Allylic and benzylic oxidation reactions with sodium chlorite

Various allylic and benzylic substrates were selectively oxidized to the corresponding enones in good yields using sodium chlorite, either in combination with tert-butyl hydroperoxide in stoichiometric conditions, or associated with N-hydroxyphthalimide as catalyst. These oxidation reactions were effectively and economically performed under mild, transition-metal free conditions and therefore the dual challenge of cost effectiveness and benign nature of the processes was met with.     

Peculiar features of the oxidation of cellulose with sodium periodate and with sodium chlorite

Summary Sodium periodate oxidizes not only the -glycol grouping, but also the alcohol group in the 6-position of cellulose, to aldehyde and carboxy groups.     

The reaction of sodium arsenite with sodium chlorite

Existing procedures for the standardisation of sodium chlorite solutions are critically examined and a suitable method detailed. The reaction between sodium chlorite and sodium arsenite solutions is discussed; reaction is quantitative in the presence of sodium bicarbonate and osmic acid as catalyst.     

Determination of sorbic acid with sodium chlorite

A new method for the determination of sorbic acid is proposed, using sodium chlorite in hydrochloric add medium as reagent. In these conditions the hydrochloric acid is oxidized to chlorine which adds on to the double bonds of the sorbic acid. The addition is rapid (30-90 sec) and for this reason the determination is more rapid then others similar to it. Sorbic acid has been determined in foods by this method, after a preliminary solvent extraction or steam-distillation.     

Epoxidation by sodium chlorite with aldehyde-promoted chlorine dioxide formation

An improved method is described for selective room temperature epoxidation of alkenes by sodium chlorite in a solvent mixture of ethanol, acetonitrile, and water buffered at pH 7. In addition, the use of aldehydes as promoters in chlorite oxidations is described for the first time. The amount of sodium chlorite, the solvent mixture, and the addition of formaldehyde as a practical promoter were optimized. Styrene was used as a test substrate in the optimization studies and the generality of the method was assessed by using a variety of nucleophilic and electrophilic substrates. Yields up to 89% were obtained with styrene and other nucleophilic alkenes are readily converted into epoxides.     

Characteristics of the complexing of chitosan with sodium dodecyl sulfate,according to IR spectroscopy data and quantum-chemical calculations

The complexing of protonated chitosan with dodecyl sulfate ions in water solutions is studied using IR spectroscopy data and quantum-chemical calculations. It is established that the electrostatic interaction between the protonated amino groups of chitosan and dodecyl sulfate ions is apparent in the IR spectrum as a band at 833 cm^?1. The need to consider the effect the solvent has on the formation of hydrogen-bound ion pairs [CTS⁺ ? C₁₂H₂₅O₃^-] is shown via a quantum-chemical simulation of the equilibrium geometry and the energy characteristics of complexing and hydration.     

Oxidative aromatization of Hantzsch 1,4-dihydropyridines by sodium chlorite

Hantzsch 1,4-dihydropyridines were converted to the corresponding pyridines efficiently by sodium chlorite under mild conditions in excellent yields.     

Conversion of furans into gamma-hydroxybutenolides: use of sodium chlorite

3,4-disubstituted furans are converted into gamma-hydroxy-butenolides by treatment with NaClO(2) in aqueous EtOH containing NaH(2)PO(4).     

Direct chemical method for preparing 2,3-epoxyamides using sodium chlorite

A direct method for preparing 2,3-epoxyamides from tertiary allylamines via a tandem C-H oxidation/double bond epoxidation using sodium chlorite is reported. Apparently, the reaction course consists of two steps: (i) allylic oxidation of the starting allylamine to corresponding unsaturated allylamide with sodium chlorite followed by (ii) epoxidation of the allylamide to the 2,3-epoxyamide mediated by hypochlorite ion, which is formed in situ by reduction of sodium chlorite. The reaction conditions tolerate the presence of free hydroxyl groups and typical functional groups such as TBS, aryl, alkyl, allyl, acetyl, and benzyl groups; however, when an activated aromatic ring (e.g., sesamol) is present in the substrate, the use of a scavenger is necessary.     

Chemically peeling layers of cellulose nanocrystals by periodate and chlorite oxidation

Layers of cellulose nanocrystals are peeled off by controlled periodate and chlorite oxidation to produce nanocrystals with a tunable width. The chemical modification increases the solubility of the polymers at the crystal surface to the extent that they preferentially exist in solution and detach from the crystal. The number of layers removed is controlled by the degree of partial oxidation. The reaction occurs on the crystal surface and at the crystal ends, resulting in crystals which are both shorter and thinner, likely with dangling chains at each end. The crystallinity index is reduced with each layer removed.     

Ruthenium-catalyzed oxidation of alcohols with sodium bromate

Ruthenium trichloride-catalyzed oxidation of secondary alcohols with sodium bromate under basic conditions affords ketones in the excellent yields.     

