Kinetics of the alkaline hydrolysis of 3-sulfolanol phenyl ethers

A scheme for the elimination of aryloxy groups via an ElcB mechanism is proposed on the basis of data on the kinetics of the alkaline hydrolysis of 3-sulfolanol phenyl ethers in H₂O and D₂O.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1200–1203, September, 1974.     

Analysis of linear free-energy relationships combined with activation parameters assigns a concerted mechanism to alkaline hydrolysis of x-substituted phenyl diphenylphosphinates

A kinetic study is reported for alkaline hydrolysis of X‐substituted phenyl diphenylphosphinates ( 1 a – i ). The Brønsted‐type plot for the reactions of 1 a – i is linear over 4.5 pK_a units with β_lg=?0.49, a typical β_lg value for reactions which proceed through a concerted mechanism. The Hammett plots correlated with σ^o and σ^? constants are linear but exhibit many scattered points, while the corresponding Yukawa–Tsuno plot results in excellent linear correlation with ρ=1.42 and r=0.35. The r value of 0.35 implies that leaving‐group departure is partially advanced at the rate‐determining step (RDS). A stepwise mechanism, in which departure of the leaving group from an addition intermediate occurs in the RDS, is excluded since the incoming HO^? ion is much more basic and a poorer nucleofuge than the leaving aryloxide. A dissociative (D_N + A_N) mechanism is also ruled out on the basis of the small β_lg value. As the substituent X in the leaving group changes from H to 4‐NO₂ and 3,4‐(NO₂)₂, ΔH ^≠ decreases from 11.3 kcal mol^?1 to 9.7 and 8.7 kcal mol^?1, respectively, while ΔS ^≠ varies from ?22.6 cal mol^?1 K^?1 to ?21.4 and ?20.2 cal mol^?1 K^?1, respectively. Analysis of LFERs combined with the activation parameters assigns a concerted mechanism to the current alkaline hydrolysis of 1 a – i .     

不饱和半夹芯式16e化合物Cp*Ir(S2C2B10H10)与邻、间位取代苯基叠氮的反应性

考虑取代基的位置和电子效应对反应体系的影响, 本文系统地研究了16e化合物Cp^*Ir(S₂C₂B₁₀H₁₀) (1)与邻、间位取代苯基叠氮的反应。研究结果表明：与邻、间位取代苯基叠氮反应均生成苯环邻位碳发生C-H 活化形成C-S 键的金属配合物。这些配合物通过核磁(¹H、¹¹B、¹³C)、红外、质谱、元素分析和单晶结构解析进行了全面地表征。在光照反应结果的基础上, 提出了形成这类产物的自由基机理。     

Solvation Dynamics of a Radical Ion Pair in Micro‐Heterogeneous Binary Solvents: A Semi‐Quantitative Study Utilizing MARY Line‐Broadening Experiments

This work aims at elucidating the mechanism of solvation of a radical ion pair (RIP) in a micro‐heterogeneous binary solvent mixture using magnetically affected reaction yield (MARY) spectroscopy. For the exciplex‐forming 9,10‐dimethylanthracene/N,N‐dimethylaniline system a comparative, composition‐dependent MARY line‐broadening study is undertaken in a heterogeneous (toluene/dimethylsulfoxide) and a quasi‐homogenous (propyl acetate/butyronitrile) solvent mixture. The half‐saturation field extrapolated to zero‐quencher concentration, B_1/2, and the self‐exchange rate constants are analyzed in the light of solvent dynamical properties of the mixtures and a dielectric continuum solvation model. The dependence of B_1/2 on the solvent composition is explained by cluster formation giving rise to shortened RIP lifetimes. The results are in qualitative agreement with the continuum solvation model suggesting that it could serve as a theoretical basis for quantitative modeling.     

Spectrometric study of solute–solvent interactions for the solvolysis of chloropentaamine cobalt(III) complex in binary aqueous mixtures

Kinetic studies of solvent structure effects and solute–solvent interactions on the solvolysis of [Co(NH₃)₅Cl]²⁺ complex ion have been investigated spectrophotometrically in binary aqueous mixtures. Three cosolvents were used (acetonitrile, dimethylsulfoxide, and urea) over a wide range of temperatures. Nonlinear plots were found for log(rate constant) against the reciprocal of the relative permitivity of the medium. The enthalpy and entropy of activation (ΔH^# and ΔS^#) exhibited extrema in the same composition region where the physical properties indicate sharp changes in the structure of the solvent, confirming that the solvent structure is an important factor in determining the solvolytic reactivity. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 416–422, 2008     

Radical anions of 3,3′-bi(2-R-5,5-dimethyl-4-oxopyrrolinylidene) 1,1′-dioxides in MeCN-H<Subscript>2</Subscript>O solvent mixtures

