Synthesis of 1‐amino‐2‐methylindoline by Raschig process: Parallel reactions,modeling, and optimization

The reaction between chloramine and 2‐methylindoline was studied at pH 12.89, T = 40°C, and for different initial concentrations of reactants. The interaction includes two concurrent bimolecular mechanisms leading to 1‐amino‐2‐methylindoline and 2‐methylindole. The rate laws were determined at the first moments of the reaction by using a differential method. By considering the totality of the reactions that occur in the medium, an appropriate mathematical model was developed. It permits to follow the evolution of the system over time and to calculate the final yields of reaction products. An optimization in terms of the initial contents of 2‐methylindoline and chloramine was performed. It indicated that the maximum yield of 1‐amino‐2‐methylindoline does not exceed 56%. The results show the limit of the Raschig process for the synthesis of indolic hydrazines in aqueous medium. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 575–584, 2002     

Synthesis and characterization of new heterocyclic derivatives by oxidation of 1‐amino‐2‐methylindoline

1‐Amino‐2‐methylindoline is a precursor used in the synthesis of antihypertension drugs. It reacts with monochloramine to lead to the formation of 1‐amino‐2‐methylindole and azo(2‐methyl)indoline. These new products have been isolated and characterized by microanalysis, uv, gc/ms, ir, and ¹H/¹³C nmr. The reaction leads to the transient formation of an indolic aminonitrene. 1‐Amino‐2‐methylindole formation proceeds in strongly alkaline medium by rearrangement of a diaziridine intermediate. In neutral or slightly alkaline medium, one obtains a precipitate of tetrazene type (‐N‐N=N‐N‐), the azo(2‐methyl)indoline. The study of the thermochemical properties shows that tetrazene decomposes towards 150 °C to give the 1,1′‐bi(2‐methyl)indoline. The stability of the starting reagents and products was the subject of a systematic investigation. A reaction mechanism is proposed.     

Kinetic characterization of a transient reaction by degeneration of the precursor mechanism: Application to the synthesis of 3,4‐diazabicyclo[4.3.0]‐ non‐2‐ene

The rate of the oxidation of N‐amino‐3‐azabicyclo[3.3.0]octane by chloramine has been studied by GC and HPLC between pH 10.5 and 13.5. The second‐order reaction exhibits specific acid catalysis. The formation of N,N′‐azo‐3‐azabicyclo[3.3.0]octane or 3,4‐diazabicyclo[4.3.0]non‐2‐ene is pH, concentration, and temperature dependent. In alkaline media, the exclusive formation of 3,4‐diazabicyclo[4.3.0]non‐2‐ene is observed. Kinetic studies show that the oxidation of N‐amino‐3‐azabicyclo[3.3.0]octane by chloramine is a multistep process with the initial formation of a diazene‐type intermediate, which is converted by hydroxide ions into 3,4‐diazabicyclo[4.3.0]non‐2‐ene. Because it was not possible to follow the rate of change of the intermediate concentration, to determine the kinetics of 3,4‐diazabicyclo[4.3.0]non‐2‐ene formation, a procedure based on the degeneration of the precursor process was adopted. An appropriate mathematical treatment allowed a quantitative interpretation of all the phenomena observed over the given pH interval. The activation parameters were determined. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 327–338, 2006     

Kinetics and mechanism of oxidation of neutral α ‐amino acids by sodium N‐chloro‐p‐toluenesulfonamide in acid medium

Kinetics of oxidation of α ‐amino acids, glycine, valine, alanine, and phenylalanine, by sodium N‐chloro‐p‐toluenesulfonamide or chloramine‐T (CAT) has been investigated in HClO₄ medium at 30°C. The rate shows first‐order dependence on both CAT and amino acid concentrations and an inverse first‐order on [H⁺]. The variation of ionic strength and the addition of p‐toluenesulfonamide and Cl^? ion had no effect on the reaction rate. Decrease of dielectric constant of the medium by increasing the MeOH content decreased the rate. Rate studies in D₂O medium showed the inverse solvent‐isotope effect of k_D2O/k_H2O=0.50. Proton‐inventory studies were carried out using H₂O–D₂O mixtures. The activation parameters have been computed. The proposed mechanism and the derived rate law are consistent with the observed kinetic data. An isokinetic relationship is observed with β=323 K, indicating enthalpy as a controlling factor. The rate of oxidation increases in the following order: Gly < Val < Phe < Ala. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 34: 49–55, 2002     

