Halogen oxidation of mixed amine(tricarbonyl)chromiums

Summary Bromine and iodine oxidation of some mixed amine-(tricarbonyl)chromiums Cr(CO)₃(L-L)(amine) (L-L=o-phen or 2,2-bipy; amine=cyclohexylamine, piperidine and n-butylamine), at ambient temperature lead to the formation of [Cr(CO)₂(L-L)(amine)Br]Br₃ and [Cr(CO)₂(L-L)(amine)I]I complexes which have been characterised by elemental analysis, i.r. spectra, conductivity and magnetic moment measurements.     

Quinonimines and aminoquinones, the reaction products of 3,6-di(tert-butyl)-o-benzoquinone with primary and secondary amines

Reactions of 3,6-di(tert-butyl)-o-benzoquinone with primary amines occur by the nucleophilic 1,4-addition mechanism and lead to the corresponding 2-hydroxy-p-quinonimines, which exist in solutions in equilibrium with tautomeric 4-amino-o-quinones. The thermodynamic parameters of this prototropic isomerism were determined by NMR spectroscopy. In the case of a secondary amine (piperidine), a derivative of 4-amino-o-quinone was obtained; the corresponding o-semiquinone complexes were studied in solution by ESR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1151–1155, July, 2006.     

Dipole moment characterization of phenol–, o-cresol–, and p-cresol–formaldehyde resins

Dipole moments and their temperature dependence have been measured in p-dioxane for fractionated novolac phenol–, o-cresol–, and p-cresol–formaldehyde polymers. The phenol–formaldehyde fractions covered a molecular weight range of 200 to 6100, and the limiting dipole moment ratio 〈μ²〉/xm² is 1.48. The p-cresol–formaldehyde dipole-moment ratio at a DP of 4 is 2.47, whereas the phenol–formaldehyde dipole-moment ratio is 1.40. That for o-cresol–formaldehyde is intermediate in value. The dipole-moment temperature coefficients are positive for p-cresol chains and negative for the phenol–formaldehyde chains. These results indicate that the hydroxyl groups along the p-cresol–formaldehyde polymer are highly ordered, with the aromatic rings closer to the sterically hindered planar position than in the phenol–formaldehyde polymers.     

Studies of the formation of thermosetting resins. XII. Computer simulation of the reactions of phenols with formaldehyde

The mechanism of the reaction of phenols with formaldehyde was studied by computer simulation. At first starting molecules were stored in a computer and the hypothetical reaction yielded conditions like the reactivity ratio of hydroxymethyl group to formaldehyde and that of orthohydrogen to parahydrogen. The molecular weight distribution of the hypothetical product in the computer was compared with that of the prepared resin determined from GPC measurement. Reaction mechanisms were discussed. We also confirmed, by computer simulation, that the rate of methylenation is larger than that of hydroxymethylation in an acid-catalyzed system and that the reactivity ratio of hydroxymethyl group to formaldehyde is 5–12 for the reaction of phenols such as o-cresol, p-cresol, and phenol with formaldehyde. The opposite results were obtained in a base-catalyzed system. It also became apparent that information regarding molecular structures, such as the number of branches, the number of phenolic nuclei in the longest chain, and the number of o,o′-,o,p′- and p,p′-methylene linkages, can be obtained by computer simulation. The most probable values of these factors for 10 mer of a phenol–formaldehyde condensation molecule are 2, 7, 2, 5, and 2.     

Halogen oxidation of mixed aminetungsten tricarbonyls

Summary Halogen oxidation of mixed aminetungsten tricarbonyls, (L-L.) (amine) (CO)₃ W (L-L. =o-phen or 2,2-bipy; amine = cyclohexylamine, piperidine, morpholine, n-butylamine and n-hexylamine), at ambient temperature resulted in the formation of unusual products (L-L)(amine)(CO)₃ W. nX₂ (X = 1, n = 1; X = Br, n = 2). Their formation has been inferred on the basis of elemental analysis, i.r. and conductivity measurements.     

Flow injection-spectrophotometric determination of cresol compounds in water by reaction withp-aminophenol

A spectrophotometric method has been developed for the simultaneous determination ofo-cresol andm-cresol in water by reaction withp-aminophenol (PAP). Three different methodologies have been assayed; (i) batch analysis, after reaction in an alkaline medium in the presence of dissolved molecular oxygen as oxidizing agent, (ii) a stopped-flow procedure, carried out in the presence of KIO₄ and (iii) a flow injection method based on the same approach. The batch procedure requires 22 min for the full development of colour witho-cresol and 12 min form-cresol. In the stopped-flow mode, using KIO₄ and a reaction time of 12 min, better sensitivity can be obtained for both compounds and limits of detection of 10 g 1^–1 foro-cresol and 30 g 1^–1 form-cresol were found. The flow injection method has a lower sensitivity but permits more than 80 injections per hour. Based on the different maximum absorbance wavelengths obtained for the reaction products of PAP witho-cresol (614 nm) andm-cresol (632 nm), both compounds can be simultaneously determined in water samples and recoveries of 90 to 115% were found in spiked water samples of different types.     

