- Kinetic challenges facing oxalate, malonate, acetoacetate, and oxaloacetate decarboxylases
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To compare the powers of the corresponding enzymes as catalysts, the rates of uncatalyzed decarboxylation of several aliphatic acids (oxalate, malonate, acetoacetate, and oxaloacetate) were determined at elevated temperatures and extrapolated to 25 °C. In the extreme case of oxalate, the rate of the uncatalyzed reaction at pH 4.2 was 1.1 × 10-12 s-1, implying a 2.5 × 1013-fold rate enhancement by oxalate decarboxylase. Whereas the enzymatic decarboxylation of oxalate requires O 2 and MnII, the uncatalyzed reaction is unaffected by the presence of these cofactors and appears to proceed by heterolytic elimination of CO2.
- Wolfenden, Richard,Lewis, Charles A.,Yuan, Yang
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- Research and development of method for potassium acetate of high purity
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Crystallization of potassium acetate from aqueous solutions, an effect of product yield and washing of its crystals on an efficiency of purification were investigated. Behavior of KCH3COO·1.5H2O was studied in heating. Based on data of the study a technological scheme of producing anhydrous potassium acetate of high purity was developed.
- Fakeev,Murskii,Krasil'Shchik
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- Acetonitrile hydration and ethyl acetate hydrolysis by pyrazolate-bridged cobalt(II) dimers containing hydrogen-bond donors
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The preparation of new CoII-μ-OH-CoII dimers with the binucleating ligands 3,5-bis{bis[(N′-R-ureaylato)-N-ethyl]- aminomethyl}-1H-pyrazolate ([H4PRbuam]5-, R = tBu, iPr) is described. The molecular structure of the isopropyl derivative reveals that each CoII center has a trigonal-bipyramidial coordination geometry, with a Co...Co separation of 3.5857(5) A. Structural and spectroscopic studies show that there are four hydrogen-bond (H-bond) donors near the CoII-μ-OH-CoII moiety; however, they are too far away to be form intramolecular H-bonds with the bridging hydroxo ligand. Treating [CoII2H 4PRbuam(μ-OH)]2- with acetonitrile led to the formation of bridging acetamidato complexes, [CoII 2H4PRbuam(μ-1,3-OC(NH)CH3)] 2-; in addition, these CoII-μ-OH-CoII dimers hydrolyze ethyl acetate to form CoII complexes with bridging acetato ligands. The CoII-1,3-μ-X′-CoII complexes (X′ = OAc-, [OC(NH)CH3]-) were prepared independently by reacting [CoII2H3P Rbuam]2- with acetamide or [CoII 2H4PRbuam]- with acetate. X-ray diffraction studies show that the orientation of the acetate ligand within the H-bonding cavity depends on the size of the R substituent appended from the urea groups. The tetradentate ligand 3-{bis[(N′-tert-butylureaylato)-N-ethyl] aminomethyl}-5-tert-butyl-1H-pyrazolato ([H2PtBuuam] 3-) was also developed and its CoII-OH complex prepared. In the crystalline state, [CoIIH2PtBuuam(OH)] 2- contains two intramolecular H-bonds between the urea groups of [H2PtBuuam]3- and the terminal hydroxo ligand. [nPr4N]2[CoIIH2P tBuuam(OH)] does not hydrate acetonitrile or hydrolyze ethyl acetate. In contrast, K2[CoIIH2PtBuuam(OH)] does react with ethyl acetate to produce KOAc; this enhanced reactivity is attributed to the presence of the K+ ions, which can possibly interact with the CoII-OH unit and ester substrate to assist in hydrolysis. However, K2[CoIIH2P tBuuam(OH)] was still unable to hydrate acetonitrile.
