- METHOD FOR MANUFACTURE OF 1,1,1-TRIFLUORO-2-CHLOROETHANE (HCFC 133A) AND/OR TRFLUOROETHYLAMINE (TFEA)
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A method for manufacture of 1, 1, 1-trifluoro-2-chloroethane (HCFC-133a) and/or trifluoroethylamine (TFEA), wherein at least one reaction step takes place in a microreactor that is comprising or is made of SiC-microreactor, the processes can be efficiently combined in that HCFC-133a produced by using a microreactor, may preferably advantageously serve as starting material and/or intermediate material in the manufacture of TFEA. The HCFC-133a and/or the TFEA can be easily, by a method with only low energy consumption, purified and/or isolated, and preferably the process for purifying and/or isolating does not require a distillation. Advantageously, the separation from excess hydrogen fluoride (HF) and catalyst can easily take place in an energy-saving manner by phase separation.
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Page/Page column 28
(2020/06/05)
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- Catalytic preparation method of trifluoroethylamine compound
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The invention provides a preparation method of 2,2,2-trifluoroethylamine. Trifluoroformaldehyde or trifluoroacetaldehyde hydrate and ammonia water are taken as raw materials and subjected to reactionin the presence of a mesoporous molecular sieve supported catalyst and a suitable hydrogen donor, a product is subjected to secondary reduction, and trifluoroethylamine is prepared. The process does not need high temperature or high pressure, has mild reaction conditions, high conversion rate, few byproducts and low cost, is clean and environmentally friendly, conforms to the trend of green chemical industry nowadays and has higher industrial production value, and a catalyst is easy to recycle.
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Paragraph 0042-0052
(2019/01/14)
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- Catalytic reduction of amides to amines by electrophilic phosphonium cations via FLP hydrosilylation
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A catalytic methodology for the conversion of amides to amines is reported. Of the 25 examples described, 14 examples involve the reduction of N-trifluoroacetamides to the corresponding trifluoroethylamines. These reductions are achieved by catalytic hydrosilylation of the amide mediated by an electrophilic phosphonium cation (EPC) catalyst.
- Augurusa, Alessandra,Mehta, Meera,Perez, Manuel,Zhu, Jiangtao,Stephan, Douglas W.
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supporting information
p. 12195 - 12198
(2016/10/21)
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- Kinetic study of the formation of N-chloro compounds using N-chlorosuccinimide
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Second-order rate constants were determined for the chlorination reaction of 2,2,2-trifluoethylamine and benzylamine with N-chlorosuccinimide at 25 °C and an ionic strength of 0.5 M. These reactions were found to be of first order in both reagents. According to the experimental results, a mechanism reaction was proposed in which a chlorine atom is transferred between both nitrogenous compounds. Kinetics studies demonstrate that the hydrolysis process of the chlorinating agent does not interfere in the chlorination process, under the experimental conditions used in the present work. Free-energy relationships were established using the results obtained in the present work and others available in the literature for chlorination reactions with N-chlorosuccinimide, being the pKa range included between 5.7 and 11.22. Copyright
- Pastoriza, Cristina,Antelo, Juan Manuel,Crugeiras, Juan,Pena-Gallego, Angeles
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p. 407 - 418
(2014/05/06)
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- N-methylimidazole promotes the reaction of homophthalic anhydride with imines
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The addition of N-methylimidazole (NMI) to the reaction of homophthalic anhydride with imines such as pyridine-3-carboxaldehyde-N-trifluoroethylimine (9) reduces the amount of elimination byproduct and improves the yield of the formal cycloadduct, tetrahydroisoquinolonic carboxylate 10. Carboxanilides of such compounds are of interest as potential antimalarial agents. A mechanism that rationalizes the role of NMI is proposed, and a gram-scale procedure for the synthesis and resolution of 10 is also described.