Radical anions of cyclic dinitrones, 3,3′-bi(2-R-5,5-dimethyl-4-oxopyrrolinylidene) 1,1′-dioxides (R = Me, Ph, Bu^t, CF₃) have been studied by ESR in combination with quantum chemical calculations of geometrical parameters and isotropic hyperfine interaction constants by the DFT/PBE methods in the 3z basis set and UB3LYP in the 6–31+G* basis set with allowance for the solvation in the framework of continual PCM model. The radical anions were generated electrochemically by reduction of their neutral precursors in MeCN-H₂O solvent mixtures and found to possess enough stability for measurement of their ESR spectra in a wide range of the mixture compositions. Radical anions of compounds of nitrone series were generated and characterized in MeCN-H₂O mixtures and water (for the dinitrone with R = Me) for the first time. Differences in the solvent depending behavior of the nitrogen hyperfine interaction constants in the series of radical anions with various substituents R are explained by competition of transsolvation and structural effects.     

不饱和半夹芯式16e化合物Cp*Ir(S2C2B10H10)与邻、间位取代苯基叠氮的反应性

考虑取代基的位置和电子效应对反应体系的影响, 本文系统地研究了16e化合物Cp^*Ir(S₂C₂B₁₀H₁₀) (1)与邻、间位取代苯基叠氮的反应。研究结果表明:与邻、间位取代苯基叠氮反应均生成苯环邻位碳发生C-H 活化形成C-S 键的金属配合物。这些配合物通过核磁(¹H、¹¹B、¹³C)、红外、质谱、元素分析和单晶结构解析进行了全面地表征。在光照反应结果的基础上, 提出了形成这类产物的自由基机理。     

VINYL RADICAL POLYMERIZATION INITIATED WITH CERIC ION AND N-(SUBSTITUTED PHENYL) ACETAMIDE SYSTEMS

The polymerization of acrylamide (AAM)in H_2O/DMF or in H_2O/CH_3CN mixed solvent initiated with ceric ion (Ce~(4+) )/N-(substituted phenyl)-acetamide systems have been studied. The redox polymerization was revealed by the low value of overall activation energy (E_α) of AAM polymerization using ceric ion/N-(substituted phenyl) acetamide system as an initiator. The end group of polymer formed was detected by IR spectrum analysis method, it revealed the presence of N-(m-acetoxy-methylphenyl) acetamide (m-AAe) moiety end group in the polymer obtained with ceric ion/m-AAe initiation system.     

Probing the Rotational Dynamics of meso‐(2‐Substituted)aryl Substituents in A2B‐Type Subporphyrins

A₂B‐type B‐methoxy subporphyrins 3 a – g and B‐phenyl subporphyrins 7 a – c , e , g bearing meso‐(2‐substituted)aryl substituents are synthesized, and their rotational dynamics are examined through variable‐temperature (VT) ¹H NMR spectroscopy. In these subporphyrins, the rotation of meso‐aryl substituents is hindered by a rationally installed 2‐substituent. The rotational barriers determined are considerably smaller than those reported previously for porphyrins. Comparison of the rotation activation parameters reveals a variable contribution of ΔH^≠ and ΔS^≠ in ΔG^≠. 2‐Methyl and 2‐ethyl groups of the meso‐aryl substituents in subporphyrins 3 e , 3 f , and 7 e induce larger rotational barriers than 2‐alkoxyl substituents. The rotational barriers of 3 g and 7 g are reduced by the presence of the 4‐dibenzylamino group owing to its ability to stabilize the coplanar rotation transition state electronically. The smaller rotational barriers found for B‐phenyl subporphyrins than for B‐methoxy subporphyrins indicate a negligible contribution of S_N1‐type heterolysis in the rotation of meso‐aryl substituents.     

Rôle catalytique de l'eau et des sels lors de l'hydrolyse alcaline des esters en milieu hydro-alcoolique: Mise en évidence par spectrométrie ir des associations ester-solvant et ester-cation

Infrared spectra of esters in water-alcohol mixtures, with or without added salts, indicate the formation of 1:1 or 1:2 complexes through hydrogen bonding between the ester carbonyl group and the proton donor molecules of the solvent, as well as the formation of a donor-acceptor complexes with Li⁺ or Ba²⁺. These complexes facilitate nucleophilic attack at the carbon of the carbonyl group by hydroxyl anions. Depending on the water content of the mixture, the addition of LiCIO₄ increases or decreases the rate constant of the reaction. The displacement of equilibria between different entities explains a higher rate constant in water-tert-butanol than in water-methanol mixtures of the alkaline hydrolysis of ethyl acetate.     