- Zinn, Paul J.,Sorrell, Thomas N.,Powell, Douglas R.,Day, Victor W.,Borovik
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- Catalytic oxidation of soot over alkaline niobates
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The lack of studies in the current literature about the assessment of alkaline niobates as catalysts for soot oxidation has motivated this research. In this study, the synthesis, characterization and assessment of alkaline metal niobates as catalysts for soot combustion are reported. The solids MNbO 3 (M = Li, Na, K, Rb) are synthesized by a citrate method, calcined at 450 °C, 550 °C, 650 °C, 750 °C, and characterized by AAS, N2 adsorption, XRD, O2-TPD, FTIR and SEM. All the alkaline niobates show catalytic activity for soot combustion, and the activity depends basically on the nature of the alkaline metal and the calcination temperature. The highest catalytic activity, expressed as the temperature at which combustion of carbon black occurs at the maximum rate, is shown by KNbO3 calcined at 650 °C. At this calcination temperature, the catalytic activity follows an order dependent on the atomic number, namely: KNbO3 > NaNbO3 > LiNbO3. The RbNbO3 solid do not follow this trend presumably due to the perovskite structure was not reached. The highest catalytic activity shown by of KNbO3, despite the lower apparent activation energy of NaNbO3, stress the importance of the metal nature and suggests the hypothesis that K+ ions are the active sites for soot combustion. It must be pointed out that alkaline niobate subjected to consecutive soot combustion cycles does not show deactivation by metal loss, due to the stabilization of the alkaline metal inside the perovskite structure.
- Pecchi,Cabrera,Buljan,Delgado,Gordon,Jimenez
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- Osmium(VIII)/ruthenium(III) catalysis of periodate oxidation of acetaldehyde in aqueous alkaline medium
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Os(VIII) and Ru(III) catalysis of the periodate oxidation of acetaldehyde in aqueous alkaline medium was investigated. The catalytic efficiency is Ru(III) 3-. The stoichiometry is the same in both catalyzed reactions, i.e. [IO4-]:[CH3CHO] = 1:1. Probable mechanisms are proposed and discussed. The reaction constants involved in the mechanisms are derived.
- Kamble, Dasharath L.,Nandibewoor, Sharanappa T.
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- IR spectroscopy studies of molecular states of alkali-metal acetates in acetic acid solution
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This work presents the results of IR spectroscopic studies of the molecular states of alkali-metal (Li, Na, K, Cs) acetates in glacial acetic acid. The associates M(Ac·nHAc)·pHAc (I) have been shown to form with n ≈ 8-9 and varying number p of the outersphere HAc molecules, depending on the salt concentration. The anion Ac·nHAc- is symmetrical about the central fragment O-H?-O with a very strong H-bond. The anion negative charge is located mainly on this fragment and on the two nearest O?-H-O fragments. The first coordination sphere of M+ comprises only oxygen atoms from the O-H?-O group and from the anion's terminal C=O groups. Associates I form a microvolume of structurized liquid phase which can be considered as a prototype of liquid-crystalline lamellar or ribbon-like structures produced by alkali acid soaps. When water is added, H2O molecules hydrate both anions and cations, M+, equalizing the polarizing influence of the latter on the anion. For hydrated salts the radius of the ordered liquid-phase microvolume around the cation M+ increases. On the whole, water addition produces a similar effect on the composition and structure of associates I as it does with liquid-crystalline water-free alkali acid soaps.
- Stoyanov, Evgenii S.,Chesalov, Yurii A.
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- Degradation of Organic Cations under Alkaline Conditions
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Understanding the degradation mechanisms of organic cations under basic conditions is extremely important for the development of durable alkaline energy conversion devices. Cations are key functional groups in alkaline anion exchange membranes (AAEMs), and AAEMs are critical components to conduct hydroxide anions in alkaline fuel cells. Previously, we have established a standard protocol to evaluate cation alkaline stability within KOH/CD3OH solution at 80 °C. Herein, we are using the protocol to compare 26 model compounds, including benzylammonium, tetraalkylammonium, spirocyclicammonium, imidazolium, benzimidazolium, triazolium, pyridinium, guanidinium, and phosphonium cations. The goal is not only to evaluate their degradation rate, but also to identify their degradation pathways and lead to the advancement of cations with improved alkaline stabilities.
- You, Wei,Hugar, Kristina M.,Selhorst, Ryan C.,Treichel, Megan,Peltier, Cheyenne R.,Noonan, Kevin J. T.,Coates, Geoffrey W.