- Liu, Jian,Wang, Zheng,Levin, Aaron,Emge, Thomas J.,Rablen, Paul R.,Floyd, David M.,Knapp, Spencer
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supporting information
p. 7593 - 7599
(2014/09/16)
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- Probing the nature of the Co(III) ion in corrins: Comparison of reactions of aquacyanocobyrinic acid heptamethyl ester and aquacyano-stable yellow cobyrinic acid hexamethyl ester with neutral N-donor ligands
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Equilibrium constants (log K) for substitution of coordinated H 2O in aquacyanocobyrinic acid heptamethyl ester (aquacyanocobester, ACCbs) and aquacyano-stable yellow cobyrinic acid hexamethyl ester (aquacyano-stable yellow cobester, ACSYCbs), in which oxidation of the C5 carbon of the corrin interrupts the normal delocalized system of corrins, by neutral N-donor ligands (ammonia, ethanolamine, 2-methoxyethylamine, N-methylimidazole, and 4-methylpyridine) have been determined spectrophotometrically as a function of temperature. Log K values increase with the basicity of the ligand, but a strong compensation effect between ΔH and ΔS values causes a leveling effect. The aliphatic amines with a harder donor atom produce ΔH values that are more negative in their reactions with ACSYCbs than with ACCbs, while the softer, aromatic N donors produce more negative ΔH values with ACCbs than with ACSYCbs. Molecular modeling (DFT, M06L/SVP, and a quantum theory of atoms in molecules analysis of the electron density) shows that complexes of the aliphatic amines with SYCbs produce shorter and stronger Co-N bonds with less ionic character than the Co-N bonds of these ligands with the cobester. Conversely, the Co-N bond to the aromatic N donors is shorter, stronger, and somewhat less ionic in the complexes of the cobester than in those of the SYCbs. Therefore, the distinction between the harder Co(III) in ACSYCbs and softer Co(III) in ACCbs, reported previously for anionic ligands, is maintained for neutral N-donor ligands.
- Chemaly, Susan M.,Kendall, Louise,Nowakowska, Monika,Pon, Dale,Perry, Christopher B.,Marques, Helder M.
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p. 1077 - 1083
(2013/03/13)
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- Biomimetic reductive amination under the continuous-flow reaction conditions
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This study present a full account of continuous-flow reaction conditions for biomimetic reductive amination of fluorinated carbonyl compounds to corresponding amines and amino acids of biomedical importance. We demonstrate that simple silica-adsorbed DBU can be used as efficient catalysts for on-column 1,3-proton shift reaction, a key transformation in the biomimetic reductive amination process. This new on-column process features operationally convenient conditions, higher chemical yields, enantioselectivity and purity of the corresponding products as compared with traditional in-flask reactions. Moreover the removal of base-catalyst, the most delicate problem of the in-flask reactions, is not an issue in the on-column process, as the silica-adsorbed DBU or polymer-bound guanidine remains on the column and can be reused. This feature renders the overall process substantially more economical and synthetically efficient, in particular, for large-scale synthesis of the corresponding fluorinated amines and amino acids target.
- Soloshonok, Vadim A.,Catt, Hector T.,Ono, Taizo
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body text
p. 261 - 265
(2010/04/05)
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- Acid-catalysed chlorine transfer from N-chloramines to iodide ion: Experimental evidence for a predicted change in mechanism
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Rate constants for acid catalysis of the reactions of N-chlorodimethylamine (1), N-chloro-2,2,2-trifluoroethylamine (2) and N,N-dichlorotaurine (3) with iodide ion were determined in H2O at 25°C and I = 0.5 (NaClO 4). The failure to detect significant catalysis by general acids of chlorine transfer from 1 to the nucleophile, together with the observed inverse solvent deuterium isotope effect on the hydronium ion-catalysed reaction (k H/kD = 0.37), indicates that this process occurs by protonation of 1 in a fast equilibrium step, followed by rate determining chlorine transfer to iodide ion. The appearance of general acid catalysis for the reactions of 2 and 3 shows that increasing the leaving group ability leads to a change to a concerted mechanism, which is suggested to be enforced by the absence of a significant lifetime of the protonated chloramine intermediate in the presence of iodide ion.
- Calvo, Paula,Crugeiras, Juan,Rios, Ana
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supporting information; experimental part
p. 4137 - 4142
(2010/10/19)
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- Facile preparation of polyfluoroalkylated aldimines from polyfluoroalkanoic acids
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Polyfluoroalkylated aldimines were prepared by reducing polyfluoroalkyl imidoyl chlorides, which are readily available from polyfluoroalkanoic acids, with LTBA (lithium tri-tert-butoxyaluminum hydride). Georg Thieme Verlag Stuttgart.