Comparison of the hydrogen‐bond patterns in 2‐amino‐1,3,4‐thiadiazolium hydrogen oxalate, 2‐amino‐1,3,4‐thiadiazole–succinic acid (1/2), 2‐amino‐1,3,4‐thiadiazole–glutaric acid (1/1) and 2‐amino‐1,3,4‐thiadiazole–adipic acid (1/1)

The X‐ray single‐crystal structure determinations of the chemically related compounds 2‐amino‐1,3,4‐thiadiazolium hydrogen oxalate, C₂H₄N₃S⁺·C₂HO₄⁻, (I), 2‐amino‐1,3,4‐thiadiazole–succinic acid (1/2), C₂H₃N₃S·2C₄H₆O₄, (II), 2‐amino‐1,3,4‐thiadiazole–glutaric acid (1/1), C₂H₃N₃S·C₅H₈O₄, (III), and 2‐amino‐1,3,4‐thiadiazole–adipic acid (1/1), C₂H₃N₃S·C₆H₁₀O₄, (IV), are reported and their hydrogen‐bonding patterns are compared. The hydrogen bonds are of the types N—H...O or O—H...N and are of moderate strength. In some cases, weak C—H...O interactions are also present. Compound (II) differs from the others not only in the molar ratio of base and acid (1:2), but also in its hydrogen‐bonding pattern, which is based on chain motifs. In (I), (III) and (IV), the most prominent feature is the presence of an R₂²(8) graph‐set motif formed by N—H...O and O—H...N hydrogen bonds, which are present in all structures except for (I), where only a pair of N—H...O hydrogen bonds is present, in agreement with the greater acidity of oxalic acid. There are nonbonding S...O interactions present in all four structures. The difference electron‐density maps show a lack of electron density about the S atom along the S...O vector. In all four structures, the carboxylic acid H atoms are present in a rare configuration with a C—C—O—H torsion angle of ∼0°. In the structures of (II)–(IV), the C—C—O—H torsion angle of the second carboxylic acid group has the more common value of ∼|180|°. The dicarboxylic acid molecules are situated on crystallographic inversion centres in (II). The Raman and IR spectra of the title compounds are presented and analysed.     

Synthesis and reaction of β‐hydroxyaspartic acid‐based polymethacrylate

O‐Methacryloyl‐N‐(tert‐butoxycarbonyl)‐β‐hydroxyaspartic acid dimethyl ester was synthesized by methyl esterification of β‐hydroxyaspartic acid, followed by protection of the amino group with the tert‐butoxycarbonyl group and then the reaction of the hydroxyl group with methacryloyl chloride. The monomer efficiently underwent radical polymerization to afford the corresponding polymer with a number‐average molecular weight of 42,000 in good yields. The alkaline hydrolysis of the polymer occurred not only at the methyl ester but also at the ester moiety between the main and side chains of the polymer. The methyl ester‐free polymer gradually released β‐hydroxyaspartic acid moiety in a phosphate buffer solution with pH = 7.3 and 7.8. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2782–2788, 2002     

Palladium(II) complexes of aliphatic amines and their oxidation by chloramine‐T in perchloric acid medium

The formation of palladium(II) complexes with aliphatic amines and their oxidation by chloramine‐T in perchloric acid medium has been studied. The spectrophotometric studies showed the formation of 1:1 and 1:2 complexes between palladium(II) and amine in absence of HClO₄. An increase in [HClO₄] in reaction mixture suppresses the complex formation and in presence of [HClO₄] ～10^?3 mol dm^?3 only a 1:1 complex between palladium(II) and amine has been observed. The effect of Cl^? on the complex formation has also been studied. Palladium(II)‐catalyzed oxidation of these amines by chloramine‐T showed a first‐order dependence of rate with respect to each—oxidant, substrate, catalyst, and H⁺. The mechanism consistent with kinetic data for the oxidation process has been proposed in absence as well as in presence of initial [Cl^?]. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 603–612, 2002     