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supporting information
p. 254 - 263
(2020/12/23)
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- Cobalt-Catalyzed Acceptorless Dehydrogenation of Alcohols to Carboxylate Salts and Hydrogen
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The facile oxidation of alcohols to carboxylate salts and H2 is achieved using a simple and readily accessible cobalt pincer catalyst (NNNHtBuCoBr2). The reaction follows an acceptorless dehydrogenation pathway and displays good functional group tolerance. The amine-amide metal-ligand cooperation in cobalt catalyst is suggested to facilitate this transformation. The mechanistic studies indicate that in-situ-formed aldehydes react with a base through a Cannizzaro-type pathway, resulting in potassium hemiacetolate, which further undergoes catalytic dehydrogenation to provide the carboxylate salts and H2
- Gunanathan, Chidambaram,Kishore, Jugal,Pattanaik, Sandip,Pradhan, Deepak Ranjan
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supporting information
(2020/03/03)
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- RECOVERY OF ORGANIC ACID USING A COMPLEX EXTRACTION SOLVENT
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A method is disclosed for the recovery of an organic acid from a dilute salt solution in which the cation of the salt forms an insoluble carbonate salt. An amine, C02 and a water immiscible solvent are introduced to the solution to form the insoluble carbonate salt and a complex between the acid and the amine that is soluble in both an aqueous and a solvent phase. The complex is extracted into the solvent phase which is than distilled to recover the acid or an ester of the acid in a concentrated form.
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Page/Page column 34-35
(2012/05/05)
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- A structure and reactivity analysis of monomeric Ni(ii)-hydroxo complexes prepared from water
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The nickel(ii) chemistry with the tridentate ligands bis[(N′-R- ureido)-N-ethyl]-N-methylamine (H41R, R = isopropyl, tert-butyl) is described. The Ni(ii)-OH complexes, [NiIIH 21R(OH)]- were
- Powell-Jia, Darla,Ziller, Joseph W.,Dipasquale, Antonio G.,Rheingold, Arnold L.,Borovik
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p. 2986 - 2992
(2009/08/08)
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- Mechanistic change in the reactivity of substituted phenyl acetates over phenyl thiolacetates toward imidazole in aqueous phase
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The kinetics of aminolysis of several substituted phenyl acetates by imidazole is studied in aqueous medium at 20°C and an ionic strength of 0.1 M (KCl). By following the leaving groups spectrophotometrically (λ max = 272-401 nm), under excess free imidazole, pseudo-first-order rate constants (κobs) are obtained. For the esters with good nucleofuges, the reaction follows clean second-order kinetics and the plots of (κobs - κH) against free imidazole concentration are linear at constant pH. The macroscopic nucleophilic substitution rate constants (κN) are obtained as the slopes of these plots and found to be pH independent. For the esters with poor nucleofuges, a rate dependence on more than first power of the free imidazole and a linear dependence of κ′2 on free imidazole is observed. Accordingly, the microscopic rate constants for the assisted paths viz. κga and κgb have been disseminated besides for simple bimolecular attack. The Broensted-type plots and Hammett plots were constructed whose slope values are consistent with a stepwise mechanism through a bipolar tetrahedral addition intermediate whose formation or breakdown being rate determining for various paths. Comparison of this reaction of oxyesters with the earlier reported works on similar reaction of analogue thiolesters under identical reaction conditions showed remarkable mechanistic differences which are discussed in detail. The discussion is extended to include the details on previously studied ammonolysis of these two types of esters wherein thiolesters showed differed reactivity than that reported in the present study.
- Rajarathnam,Jeyakumar,Nadar, P. Ananthakrishna
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p. 211 - 221
(2007/10/03)
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- A METHOD OF MAKING SALT
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A method of making the salt of an acid, includes the steps of combining and mixing the acid and a base selected from the oxides, hydroxides and carbonates of sodium, potassium, calcium and magnesium, in a first reaction zone over a first period to produce a reaction mixture. The reaction mixture is transferred at the end of the first period from the first reaction zone to a second reaction zone the transferring step being carried out over a second period. Heat generated by reaction between the acid and the base in the second reaction zone drives off sufficient water to produce a product mixture containing less than about 8 % (m/m) water. The first period is between about 1 and 180 seconds and the second period is between about 2 and 60 seconds.
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Page/Page column 16-17
(2008/06/13)
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- Kinetics and mechanism of ammonolysis and alkaline hydrolysis of naphthyl acetates in aqueous medium: Part 1 - 4-Substituted 1-naphthyl acetates
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A series of 4- substituted 1-naphthyl acetates have been prepared. The kinetics of their ammonolysis have been followed at 20°, 25° and 30°C under pseudo-first order conditions at different pH in water containing 1% dioxan at an ionic strength of 1.0 mol dm-3. The possible mechanisms suggest the existence of general base catalysis for 4-methyl-1-naphthyl acetate. For esters with electron-withdrawing substituents, ammonolysis proceeds through an unassisted simple nucleophilic substitution pathway. The alkaline hydrolysis of all the esters is also followed under identical reaction conditions.