Nitrosation kinetics of phenolic components of foods and beverages

The kinetics of the reactions between sodium nitrite and phenol or m-, o-, or p-cresol in potassium hydrogen phthalate buffers of pH 2.5–5.7 were determined by integration of the monitored absorbance of the C-nitroso reaction products. At pH > 3, the dominant reaction was C-nitrosation through a mechanism that appears to consist of a diffusion-controlled attack on the nitrosatable substrate by NO⁺/NO₂H₂⁺ ions followed by a slow proton transfer step; the latter step is supported by the observation of basic catalysis by the buffer which does not form alternative nitrosating agents as nitrosyl compounds. The catalytic coefficients of both anionic forms of the buffer have been determined. The observed order of substrate reactivities (o-cresol ≈ m-cresol > phenol ≫ p-cresol) is explained by the hyperconjugative effect of the methyl group in o- and m-cresol, and by its blocking the para position in p-cresol. Analysis of a plot of ΔH^# against ΔS^# shows that the reaction with p-cresol differs from those with o- and m-cresol as regards the formation and decomposition of the transition state. The genotoxicity of nitrosatable phenols is compared with their reactivity with NO⁺/NO₂H₂⁺. © 1997 John Wiley & Sons, Inc.     

The Synthesis,Characterization and Conductance Studies of New Cu(II), Ni(Ii) And Zn(II) Complexes with the Schiff Base Derived from 1,2-Bis-(o-Aminophenoxy)Ethane and Salicylaldehyde

Cu(II), Ni(II) and Zn(II) complexes with the Schiff base derived from 1,2-bis-(o-aminophenoxy)ethane with salicylaldehyde have been prepared. The complexes have been characterized by elemental analysis, magnetic measurements, ¹H NMR, ¹³C NMR, UV, visible and IR spectra as well as conductance measurements. The ligand is coordinated to the central metal as a tetradentate ONNO ligand. The four bonding sites are the central azomethine nitrogen and aldehydic OH groups. The ligand was used for complexation studies. Stability constants were measured by a conductometric method. Furthermore, the stability constants for complexation between ZnCl₂ and Cu(NO₃)₂ salts and N,N′-bis(salicylidene)-1,2-bis-(o-aminophenoxy)ethane (H₂L) in 80% dioxane/water and pure methanol were determined from conductance measurements. The magnitudes of these ion association constants are related to the nature of the solvation of the cation and the complexed cation. The mobilities of the complexes are also dependent, in part, upon solvation effects.     

Grafting onto wool. IV. Effect of amines upon ceric ion-initiated grafting of poly(methyl acrylate)

Grafting of poly(methyl acrylate) onto wool has been carried out in an aqueous medium at 45 ± 1°C by using ceric ammonium nitrate (CAN) in the presence of triethylamine, diethylamine, n-butylamine, triethanolamine, and N,N-dimethylaniline. The percentage of grafting varied with the nature and concentrations of the amines. Reactivity of the different amines toward grafting reactions followed the order: triethylamine > diethylamine > n-butylamine > triethanolamine ≥ N,N-dimethylaniline. In the presence of N,N-dimethylaniline grafting did not occur. An attempt has been made to explain the observed reactivity of Ce⁴⁺ in various amine systems in graft copolymerization reactions.     

Post-Metalation Modification of a Macrocyclic Dicobalt(III) Metallohost by Site-Selective Ligand Exchange for Guest Recognition Control

We propose post-metalation modification as a useful strategy to control the guest recognition behavior of a metal-containing macrocyclic host. This is based on the ligand exchange of the axial ligands of a cobalt(III) dinuclear macrocyclic host, [LCo₂X₄]²⁺ (X=axial amine ligand). Four piperidine ligands in [LCo₂(pip)₄]²⁺ (pip=piperidine) were site-selectively replaced with primary amines. The competitive experiments revealed that the order of the affinity toward the cobalt centers in [LCo₂X₄]²⁺ is primary amine > secondary amine > tertiary amine and that the piperidine-coordinating complex, [LCo₂(pip)₄]²⁺, was reasonably reactive among the isolable complexes. Indeed, two piperidine ligands at the diagonal positions in [LCo₂(pip)₄]²⁺ were site-selectively replaced with pyridine or acetate ion. The replacement of piperidine with acetate ion significantly enhanced the recognition ability towards Na⁺.     

