Kinetics of hydrolyses of o-methylbenzylideneaniline and o-hydroxybenzylideneaniline

1968 ◽  
Vol 46 (9) ◽  
pp. 1589-1592 ◽  
Author(s):  
Alfred V. Willi ◽  
José F. Siman
Keyword(s):  
Hydrogen Bond ◽  
Schiff Base ◽  
Rate Constants ◽  
Experimental Error ◽  
Steric Effect ◽  
Hydrolysis Rate ◽  
Aqueous Methanol ◽  
Buffer Solutions ◽  
Acid Catalyzed ◽  
Kinetics Of

Rates of hydrolysis have been measured for o-methylbenzylideneaniline, o-hydroxybenzylideneaniline, and benzylideneaniline in various buffer solutions in 20% (by volume) aqueous methanol at 29.9 °C. Rate constants for the o-CH3 compound and the unsubstituted Schiff base agree within experimental error which indicates that there is no appreciable rate retarding steric effect. The o-OH group decreases the hydrolysis rate at pH = 5.6 – 6.6 by approximately one power of ten. This effect is caused by the hydrogen bond between the OH group and the azomethine N, which renders the Schiff base less accessible to acid-catalyzed hydrolysis.

Kinetics of acid-catalyzed hydration in aqueous solution of 1-methoxy- and 1-methylthio-2-phenylethyne and some related acetylenes

1987 ◽  
Vol 65 (2) ◽  
pp. 441-444 ◽  
Author(s):  
N. Banait ◽  
M. Hojatti ◽  
P. Findlay ◽  
A. J. Kresge
Keyword(s):  
Aqueous Solution ◽  
Proton Transfer ◽  
Isotope Effect ◽  
Rate Constants ◽  
Acid Catalysis ◽  
The Other ◽  
Buffer Solutions ◽  
Hydronium Ion ◽  
Acid Catalyzed ◽  
Kinetics Of

The rates of conversion of C6H5C≡COCH3 to C6H5CH2CO2CH3 were measured in dilute HClO4/H2O, DCIO4/D2O, and H3PO4–H2PO2−/H2O buffer solutions, and the rates of conversion of C6H5C≡CSCH3 to C6H5CH2COSCH3, C6H5C≡CH to C6H5COCH3, 2,4,6-(CH3)3C6H2C≡CH to 2,4,6-(CH3)3C6H2COCH3, and p-CH3OC6H4C≡CCH3 to p-CH3OC6H4COCH2CH3 were measured in concentrated HClO4/H2O solutions, all at 25 °C. The reaction of C6H5C≡COCH3 showed general acid catalysis and gave the isotope effect [Formula: see text], which indicates that it proceeds through rate-determining proton transfer from catalyst to substrate. The hydronium ion catalytic coefficient for this reaction is [Formula: see text], and those for the other four, in the order given above, are [Formula: see text], and 8.5 × 10−6 M−1 s−1. Relative reactivities based on these rate constants are discussed.

scholarly journals Kinetics of the reactions of isoprene-derived hydroxynitrates: gas phase epoxide formation and solution phase hydrolysis

2014 ◽  
Vol 14 (8) ◽  
pp. 12121-12165 ◽  
Author(s):  
M. I. Jacobs ◽  
W. J. Burke ◽  
M. J. Elrod
Keyword(s):  
Gas Phase ◽  
Hydrolysis Rate ◽  
Ionization Mass ◽  
Volatile Organic ◽  
Isoprene Oxidation ◽  
Gas Phase Oxidation ◽  
Acid Catalyzed ◽  
Regional Formation ◽  
A Minor ◽  
Kinetics Of

Abstract. Isoprene, the most abundant non-methane volatile organic compound (VOC) emitted into the atmosphere, is known to undergo gas phase oxidation to form eight different hydroxynitrate isomers in "high NOx" environments. These hydroxynitrates are known to affect the global and regional formation of ozone and secondary organic aerosol (SOA), as well as affect the distribution of nitrogen. In the present study, we have synthesized three of the eight possible hydroxynitrates: 4-hydroxy-3-nitroxy isoprene (4,3-HNI) and E/Z-1-hydroxy-4-nitroxy isoprene (1,4-HNI). Oxidation of the 4,3-HNI isomer by the OH radical was monitored using a flow tube chemical ionization mass spectrometer (FT-CIMS), and its OH rate constant was determined to be (3.64 ± 0.41) × 10−11 cm3 molecule−1 s−1. The products of 4,3-HNI oxidation were monitored, and a mechanism to explain the products was developed. An isoprene epoxide (IEPOX) – a species important in SOA chemistry and thought to originate only from "low NOx" isoprene oxidation – was found as a minor, but significant product. Additionally, hydrolysis kinetics of the three synthesized isomers were monitored with NMR. The bulk, neutral solution hydrolysis rate constants for 4,3-HNI and the 1,4-HNI isomers were (1.59±0.03 × 10−5 s−1 and (6.76 ± 0.09) × 10−3 s−1, respectively. The hydrolysis reactions of each isomer were found to be general acid-catalyzed. The reaction pathways, product yields and atmospheric implications for both the gas phase and aerosol-phase reactions are discussed.