- Ananthakrishna Nadar,Rajarathinam
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p. 749 - 753
(2007/10/03)
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- Effective charge development in the transfer of the acetyl group between nucleophiles in acetonitrile solution: Acetolysis and butylaminolysis of substituted phenyl esters
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Equilibrium and rate constants have been measured for the phenolyses of acetic anhydride in acetonitrile solution. Acetolysis of substituted phenyl acetates by acetate ion possesses a Bronsted βlg value of -1.50 which, together with a βeq value of 2.86, indicates substantial fission of the C-OAr bond in the transition structure. The value of βeq is employed to identify the rate-limiting steps in aminolyses in acetonitrile. Butylaminolysis of substituted phenyl acetates in acetonitrile solution yields amide and substituted phenolate anion and the kinetics obey the general rate law: Rate = k1[ester][amine] + k2[ester][amine]2 + k3[ester][amine][18-crown-6] Free energy plots of log k1 and log k2 exhibit breaks near pKaArOH values of 9 and 8, respectively, and these can be interpreted by a mechanism which involves a common zwitterionic adduct T±, which partitions to give the product by two routes: A involving direct expulsion of the phenolate ion leaving group (k1 parameter) and B involving proton transfer prior to phenolate ion expulsion (k2 parameter). The formation of T± is rate-limiting for the A path and C-OAr bond fission is rate-limiting for the B mechanism.
- Maude, Antony B.,Williams, Andrew
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p. 179 - 183
(2007/10/03)
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- Kinetics and Equilibria of Reactions between Acetic Anhydride and Substituted Phenolate Ions in Aqueous and Chlorobenzene Solutions
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Potassium acetate, solubilised in chlorobenzene by 18-crown-6, displaces the phenolate ion from substituted phenyl acetates by a second-order (kCl-2) process.Potassium phenolate ions, under similar conditions, react with acetic anhydride via a second order (kCl2) to yield the phenyl acetate.The concentration of the crown does not affect the reactivity unless it is not sufficient to solubilise the reactants.The rate constants correlate with the ionisation of the substituted phenols in water: log kCl2=1.60+/-0.23pKArOH(aq)a - 9.06+/-1.4 log kCl-2=-0.97+/-0.12pKArOH(aq)a + 4.78+/-0.78.The equilibrium constant for transfer of the acetyl group between phenolate ions and acetic anhydride in chlorobenzene has a Broensted βCleq of 2.6 measured against pKArOH(aq)a.The second-order rate constants (k2aq) have been measured for the reaction of substituted phenolate ions with acetic anhydride in water and they obey the Broensted equation: log (k2aq) = 0.56 +/- 0.06 pKArOH(aq)a - 2.52 +/- 0.51 Comparison of the value of the Broensted exponent for the equilibrium constant in chlorobenzene (β = 2.6) compared with that for aqueous solution (β = 1.7) indicates a greater development of effective charge consistent with the weaker solvating power of chlorobenzene.The reaction of substituted phenoxide ion with acetic anhydride has a Leffler α value of 0.33 and 0.62 for aqueous and chlorobenzene solutions, respectively, indicating a more advanced bond formation in the transition state of the reaction in the latter solvent even though the reactions in chlorobenzene are faster than in water.
- Ba-Saif, Salem A.,Maude, Antony B.,Williams, Andrew
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p. 2395 - 2400
(2007/10/02)
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- KINETIC AND EQUILIBRIUM STUDIES OF THE REACTION OF 1,3,5-TRINITROBENZENE WITH POTASSIUM ACETATE AND 18C6 CROWN ETHER (1:1) IN APROTIC SOLVENTS
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Kinetic and equilibrium data are reported for the formation of 1:1- adduct from 1,3,5-trinitrobenzene (TNB) with acetate ion derived from potassium acetate and 18C6 crown ether (1:1) in aprotic solvents acetonitrile, tetrahydrofurane, isopropyl ether and toluene.The influence of solvents on the rate constants, activation and reaction parameters are discussed.
- Schroeder, G.,Tokarski, T.