- Takagi, Jun,Takihana, Ryozo,Kuwano, Akiko,Uneyama, Kenji
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p. 1624 - 1628
(2008/02/05)
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- Mechanisms of acid decomposition of dithiocarbamates. 1. Alkyl dithiocarbamates
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The acid decomposition of some substituted methyldithiocarbamates was studied in water at 25°C in the range of rio -5 and pH 5. The pH-rate profiles showed a bell-shaped curve from which were calculated the acid dissociation constants of the free and conjugate acid species and the specific acid catalysis rate constants k(H). The Bronsted plot of k(H) vs pK(N), the dissociation constant of the conjugate acid of the parent amine, suggests that the acid cleavage occurs through two mechanisms that depend on the pK(N). The plot presents a convex upward curve with a maximum at pK(N) 9.2, which is consistent with the cleavage of the dithiocarbamate anion through a zwitterion intermediate and two transition states. For pK(N) 9.2, the C-N bond breakdown is the slowest step, and according to the inverse SIE, the transition state changes rapidly with the increase of pK(N) to a late transition state. The plot shows a minimum at pK(N) ?10, indicating that a new mechanism emerges at higher values, and it is postulated that it represents a path of intramolecular S to N proton-transfer concerted with the C-N bond breakdown. The thiocarbonyl group acts as a powerful electron- withdrawing group, decreasing the basicity of the nitrogen of the parent amine by 14.1 pK units.
- Humeres, Eduardo,Debacher, Nito A.,Marta de S. Sierra,Franco, Jose Dimas,Schutz, Aldo
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p. 1598 - 1603
(2007/10/03)
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- Iodide Reduction of Sulfilimines. 2. Evidence for Concurrent Stepwise and Concerted Mechanisms for the Decomposition of Sulfurane Intermediates
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The iodide reduction of N-(substituted ethyl or phenyl)-S,S-dimethylsulfilimmonium salts (aqueous solution, 25 deg C, μ = 1.0 with KCl) is first order in proton activity and iodide concentration in the pH range 0.5-5.The solvent deuterium isotope effects for the reduction reaction vary in the range kH/kD = 0.26-0.48 as the nitrogen substituent is changed from ethyl- to trifluoroethylamine.Electron-withdrawing groups in the leaving group decrease the rate of the reaction and give βl.g. values of ca. 0.7 for cyanoethyl- and trifluoroethylamine leaving groups and ca. 0.1 for the more basic ethylamine derivatives; a βl.g. of 0.58 is observed for aniline derivatives.General acid catalysis is observed in the reduction of the acidic ethylamine and aniline derivatives with Broensted α values of 0.59 and 0.39 for cyanoethyl- and trifluoroethylamine leaving groups, respectively; for anilines, the Broensted α values decreased from 0.67 to 0.50 as the leaving group is changed from 4-methyl- to 3-nitroaniline.The value of βl.g. decreases with decreasing strength of the catalyzing acid and the term pxy = (δβl.g./δpKaHA) = (δα/δKal.g.) ca. -0.06 to -0.1.The solvent deuterium isotope effect on the general catalyzed reduction reaction increases with increasing acid strength; for the cyanoethylamine derivative, kBH/kBD = 1.47-2.32 for acetic and chloroacetic acids, respectively.A mechanism is suggested involving concurrent stepwise and concerted mechanisms for the reduction reaction; the mechanism observed seems to depend on the nature of the catalyzing acid.
- Young, Paul R.,Huang, H. C.
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p. 1805 - 1809
(2007/10/02)
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- Structural effects on reactivity in intramolecular catalysis. The hydrolysis of N-alkylated monoamides derived from norbornene-2,3-dicarboxylic acid
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Monoamides of 2,3-endo-cis-5-norbornene dicarboxylic acid (compounds 1-5) were prepared by addition of primary alkyl amines (n-propyl-, 2-methoxyethyl-, 2-fluoroethyl-, 2,2-difluoroethyl-, 2,2,2-trifluoroethyl-) to 2,3-endo-cis-5-norbornene dicarboxylic anhydride.The rates of hydrolysis of each compound in solutions whose acid concentration ranged from 0.01 M to 9 M were determined.Rates increase with acidity above 0.1 M until a maximum rate is achieved in strong acid.The results are consistent with a mechanism involving intramolecular catalysis of the hydrolysis of the amide by the adjacent carboxylic acid.The dependence of rate on acidity can be interpreted in terms of a multistep mechanism involving formation of an intramolecular tetrahedral adduct, tautomerization of the adduct, and expulsion of the amine to give the anhydride.The identity of the rate-determining step is a function of the basicity of the substrate and the acidity of the medium.Analysis of the data in terms of the proposed mechanism suggests that the effective molarity of the groups involved in tautomerization of the tetrahedral internal addition intermediate is higher than in other rigid systems which lack the norbornene structure.It is proposed that ring strain and rotational entropy control cyclization and elimination steps.Interactions of the solvent with the entire substrate control reorganization of the intermediate.Conjugation of the interacting functional groups does not appear to have a significant effect upon their reactivity.
