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![Figure 3: Conductance versus [SDS] plot at 30 °C. a in water, b in...](publication/304747291/figure/fig9/AS:391273904132108@1470298376716/Conductance-versus-SDS-plot-at-30-C-a-in-water-b-in-malonic-acid-CrVI-10_Q320.jpg)
Chromic acid oxidation of malonic acid in aqueous media has been investigated spectrophotometrically at 303 K. The product glyoxylic acid has been characterized by 13C-NMR and FTIR spectroscopy. Three representative N-heteroaromatic nitrogen base promoters, 2-picolinic acid, 2,2′-bipyridine (bpy) and 1,10-phenanthroline, in combination with the ani...
Citations
... The two different oxidation states bear extensively different effects on flora and fauna. [3][4][5] Cr(III) with an approximated 5.5×10 -8 mol dm -3 quantity in a particular healthy human plasma is beneficial by playing an vital role in glucose, protein and insulin metabolism. [6] On the other side the kinetically labile Cr(VI) follows the SO4 2uptake pathway to swiftly cross the cell membrane and enter living cells; where a successive one electron reduction of Cr(VI) leads to the kinetically inert Cr(III) introducing carcinogenic Cr(V) and Cr(IV) in the cellular systems. ...
The presence of hexavalent chromium in our environment is a potential mutagenic hazard for the whole animal and plant kingdom including humans. In the last five decades numerous physico-chemical and biochemical mechanisms have been proposed for the detection of chromium speciation, extraction and remediation of the same from contaminated environmental samples. This present review is dedicated on the discussions of detection of chromium speciation in various environmental samples viz., industrial wastes, workplace particulates, plants, aquatic animals and food samples. Different physical, chemical and biological analytical methods have been presented. Mechanisms of such detection, extraction/remediation techniques are also emphasised. The aim of this article is to comprehend the contemporary advancement in this field that may be applied from lab to industry levels.
... Oxidation of Carboxylic acids: Chromic acid oxidation of malonic acid in aqueous media has been investigated at 303K to yield glyoxylic acid as product 108 . Combination of Sodium Dodecyl sulphate and 2,2'-Bipyridine has been done for hundred-fold rate enhancement of chromium (VI) oxidation of malonic acid using a greener approach and the product was characterized by 13 C-NMR and FTIR spectroscopy. ...
Chromium(VI) complexes are among the most interesting transition metal complexes that have attracted great attention over the past decades. Due to their appealing catalytic and oxidizing properties, they have been widely explored since the very beginning of organic chemistry. The topic remains of current interest as exemplified by the huge number of reactions involving the use of chromium (VI) reagents. Moreover, a plethora of chromium reagents and procedures have been proposed and described extensively. The main objective of the present study is to briefly summarize and explore the available literature on oxidation of different organic substrates by Chromium (VI) reagents and encourage its various contributions to the important and exciting field of synthetic organic chemistry.
... It is quite convincing that the saponin micelles were roughly spherical prior to the addition of pyrene in the medium, while upon addition of pyrene the morphology of the micellar surface has considerably changed. The change in shape, size and structural morphologies of mi- Figure 5 The UV spectra of pyrene in (a) saponin micellar system and (b) SDBS micellar solution respectively celle supports the interaction of the substrate with surfactant nano aggregates [32,33]. ...
Solubilisation of pyrene (PAHs) in aqueous micellar solutions of natural surfactant saponin and conventional surfactant sodium dodecylbenzene sulfonate (SDBS) has been examined by UV-Vis and steady state fluorescence spectrometry at 308C. The effect of addition of common salt NaCl on the I1/I3 of fluorescence has also been determined. The experiment concludes that the pyrene molecules were incorporated in the palisade layers of both micelles because of their hydrophobic character. The interaction of pyrene with a neutral saponin micelle resulted in a red shift of UV absorption spectra, while the negative headed surfactant SDBS showed no such phenomena. The resulting thermodynamic parameters proved the better efficiency of the bio-surfactant saponin for the solubilization of pyrene with respect to that of the conventional surfactant SDBS. With increasing ionic strength (on addition of NaCl) the solubilization of pyrene was found to be better and effective in both the surfactant mediums.
... The very low reactiontime, i.e. fast kinetics, with satisfactory high yield of product, which requires no supplement of extreme and drastic condition proved it to be a greener approach. 23 There has been a flow of interest on catalysis of reactions by surfactant micelles with a view of their extensive applications in chemical, industrial, pharmaceutical, environmental and biological fields. [24][25][26] A systematic study of associated systems comprising electron transfer reaction and micelle formation process of surfactants might therefore be helpful to understand the electron transport system in catalysis. ...
... The existence of Cr(III) in the product mixture was established from the absorption maximum at 580 nm in this work and also supported from earlier reports. 16,23,30 The stoichiometry of the reaction was determined by spectrophotometric titration. Several kinetic runs were carried out by taking [acetaldehyde] >>[chromium(VI)] at fixed [H + ] and kept the reaction mixture for 48 h at 30 • C. ...
... As a consequence the local concentration effect of the reactant molecule in the Stern-region of SDS micelle significantly participate to increase the rate of reaction in SDS micellar medium than that in aqueous medium. 23 The hydrophilic interaction between nonionic (TX-100) micelle and either reactants or reaction intermediate and local concentration effect appeared to be the probable source of micellar catalysis. ...
