scholarly journals Voltammetric optimisation of TEMPO-mediated oxidations at cellulose fabric

2014 ◽  
Vol 16 (6) ◽  
pp. 3322-3327 ◽  
Author(s):  
Yun Jin ◽  
Karen J. Edler ◽  
Frank Marken ◽  
Janet L. Scott
Keyword(s):  
Electrochemical Oxidation ◽  
Relative Efficiency ◽  
Cotton Cloth ◽  
Reaction Conditions ◽  
Simple Method ◽  
Cellulose Fabric ◽  
Optimum Ph

A simple method for rapid voltammetric screening of N-oxyl based mediators and reaction conditions for electrochemical oxidation of cellulose is described. Using immobilised cellulose (cotton cloth) the screening requires small quantities of mediator and yet yields information about relative efficiency of mediator, optimum pH, and preferred buffer identity.

scholarly journals Immobilization of alpha-amylase produced by Bacillus circulans GRS 313

2003 ◽  
Vol 46 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Gargi Dey ◽  
Singh Bhupinder ◽  
Rintu Banerjee
Keyword(s):  
Calcium Alginate ◽  
Immobilized Enzyme ◽  
Fold Increase ◽  
Alginate Beads ◽  
Hydrolysis Kinetics ◽  
Initial Activity ◽  
Reaction Conditions ◽  
Bead Size ◽  
Optimum Ph ◽  
Optimum Ph And Temperature

A maltooligosaccharide-forming amylase from B circulans GRS 313 was immobilized by entrapment in calcium alginate beads. The immobilized activity was affected by the size of the bead and bead size of 2mm was found to be most effective for hydrolysis. Kinetics constants, Km and Vmax were estimated and were found to be affected by the bead size. The catalytic activity of the enzyme was studied in presence of various starchy residues and metal ions. HgCl2, CuSO4 and FeCl3 caused inhibition of the enzyme. The reaction conditions, pH and temperature, was optimized using response surface methodology. At the optimum pH and temperature of 4.9 and 57ºC, the apparent activity was 25.6U/g of beads, resulting in almost 2-fold increase in activity. The immobilized enzyme showed a high operational stability by retaining almost 85% of the initial activity after seventh use.

The Preparation of Black Phosphorus Quantum Dots by Gas Exfoliation with the Assistance of Liquid N2

2020 ◽  
Vol 20 (10) ◽  
pp. 6458-6462
Author(s):  
Honghong Liu ◽  
Peichao Lian ◽  
Yongwei Tang ◽  
Zhenting Zhao ◽  
Yi Mei
Keyword(s):  
Quantum Dots ◽  
Black Phosphorus ◽  
Inert Gas ◽  
Lateral Size ◽  
Reaction Conditions ◽  
Simple Method ◽  
Chemical Impurities ◽  
Black Phosphorus Quantum Dots ◽  
First Time ◽  
Application Prospects

Black phosphorus quantum dots (BPQDs), a type of nanoscale black phosphorus (BP), have fantastic application prospects in various fields. However, the premise of the application of BPQDs depends on its effective preparation. At present, most of preparation processes of BPQDs involve in organic solvents which may be harmful to humans and the environment. Furthermore, some chemical impurities may inevitably be introduced into the final product. In addition, all the preparation processes need to be carried out under an inert gas due to the instability of BPQDs, which makes the reaction conditions more harsh and complicated. Therefore, an efficient and simple method for the preparation of BPQDs by gas exfoliation with the assistance of liquid N2 (l-N2) was developed for the first time in this study. This method is environmentally friendly and impurity-free because l-N2 is a nontoxic liquid that can be gasified to form N2. The obtained BPQDs were characterized by XRD, Raman, SEM, TEM and UV-Vis techniques and they had a lateral size of 9±3 nm.

scholarly journals The First Stages of Chemical and Electrochemical Aniline Oxidation—Spectroscopic Comparative Study

2020 ◽  
Vol 10 (6) ◽  
pp. 2091 ◽  
Author(s):  
Zuzana Morávková ◽  
Ivana Šeděnková ◽  
Patrycja Bober
Keyword(s):  
Comparative Study ◽  
Electrochemical Oxidation ◽  
Film Formation ◽  
Pani Film ◽  
Redox Behavior ◽  
Reaction Conditions ◽  
Chemical Polymerization ◽  
Polyaniline Film ◽  
Aniline Oxidation ◽  
Aniline Oligomers

There are several types of aniline oligomers that can be formed in the early stages of aniline oxidation: linear oligomers with repeating units joined in para positions, and various branched and polycyclic oligomers, being the two most important groups. The fraction of these different oligomeric groups depends upon the reaction conditions of aniline oxidation. The aim of this study was to analyze the first products of the chemical and electrochemical oxidation of aniline at the (starting) pH 1 and 7, in order to specify the conditions of the formation of phenazine-like oligomers, and to test the theory that they have an important role in polyaniline film formation. We have confirmed that phenazine-like oligomers do not form at pH 1, neither in the chemical nor the electrochemical oxidation of aniline; however, they form in both chemical and electrochemical oxidation of aniline at pH 7. Phenazine-like oligomers are thus definitely not necessary intermediates for PANI film formation, not even in the chemical polymerization of aniline. Finally, the redox behavior of phenazine-like oligomers was demonstrated in a medium at pH 1.