The synthesis and transformations of 2‐[2‐ethoxycarbonyl‐2‐(2‐pyridinyl)ethenyl]amino‐3‐dimethylaminopropenoates. the synthesis of substituted β‐amino‐α,β‐didehydro‐a‐amino acid derivatives

Alkyl (Z)‐2‐[(E)‐2‐ethoxycarbonyl‐2‐(2‐pyridinyl)ethenyl]amino‐3‐dimethylaminopropenoates 7 and 8 were prepared from ethyl 2‐pyridinylacetate (1) in two steps. Substitution of the dimethylamino group with alkyl‐, aryl‐, or heteroarylamines afforded the corresponding β‐alkyl‐ 22–24 , β‐aryl‐ 25–35 , and β‐herteroaryl‐amino‐α,β‐didehydro‐α‐amino acid 36 and 37 derivatives, intermediates for further preparation of various heterocyclic systems. The orientation around both double bonds were determined by various nmr techniques.     

Study of the oxidation of some catechols in the presence of 4‐amino‐3‐thio‐1,2,4‐triazole by digital simulation of cyclic voltammograms

Electrochemical oxidation of catechol and its derivatives ( 1a–d ) has been studied in the presence of 4‐amino‐3‐thio‐1,2,4‐triazole ( 3 ) at various pHs. Some electrochemical techniques such as cyclic voltammetry using the diagnostic criteria derived by Nicholson and Shain for various electrode mechanisms and controlled‐potential coulometry were used. Results indicate the participation of catechols ( 1a–d ) with 3 in an intramolecular cyclization reaction to form the corresponding 1,2,4‐triazino[5,4‐b]‐1,3,4‐thiadiazine derivatives. In various scan rates, based on an electron transfer–chemical reaction–electron transfer–chemical reaction mechanism, the observed homogeneous rate constants (k_obs) for Michael addition reaction were estimated by comparing the experimental cyclic voltammetric responses with the digital simulated results. The oxidation reaction mechanism of catechols ( 1a–d ) in the presence of 4‐amino‐3‐thio‐1,2,4‐triazole ( 3 ) was also studied. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 340–345, 2007     

1H and 13C NMR spectroscopic study of oxidation of D,L‐cystine and 3,3′‐dithiobis(propionic acid) with hydrogen peroxide in aqueous solution

The oxidation of symmetrical disulfides [D ,L ‐cystine ( 1 ) and 3,3′‐dithiobis(propionic acid) ( 2 )] with hydrogen peroxide in D₂O–NaOH solution (pH 10–11) was studied by NMR spectroscopy. Assignments of the proton and carbon NMR signals of starting materials ( 1 and 2 ) and products of oxidation are based on conventional 1D NMR methods (DEPT, selective spin decoupling). Formation of C—S bond cleavage products or, in case of 2 , partially oxidized intermediates was not detected. The accelerating effect of Cu²⁺ cations, but not Fe³⁺ cations, on the oxidation rate of 1 in basic medium was demonstrated. Copyright © 2002 John Wiley & Sons, Ltd.     

Kinetics of electropolymerization of 1‐amino‐9,10‐anthraquinone

1‐Amino‐9,10‐anthraquinone was electropolymerized on platinum substrates either from aqueous or nonaqueous electrolytes. The aqueous electrolyte was 6.0 mol L^?1 H₂SO₄, and the nonaqueous solvent was acetonitrile containing lithium perchlorate, LiClO₄, as a supporting electrolyte. The formed polyaminoanthraquinone was stable, and the polymerization process was reproducible. The kinetics of the electropolymerization process was investigated by determining the charge consumed during the electropolymerization as a function of time at different concentrations of the electrolyte components. The results of chronoamperometry have been used to determine the orders of reaction. In either aqueous or nonaqueous solution, the electropolymerization process follows first‐order kinetics with respect to the monomer concentration. In nonaqueous solution, the very small concentrations of water did not affect the order of reaction. The order of reaction with respect to the traces of water and the supporting electrolyte concentration was found to be zero. In aqueous solution, the order of the electropolymerization reaction with respect to the concentration of H₂SO₄ was found to be negative (?0.66), which means that the aqueous electrolyte inhibits the polymerization reaction. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 141–146, 2011     

