Kinetics of oxidation of deoxybenzoin by chromic acid

The kinetics of the oxidation of deoxybenzoin by chromic acid in 95% (vol/vol) aqueous acetic acid has been investigated. The reaction rate is first order with respect to the oxidant as well as to the organic substrate. The reaction rate decreases in the presence of added Mn (II) ions. The presence of complexing agents like succinic acid, piperidine, etc. decreases the rate. The thermodynamic parameters for the oxidation have been computed. A mechanism proceeding through an enol intermediate has been suggested.     

The chromic acid oxidation of aliphatic secondary alcohols—substituent effects and the mechanism

The mechanism of the chromic acid oxidation of a number of substituted propan-2-ols has been studied in aqueous acetic acid medium. Electron withdrawing substituents retard the reaction considerably while electron-releasing substituents accelerate the reaction. A good correlation exists between the rate and σ* values. The ρ* value is ?1.60. The results are interpreted in terms of a rate-determining abstraction of the secondary hydrogen as a hydride anion.     

Kinetics of Thallium (III) oxidation of aromatic ketones

The kinetics of oxidation of acetophenone and six substituted acetophenones by Thallium (III) acetate have been studied in 95% (v/v) aqueous acetic acid. The reaction is first order with respect to the oxidant as well as the organic substrate and acid catalysed. The probable nature of Tl (III) species in aqueous acetic acid has been indicated. The rate data fitted well with Brown’sσ ⁺ values withρ ⁺ = ?0.70. A mechanism for the Tl (III) oxidation of aromatic ketones has been proposed.     

Kinetics of the thallic ion oxidation of olefins

The kinetics of oxidation of chalkone (phenyl styryl ketone) and cinnamaldehyde by T1 (III) acetate in aqueous acetic acid is of the first order in olefin and first order with respect to the oxidant. The parameters of the transition state theory have been computed. The rate of the reaction is strongly accelerated by increasing acid concentration. The reaction rate is also retarded by added sodium chloride and sodium acetate. The results have been interpreted in the light of the ionic mechanism considering T1 (OAc)₃ to be the active oxidant in aqueous acetic acid.     

Catalysed bromination of aromatic substrates

The kinetics of bromination of a reactive substrate like anisole and a less reactive substrate likep-nitrophenol has been investigated in acetic acid medium with iodine added to accelerate the reaction. The effective catalyst has been shown to be iodine bromide. The experimental results obtained from a study of the phenomenon of catalytic maximum in these reactions are in good agreement with the theoretical expectations.     

Studies in oxidation

The kinetics of the oxidation of toluene and its ring-substituted derivatives as well as of diphenyl methane by chromic acid have been studied in acetic acid-water systems. The reaction had to be in unbuffered solutions to get a measureable rate. Product analysis showed a step-wise reaction. Rate constants have been evaluated, using a graphical method, for a three-stage consecutive and concurrent reaction, the values being obtained for the first and last stages alone. Electron attracting substituents retard the reaction while those facilitating electron release accelerate the reaction. Diphenylmethane also undergoes only a step-wise reaction with the second step much slower than the first. A comparison of experimental activation energies indicates clearly that the entropy term of the rate equation exerts possibly an even greater influence on the reaction.     

Structure-reactivity relationship in the oxidation of aryl aliphatic ketones by CeIV

Kinetics of oxidation of aryl aliphatic ketones by Ce^IV in presence of HClO₄ in aqueous acetic acid medium has been studied. Reactivity has been found to be that substituents of electron withdrawing nature accelerate the reaction and the reverse is true with electron releasing substituents. A mechanism of radical intermediate is postulated to explain the observed phenomena. The unusual reactivity of the alkoxy derivatives may be traced to a change in the mechanism routed through a carbonium ion centre or alternatively it might be due to the hydrolysis of the alkoxy derivatives leading to the higher reactivity observed.     

Studies in the formation of heterocyclic rings containing nitrogen: Part XXIII. Condensation ofo-aminobenzamide with aldehydes and schiff bases

N-Arylidene orthanilamides undergo isomeric cyclisation in acetic acid to the corresponding 2-aryl-1, 2, 3, 4-tetrahydro-4-oxoquinazolines. The u.v. and n.m.r. spectra of some of the arylidene derivatives and their isomeric tetrahydroquinazolines have neeb studied. Condensation ofo-aminobenzamide either with aromatic aldehydes in nitrobenzene or Schiff bases in acetic acid has yielded 2-aryl-4 (3H)-quinazolinones.     

