Nachbargruppeneffekte bei der Aminolyse von Estern, II Die Aminolyse von 2-(2-Hydroxybenzyl)phenylacetaten / Neighboring Group Effects in the Aminolysis of Esters, II The Aminolysis of 2-(2-Hydroxybenzyl)phenylacetates

1978 ◽  
Vol 33 (4) ◽  
pp. 439-449 ◽  
Author(s):  
Volker Böhmer ◽  
Klaus Wörsdörfer
Keyword(s):  
Second Order ◽  
Phenyl Acetate ◽  
Third Order ◽  
Neighboring Group ◽  
Rate Law ◽  
Order Rate ◽  
Methyl Phenyl ◽  
Group Effects

Abstract The aminolysis of 2-(2-hydroxybenzyl)phenyl acetates with n-butylamine in dioxane is much faster than for the corresponding 2-(2-methoxybenzyl)phenyl acetates or 2-methyl-phenyl acetates. The kinetic results can be explained by two equivalent mechanisms. Both of them include the formation of a 1:1-complex between 2-(2-hydroxybenzyl)phenyl acetate and n-butylamine which is formed in an equilibrium. The reaction of this complex according to a second order rate law seems to be more probable than the reaction of the free ester according to a third order rate law.

Termolecular ion–molecule reactions involving C3H5+

1970 ◽  
Vol 48 (22) ◽  
pp. 3549-3553 ◽  
Author(s):  
A. G. Harrison ◽  
A. A. Herod
Keyword(s):  
Kinetic Energy ◽  
Molecular Size ◽  
Order Rate Constant ◽  
Second Order ◽  
Rate Coefficients ◽  
Third Order ◽  
Order Rate ◽  
Ion Molecule Reactions ◽  
Similar Dependence ◽  
Ion Kinetic Energy

The reaction of C3H5+ with C2D4 to produce C5H5D4+ is shown to be second order in C2D4. The rate coefficients are in the range 10−24 to 10−25 cm6 molecule−2 s−1 but decrease markedly with increasing ion kinetic energy. This decrease reflects the effect of the ion kinetic energy on the lifetime of the initial collision complex. Small differences in rate coefficients are observed depending on the source of the C3H5+ ion but these are insufficient to distinguish between possibly different ionic structures. The reaction of C3H5+ with C2H3F forms C5H7+ in a reaction second order in C2H3F. The rate coefficients are also in the range 10−24 to 10−25 cm6 molecule−1 s−1 and show a similar dependence on ion kinetic energy. These high third order rate constants are compared with data for other termolecular reactions and are shown to be consistent with the effect of molecular size on the third order rate constant.

1H-DNMR-Untersuchungen zur inter- und intramolekularen Ligandenmobilität im System Co(II)/[18]Krone-6 / 1H DNMR Studies on the Inter- and Intramolecular Ligand Mobility in the System Co(II)/[18]crown-6

1984 ◽  
Vol 39 (1) ◽  
pp. 69-73 ◽  
Author(s):  
Franz L. Dickert ◽  
Walter Gumbrecht
Keyword(s):  
Crown Ether ◽  
Intermediate Product ◽  
Outer Sphere ◽  
Second Order ◽  
Ligand Concentration ◽  
Rate Law ◽  
First Order ◽  
Order Rate

The crown ether exchange could be studied in non-coordinating solvents by using the hy­drophobic complex [Co([18]crown-6)] + + . Appreciable outer-sphere association between complex and ligand (K°(50 °C) = 12 ± 0.5 M-1) occurs. This changes the second order rate law to first order (kmono(50 °C) = 7900 ± 500 s_1) with increasing ligand concentration. In the complex mer-[Co([18]crown-6)(CH3OH)3]+ + the stereochemical rearrangement of the uncoordinated part of the crown ether follows an intramolecular pathway via the complex [Co([18]crown-6)]++ as an intermediate product.

Micellar Catalysis of Organic-Reactions. XXI. A Comparison of the Catalytic Activity of Micelles of Cetyltrimethylammonium Bromide and Sulfate on Ester, Amide and Carbamate Hydrolyses

1988 ◽  
Vol 41 (3) ◽  
pp. 325
Author(s):  
TJ Broxton ◽  
JR Christie ◽  
SM Mannas
Keyword(s):  
Catalytic Activity ◽  
Rate Constants ◽  
Cetyltrimethylammonium Bromide ◽  
Second Order ◽  
Phenyl Acetate ◽  
Bond Breaking ◽  
Order Rate ◽  
Cationic Micelles ◽  
Hydrolysis Of ◽  
Reaction In Water