Design of two series of 1:1 cocrystals involving 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine and carboxylic acids

Two series of a total of ten cocrystals involving 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine with various carboxylic acids have been prepared and characterized by single‐crystal X‐ray diffraction. The pyrimidine unit used for the cocrystals offers two ring N atoms (positions N1 and N3) as proton‐accepting sites. Depending upon the site of protonation, two types of cations are possible [Rajam et al. (2017). Acta Cryst. C 73 , 862–868]. In a parallel arrangement, two series of cocrystals are possible depending upon the hydrogen bonding of the carboxyl group with position N1 or N3. In one series of cocrystals, i.e. 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–3‐bromothiophene‐2‐carboxylic acid (1/1), 1 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–5‐chlorothiophene‐2‐carboxylic acid (1/1), 2 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–2,4‐dichlorobenzoic acid (1/1), 3 , and 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–2‐aminobenzoic acid (1/1), 4 , the carboxyl hydroxy group (–OH) is hydrogen bonded to position N1 (O—H…N1) of the corresponding pyrimidine unit (single point supramolecular synthon). The inversion‐related stacked pyrimidines are doubly bridged by the carboxyl groups via N—H…O and O—H…N hydrogen bonds to form a large cage‐like tetrameric unit with an R₄²(20) graph‐set ring motif. These tetrameric units are further connected via base pairing through a pair of N—H…N hydrogen bonds, generating R₂²(8) motifs (supramolecular homosynthon). In the other series of cocrystals, i.e. 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–5‐methylthiophene‐2‐carboxylic acid (1/1), 5 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–benzoic acid (1/1), 6 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–2‐methylbenzoic acid (1/1), 7 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–3‐methylbenzoic acid (1/1), 8 , 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–4‐methylbenzoic acid (1/1), 9 , and 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–4‐aminobenzoic acid (1/1), 10 , the carboxyl group interacts with position N3 and the adjacent 4‐amino group of the corresponding pyrimidine ring via O—H…N and N—H…O hydrogen bonds to generate the robust R₂²(8) supramolecular heterosynthon. These heterosynthons are further connected by N—H…N hydrogen‐bond interactions in a linear fashion to form a chain‐like arrangement. In cocrystal 1 , a Br…Br halogen bond is present, in cocrystals 2 and 3 , Cl…Cl halogen bonds are present, and in cocrystals 5 , 6 and 7 , Cl…O halogen bonds are present. In all of the ten cocrystals, π–π stacking interactions are observed.     

Antagonism in (conventional anionic–gemini anionic) mixed micelle catalyzed oxidation of D‐fructose by alkaline chloramine‐T: A kinetic study

The catalytic effect of individual conventional anionic surfactant, namely, sodium lauryl sulfate (NaLS), anionic gemini surfactant, namely, sodium salt of bis(1‐dodecenyl succinamic acid) (NaBDS), and mixed surfactant (NaLS + NaBDS) on the rate of oxidation of D ‐fructose by alkaline chloramine‐T has been investigated. The reaction always showed a first‐order dependence of rate with respect to each fructose, alkali, and chloramine‐T. The rate was proportional to (k′+k″ [surfactant]), where k′ and k″ are the rate constants in the absence and presence of the surfactant, respectively. The binding parameters have been evaluated. The observed catalytic effect of mixed micelle on the rate of oxidation was always less than the algebraic sum of the catalytic effect of two surfactants when they were taken separately, suggesting an antagonism (negative synergism) in mixed micelle. The antagonism has also been confirmed by determining critical micelle concentration and interaction parameter (β^m) of mixed micelle under the experimental conditions of kinetics, that is, in alkaline medium. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 123–132, 2009     

Oxidation of isoniazid by N‐haloarenesulfonamidates in alkaline medium: A kinetic and mechanistic study