Copper(II)-promoted solvolyses of nickel(II) complexes. II. Tridentate and tetradentate Schiff base ligands containing remote substituents

1973 ◽  
Vol 26 (7) ◽  
pp. 1459 ◽  
Author(s):  
WW Fee ◽  
JD Pulsford ◽  
PD Vowles
Keyword(s):  
Schiff Base ◽  
Schiff Bases ◽  
Rate Constants ◽  
Dimethyl Sulphoxide ◽  
Common Mechanism ◽  
Schiff Base Ligands ◽  
Dissociative Mechanism ◽  
Tetradentate Schiff Base ◽  
Kinetics Of ◽  
Mechanism Operative

The kinetics of copper(II)-promoted solvolyses of two series of nickel(II) complexes containing polydentate Schiff bases with various remote substituents, in dimethyl sulphoxide (dmso), are discussed from the viewpoints of rate constants and of enthalpies and entropies of activation. Appearance of an isokinetic relation for the tridentate (ONS donors) reactants may indicate a common mechanism operative within this reactant series. Rate constants appear related to σp values in such a way that a dissociative mechanism appears important for the tridentate reactants, while characterization in terms of associative behaviour is indicated for the tetradentates.

scholarly journals Kinetics of the reaction of 5-substituted orotic acids with diazodiphenylmethane

2004 ◽  
Vol 69 (11) ◽  
pp. 949-953 ◽  
Author(s):  
Bratislav Jovanovic ◽  
Fathi Assaleh ◽  
Aleksandar Marinkovic
Keyword(s):  
Rate Constants ◽  
Steric Effect ◽  
Substituent Effects ◽  
Electrical Effect ◽  
Kinetics Of

Rate konstants for the reaction of eight 5-substituted orotic acids with diazodiphenylmethane (DDM) in dimethylformamide (DMF) were determined at 30 ?C by the known spectrophotometricmethod. The determined rate constants were correlated with the equations: logk2 = ??1+??R+h logk2 = ??1+??R+??+h to detect the presence and investigate the influence of both electrical and steric substituent effects. The obtained results show that the electrical effect (the localized ? field and delocalized ? resonance) is predominant and that the steric effect, althought present, is releatively small in this reaction.

Kinetics of Methylation of Methyl 5-Deoxy-α/β-D-xylofuranosides

2004 ◽  
Vol 69 (10) ◽  
pp. 1877-1888
Author(s):  
Mária Oščendová ◽  
Jitka Moravcová
Keyword(s):  
Sodium Hydroxide ◽  
Methyl Iodide ◽  
Rate Constants ◽  
Reaction Rate ◽  
Steric Effect ◽  
Order Reaction ◽  
Half Time ◽  
First Order ◽  
Consecutive Reactions ◽  
Kinetics Of

The kinetics of methylation of methyl 5-deoxy-α-D-xylofuranoside (1), methyl 5-deoxy-β-D-xylofuranoside (2) and their partly methylated derivatives with methyl iodide in the presence of sodium hydroxide in acetonitrile was studied. The reaction rate was independent of the base concentration during the first half-time only and the methylation proceeded as a first-order reaction. The rate constants of all side and consecutive reactions were calculated and the influence of both polar and steric effect is discussed. The methylation of 1 was highly regioselective giving almost exclusively 5-deoxy-2-O-methyl-α-D-xylofuranoside.

Kinetics and Mechanism of Acid Catalyzed Decomposition of 1-Phenyl-3,3-dialkyltriazenes

1994 ◽  
Vol 59 (2) ◽  
pp. 401-411 ◽  
Author(s):  
Miroslav Ludwig ◽  
Pavla Valášková ◽  
Oldřich Pytela
Keyword(s):  
Rate Constants ◽  
Steric Effect ◽  
Aqueous Ethanol ◽  
Pivalic Acid ◽  
Decomposition Kinetics ◽  
Methyl Ethyl ◽  
Rate Determining Step ◽  
Alkyl Groups ◽  
Acid Catalyzed ◽  
Catalytic Rate

Five model 1-phenyl-3,3-dialkyltriazenes (methyl, ethyl, 2-propyl, butyl, cyclohexyl) have been synthesized and their acid-catalyzed decomposition kinetics have been investigated spectrophotometrically in aqueous ethanol (40 vol.%) with pivalic acid as the catalyst. The results show that the rate-determining step is catalyzed by the proton. The decrease in the observed rate constant at higher concentrations of pivalic acid is explained by the formation of an unreactive complex of the nondissociated acid and respective triazene. The steric effect of alkyl groups on the catalytic rate constants is discussed.

scholarly journals Kinetics of the reactions of isoprene-derived hydroxynitrates: gas phase epoxide formation and solution phase hydrolysis