The basic hydrolyses of phenyl acetate, N,4-dimethyl-N-(3′- nitrophenyl ) benzamide , methyl N-methyl-N-(4′-nitrophenyl) carbamate and methyl N-(3′,5′-dinitrophenyl)-N-methylcarbamate have been studied in cationic micelles of cetyltrimethylammonium bromide (ctab) and sulfate (ctas). Hydrolysis of phenyl acetate and the 4′-nitro carbamate, which involve rate-determining hydroxide attack, exhibit weak catalysis by both micelles, and the observed rates in each micelle are similar. The hydrolysis of the benzamide and the 3′,5′-dinitro carbamate, which involve rate determining C-N bond breaking, show larger catalysis, and, furthermore, micelles of ctab are more effective than micelles of ctas. The observed rates can be explained by the pseudo-phase kinetic model. For reactions involving rate-determining hydroxide attack, the calculated second-order rate constants in micelles of ctab and ctas are similar and much less than those for reaction in water. For reactions involving rate-determining C-N bond breaking the calculated second-order rate constants in micelles of ctab are greater than in micelles of ctas, and similar to those for reaction in water.

scholarly journals Kinetics of Reactive Blue 21 Decolorization Using Peracetic Acid

2017 ◽  
Vol 33 (3) ◽  
Author(s):  
Vu Duy ◽  
Le Van Chieu ◽  
Cao The Ha
Keyword(s):  
Aqueous Solutions ◽  
Reaction Kinetics ◽  
Peracetic Acid ◽  
Light Absorption ◽  
Second Order ◽  
Catalytic Reactions ◽  
Rate Law ◽  
Order Rate ◽  
Decolorization Rate ◽  
Kinetics Of

Decolorization rate of Reactive Blue 21 by peracetic acid in aqueous solutions was measured at pH 6.0. Concentrations of peracetic acid were applied in the range of 1 - 3 mM. The reaction kinetics were monitored by recording the light absorption of the Reactive Blue 21 at 660 nm. The obtained results showed that the decolorization happened via non-catalytic and auto-catalytic reactions. Both the reactions were proposed to obey the second-order rate law.

scholarly journals Kinetics and mechanisms of polycondensation reactions between aryl halides and bisphenol A

2020 ◽  
Vol 11 (31) ◽  
pp. 5078-5087
Author(s):  
Yi Yang ◽  
Christopher L. Muhich ◽  
Matthew D. Green
Keyword(s):  
Bisphenol A ◽  
Experimental Verification ◽  
Second Order ◽  
Aryl Halides ◽  
Third Order ◽  
Rate Expression ◽  
Order Rate

Computational and experimental verification of a second-order rate expression for polysulfones synthesized using diphenyldichloro sulfone versus a third-order rate expression for polysulfones synthesized using diphenyldifluoro sulfone.

Inhibition in Purified Systems and in Human Plasma of Chimaeric Plasminogen Activators Consisting of the NH2-Terminal Region of Tissue-Type Plasminogen Activator and the COOH-Terminal Region of UrokinaseType Plasminogen Activator

1988 ◽  
Vol 60 (02) ◽  
pp. 247-250 ◽  
Author(s):  
H R Lijnen ◽  
L Nelles ◽  
B Van Hoef ◽  
F De Cock ◽  
D Collen
Keyword(s):  
Plasminogen Activator ◽  
Rate Constants ◽  
Plasminogen Activators ◽  
Second Order ◽  
Tissue Type ◽  
Single Chain ◽  
Chain Molecules ◽  
Order Rate ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator

SummaryRecombinant chimaeric molecules between tissue-type plasminogen activator (t-PA) and single chain urokinase-type plasminogen activator (scu-PA) or two chain urokinase-type plasminogen activator (tcu-PA) have intact enzymatic properties of scu-PA or tcu-PA towards natural and synthetic substrates (Nelles et al., J Biol Chem 1987; 262: 10855-10862). In the present study, we have compared the reactivity with inhibitors of both the single chain and two chain variants of recombinant u-PA and two recombinant chimaeric molecules between t-PA and scu-PA (t-PA/u-PA-s: amino acids 1-263 of t-PA and 144-411 of u-PA; t-PA/u-PA-e: amino acids 1-274 of t-PA and 138-411 of u-PA). Incubation with human plasma in the absence of a fibrin clot for 3 h at 37° C at equipotent concentrations (50% clot lysis in 2 h), resulted in significant fibrinogen breakdown (to about 40% of the normal value) for all two chain molecules, but not for their single chain counterparts. Preincubation of the plasminogen activators with plasma for 3 h at 37° C, resulted in complete inhibition of the fibrinolytic potency of the two chain molecules but did not alter the potency of the single chain molecules. Inhibition of the two chain molecules occurred with a t½ of approximately 45 min. The two chain variants were inhibited by the synthetic urokinase inhibitor Glu-Gly-Arg-CH2CCl with apparent second-order rate constants of 8,000-10,000 M−1s−1, by purified α2-antiplasmin with second-order rate constants of about 300 M−1s−1, and by plasminogen activator inhibitor-1 (PAI-1) with second-order rate constants of approximately 2 × 107 M−1s−1.It is concluded that the reactivity of single chain and two chain forms of t-PA/u-PA chimaers with inhibitors is very similar to that of the single and two chain forms of intact u-PA.