Studies of the association of chitosan and alkylated chitosan with oppositely charged sodium dodecyl sulfate

Cationic biopolymer chitosan has many applications in food, cosmetic and pharmaceutical industries. Grafting alkylated chains on its backbone can hydrophobically modify this water-soluble polymer.This paper concerns unmodified chitosan, alkylated chitosan and their interactions with a model anionic surfactant, sodium dodecyl sulfate (SDS). The solvent is pH 4 acetic acid solution. The purpose of this study is to highlight the hydrophobicity brought by the alkylated chains by comparing surface tension measurements and rheological properties of hydrophobically modified polymer (HMP) and chitosan solutions at 25 °C.Interactions of chitosan and HMP with surfactant have also been investigated giving information about surface activity and electrical conductivity of such systems. It results that alkylated chitosan/SDS system is more surface active than chitosan/SDS and it offers new potential applications in pharmaceutical and cosmetic fields because of the formation of amphiphilic complexes.     

In-situ IR spectroscopy with a gas diffusion cell CO adsorption and oxidation on Pt

A gas diffusion cell allowing ready access of reactant to the electrode through the thin electrolyte layer has been used to obtain in-situ infra-red spectra from adsorbed CO on Pt under conditions of sustained reaction. The potential dependence of CO oxidation and adsorption and the inhibition of CO oxidation by adsorbed CO have been investigated.     

在中性条件下用亚氯酸钠和双氧水氧化芳香醛

本文优化了中性环境中亚氯酸钠和双氧水氧化醛的反应条件,采用正交实验设计法考察了溶剂、亚氯酸钠和双氧水的用量以及反应温度对醛氧化产率的影响,确定最佳工艺条件为以乙醇作溶剂,亚氯酸钠、双氧水、醛的摩尔比为1.1: 2: 1。在优化的反应条件下对醛进行底物扩展验证其适应性,并通过放大实验说明其工业生产适用性,本方法具有产率高、后处理简单、副产物绿色无污染的优点。     

Radiochemical study of Co2+ sorption on chlorite and kaolinite

In this work, the sorption behavior of Co(II) ions on natural chlorite and kaolinite as a function of time, concentration and temperature was studied.⁶⁰Co radiotracer method and the batch technique were used. The kinetic results indicated that about one day of contact time was enough to achieve equilibrium. The sorption process was described by Freundlich type isotherms. Sorption of Co(II) ions on both clays was found to be endothermic with ΔH ⁰ (kJ/mol) and ΔS ⁰ (kJ/mol·K) being 33 and 0.14 for kaolinite and 17 and 0.102 for chlorite, respectively. The magnitudes of the corresponding ΔG ⁰ values suggest that sorption occur mainly via an ion exchange mechanism on both clays.     

A temperature-programmed desorption and IR spectroscopic study of the mechanism of carbon monoxide oxidation on copper-containing catalysts

Kinetics and Catalysis - With the use of the temperature-programmed desorption of CO and IR spectroscopy, it was found that, after the adsorption of carbon monoxide on the oxidized 5% CuO/CeO2, 5%...     

Reaction kinetic behavior of different carbon monoxide adspecies on palladium-alumina during oxidation: an in-situ IR study

Carbon monoxide oxidation on Pd(10 w.t.%)-alumina was studied by in-situ infrared spectroscopy. It was found that the oxidation reactivities vary with different CO adspecies: linear COad > 2-fold bridged COad > multi-bridged COad.     

Nitroarene catalyzed oxidation with sodium percarbonate or sodium perborate as the terminal oxidant

A new catalytic oxidation method for the preparation of aromatic carboxylic acids from methyl aryl ketones is reported. The method is an alternative to the haloform reaction; it is benign and affords the desired product without production of any harmful side products. The catalytic cycle is based on the use of an electron-deficient nitroarene as catalyst with either of the two cheap and green oxidants sodium percarbonate or sodium perborate. The method gives a good yield (87%) and shows excellent selectivity when the model substrate (acetophenone) is oxidized. A series of benzoic acids of industrial interest were prepared by means of this method.     

Determination of degree of substitution for N-acylated chitosan using IR spectra

Chitosans with various degrees of deacetylation (D.D.), which were used as standard sample for FTIR determination, were prepared from completely deacetylated chitosan by homogeneous N-acetylation reaction. By combining four probable probe bands, i.e. 1655, 1560, 1380 and 1320 cm-1, eight probable reference bands, i.e. 3430, 2920, 2880, 1425, 1155, 1070, 1030 and 895 cm-1 and two baseline methods, the most suitable ratios Aprobe band/Aeterence band from IR spectra to determine the degree of acetylation of chitosan were evaluated from 48 combinations to be A1560/A2880, A1560/A2920 and A1655/A3430(A1560/A2880 is mostly recommended). The second baseline method, i.e. linking between adjacent two valleys, was better for measuring the absorbances of 1560 and 1655 cm-1 bands. The determination range of the D.D. (1%-100%) covered almost the whole range. The standard curves with A1560/A2880 and A1655/A3430 were also suitable for the determination of degree of substitution of other N-acylated chitosan, such as N-pr