Ortho effects in organic molecules on electron impact: XI—the interesting ortho effect of the methoxy group in o-methoxy aromatic thioamides

It has been noticed that the major part of the loss of ?H from the molecular ion of most of the o-methoxythioamides results from an ortho effect of the methoxy group. Comparison of the MIKE spectra of the [M? SH]⁺ of 1-(2-methoxyphenylthioxomethyl)piperidine and 1-(2-methoxyphenylthioxomethyl)pyrrolidine with the MIKE spectra of [M? SH]⁺ of the corresponding unsubstituted compounds, reported earlier, indicated two parallel pathways for the formation of [M? SH]⁺ in the o-methoxy compounds. In the first pathway, as has been noticed in thioamides in general, the loss of ?H involves the migration of either the α-hydrogen in the amine moiety or the hydrogen attached to nitrogen. In the second pathway, the migration of a hydrogen from the o-methoxy group to the sulphur atom followed by ejection of SH from the molecular ion leads to a stable cyclized ion. Interesting secondary fragmentations as a consequence of this ortho effect have also been noticed.     

Influence of tertiary aromatic diamines on the n-buLi-initiated polymerization of isoprene in hexane solution

The influence of three aromatic tertiary diamines, bis(4-dimethylamino phenyl) methane (DMAPM), N,N,N′,N′-tetramethyl-p-phenylenediamine (p-TMPDA), and N,N,N′,N′-tetramethyl-o-phenylenediamine (o-TMPDA), on the kinetics of polymerization of isoprene in hexane solution, with n-BuLi as initiator, was studied for different values of ratio r = [amine]/[n-BuLi]. It is shown that added amine increases initiation rate according to its complexing ability (DMAPM < p-TMPDA « o-TMPDA); this result is explained by the formation of complexes between amine A and n-BuLi, (n-BuLi, A)_x, where x = 6, 4, and 1 for the three amines, respectively. The propagation rate and the structure of polyisoprene are modified with o-TMPDA only; the decrease in propagation rate and the increase in 3,4 units in the polymer obtained when r increases are assigned to the formation of solvated ion pairs PI^?Li⁺, o-TMPDA.     

Fundamental- and Second-Harmonic Tensammetry of DI-(2-ethylhexyl)phosphoric Acid

Abstract

The tenaammetric behavior of di-(2-ethylhexyl)phosphoric acid (D2KHPA) was investigated by non-phase-selective AC polarography. D2EHPA produces in alkali sulfate supporting electrolytes a decrease of the capacitive current in the region of zero-charge potential, as well as a tensammetric peak located between -1.0 and -1.3 V vs. SCE. In the same range, the second harmonic has a characteristic maximum. The pH of the solution and the nature of the cation in the supporting electrolyte affect both the height and the position of the tensammetric peaks. The tensammetric method allows determination of D2EHPA at concentrations ranging from 0.5 to 200 mg/1. Maximum sensitivity is obtained by measuring the second harmonic.     

Acute Toxicity of Cresols to Pseudomonas — An Initial Oxygen Uptake Method

Acute toxicity of cresols to both Pseudomonas I and II was estimated by an initial oxygen uptake method. Inhibition studies of toluene and cresols on the oxidation of either benzoate by Pseudomnas I or phenol by Pseudomonas II were analyzed and expressed as oxygen uptake rates. Double reciprocal plots for the inhibiton by cresols of oxygen uptake in Pseudomonas, two physical constants, Vmaxi and Ki, were obtained. The Vmaxi of o?, m? and p-cresol were 80%, 81% and 57% of Vmax in Pseudomnas I, and 10%, 25% and 36% in Pseudomonas II, respectively. Thus, the toxicity to Pseudomonas I decreases in the order p- > o- ≥ m-cresol, whereas to Pseudomonas II, the order is changed to o- > m- > p-cresol. This difference in the toxicity order is probably due to the allosteric effect of p-cresol towards Pseudomonas II. Inasmuch as most compounds inhibit noncompetively, the relative toxicity of different compounds can be estimated by a new toxicity parameter RI (relative inhibition) which is defined as 100/Ki. By comparing the RI value of each compound, the toxicity to Pseudomonas I decreases in the order m-chlorophenol > p-cresol > p-chlorophenol > o-cresol ≥ m-cresol > o-chlorophenol > toluene > phenol.     

Lanthanum(III) chloride complexes with heterocyclic Schiff bases

Condensation of 2-amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene with carbonyl compounds such as isatin, o-hydroxyacetophenone or benzoin in 1:1 ratio in ethanol medium yielded three distinctly different heterocyclic Schiff bases viz. 2-(N-indole-2-one)amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene (ISAT), 2-(N-o-hydroxyacetophenone)amino- 3-carboxyethyl-4,5,6,7-tetrahydro-benzo[b]thiophene (HAAT) or 2-(N-benzoin)amino-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene (HBAT) respectively. These ligands formed well defined complexes with lanthanum(III) chloride under suitable conditions. The ligands and the complexes have been characterized on the basis of elemental analyses, molar conductance measurements, UV-visible, IR and proton NMR spectral studies. Kinetics and mechanism of the thermal decomposition of the ligands and the metal complexes have been studied using non-isothermal thermogravimetry. Kinetic parameters were calculated for each step of the decomposition reactions using Coats-Redfern equation. The rate controlling process for all the ligands and complexes is random nucleation with the formation of one nucleus on each particle (Mampel equation). Relative thermal stabilities of the ligands and the metal complexes have been compared.     