The kinetics of oxidation of Isoniazid (INH) by sodium N‐haloarenesulfonamidates, chloramine‐T (CAT), bromamine‐T (BAT), chloramine‐B (CAB), and bromamine‐B (BAB), has been studied in alkaline medium at 303 K. The oxidation reaction follows identical kinetics with a first‐order dependence on each [oxidant] and [INH] and an inverse fractional‐order on [OH^−:]. Addition of the reaction product (p‐toluenesulfonamide or benzenesulfonamide) had no significant effect on the reaction rate. Variation of ionic strength and addition of halide ions have no influence on the rate. There is a negative effect of dielectric constant of the solvent. Studies of solvent isotope effects using D₂O showed a retardation of rate in the heavier medium. The reaction was studied at different temperatures, and activation parameters have been computed from the Arrhenius and Eyring plots. Isonicotinic acid was identified as the oxidation product by GC‐MS. A two‐pathway mechanism is pro‐posed in which RNHX and the anion RNX⁻ interact with the substrate in the rate‐limiting steps. The mechanism proposed and the derived rate laws are consistent with the observed kinetics. The rate of oxidation of INH increases in the order: BAT > BAB > CAT > CAB. This effect is mainly due to electronic factors. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 221–230, 2000     

Synthesis of new substituted 5‐methyl‐3,5‐diphenylimidazolidine‐2,4‐diones from substituted 1‐(1‐cyanoethyl‐1‐phenyl)‐3‐phenylureas

The reaction of substituted phenyl isocyanates with 2‐amino‐2‐phenylpropanenitrile and 2‐amino‐2‐(4‐nitrophenyl)propanenitrile has been used to prepare substituted 1‐(1‐cyanoethyl‐1‐phenyl)‐3‐phenylureas. In anhydrous phosphoric acid the first products to be formed from 1‐(1‐cyanoethyl‐1‐phenyl)‐3‐phenylureas are phosphates of 4‐methyl‐4‐phenyl‐2‐phenylimino‐5‐imino‐4,5‐dihydro‐1,3‐oxazoles, which on subsequent hydrolysis give the respective ureidocarboxylic acids. On prolongation of the reaction time, the phosphates of 4‐methyl‐4‐phenyl‐2‐phenylimino‐5‐imino‐4,5‐dihydro‐1,3‐oxazoles rearrange to give phosphates of 5‐methyl‐4‐imino‐3,5‐diphenylimidazolidin‐2‐ones, and these are subsequently hydrolysed to the respective substituted 5‐methyl‐3,5‐diphenylimidazolidin‐2,4‐diones. The ureidocarboxylic acids were also prepared by alkaline hydrolysis of 5‐methyl‐3,5‐diphenylimidazolidin‐2,4‐diones. The 5‐methyl‐3,5‐diphenylimidazolidin‐2,4‐diones and ureidocarboxylic acids were characterised by their ¹H and ¹³C NMR spectra. Structure of the 5‐methyl‐5‐(4‐nitrophenyl)‐3‐phenylimidazolidine‐2,4‐dione was verified by X‐ray diffraction. The alkaline hydrolysis of individual imidazolidine‐2,4‐diones was studies spectrophoto‐metrically in sodium hydroxide solutions at 25 °C. The rate‐limiting step of the base catalysed hydrolysis consists in decomposition of the tetrahedral intermediate. The reaction is faster if electron‐acceptor sub‐stituents are present in the 3‐phenyl group of imidazolidine‐2,4‐dione cycle. The pK_a values of individual 5‐methyl‐3,5‐diphenylimidazolidine‐2,4‐diones have been determined kinetically.     

Synthesis of novel N1‐(2‐furanidyl)‐5‐fluorouracil derivatives of α‐hydroxy(thio)phosphonates

Several N¹‐(2‐furanidyl)‐5‐fluorouracil derivatives of α‐hydroxythiophosphonates were synthesized via oxidation by Moffatt's method of N¹‐(2‐furanidyl)‐N³‐(hydroxyalkyl)‐5‐fluorouracil, followed by the addition of diethyl thiophosphite. The phosphonate products were obtained by the oxidation of the corresponding thiophosphonates with m‐chloroperoxybenzoic acid. The crystal structure of compound 6a was determined by X‐ray diffraction. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:211–215, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10021     

Reactions of N‐arylmaleimides with 3‐amino‐1,2,4‐triazole and 2‐aminobenzimidazole