Bulk Contributions Modulate the Sum-Frequency Generation Spectra of Interfacial Water on Model Sea-Spray Aerosols

2018 ◽  
Author(s):  
Sandeep K. Reddy ◽  
Raphael Thiraux ◽  
Bethany A. Wellen Rudd ◽  
Lu Lin ◽  
Tehseen Adel ◽  
...  
Keyword(s):  
Single Layer ◽  
Sum Frequency Generation ◽  
Second Order ◽  
Interfacial Structure ◽  
Sea Spray ◽  
Third Order ◽  
Systematic Analysis ◽  
Sum Frequency ◽  
Structure Of Water ◽  
Frequency Generation

Vibrational sum-frequency generation (vSFG) spectroscopy is used to determine the molecular structure of water at the interface of palmitic acid monolayers. Both measured and calculated spectra display speci c features due to third-order contributions to the vSFG response which are associated with nite interfacial electric potentials. We demonstrate that theoretical modeling enables to separate the third-order contributions, thus allowing for a systematic analysis of the strictly surface-sensitive, second-order component of the vSFG response. This study provides fundamental, molecular-level insights into the interfacial structure of water in a neutral surfactant system with relevance to single layer bio-membranes and environmentally relevant sea-spray aerosols. These results emphasize the key role that computer simulations can play in interpreting vSFG spectra and revealing microscopic details of water at complex interfaces, which can be difficult to extract from experiments due to the mixing of second-order, surface-sensitive and third-order, bulk-dependent contributions to the vSFG response.

Hydrogen Atom Transfer Reaction Free Energy as a Predictor of Abiotic Nitroaromatic Reduction Rate Constants: A Comprehensive Analysis

2019 ◽  
Author(s):  
Dominic Di Toro ◽  
Kevin P. Hickey ◽  
Herbert E. Allen ◽  
Richard F. Carbonaro ◽  
Pei C. Chiu
Keyword(s):  
Free Energy ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Energy Model ◽  
Second Order ◽  
Transfer Model ◽  
Atom Transfer ◽  
Order Rate ◽  
Linear Free Energy ◽  
Free Energy Model

<div>A linear free energy model is presented that predicts the second order rate constant for the abiotic reduction of nitroaromatic compounds (NACs). For this situation previously presented models use the one electron reduction potential of the NAC reaction. If such value is not available, it has been has been proposed that it could be computed directly or estimated from the electron affinity (EA). The model proposed herein uses the Gibbs free energy of the hydrogen atom transfer (HAT) as the parameter in the linear free energy model. Both models employ quantum chemical computations for the required thermodynamic parameters. The available and proposed models are compared using second order rate constants obtained from five investigations reported in the literature in which a variety of NACs were exposed to a variety of reductants. A comprehensive analysis utilizing all the NACs and reductants demonstrate that the computed hydrogen atom transfer model and the experimental one electron reduction potential model have similar root mean square errors and residual error probability distributions. In contrast, the model using the computed electron affinity has a more variable residual error distribution with a significant number of outliers. The results suggest that a linear free energy model utilizing computed hydrogen transfer reaction free energy produces a more reliable prediction of the NAC abiotic reduction second order rate constant than previously available methods. The advantages of the proposed hydrogen atom transfer model and its mechanistic implications are discussed as well.</div>

Evidence for general base catalysis by protic solvents in a kinetic study of alcoholyses and hydrolyses of 1-(phenoxycarbonyl)pyridinium ions under both solvolytic and non-solvolytic conditions

2009 ◽  
Vol 74 (1) ◽  
pp. 43-55 ◽  
Author(s):  
Dennis N. Kevill ◽  
Byoung-Chun Park ◽  
Jin Burm Kyong
Keyword(s):  
Second Order ◽  
Base Catalysis ◽  
Substitution Reactions ◽  
Third Order ◽  
Methoxy Derivative ◽  
First Order ◽  
General Base ◽  
Protic Solvents ◽  
Kinetics Of ◽  
Pyridinium Ions

The kinetics of nucleophilic substitution reactions of 1-(phenoxycarbonyl)pyridinium ions, prepared with the essentially non-nucleophilic/non-basic fluoroborate as the counterion, have been studied using up to 1.60 M methanol in acetonitrile as solvent and under solvolytic conditions in 2,2,2-trifluoroethan-1-ol (TFE) and its mixtures with water. Under the non- solvolytic conditions, the parent and three pyridine-ring-substituted derivatives were studied. Both second-order (first-order in methanol) and third-order (second-order in methanol) kinetic contributions were observed. In the solvolysis studies, since solvent ionizing power values were almost constant over the range of aqueous TFE studied, a Grunwald–Winstein equation treatment of the specific rates of solvolysis for the parent and the 4-methoxy derivative could be carried out in terms of variations in solvent nucleophilicity, and an appreciable sensitivity to changes in solvent nucleophilicity was found.

Sign in / Sign up

Export Citation Format

Share Document