Kinetics of the hydrolysis of acyl chlorides in pure water

1967 ◽  
Vol 45 (14) ◽  
pp. 1619-1629 ◽  
Author(s):  
A. Queen
Keyword(s):  
Pure Water ◽  
Activation Parameters ◽  
Acyl Chlorides ◽  
Reversible Addition ◽  
Electron Donation ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Chlorine Bond ◽  
Oxygen Bond ◽  
Bimolecular Mechanism

The activation parameters ΔH≠, ΔS≠, and ΔCP≠ for the hydrolyses of a series of alkyl chloroformates and dimethylcarbamyl chloride in water have been determined. The results indicate that, with increasing electron donation to the chlorocarbonyl group, the mechanism changes from bimolecular to unimolecular (SN1) displacement at this position. For isopropyl chloroformate, some concurrent alkyl–oxygen bond fission is also indicated. The bimolecular mechanism involves reversible addition of water to the carbonyl group followed by ionization of the carbon–chlorine bond.

Kinetics of the hydrolysis of thiochloroformate esters in pure water

1970 ◽  
Vol 48 (4) ◽  
pp. 522-527 ◽  
Author(s):  
A. Queen ◽  
T. A. Nour ◽  
M. N. Paddon-Row ◽  
K. Preston
Keyword(s):  
Isotope Effect ◽  
Structural Changes ◽  
Pure Water ◽  
Activation Parameters ◽  
Deuterium Isotope Effect ◽  
Hydro Carbon ◽  
Electron Donation ◽  
Kinetics Of ◽  
Hydrolysis Of

The effects of structural changes on the rates of hydrolysis of a series of thiochloroformate esters in water have been investigated. The reactivity is enhanced by increased electron donation by the hydro carbon group. These results, the activation parameters for the hydrolysis of methyl thiochloroformate and the solvent deuterium isotope effect, are shown to be consistent with the operation of the SN1 mechanism.

Synthesis and Base Hydrolysis of the Pentaammine(dimethyl sulfide)cobalt(III) Ion

1992 ◽  
Vol 45 (12) ◽  
pp. 2049 ◽  
Author(s):  
A Ellis ◽  
A Fultz ◽  
R Hicks ◽  
T Morgan ◽  
L Parsons ◽  
...  
Keyword(s):  
Linear Dependence ◽  
Reaction Rate ◽  
Dimethyl Sulfide ◽  
Activation Parameters ◽  
Base Hydrolysis ◽  
Basic Solution ◽  
Acidic Solutions ◽  
Temperature Range ◽  
Kinetics Of ◽  
Hydrolysis Of

The synthesis of the trifluoromethanesulfonate salt of the pentaarnmine (dimethy1 sulfide)-cobalt(III) ion, [NH3)5Co-S(CH3)2]3+, is described along with the kinetics of its hydrolysis in basic and acidic solutions. The synthesis proceeds in 44% yield from the reaction of [(NH3)5Co-OSO2CF3] (CF3SO3)2 with CH3SCH3 in tetramethylene sulfone at 80�C. The salt has been characterized by elemental analysis, visible-U.V. spectroscopy, and 1H n.m.r. In basic solution the complex decomposes by Co-S cleavage to yield [(NH3)5CO-OH]2+ and non-coordinated CH3SCH3. The kinetics of this reaction were studied in phosphate buffers ranging from pH 8.50 to 11.67 ( �= 1.0 M); a linear dependence of the reaction rate on [OH-] was observed. At 25�C, kOH = 8.8 � 0.2 dm3 mol-1 s-1. Activation parameters, determined over a temperature range from 15 to 44�C, were ΔH‡ = 152 � 3 kJ mol-1 and Δ S‡ = 286 � 9 J K-1 mol-1. In 0.01 M HClO4 ( � = 1.0 M, 25�C), the cobaltsulfur bond is cleaved at a rate of 1.6×10-6 s-l. Activation parameters, determined over a temperature range from 25 to 60�C, were ΔH‡ = 106 � 5 kJ mol-1 and ΔS‡= -2 � 16 J K-1 mol-1.

Solvolysis rates in aqueous – organic mixed solvents. V. Kinetics of the alkaline decarboxylation of trichloroacetate ion in water – ethanol solutions

1978 ◽  
Vol 56 (15) ◽  
pp. 2053-2057 ◽  
Author(s):  
El-Hussieny M. Diefallah ◽  
A. M. El-Nadi
Keyword(s):  
Mole Fraction ◽  
Pure Water ◽  
Mixed Solvents ◽  
Activation Parameters ◽  
Solvent Mixtures ◽  
Rate Of Reaction ◽  
Ethanol Addition ◽  
Regular Increase ◽  
Aqueous Organic Mixed Solvents ◽  
Kinetics Of

The kinetics of the alkaline decarboxylation of trichloroacetate ion in ethanol–water solutions have been studied over the temperature range 35.0 to 70.0 °C. The rate of reaction is first order with respect to the trichloroacetate ion and is independent of the concentration of the hydroxide ion. The reactivity is enhanced by increasing the concentration of ethanol in the water–ethanol solutions and the rate of reaction varies with ethanol addition in a nonlinear manner. The rate of reaction increases with the reciprocal of the dielectric constant of the medium and the plot of log k vs. 1/D is approximately linear for solvent mixtures with less than about 0.7 water mole fraction but is strongly curved towards the pure water end. The activation parameters for the reaction show a regular increase in the solvent composition range 0.3 to 1.0 water mole fraction. The results are discussed in terms of the influence of solvent internal pressure and polarity on reactivity and of the increased amount of hydrogen-bonded structure in the water-rich solutions.