- Kluger, Ronald,Brandl, Michael
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p. 2515 - 2520
(2007/10/02)
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- Substituen Effect of Chelated Cobalt. 5. Acidities of (Carboxymethyl)- and (1-Carboxyethyl)cobaloximes. A Quantitative Analysis of the β Effect
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pKa's of the weakly acidic (carboxymethyl)(ligand)cobaloximes and (1-carboxyethyl)(ligand)cobaloximes with 16 different axial ligands have been determined and correlated with those of 11 substituted acetic acids or 9 1-substituted propionic acids, respectively.Comparison of apparent ?1 values thus calculated with those previously determined by correlation of (carboxyethyl)(ligand)cobaloxime pKa's with the pKa's of 2-substituted propionic acid indicates that the (1-carboxyalkyl)cobalt comlexes show a substantial β effect as an apparent extreme donation density to the carboxyl carbon.The β effect in these complexes has been quantitated by use of a dual substituent parameter equation, the results of which show that the effect is only some 8-10percent enhanced in (1-carboxyethyl)cobaloximes relative to (carboxymethyl)cobaloximes.This result is consistent with the β effect being mediated by ?-? hyperconjugation rather than neighboring group participation.Structural effects on the extent of ?-? conjugation and the effects of ?-? conjugation on reactivity of the cobalt atom in these complexes are discussed.
- Brown, Kenneth L.,Zahonyi-Budo, Eva
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p. 4117 - 4124
(2007/10/02)
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- The Chemical Reactivity of Penicillins and Other β-Lactam Antibiotics
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The rates of the acid catalysed hydrolysis of penicillins and cephalosporins are linear in Ho and, unlike other amides, show no rate maximum with increasing acidity.Electron-withdrawing substituents at C-6 in penicillins decrease the rate of hydrolysis with a ρI of ca. 4 and they decrease the rate when attached to the amine leaving group.The acylamido-group at C-6 in penicillins, but not at C-7 in cephalosporins, exhibits neighbouring group participation with a rate enhancement of ca. 103.The absence of penicillenic acid formation from benzylpenicillin in acidic solution is not due to the ionisation of the carboxy-group.These observations are rationalised by a scheme involving N-protonation and formation of an acylium ion intermediate.The alkaline hydrolysis of penicillins proceeds 102 faster than a β-lactam after correction for substituent effects.There is no evidence for substantial inhibition of amide resonance in the bicyclic β-lactam antibiotics, little evidence to indicate extra strain in these systems and no evidence that expulsion of the leaving group at C-3 in cephalosporins occurs in the transition state.
- Proctor, Philip,Gensmantel, Nigel P.,Page, Michael I.
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p. 1185 - 1192
(2007/10/02)
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- Hydrogen bonding solvent effect on the basicity of primary amines CH3NH2, C2H5NH2, and CF3CH2NH2
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The equilibria RNH3+(H2O)n-1 + H2O = RNH3+(H2))n were measured for R=CH3, C2H5, and CF3CH2 from n=1 to n=3 with a pulsed electron beam high ion source pressure mass spectrometer.The proton and hydrate transfer equilibria CH3NH3+(H2O)n + C2H5NH2 = CH3NH2 + C2H5NH3+(H2))n were measured for n=0 to n=3.These data allow the evaluation of ΔH0 and ΔG0 for the reactions: R0NH3+(H2))N + RNH3+ = R0NH3+ +RNH3+(H2O)n. ΔH0=δΔH00,n(RNH3+),ΔG=δΔG00,n(RNH3+).These data are compared with δΔE0,3(STO-3G) evaluated by Hehre and Taft.In general good agreement is observed at n=3.The δΔH00,3(RNH3+) ca. δΔE0,3(RNH3+)are also found close to the ion hydration free energy difference in aqueous solutions.