Kalidoss—Jacobson Free Length Theory Applied to Binary Liquid Mixtures of CCI4+Toluene/Aniline/oCresol m-cresol p-Cresol

Abstract

Ultrasonic velocities and intermolecular free lengths in binary liquid mixtures of CC4 with toluene, aniline, o-cresol, m-cresol and p-cresol have been calculated theoretically, at different compositions and at temperature 298 K, based on Free Length Theory as revised recently by Kalidoss. It is observed that there is a close agreement of calculated velocities with experimental ones. The shape and thermostatic state picture built up in this formulation could be considered as a good representation of molecular state.     

Phase equilibria in systems containing o-cresol,p-cresol,carbon dioxide,and ethanol at 323.15–473.15 K and 10–35 MPa

Phase equilibria in binary and ternary systems containing o-cresol, p-cresol, carbon dioxide, and ethanol have been investigated experimentally at temperatures between 323.15 K and 473.15 K and pressures ranging from 10 MPa to 35 MPa. The experimental results provide a systematic basis of phase equilibrium data, yielding the effect of temperature on the influence of the position of the methyl groups of cresols that are in phase equilibria with carbon dioxide. Based on the different solubilities of the cresol isomers in carbon dioxide, the separation of o-cresol and p-cresol was investigated. The dependence of the separation factor between both cresol isomers on concentration, temperature, and pressure is obtained from experiments in the ternary system, o-cresol+p-cresol+carbon dioxide. The influence of ethanol added to each of the binary systems, cresol isomer+carbon dioxide, in order to enhance the solubility of the cresols in the carbon dioxide-rich phase is also shown. The experimental data have been correlated using seven different equations of state, whereof four explicitly account for intermolecular association: Statistical Association Fluid Theory (SAFT) by Chapman, Gubbins, Huang and Radosz, the SAFT modification by Pfohl and Brunner for near-critical fluids, a modified cubic-plus-association equation of state (CPA EOS) according to the ideas by Tassios et al., and one of the EOS by Anderko. The mixing rule proposed by Mathias, Klotz, and Prausnitz, with two binary interaction parameters per binary system influencing intermolecular attractive forces, is used for all EOS as a basis for an objective comparison of the EOS.     

Solid + liquid phase diagrams,NMR and colorimetric measurements of mixtures

Solid+liquid equilibrium, NMR and colorimetric measurements have been made for the mixtures of o-phenylenediamine+phenol, p-phenylenediamine+hydroquinone, m-phenylenediamine+phenol, m-phenylenediamine+hydroquinone, p-phenylenediamine+phenol, and p-phenylenediamine+hydroquinone. The types and melting temperatures of the complexes formed in these mixtures were ascertained from phase diagrams. The nature of the complexes was ascertained from colorimetric and NMR data.     

Equilibres Liquide-vapeur Isothermes De Melanges Binaires, Amine+amine

The authors have measured the vapour pressure of the binary systems, piperidine+n -butylamine, piperidine+dipropylamine, piperidine+N-methyl piperidine, piperidine+N,N-dimethyl amino butane and N-methyl piperidine+n -butylamine. The measurements were carried out using an isoteniscope built by Jose [1]. The vapour pressure, excess Gibbs free energies at 298,15, 303,15, 313,15, 323,15, 333,15, and 325,15 K, are reported for these mixtures. The excess Gibbs free energies have been fitted to Redlich-Kister equation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ruthenium(II) carbonyl complexes with tridentate Schiff bases and their antibacterial activity

The products obtained by reacting ruthenium (II) complexes [RuHCl(CO)(PPh₃)₂(B)] [B = PPh₃, pyridine (py) or piperidine (pip)] with tridentate Schiff base ligands derived by condensing salicylaldehyde or o-vanillin with o-aminophenol and o-aminothiophenol, have been characterised by analytical, i.r., electronic, ¹H-n.m.r. and ³¹P-n.m.r. spectral studies and formulated as [Ru(L)(CO)(PPh₃)(B)] (L = bifunctional tridentate Schiff base anion, B = PPh₃, py or pip). An octahedral structure has been tentatively proposed for the new complexes. Some have been tested for the in vitro growth inhibitory activity against bacteria Escherichia coli, Bacillus sp. and Pseudomonas sp.