2014 ◽  
Vol 14 (17) ◽  
pp. 8933-8946 ◽  
Author(s):  
M. I. Jacobs ◽  
W. J. Burke ◽  
M. J. Elrod
Keyword(s):  
Gas Phase ◽  
Hydrolysis Rate ◽  
Ionization Mass ◽  
Volatile Organic ◽  
Isoprene Oxidation ◽  
Gas Phase Oxidation ◽  
Acid Catalyzed ◽  
Regional Formation ◽  
A Minor ◽  
Kinetics Of

Abstract. Isoprene, the most abundant non-methane volatile organic compound (VOC) emitted into the atmosphere, is known to undergo gas phase oxidation to form eight different hydroxynitrate isomers in "high-NOx" environments. These hydroxynitrates are known to affect the global and regional formation of ozone and secondary organic aerosol (SOA), as well as affect the distribution of nitrogen. In the present study, we have synthesized three of the eight possible hydroxynitrates: 4-hydroxy-3-nitroxy isoprene (4,3-HNI) and E / Z-1-hydroxy-4-nitroxy isoprene (1,4-HNI). Oxidation of the 4,3-HNI isomer by the OH radical was monitored using a flow tube chemical ionization mass spectrometer (FT-CIMS), and its OH rate constant was determined to be (3.64 ± 0.41) × 10−11 cm3 molecule−1 s−1. The products of 4,3-HNI oxidation were monitored, and a mechanism to explain the products was developed. An isoprene epoxide (IEPOX) – a species important in SOA chemistry and thought to originate only from "low-NOx" isoprene oxidation – was found as a minor, but significant, product. Additionally, hydrolysis kinetics of the three synthesized isomers were monitored with nuclear magnetic resonance (NMR). The bulk, neutral solution hydrolysis rate constants for 4,3-HNI and the 1,4-HNI isomers were (1.59 ± 0.03) × 10−5 s−1 and (6.76 ± 0.09) × 10−3 s−1, respectively. The hydrolysis reactions of each isomer were found to be general acid-catalyzed. The reaction pathways, product yields and atmospheric implications for both the gas phase and aerosol phase reactions are discussed.

Kinetics of acid-catalyzed hydrolysis of fluorinated propanoates

1983 ◽  
Vol 48 (10) ◽  
pp. 2805-2811 ◽  
Author(s):  
Oldřich Paleta ◽  
Jaroslav Kvíčala ◽  
Václav Dědek
Keyword(s):  
Rate Constants ◽  
Relative Rate ◽  
Chloride Concentration ◽  
Activation Entropy ◽  
High Activation ◽  
Isokinetic Relationship ◽  
Relative Rate Constants ◽  
Acid Catalyzed ◽  
Kinetics Of ◽  
Hydrolysis Of

Rates of hydrolysis, kH+, of methyl 2-chloro-2,3,3,3-tetrafluoro-(III), 2,3-dichloro-2,3,3-trifluoro-(IV), 2,2,3-trichloro-3,3-difluoro-(V), 2,3,3,3-tetrafluoro-(VI) and 3-chloro-2,3,3-trifluoropropanoate (VII) were measured in 0.5M-HCl in aqueous methanol (80% vol; 76% wt) at 40, 50 and 60 °C. The relative rate constants, krel (50 °C), (for the propanoate III, kH+ = 4.3 . 10-5 l mol-1 s-1; krel = 100) are 311, 100, 38, 9.4, 44 and 15 for the esters II, III, IV, V, VI and VII, respectively (experimental error ±9%). It was found that krel = αβ where α and β are the following factors for groups in the position 2 and 3: CClF 10, CHF 4.2, CCl2 2.8, CF3 10 and CClF2 3.6. The rate constants obey the isokinetic relationship. For the ester III the dependence of log kobs on logarithm of hydrogen chloride concentration is linear at concentrations 0.08-2.4 mol l-1 which, together with high activation entropy ΔS≠ for the esters III-VII (-167 to -217 J mol-1 K-1), shows that the hydrolysis proceeds by an AAC2 mechanism.

Kinetics of the Nitrosation of Pyrrolidine and Proline

1974 ◽  
Vol 52 (7) ◽  
pp. 1050-1053 ◽  
Author(s):  
A. Okany ◽  
T. F. Massiah ◽  
L. J. Rubin ◽  
K. Yates
Keyword(s):  
Rate Constants ◽  
Nitroso Compounds ◽  
Meat Processing ◽  
Temperature Range ◽  
Buffer Solutions ◽  
Entropy Of Activation ◽  
Kinetics Of

The kinetics of the nitrosation of pyrrolidine and proline have been investigated in buffer solutions of mildly acidic pH's in the temperature range 40–100 °C. The rate constants were determined and the enthalpy and the entropy of activation were calculated for both reactions. Examples are presented in which are estimated the maximum amounts of nitroso compounds formed under conditions relevant to meat processing.

Sign in / Sign up

Export Citation Format

Share Document