Synthesis of halo-fluoro-substituted adamantanes by electrophilic transannular cyclization of bicyclo[3.3.1]nonane dienes

3,7-Dimethylenebicyclo[3.3.1]nonane and its derivatives with a methyl or phenyl substituent in a methylene group react, with N-halosuccinimides NXS (X=Cl, Br, I) in dichloromethane in the presence of tetrabutylammonium dihydrotrifluoride or polyfluorinated alcohols via a transannular cyclization leading to the corresponding 1-fluoro- or 1-polyfluoroalkoxy-3-halomethyladamantanes. The reaction of the dienes with NXS and Bu₄N⁺H₂F₃⁻ conducted in THF, oxetane or ethylene oxide runs through a cascade addition of electrophiles (positively charged halogen atoms) and external nucleophiles (solvent molecules and halide anions) to the starting diene substrate and intermediate adamantyl carbocation.     

A Potassium Diboryllithate: Synthesis,Bonding Properties,and the Deprotonation of Benzene

A potassium diboryllithate (B₂LiK) was synthesized and structurally characterized. DFT calculations, including NPA and AIM analyses of B₂LiK, revealed ionic interactions between the two bridging boryl anions and Li⁺ and K⁺. Upon standing in benzene, B₂LiK deprotonated the solvent to form a hydroborane and a phenylborane. On the basis of DFT calculations, a detailed reaction mechanism, involving deprotonation and hydride/phenyl exchange processes, is proposed. An NBO analysis of the transition state for the deprotonation of benzene suggests that the deprotonation should be induced by the coordination of benzene to the K⁺.     

A Potassium Diboryllithate: Synthesis,Bonding Properties,and the Deprotonation of Benzene

A potassium diboryllithate (B₂LiK) was synthesized and structurally characterized. DFT calculations, including NPA and AIM analyses of B₂LiK, revealed ionic interactions between the two bridging boryl anions and Li⁺ and K⁺. Upon standing in benzene, B₂LiK deprotonated the solvent to form a hydroborane and a phenylborane. On the basis of DFT calculations, a detailed reaction mechanism, involving deprotonation and hydride/phenyl exchange processes, is proposed. An NBO analysis of the transition state for the deprotonation of benzene suggests that the deprotonation should be induced by the coordination of benzene to the K⁺.     

Coordination Chemistry of Higher Oxidation States. Part 36. Periodato Complexes of Palladium(IV) and Platinum(IV). Crystal Structure of K4Na2[Pt(OH)2(HIO6)2]·10H2O

Abstract

Periodate complexes of Pd(IV) and Pt(IV) have been prepared from [MC1₆]^2- (M = Pd or Pt) and IO₄ ^? in aqueous alkaline solution. They are formulated as M'₆[M(OH)₂(HIO₆)₂].nH₂O (M' = Na or K) on the basis of analysis, vibrational spectroscopy, and an X-ray structure determination of the platinum complex. The title compound crystallizes in the triclinic space group PI with unit cell parameters a = 7.588(2), b = 8.110(2), c = 9.864(2) Å, a = 82.00(2), β = 83.79(2), γ = 81.76(2)° with Z = 1. Based on 2283 observed reflections (F > 3σ(F)), the structure refined to R = 0.034. Two bidentate [HIO₆]^4- anions coordinate to a central Pt atom which is also coordinated by two trans OH groups. The charge balance is maintained by sodium and potassium cations which are extensively hydrated. ¹⁹⁵Pt and ¹²⁷I NMR data are reported, and the variation in the former with pH interpreted in terms of differing degrees of protonation of the anions. EXAFS data are reported for the platinum complex in solution at pH = 2.     

Theoretical study on ionic liquids based on DBUH+: Molecular engineering and hydrogen bond evaluation

The new generation of the ionic liquids (ILs) based on 1,8-diazobicylo [5,4,0] undec-7-ene (DBU) are applied as the solvent in organic reactions. In this work, by using a theoretical procedure, the most probable interactions between the ion pairs of DBUH⁺ based ILs, including 10 functionalized imidazole anions were investigated. For this purpose, the electrostatic potential surfaces were analyzed to detect the most probable interaction sites of DBUH⁺. On the basis of the obtained results, hydrogen bond formation between the anions and DBUH⁺ is influenced by the electronic effect of the substituted functional groups. This means that electron donating groups, such as phenyl has a stabilizing effect on the ion pairs, while electron-withdrawing groups, such as nitro, induces a destabilizing effect. These behaviors are described based on the interaction energy values (ΔE_int). To investigate the dispersion interaction effects in ILs formation, M06-2X-D3 functional was applied in energy analysis. The solvent reaction field was investigated by the polarizable continuum model in ethanol and chloroform as the solvent. The results showed that ethanol has a greater effect on the interaction energy of the ILs. Finally, to have a comprehensive understanding of the charge transfer effect on the stability of the studied ILs and to characterize the most probable interactions, natural bond orbital and quantum theory of atoms in molecules analyses were applied and the obtained results were analyzed.     