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p. 641 - 645
(2007/10/02)
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- Bioreversible Protection for the Phospho Group: Bioactivation of the Di(4-acyloxybenzyl) and Mono(4-acyloxybenzyl) Phosphoesters of Methylphosphonate and Phosphonoacetate
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The di(4-acetoxybenzyl) ester of methylphosphonate 4 (X = H, R = Me) and the di(4-acyloxybenzyl) esters of methoxycarbonylmethylphosphonate 4 (X = MeO2C, R = Me, Et, Pr, iPr, Bu or tBu) were prepared from the appropriate benzyl alcohol and phosphonic dichloride.At pD 8.0 and 37 deg C, both series of compounds hydrolyse with half-lives greater than 24 h to the corresponding mono(4-acyloxybenzyl) esters 5 (X = H or MeO2C, R = Me, Et, Pr, iPr, Bu or tBu) which were prepared by treatment of the di(4-acyloxybenzyl) esters 4 with sodium or lithium iodide.The mono(4-acyloxybenzyl) esters 5 (X = H, R = Me) and 5 (X = MeO2C, R = Me, Et, Pr, iPr or tBu) undergo chemical hydrolysis to methylphosphonate 6 (X = H), and methoxycarbonylmethylphosphonate 6 (X = MeO2C), respectively, together with 4-hydroxybenzyl alcohol and the appropriate acylate anion.The rates of hydrolysis of the mono(4-acyloxybenzyl) esters decrease as the length and steric bulk of the acyl group increases, with half-lives ranging from ca. 150 h for the acetyl analogues to 2240 h for the pivaloyl derivative.The hydrolyses of the di- and mono-(4-acyloxybenzyl) esters were catalysed by porcine liver carboxyesterase (PLCE), and in all cases the acylate anion was formed.The rate of enzymatic hydrolysis was most rapid for the 4-butanoyloxybenzyl and 4-isobutanoyloxybenzyl analogues.The methoxycarbonyl ester of the phosphonoacetate analogues was not cleaved by PLCE.The methylphosphonate generated from the reaction of 4 (X = H, R = Me) in the presence of esterase and H2(18)O, did not contain (18)O attached directly to phosphorus.These results suggest that both the chemical and enzymatical hydrolyses of themono(4-acyloxybenzyl) esters and the PLCE-catalysed hydrolyses of the di(4-acyloxybenzyl) esters proceed via hydrolysis of the acyl group to give the acylate anion and the unstable 4-hydroxybenzyl esters.The electron-donating 4-hydroxy group facilitates the cleavage of the benzyl-oxygen bond with the formation of the 4-hydroxybenzyl carbonium ion 9, which readily reacts either with water or the phosphate buffer.The 4-acyloxybenzyl phosphoesters provide the first example of a protecting group which will enable the bioactivation of phosphonate prodrugs at rates appropriate to biological systems.
- Mitchell, Anthony G.,Thomson, William,Nicholls, Dave,Irwin, William J.,Freeman, Sally
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p. 2345 - 2354
(2007/10/02)
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- Preparation of anhydrous organic acid salts
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One-step process for preparing anhydrous, organic acid alkali or alkaline earth metal salts by contacting and reacting an organic or polymeric acid fluoride, anhydride or ester and an organic alkali or alkaline earth metal silanolate.
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- PYROLYTIC TRANSFORMATION OF THE VINYL MONOETHERS OF DIOLS IN THE PRESENCE OF ALKALIS
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The alkaline pyrolysis of the vinyl monoethers of diols takes place at 170-250 deg C and is accompanied by cycloacetalization (ethylene glycol, 1,3-propanediol), by processes involving cleavage of the C-O bonds (diethylene glycol, 1,4-butanediol), and also by the release of hydrogen, carbon dioxide, methane, ethane, acetylene, and C3 to C5 hydrocarbons.Distillation of ethylene glycol vinyl monoether with potassium hydroxide, sodium hydroxide, and lithium hydroxide can result in explosion as a result of the vigorous and exothermic release of gas.
- Trofimov, B. A.,Oparina, L. A.,Parshina, L. N.,Lavrov, V. I.,Grigorenko, V. I.,Zhumabekov, M. K.