Bicyclization of aza-compounds by positive halide ions. I. Cyclic amines

1985 ◽  
Vol 63 (6) ◽  
pp. 1170-1172 ◽  
Author(s):  
R. M. Elofson ◽  
F. F. Gadallah ◽  
J. K. Laidler
Keyword(s):  
Electrochemical Oxidation ◽  
Halide Ions ◽  
Cyclic Amine ◽  
Reaction Conditions ◽  
Specific Reaction ◽  
Cyclic Amines ◽  
Bicyclic Compounds

Cyclic amines are oxidized to the bicyclic compounds by electrochemical oxidation. The presence of halide ions is found necessary for the reaction to proceed and to produce any bicyclic products. It is postulated that a positive halide species, X(+), is produced electrochemically and stabilized under the specific reaction conditions. The X(+) ion forms a complex with the parent cyclic amine which decomposes to the bicyclic product and HX. An analogy between the Hofer–Moest reaction to produce C(+) and this reaction to produce X(+) is postulated

scholarly journals Synthesis of Deuterated Poly(4-acetoxystyrene) by a Polymer-analogous Reaction Sequence

2016 ◽  
Vol 2 (4) ◽  
Author(s):  
Khalifa M. ,  Youssef A
Keyword(s):  
Acetyl Chloride ◽  
Cost Effective ◽  
Reaction Conditions ◽  
Simple Method ◽  
Thermal Reactions ◽  
Acetyl Group ◽  
Ft Ir ◽  
Future Work ◽  
Ft Ir Spectroscopy ◽  
Villiger Oxidation

This study describes a new simple method for preparing deuterated poly(4-acetoxystyrene). The new method offers cost-effective and alternative route to preparing deuterated polymers that otherwise have to be prepared from the deuterated monomers. Deuterated poly(4-acetylstyrene) (ACPS-d4) and poly(4-acetoxystyrene) (APS-d4) were synthesised from deuterated polystyrene under thermal reactions. The polystyrene-d5 (PS-d5) was acetylated using cyclohexane as solvent instead of carbon disulfide (a highly toxic and flammable solvent) and acetyl chloride as the acetylating agent. Using commercially available reagents, the acetyl group was converted to an acetoxy group by Baeyer-Villiger oxidation. The oxidation of ACPS was carried out with various agents and reaction conditions. The oxidation kinetics with peracetic acid was followed by FT-IR spectroscopy. The duterated polymers were characterised by nuclear magnetic resonance (NMR) and fourier transform infrared spectroscopy (FTIR). The optimised procedure will make future work using neutron scattering possible.     

Preparation of Biscarbonylmethylenetriphenylphosphorane Derivatives: A Mini-Review

2019 ◽  
Vol 16 (10) ◽  
pp. 769-778
Author(s):  
Andrés-Felipe Villamizar-Mogotocoro ◽  
Juan-Manuel Urbina-González ◽  
Ingrid Rincón-Valdivieso
Keyword(s):  
Biological Activity ◽  
Electrochemical Oxidation ◽  
Oxidation Products ◽  
Thermal Treatments ◽  
Reaction Conditions ◽  
Complex Molecules ◽  
High Importance

Biscarbonylmethylenetriphenylphosphoranes are versatile compounds derived from stabilized α-carbonylmethylenetriphenylphosphoranes, mainly prepared by transylidation or by analogue methodologies; other procedures include electrochemical oxidation, palladium-catalized insertions and displacements reactions with tellurol esters, as well as the use of Bestmann’s ylide with different reagents and reaction conditions. These biscarbonylmethylenetriphenylphosphoranes are usually converted into acetylenes by thermal treatments. Biscarbonylmethylenetriphenylphosphoranes and their oxidation products -vicinal tricarbonyl compounds- are of high importance due to their use as synthons of more complex molecules and their promising biological activity.