The reaction of 3‐amino‐1,2,4‐triazole ( 1 ) with N‐arylmaleimides leads to azolopyrimidines 4 and 5 . The 2‐aminobenzimidazole ( 2 ) in the reaction with 3 gives the pyrimidobenzimidazoles 6 . In similar conditions, the reaction of amine 2 with maleic anhydride ( 7 ) leads to formation of 2‐oxo‐1,2,3,4‐tetrahydropyrimido[1,2‐a]benzimidazole‐4‐carboxylic acid ( 8 ). The structures of 4 , 5 , 6 , and 8 were proved by X‐Ray and NOE NMR measurements. J. Heterocyclic Chem., (2011)     

Oxidation of 2‐Phenylethylamine with N‐Bromosuccinimide in Acid and Alkaline Media: A Kinetic and Mechanistic Study

A kinetic study of oxidation of 2‐phenylethylamine (PEA), a bioactive compound, with potent oxidant, N‐bromosuccinimide (NBS) has been carried out in HCl and NaOH media at 313 K. The experimental rate laws obtained are: ‐d [NBS] /dt = k[NBS][PEA][H⁺] in hydrochloric acid medium and ‐d [NBS]/dt = k[NBS][PEA]^x[OH^?]^y in alkaline medium where x and y are less than unity. Accelerating effect of [Cl^?], and retardation of the added succinimide on the reaction rate have been observed in acid medium. Variation of ionic strength of the medium shows negligible effect on rate of reaction in both media. Decrease in dielectric permittivity of the medium decreased the rate in both media. The stoichiometry of the reaction was found to be 1:1 in acid medium and 1:2 in the case of alkaline medium. The oxidation products of PEA were identified as the corresponding aldehyde and nitrile in acid and alkaline medium, respectively. The reactions were studied at different temperatures and the activation parameters have been evaluated. The reaction constants involved in the proposed mechanisms were computed. The reaction was found to be faster in alkaline medium in comparison with the acid medium, which is attributed to the involvement of different oxidizing species. The proposed mechanisms and the derived rate laws are consistent with the observed experimental results.     

Kinetic and mechanistic studies on the oxidation of Norfloxacin by Chloramine‐B and N‐Chlorobenzotriazole in acidic medium

The kinetics of oxidation of Norfloxacin [1‐ethyl‐6‐fluoro‐1,4‐dihydro‐4‐oxo‐7‐(l‐piperazinyl)‐3‐quinoline carboxylic acid] by chloramine‐B and N‐chlorobenzotriazole has been studied in aqueous acetic acid medium (25% v/v) in the presence of perchloric acid at 323 K. For both the oxidants, the reaction follows a first‐order dependence on [oxidant], a fractional‐order on [Norfloxacin], and an inverse‐fractional order on [H⁺]. Dependence of reaction rate on ionic strength, reaction product, dielectric constant, solvent isotope, and temperature is studied. Kinetic parameters are evaluated. The reaction products are identified. The proposed reaction mechanism and the derived rate equation are consistent with the observed kinetic data. Formation and decomposition constants for substrate–oxidant complexes are evaluated. ©1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 153–158, 1999     

Kinetics and Mechanism of Oxidation of 1‐Methoxy‐2‐propanol and 1‐Ethoxy‐2‐propanol by Ditelluratocuprate(III) in Alkaline Medium

The kinetics of oxidation of 1‐methoxy‐2‐propanol and 1‐ethoxy‐2‐propanol by ditelluratocuprate(III) (DTC) in alkaline liquids has been studied spectrophotometrically in the temperature range of 293.2–313.2 K. The reaction rate showed first order dependence in DTC and fractional order with respect to 1‐methoxy‐2‐propanol or 1‐ethoxy‐2‐propanol. It was found that the pseudo‐first order rate constant k_obs increased with an increase in concentration of OH^? and a decrease in concentration of TeO₄^2?. There is a negative salt effect. A plausible mechanism involving a pre‐equilibrium of a adduct formation between the complex and 1‐methoxy‐2‐propanol or 1‐ethoxy‐2‐propanol was proposed. The rate equations derived from mechanism can explain all experimental observations. The activation parameters along with the rate constants of the rate‐determining step were calculated.