Different spectroscopic methods have been applied to investigate the chromic acid oxidation of acetaldehyde in aqueous media, catalysed by surfactants. Three representative heteroaromatic nitrogen base promoters, 2-picolinic acid (PA), 2,2’-bipyridine (bpy) and 1,10-phenanthroline (phen), have been associated along with surfactants as promoters to the kinetic study. Comparative studies of unpromoted and promoted reactions invoked that 2,2’-bipyridine produced maximum rate enhancement. The mechanism of the reaction path has been proposed with the help of kinetic results and spectroscopic studies. The observed net enhancement of rate effects has been explained with scientific manipulations and data obtained. The combination of TX-100 and1,10-phenanthroline is found to be most effective for acetaldehyde oxidation. Graphical Abstract: Chromium(VI) oxidation of acetaldehyde in aqueous micellar media has been carried out. Micellar catalysis by TX-100 in association with a ‘phen’ promoter increases the rate of the reaction almost 60 fold. The combination of TX-100 and ‘phen’ is the most suitable one for chromic acid oxidation of acetaldehyde to acetic acid in aqueous media. [Figure not available: see fulltext.].
Propanedioic or Malonic acid was treated with a versatile, non-aqueous oxidant Di-tertiary Butyl Chromate, by taking different molar ratios of substrate and oxidant. Various solid products formed were isolated, washed, purified and collected as samples. The formulae and structure of these oxidized products have been established with the help of elemental analysis, FTIR spectra and Thermogravimetric analysis (DTA-TGA). The products obtained by the oxidation of malonic acid with DTBC are complexes of chromium(VI) which are further used to catalyze various organic reactions.
The present research investigates the action of Di-tertiary Butyl Chromate, a chromium (VI) based oxidant, on malonic acid with the aim to investigateif chromium in reduced state enters into complexation with the oxidized fragments or with the unreacted substrate itself. It also attempts to find outif degradation occurs along with oxidationandwhether the oxidation is selective in arresting the reaction at different stages (by taking different S:O molar ratios) toyield same product or not.
The present study is an investigation of the solubilising ability of natural and conventional surfactants saponin (sapindus saponin or reetha saponin), Rhamnolipids (RLs) and N-cetylpyridinium chloride (CPC) respectively via dye-surfactant interaction. The ionic dye Congo Red was examined by absorption spectroscopy method for the study. The dye interacted strongly with oppositely charged surfactant N-cetylpyridinium chloride in the pre-micellar concentration range and formed a stable dye-surfactant complex. The thermodynamic parameter, free energy change for all the systems was calculated at a constant temperature of 25°C. The ΔG ⁰ value for N-cetylpyridinium chloride is found to be −33.269 kJ/mol while for saponin and rhamnolipids the values were −16.084 kJ/mol and −26.006 kJ/mol respectively. The values clearly indicate the efficiency of N-cetylpyridinium chloride surfactant compared to the other two surfactants. The present study aims to understand the dye solubilization in surfactant media in order to develop environmentally friendly, green and cost effective techniques.
Modern science and technology promote synthesis routes which are eco-friendly, chemicals which are promoted as “green” and solvents which are less toxic. A convenient method for the synthesis of ether by the reaction of 4-hydroxy benzoic acid and benzyl chloride using a surfactant as catalyst has been developed. The targeted ether is completely immiscible in water but in association with the interface active surfactants, the production of such a hydrophobic organic compound in water has been made possible. Micelles produce a pseudo-cellular organic environment to isolate species from the bulk solvent and favour the compartmentalization of reagents as well. Thus, the enhancement of the local concentration takes place and consequently the reactivity increases. The interaction of such unique chemo-, regio- and stereo-selectivity of surfactants made this reaction feasible. Organic species added to a micellar media are distributed between bulk water and micelles depending on their polarity, charge and dimension. This novel chemistry describes a set of green methods for carrying out this new generation Williamson reaction which can also be used for selective O-alkylation.
A little attempt has been made to get in touch with the green chemistry studying the successful occurrence of oxidation of 4-chlorobenzyl alcohol to 4-chlorobenzaldehyde in micellar media by Cr(VI), and its kinetics has been recorded spectrophotometrically following pseudo-first-order reaction conditions at λmax = 440 nm. In this purpose, some common hetero-aromatic bases like 2-picolinic acid, 1,10-phenanthroline and 2,2′-bipyridine have been utilized successfully for many fold rate enhancement of the reaction. Necessary spectroscopic evidences have been produced in support of the product formation.
Graphic abstract
Advances in science and technology are promoting eco-friendly synthesis routes, green chemicals, and non-hazardous solvents. A suitable method for the synthesis of 2-(prop-2-ynyloxy) benzaldehyde was developed using three different aqueous micellar media. The targeted product ether is completely immiscible in water, but in combination with interface active surfactants it has been possible to produce the hydrophobic organic compound in water. Micelles function as a pseudocellular organic environment to isolate species from the main solvent and favor compartmentalization of reagents. There is an increase in the local concentration and consequently the reactivity increases. The use of such unique chemo-, regio-, and stereoselectivity renders this reaction new. Organic species added to a micellar media are distributed between water and micelles depending on polarity, charge, and size. In the experiments it was observed that salicylaldehyde and propargyl bromide interacted best in CTAB media and the yield of the formed product was 96 %.
