◽  
Anodic Current ◽  
Hydrolysis Of ◽  
Acid Esters

The hydrolysis of the chromate ester, derived from 1-methylcyclohexanol, was studied by electrochemical methods. Progressive and complete hydrolysis in an open or closed system yields chromic acid and 1-methylcyclohexanol. No evidence of the presence of monoester was detected. In a closed system, where most of the hydrolyzed alcohol is retained in solution, a side reaction between chromic acid and the alcohol has been detected and followed by conductivity measurements.Electrochemical characteristics of pure iron immersed in aqueous solutions containing hydrolyzed ester were found to be identical to those in aqueous solutions containing equivalent quantities of CrVI as CrO3. Sulfuric acid additions to the above solutions still give comparable electrochemical characteristics; however, the anodic current in the passive region was found to be less for solutions containing hydrolyzed ester than for solutions containing equivalent quantities of CrVI as CrO3.

scholarly journals Chromic Acid Esters. A Correction.

1958 ◽  
Vol 12 ◽  
pp. 576-577 ◽  
Author(s):  
Ulrik Kläning ◽  
K. Hauffe ◽  
H. Kjöllesdal ◽  
P. Siekevitz ◽  
L. Ernster ◽  
...  
Keyword(s):  
Chromic Acid ◽  
Acid Esters

Comparison of Acrylamide and Agar Gels by Freeze-Etching

1977 ◽  
Vol 35 ◽  
pp. 606-607
Author(s):  
Russell L. Steere ◽  
Eric F. Erbe
Keyword(s):  
Electron Microscope ◽  
Sodium Hydroxide ◽  
Sodium Hypochlorite ◽  
Chromic Acid ◽  
Distilled Water ◽  
Thin Sheets ◽  
Acid Cleaning ◽  
Agar Gels ◽  
Freeze Etching ◽  
Water Cut

Thin sheets of acrylamide and agar gels of different concentrations were prepared and washed in distilled water, cut into pieces of appropriate size to fit into complementary freeze-etch specimen holders (1) and rapidly frozen. Freeze-etching was accomplished in a modified Denton DFE-2 freeze-etch unit on a DV-503 vacuum evaporator.* All samples were etched for 10 min. at -98°C then re-cooled to -150°C for deposition of Pt-C shadow- and C replica-films. Acrylamide gels were dissolved in Chlorox (5.251 sodium hypochlorite) containing 101 sodium hydroxide, whereas agar gels dissolved rapidly in the commonly used chromic acid cleaning solutions. Replicas were picked up on grids with thin Foimvar support films and stereo electron micrographs were obtained with a JEM-100 B electron microscope equipped with a 60° goniometer stage.Characteristic differences between gels of different concentrations (Figs. 1 and 2) were sufficiently pronounced to convince us that the structures observed are real and not the result of freezing artifacts.

Chromic Acid Etching of Polyethylene

1973 ◽  
Vol 31 ◽  
pp. 72-73
Author(s):  
J. D. Muzzy ◽  
R. D. Hester ◽  
J. L. Hubbard
Keyword(s):  
Chromic Acid ◽  
Low Cost ◽  
Acid Etching ◽  
Crystalline Morphology ◽  
Bulk Specimen ◽  
Morphological Studies ◽  
Perfect Form ◽  
Molecular Length ◽  
Lamellar Texture ◽  
Cost Studies

Polyethylene is one of the most important plastics produced today because of its good physical properties, ease of fabrication and low cost. Studies to improve the properties of polyethylene are leading to an understanding of its crystalline morphology. Polyethylene crystallized by evaporation from dilute solutions consists of thin crystals called lamellae. The polyethylene molecules are parallel to the thickness of the lamellae and are folded since the thickness of the lamellae is much less than the molecular length. This lamellar texture persists in less perfect form in polyethylene crystallized from the melt.Morphological studies of melt crystallized polyethylene have been limited due to the difficulty of isolating the microstructure from the bulk specimen without destroying or deforming it.

Freeze-etch studies of epiphyseal growth plate cartilage reveal matrix vesicles associated with calcification

1978 ◽  
Vol 36 (2) ◽  
pp. 670-671
Author(s):  
Russell N. A. Cecil ◽  
H. Clarke Anderson
Keyword(s):  
Chromic Acid ◽  
Light And Electron Microscopy ◽  
Matrix Vesicles ◽  
Matrix Vesicle ◽  
Glycerol Solution ◽  
Sprague Dawley ◽  
Epiphyseal Growth Plate ◽  
Growth Plates ◽  
Sprague Dawley Rats ◽  
Tibial Epiphyseal

Unfixed proximal tibial epiphyseal growth plates were studied by freeze-etch to confirm the presence of extracellular calcifying matrix vesicles and to determine the substructure of matrix vesicle membranes as compared to plasma and other membranes of intact chondrocytes. Growth plates from 6-10 week old Sprague-Dawley rats were cut into 1x3 mm blocks whose long dimension was oriented either perpendicular or parallel to the long axis of the tibia. Some blocks were fixed at pH 7. 0 in 0. 2M cacodylate - buffered 2. 5% glutaraldehyde for 1 hour at 4ÅC. The blocks were immersed in 30% glycerol solution at 4ÅC for 1 hour, frozen in liquid nitrogen, and then fractured, etched for 2 minutes, and coated with platinum, carbon and 0. 2% Formvar solution. The replicas were cleaned with chromic acid, floated onto Formvar coated grids, and examined with a Phillips EM 300 electron microscope.Fixed and unfixed specimens appeared similar in ultrastructure. Chondrocytes, matrix, and matrix vesicles were identified. In specimens fractured parallel to the long axis of the tibia, the reserve, proliferative, hypertrophic, and calcifying zones could be discerned as described by light and electron microscopy.

Demonstration of Retinal Glycogen with Silver Methenamine

1971 ◽  
Vol 29 ◽  
pp. 564-565
Author(s):  
A. W. Sedar ◽  
G. H. Bresnick
Keyword(s):  
Lactic Acid ◽  
Chromic Acid ◽  
Periodic Acid ◽  
Müller Cell ◽  
External Limiting Membrane ◽  
Electron Microscope Level ◽  
Reactive Process ◽  
Inner Limiting Membrane ◽  
Muller Cell ◽  
And Migration

After experimetnal damage to the retina with a variety of procedures Müller cell hypertrophy and migration occurs. According to Kuwabara and others the reactive process in these injuries is evidenced by a marked increase in amount of glycogen in the Müller cells. These cells were considered originally supporting elements with fiber processes extending throughout the retina from inner limiting membrane to external limiting membrane, but are known now to have high lactic acid dehydrogenase activity and the ability to synthesize glycogen. Since the periodic acid-chromic acid-silver methenamine technique was shown to demonstrate glycogen at the electron microscope level, it was selected to react with glycogen in the fine processes of the Müller cell that ramify among the neural elements in various layers of the retina and demarcate these cells cytologically. The Rhesus monkey was chosen as an example of a well vascularized retina and the rabbit as an example of a avascular retina to explore the possibilities of the technique.

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