Kinetics of aquation and base hydrolysis of the macrocyclic complex trans-Bromo(N-meso-5,12-dimethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene)nitro-cobalt(III) perchlorate

1976 ◽  
Vol 29 (10) ◽  
pp. 2319 ◽  
Author(s):  
GA Lawrance ◽  
RW Hay
Keyword(s):  
Activation Parameters ◽  
Macrocyclic Complex ◽  
Base Hydrolysis ◽  
Hydrolysis Kinetics ◽  
Rate Expression ◽  
Entropy Of Activation ◽  
Ph Range ◽  
Kinetics Of ◽  
Hydrolysis Of

The macrocyclic complex trans-[Co(dtcd)(NO2)Br] [ClO4] (dtcd = 5,12-dimethyl-l,4,8,1l-tetraaza-cyclotetradeca-4,ll-diene) has been prepared and its hydrolysis kinetics investigated. At 25�C and 0.1 M HN03 the aquation occurs with kaq = 6.2 x 10-3 s-1 to give the trans-Co(dtcd)(NO2)- (OH2)]2+ cation. The activation parameters at 298 K are ΔH? = 75.0 kJ mol-1 and ΔS? = -35.6 J K-1 mol-1. Hydrolysis of the bromide in the pH range 7.5-8.8 follows the rate expression kobs = kaq + kOH[OH-]. At 25�C (I = 0.1 M, NaClO4) kOH = 1.21 x 103 1. mol-1 s-1 with the activation parameters for base hydrolysis being ΔH? = 74.2 kJ mol-1 and ΔS? = +63.2 J K-1 mol-1 at 298 K. Aquation and base hydrolysis of the bromo complex at 25�C occur at rates 14 and 5 times faster respectively than those previously reported for the analogous trans-[Co(dtcd)(NO2)Cl]+ complex, the acceleration being due to a more favourable entropy of activation in each case.

Notes - Kinetics of Reaction of Acyl Chlorides. III. Hydrolysis of Phosphinyl Chlorides.

1956 ◽  
Vol 21 (2) ◽  
pp. 248-249 ◽  
Author(s):  
H. K. Hall, Jr.
Keyword(s):  
Acyl Chlorides ◽  
Kinetics Of Reaction ◽  
Kinetics Of ◽  
Hydrolysis Of

KINETICS OF THE INHIBITION OF α-CHYMOTRYPSIN BY METHANOL AND DFP

1959 ◽  
Vol 37 (8) ◽  
pp. 1272-1277 ◽  
Author(s):  
Bernard R. Stein ◽  
Keith J. Laidler
Keyword(s):  
Aqueous Solution ◽  
Substrate Concentration ◽  
Pure Water ◽  
Inhibition Constant ◽  
Specific Mechanism ◽  
Ph Optimum ◽  
Diisopropyl Phosphorofluoridate ◽  
No Inhibition ◽  
Kinetics Of ◽  
Hydrolysis Of

A study has been made of the kinetics of the α-chymotrypsin-catalyzed hydrolysis of methyl hydrocinnamate in the presence of various concentrations of methanol, of eserine, and of diisopropyl phosphorofluoridate (DFP). In 20% methanol the pH optimum, using a substrate concentration of 1.20 × 10−3M, is 7.8; in pure water it is 8.3; and at intermediate pH's the optimum varies between these values. No inhibition was observed with eserine. In aqueous solution the character of the inhibition by DFP differs from that in alcohol solutions; the inhibition is of the competitive type, and the inhibition constant varies with pH in essentially the same manner as does the rate of the reaction. This result suggests that DFP interacts with the same active groups on the enzyme as are responsible for the hydrolysis of the substrate. A specific mechanism for inhibition is suggested.

Solvolysis of Sulphonyl Halides. IV. The Hydrolysis of Some Substituted Aliphatic Sulphonyl Chlorides and of Ethanesulphonyl Bromide in Aqueous Dioxan

1962 ◽  
Vol 15 (4) ◽  
pp. 684 ◽  
Author(s):  
R Foon ◽  
AN Hambly
Keyword(s):  
Maximum Rate ◽  
Pure Water ◽  
Aqueous Media ◽  
Sulphur Atom ◽  
Enthalpy Of Activation ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Chlorine Bond ◽  
Transition Complexes ◽  
Continuous Range

The effects of substitution in the alkyl group of an alkanesulphonyl chloride, on the rate of hydrolysis, vary with the solvent composition. The relative rates can be explained in terms of the theory of Grunwald and Winstein that there is a continuous range of transition complexes, with " bond making " between the water molecule and the sulphur atom controlling the rate in the less aqueous media, while the stretching and charging of the sulphur to chlorine bond controls the rate in solvents of higher water content. The inhibition of the simple SN2 reaction, which gives rise to a maximum rate constant as the composition of the solvent approaches pure water, resembles that noted with methane- and ethanesulphonyl chlorides.�The hydrolysis of ethanesulphonyl bromide, at 25 �C, proceeds at three to eight times the rate for the corresponding sulphonyl chloride in solvents varying in composition from 0.99 to 0.2 mole fraction of water with dioxan. Over most of the solvent range both the entropy and enthalpy of activation are favourable to a higher rate of solvolysis for the sulphonyl bromide.

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