K2CO3-Promoted Highly Selective N-Hydroxymethylation of Indoles Under Metal- and Lewis Acid-free Conditions

2020 ◽  
Vol 17 ◽  
Author(s):  
Xiao-Yu Zhou ◽  
Xia Chen
Keyword(s):  
Lewis Acid ◽  
Reaction Conditions ◽  
Simple Method

Abstract: Inorganic base promoted highly selective N-hydroxymethylation of indole and its derivatives have been devel-oped. It provided a simple method for the preparation of N-hydroxymethyl indoles with polyformaldehyde as reagents under the metal- and Lewis acid-free reaction conditions. The reaction proceeded smoothly using K2CO3 as base in 1,4-dioxane to produce the corresponding N-hydroxymethyl indoles with 62%->99% yields

Electrochemical oxidation of 2-furylacetic acid derivatives

1980 ◽  
Vol 45 (5) ◽  
pp. 1361-1365 ◽  
Author(s):  
Miroslav Janda ◽  
Jan Šrogl ◽  
Eva Körblová ◽  
Ivan Stibor
Keyword(s):  
Electrochemical Oxidation ◽  
Analogous Reaction ◽  
Reaction Conditions

Depanding on reaction conditions, the electrochemical methoxylation of 2-furylacetonitrile (I) afforded either (2,5-dimethoxy-2,5-dihydro-2-furyl)acetonitrile (V) or (5-methoxy-2,5-dihydro-2-furfurylidene)acetonitrile (VIII). Analogous reaction of methyl 2-furylacetate (II) gave either methyl (2,5-dimethoxy-2,5-dihydro-2-furyl)acetate (VI) or methyl (5-methoxy-2,5-dihydro-2-furfurylidene)acetate (IX). The electrochemical ethoxylation of ethyl 2-furylacetate afforded- among other products - also γ-lactone of ethyl 3-hydroxy-2,4-hexadienedioate (X).

Comparative Analysis Between Paramecium Strains with Different Syngens Using the RAPD Method

2021 ◽  
Author(s):  
Sonoko Matsumoto ◽  
Kenta Watanabe ◽  
Akiko Imamura ◽  
Masato Tachibana ◽  
Takashi Shimizu ◽  
...  
Keyword(s):  
Rapd Analysis ◽  
Random Amplified Polymorphic Dna ◽  
Mating Types ◽  
Genetic Classification ◽  
Reaction Conditions ◽  
Free Living ◽  
Simple Method ◽  
Specific Band ◽  
Freshwater Environments

Abstract Paramecium spp. is types of free-living protists that live in freshwater environments. They are ciliates with high motility and phagocytosis and have been used to analyze cell motility and as a host model for pathogens. Besides such biological characteristics, apart from the usual morphological and genetic classification of species, the existence of taxonomies (such as syngens) and mating types related to Paramecium’s unique reproduction is known. In this study, we attempted to develop a simple method to identify Paramecium strains, which are difficult to distinguish morphologically, using random amplified polymorphic DNA (RAPD) analysis. Consequently, we can observe strain-specific band patterns. We also confirm that the presence of endosymbiotic Chlorella cells affects the band pattern of P. bursaria. Furthermore, the results of the RAPD analysis using several P. caudatum strains with different syngens show that it is possible to detect a band specific to a certain syngen. By improving the reaction conditions and random primers, based on the results of this study, RAPD analysis can be applied to the identification of Paramecium strains and their syngen confirmation tests.

Problems in extraction and spectrophotometric determination of chlorophyll from epilithic microbial biofilms: towards a standard method

1999 ◽  
Vol 79 (3) ◽  
pp. 551-558 ◽  
Author(s):  
R.C. Thompson ◽  
M.L. Tobin ◽  
S.J. Hawkins ◽  
T.A. Norton
Keyword(s):  
Standard Method ◽  
Relative Efficiency ◽  
Room Temperature ◽  
Standard Procedure ◽  
Suspended Material ◽  
Sample Collection ◽  
Simple Method ◽  
Microbial Biofilms ◽  
Epilithic Biofilms

A variety of methods are available to extract chlorophyll from epilithic biofilms using solvents. The relative efficiency of these has not been determined simultaneously and there is no recognized standard procedure. In this paper techniques for sample collection, storage, preparation and extraction are reviewed and compared experimentally.Extraction of chlorophyll was incomplete unless biofilms were fully hydrated. This factor was highly significant for all the solvents tested, with at least three times more pigment being extracted from hydrated samples than from dry ones. Methanol was the most efficient solvent, releasing over 96% of the total chlorophyll during a single extraction; hot ethanol extracted 86%, while acetone extracted less than 50%. Sonicating samples during extraction did not release any additional pigment. Centrifuging to remove suspended material did not alter estimates and was not advantageous. Rugose rock surfaces released more chlorophyll than smooth ones. However, a simple method to quantify surface rugosity at an appropriate scale was not available.Based on these observations, a standard method for chlorophyll extractions from epilithic biofilms using 100% methanol at room temperature (20°C) is proposed. This technique requires considerably less supervision than previously preferred methods and gave a chlorophyll extract which was stable for 15 h.

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