Cationic Cd(II) metal − organic framework based on tetrakis(1,2,4-triazol-1-yl)methane

Abstract

Solvothermal reaction of a multidentate ligand (tetrakis[4-(1-triazolyl)phenyl]-methane (ttpm)), with Cd(NO₃)₂ afforded a cationic Cd(II) coordination polymer {[Cd(ttpm)·DMSO]·2NO₃}_n. Single-crystal X-ray diffraction analyses showed that ttpm belonged to the tetragonal space group I4₁/a, and 1 was a 2-D (4,4) network. 1-D channels along the c direction exist in the 3D stacking map to accommodate the charge-balancing NO₃^? anions. N₂ adsorption/desorption experiments showed the framework had a BET surface area of 11.36?m²·g^?1. Compared with luminescence of ttpm, 1 showed red-shifted luminescence spectra with higher intensity from the more rigid arrangement of the π systems.     

KINETICS,MEDIUM, AND DEUTERIUM ISOTOPE EFFECTS IN THE ALKALINE DECOMPOSITION OF QUATERNARY PHOSPHONIUM SALTS III1 Tetraphenylphosphonium Chloride in Dimethylsulphoxide-Water Mixtures

Abstract

The reaction between tetraphenylphosphonium chloride and hydroxide or deuteroxide anions was studied kinetically in a series of dimethylsulphoxide-water mixtures at several temperatures. The rate is first-order in the phosphonium cation and second-order in the hydroxide or deuteroxide anions. The reaction shows a dramatic increase in rate, up to about 10¹⁰ times, as the DMSO content is increased. The rate enhancement is attributed to a considerable drop in activation energy affected not only through an increased desolvation of reactant anions, but also through an increase in solvation of the transition state, brought about by gradual addition of DMSO. The kinetic solvent deuterium isotope effect in 60% DMSO-40% D₂O is strongly dependent on temperature. The rate constant in the latter solvent mixture is represented by k ⁱ = 11.9 e ^?12700/RT l ² mole^?2 sec^?1 as compared to k ⁱ = 19.0 e ^?22500/RT l ² mole^?2 sec^?1 in the corresponding 60% DMSO-H₂O mixture. The thermodynamic parameters of activation show strong dependence on solvent composition and are related to structural changes and solvation power of the reaction medium.     

Gas phase anionic ipso substitution reactions of some alkyl phenyl ethers

It is shown by ¹⁸O labelling that phenoxide anions are formed both by an S_N2 and a nucleophilic aromatic substitution mechanism in the reaction of OH^? with methyl phenyl ether. These mechanisms are of minor importance in the ethyl phenyl ether system where phenoxide anions are generated almost exclusively by an E₂ mechanism.     

Synthesis,Structures, and Fungitoxicity of Novel Organophosphorus Compounds

Abstract

A series of biologically active organophosphorus compounds have been synthesized by the reactions of O,O-diethylchlorophosphate with Schiff bases derived from 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-oxadiazole and salicylaldehyde/2-hydroxyacetophenone. The compounds have been characterized on the basis of analyses and spectral (IR, ¹H, ¹³C NMR) data. Fungicidal activities of these derivatives against Colletotrichum falcatum, Fusarium oxysporum, and Curvularia pallescence have been evaluated. All compounds showed moderate to significant antifungal activity.     

Polarity and steric effect of the lateral substituent on the mesophase behaviour of some newly prepared liquid crystals

Eight homologous series of 2- (or 3-) substituted phenyl 4?-(4?-alkoxy phenylazo) benzoates (In_a–h) were prepared in which, within each homologous series, the length of the terminal alkoxy group varies between 6, 8, 10 and 12 carbons, while the other substituent, X, is a laterally attached polar group that alternatively changed from CH₃, H, F, Br and CN. Compounds prepared were characterised by infrared and ¹H-NMR spectroscopy, and their mesophase behaviour investigated by differential scanning calorimetry and identified by polarised light microscopy. The results were discussed in terms of polarity and steric effects. The stability of the mesophase was correlated once with the dipolar anisotropy of the whole molecule and another with the dipolar anisotropy of the substituent, X. A comparative study was made between the investigated compounds and their previously prepared linear 4-substituted isomers, namely 4-substituted phenyl 4?-(4?-alkoxy phenylazo) benzoates (In_i–k).