Influence of diffusion of a liquid on the flexural rigidity of polyformaldehyde specimens

A correlation has been established between the flexural rigidity of polyformaldehyde specimens and the diffusional characteristics of water, acetic acid, and benzine into this material.     

Oxidation ofα-hydroxy acids and derivatives by Cr(VI) oxide

The kinetics of the chromic acid oxidation ofα-hydroxy acids, their salts and esters has been investigated in binary solvent mixtures of acetic acid and water. The results indicate that the Westheimer hypothesis of a rate-determining proton-abstraction from a preformed chromate ester is unlikely. Substituent and salt effects indicate the likelihood of a mechanism involving a rate-determining hydride ion abstraction assisted by a proximate substituent.     

Polarographic reduction of pyruvic acid

The application of Delahay’s theory of kinetic polarographic currents as applied to the reduction of pyruvic acid has been examined. It is shown that the agreement between Delahay’s theory and the available data is more satisfactory, if one assumes that the current is controlled by the rate of the reaction between pyruvate ion and water molecule forming pyruvic acid and hydroxyl ion, than when one assumes the mechanism suggested by the earlier workers involving the rate of reaction between pyruvate ion and hydrogen-ion, both from the point of view of the magnitude of the diffusion current as well as its pH dependence. The results give an indication of the latter reaction being sluggish due to the activation energy requirements.     

Solvent extraction studies of indium

Solvent extraction of indium from malonic acid medium by Primene JM-T has been studied. The extraction has been studied as a function of pH and concentrations of malonic acid and sodium malonate. The nature of the acid-amine complex has been established by chemical analysis and by the application of the method of Hogfeldt and Fredlund. The equilibrium constant for the reaction has also been calculated. The nature of the indium complexes getting extracted has also been discussed.     

Free energy relationship in some electron-transfer reactions

A linear logarithmic dependence of the standard rate constant on the apparent free energy of activation for the electrode process has been observed for the reduction of zinc in the presence of alanine, glycine, aspartic acid, glutamic acid, ammonia, ethylenediamine and tartrate. The value of the slope is close to the transfer coefficient of zinc in these media. For a homogeneous electron-exchange reaction, such as the disproportionation of uranium(V) in solution, a linear free energy relation has been observed.     

Application of Pschorr reaction to N-(o-aminobenzoyl)-benzyl and phenethyl amines and to N-(o-aminophenylacetyl) anilines

Decomposition of the diazonium chloride from N-(o-aminobenzoyl)-N-methylbenzylamine led to the formation of 3-benzyl-3, 4-dihydrobenzo-triazin-4-one (8), N-benzoylbenzylamine (11), N-benzylphthalimidine (13) ando-diphenic acid N-methyl amide (14), the last one presumably through the intermediary, the expected dibenzazepinone 16. From the analogue, N-(o-aminobenzoyl)-4-methoxybenzyl amine (4), triazinone 10 and N-benzoyl-4-methoxybenzyl amine (12) were obtained. Application of Pschorr reaction to N-(o-aminobenzoyl)-N-methyl-β-(4-methoxyphenyl) ethyl amine (23) afforded 2-methoxy-7-methyl-5, 6, 7, 8- tetrahydrodibenzo (c, e) azocin-8-one (26), with an interesting conformation. From N-(o-aminophenylacetyl)-p-methoxyaniline were obtained under these conditions, indazole-3-carboxylic acidp-anisidide (35) and N-[2-(4-methoxyphenyl carbamoylmethyl) phenyl]-1-(p-methoxyphenyl) isatin-β-hydrazone (37). The structure of 37 was deduced from spectral data and hydrolysis to the acid 42. Diazotisation of N-(o-aminophenylacetyl)-1, 2, 3, 4-tetrahydroquinoline (47) led to the formation of tetrahydroquinoline (49) ando-hydroxyphenyl acetic acid (50) presumably through the salicylamide 48. A similar reaction on N-(o-aminophenylacetyl) tetrahydroisoquinoline (52) gave the benzofurandione hydrazone 55, besides tetrahydroisoquinoline. Oxindole 45 and benzofuranone 56 were likely precursors for 37 and 55 respectively. Salicylamides 5, 7, 24 and 34 were byproducts in the Pschorr reaction.     