- Lau, Yan K.,Kebarle, P.
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p. 151 - 155
(2007/10/02)
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- Hydroxy-group Participation in the Hydrolysis of Amides and its Effective Concentration in the Absence of Strain Effects
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Rate constants are reported for the alkaline- and acid-catalysed hydrolysis of endo-6-hydroxybicycloheptane-endo-2-carboxamides in aqueous solution.The product of the acid-catalysed reaction is endo-6-hydroxybicycloheptane-endo-2-carboxylic acid lactone and this lactone is also formed as an intermediate in alkaline solution before giving the hydroxy-acid anion as the product.The effective concentration of the intramolecular alkoxide ion group is ca. 1E8M.This is in good agreement with the maximum entropic advantage predicted for intramolecular reactions as the system is thought to be free of major strain energy and solvation effects.Variation of substituents in the amine leaving group gives a βlg value of +0.30 for the hydroxide-ion-catalysed lactonisation reaction.This is interpreted in terms of rate-limiting breakdown of the tetrahedral intermediate in which there is cconsiderable positive charge on the amine nitrogen.Mechanisms consistent with this involve either proton transfer from water to the amine nitrogen occuring synchronously with carbon-nitrogen bond fission or a stepwise process in which the nitrogen of the tetrahedral intermediate is fully protonated and the rate-limiting step is either diffusion apart of this intermediate and hydroxide ion or collapse of this intermediate with hydroxide ion acting as a 'spectator'.The βlg value for the acid-catalysed lactonisation reaction is 0.0.
- Morris, Jeffrey J.,Page, Michael I.
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p. 679 - 684
(2007/10/02)
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- Structure-Reactivity Relationships and the Mechanism of General Base Catalysis in the Hydrolysis of a Hydroxy-amide. Concerted Breakdown of a Tetrahedral Intermediate
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Kinetic general base catalysis is observed in the lactonisation of N-substituted endo-6-hydroxybicycloheptane-endo-2-carboxamides.The reaction mechanism is thought to involve the kinetically equivalent general-acid-catalysed breakdown of the tetrahedral intermediate, T-.The Broensted β values for the catalysed lactonisation of the N-propyl- and N-trifluoroethyl-amides are 0.70 and 0.50, respectively which are equivalent to α values of 0.30 and 0.50, respectively.These values are indicative of a concerted reaction in which proton transfer occurs synchronously with carbon-nitrogen bond fission.The dependence of the rate of reaction of N-substituted amides upon the acidity of the catalyst shows that βlg decreases with increasing acidity of the catalyst.The behaviour of the observed structure-reactivity coefficients is discussed with the aid of energy diagrams and it is concluded that proton transfer makes a significant contribution to the reaction co-ordinate.The structure-reactivity coefficients also indicate a degree of charge imbalance in the transition state.
- Morris, Jeffrey J.,Page, Michael I.
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p. 685 - 692
(2007/10/02)
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- Mechanism of Cleavage of Carbamate Anions
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Carbamates and monothiocarbamates of basic aliphatic amines undergo rate-determining C-N cleavage after a rapid equilibrium protonation step, as shown most directly by inverse solvent deuterium isotope effects of kD/kH = 3.6-4.8 for O,O- and O,S-N-n-butylcarbamates and by rapid acid-catalyzed exchange of the NH proton of n-BuNHCOS- with kexch = 5 107 M-1 s-1.The lifetimes of substituted N-protonated carbamates have been estimated to range down to -10 s.It is concluded that general acid catalysis of the cleavage of carbamates of weakly basic anilines (α = 0.84) occurs through an enforced preassociation mechanism with hydrogen bonding to the leaving protonated nitrogen atom and C-N cleavage in the rate-determining step.There is more proton transfer in the transition state (larger α) and a smaller β1g with more basic amines and upon substitution of sulfur for oxygen.The low pKa values of N-protonated carbamates and monothiocarbamates illustrate the strong electron-accepting ability of -COO- and -COS-.
- Ewing, Sheila P.,Lockshon, Daniel,Jencks, William P.
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p. 3072 - 3084
(2007/10/02)
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