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p. 1424 - 1428
(2007/10/02)
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- Mechanism of the Base-Catalyzed Elimination of Para-Substituted Phenoxides from 4-(Aryloxy)azetidin-2-ones
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4-(Aryloxy)azetidin-2-ones 4-7 react in dilute aqueous alkali to give 3-hydroxyacrylamide oxyanion and para-substituted phenolate ions.Similarly, 4-(aryloxy)-3,3-dimethylazetidin-2-ones 8-11 give 2,2-dimethylcarboxaldoacetamide and para-substituted phenolate ions.Reactivity is proportional to the fraction of (aryloxy)azetidin-2-one anions, Ka/(Ka + ).Kinetic pKa's of 4-11 and first-order k2's for (suggested) reversible E1cB elimination of para-substituted phenoxide ions from N-1 anions are reported.Reactions are further characterized kinetically by solvent deuterium isotope effects: kOH/kOD = ca. 0.5, ρ(k2) = 2.2 for 4-7 and ρ(k2) = 2.7 for 8-11, and βlg = -0.65 for 4-7 and βlg = -0.75 for 8-11.
- Fedor, Leo R.
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p. 5094 - 5097
(2007/10/02)
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- Measurement of Acid-Base Equilibrium Constants in Acetonitrile/18-Crown-6 Solutions
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Absorbance data were collected at three wavelength for different mixtures of acetonitrile solutions of acetic acid and substituted phenolates in order to define ionic equilibria.Formation of hydrogen bonded adducts between acid and phenolate in concentration-dependent stoichiometry renders the data, even from very dilute solutions, too complex for an exact algebraic analysis.A quite accurate assessment of the acid-base equilibrium constants is possible, by using only the calculated concentrations of free acids and bases at each ratio of acid/base.Plotting such apparent equilibrium constants vs. the acid/base ratio permits an extrapolation to zero acid concentration in which limit the true value of the acid-base equilibrium constant can be obtained.A similar technique can lead to an estimation of formation constants for conjugate adducts in acetonitrile.
- Kovach, Ildiko M.
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p. 2184 - 2186
(2007/10/02)
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- Kinetics and Some Equilibria of Transacylation between Oxy Anions in Aprotic Solvents
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β-Deuterium isotope effects (β-DIE) determined in acetonitrile for the following reactions are: CH3COO- + 4-NO2C6H4O2CCL3 (L = H, D) (PNPA-L3), 0.958 +/- 0.007 (5-45 deg C); CH3COO- + 2,4-(NO2)2C6H3O2CCL3 (DNPA-L3), 0.964 +/- 0.011 (5-20 deg C; OH(1-) + PNPA-L3, 0.972 +/- 0.028 (25 deg C); 4-NO2C6H4O- (PNP-) + CL3COOCOCL3, 1.00 +/- 0.02 (20 deg C); 4-NO-C6H4O- (PNOP-) + CL3COOCOCL3, 1.00 +/- 0.03 (20 deg C). β-DIEs in benzene for two of these reactions are: CH3COO- + PNPA-L3, 0.957 +/- 0.045 (10-20 deg C); CH3COO- + DNPA-L3, 0.985 +/- 0.050 (5-10 deg C).The fraction of tetrahedral character at the transition state (TS) deduced from β-DIEs for reactions of CH3COO- + PNPA is 0.32 in both CH3CN and benzene, of CH3COO- + DNPA is 0.28 in CH3CN and 0.12 in benzene, and of OH- + PNPA is 0.21 in CH3CN.These values are similar to what is found in water and indicate TSs of essentially trigonal geometry.Isotope effects (CH3)2/k(CD3)2> of unity for ester formation from CL3COOCOCL3 with phenoxides might be interpreted by two contributing factors to the observed effect; one of the usual hyperconjugation source and the other from electoststic effect of the label in the departing CL3COO-.An equilibrium isotope effect (CH3)2/K(CD3)2> of 1.03 in the direction of ester formation is calculated.A Hammett correlation of reactions of substituted phenoxides with CH3COOCOCH3 in CH3CN yielded ρ = -2.54.The reaction of CH3COO- in CH3CN could not be effected with phenyl acetate.The reaction was endergonic (ΔG0 = +2.59 kcal/mol)with PNPA and exergonic (ΔG0 = -7.61 kcal/mol) with DNPA.Activation enthalpies of these reactions decrease from H2O to CH3CN to benzene, whereas activation entropies increase in this order.
- Kovach, Ildiko M.
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p. 2235 - 2241
(2007/10/02)
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