Studies in oxidation: Oxidation of some aliphatic secondary alcohols with chromium (VI) oxide—Part I

Proceedings - Mathematical Sciences - The oxidation of isopropyl alcohol, butanol-2, pentanol-2 and octanol-2 by chromium (VI) oxide, has been studied in acetic acid-water mixtures under conditions...     

数理统计方法在青霉素质量管理中的应用

青霉素生产的质量问题一直困扰着企业，本文选取影响青霉素质量的指标──效价，指出与效价有关的因素，如：糖、苯乙酸、尿素、菌丝重、孢子数等。用回归方法，建立多无线性回归模型，并预测出效价值，从而判定青霉素生产是否正常，提高了产品质量和经济效益。     

Effect of complexing agents on the disproportionation of uranium (V)

The effect of lactate, thiocyanate, sulphate, oxalic acid and fluoride on the disproportionation of uranium (V) formed at the dropping mercury electrode has been studied. The rate constants for the disproportionation reaction are calculated and the results are discussed on the basis of the stability of the complexes.     

Oxidation studies

Studies on oxidation of water by cobaltic ions in perchloric, nitric and sulfuric acid media in the temperature range 20–30° C. at constant ionic strength of 2·2 M were carried out. An overall order of 3/2 for cobaltic ion concentration was observed in perchloric, nitric acid media and at low [Co³⁺]<4×10^?3 M in sulfuric acid medium. At high [Co³⁺] in sulfuric acid medium an order 2 was observed. In all the three acid media an inverse dependence of the rates on [H⁺] was noticed. From the experimental results, an acid-independent reaction path was inferred in perchloric and nitric acid media. The effect of ionic strength, HSO ₄ ^? and initially added cobaltous ions as well as temperature was studied. Suitable reaction schemes were suggested to explain the experimental results and activation energy values for some of the rate parameters were evaluated. Kinetic studies on oxidation of tertiary amyl and tertiary butyl alcohols in sulfuric acid medium and that of the former in perchloric acid medium were carried out. The reaction rates were found to vary linearly with [Co³⁺] and [Alcohol]. From the effect of acidity and of [HSO ₄ ^? ] in H₂SO₄ medium on the reaction rates it was concluded that in HClO₄ medium CoOH²⁺ species were the active entities while in H₂SO₄ medium Co³⁺ as well as CoOH²⁺ species were the active entities. The influence of ionic strength, temperature, etc., on the raction rates were studied and activation energy values for some rate constants were evaluated.     

Studies in the formation of heterocyclic rings containing nitrogen

Synthesis of 1-benzyl-3-methyl (I), 1-beazyl-3-substituted benzyl (II) and 1-methyl-3-substituted benzyl (III)-2-aryl benzimidazolines is described. (I) acc obtained by the condensation of N¹benzyl-N²methyl-o-phenylenediamine with various aldehydes in metharol. Compounds (II) are prepared from N¹-benzyl-N²-arylidene-o-phenylenediamines in acetic acid, through a process of disproportionation involving an oxidation-reduction process. Likewise, (III) are obtained from N¹-methyl-N²-arylidenc-o-phenylenediamines. The exact structure of N¹-benzyl-N²-arylidene-o-phenylenediamines which can exist in the open chain form or in the ring form has been investigated using nmr spectroscopy.     

Polymerization of vinyl monomers

A systematic study of the kinetics of photosensitized polymerization of vinyl monomers with the system Dye (erythrosin or acriflavine)-reducing agent (ascorbic acid), in the presence of oxygen and under buffered conditions (pH 6) in aqueous solution has been made. The determinations of the monomer disappearance, dye disappearance and of chainlengths of the polymers obtained against the different variables like light intensity, concentrations of monomer, dye, ascorbic acid, etc., have been made. A kinetic mechanism proposed for the overall reaction is discussed in the light of the experimental results and certain rate constants have also been evaluated.