The Hydrolysis of t-Butyl Chloride in Aquo-Organic Mixtures: Heat Capacity of Activation and Solvent Structure

1972 ◽  
Vol 50 (9) ◽  
pp. 1353-1360 ◽  
Author(s):  
R. E. Robertson ◽  
S. E. Sugamori
Keyword(s):  
Heat Capacity ◽  
Temperature Dependence ◽  
High Water ◽  
Remarkable Difference ◽  
Solvent Structure ◽  
Butyl Chloride ◽  
Organic Mixtures ◽  
A Value ◽  
Polar Solutes ◽  
Hydrolysis Of

The temperature dependence of the rate of solvolysis of t-butyl chloride in mixtures of tetrahydrofuran and of acetonitrile in water have been determined. In the high-water range both minor co-solvents lead to a reduction in the value of ΔH≠ similar to that found previously where alcohol was the co-solvent. However, a remarkable difference in the values of [Formula: see text] across the same concentration range reflected a difference in the effect of these two co-solvents on the structural properties of the several solvent media. Where tetrahydrofuran or alcohols are the minor co-solvent, [Formula: see text] becomes much more negative until that concentration is reached where the quasi-aqueous structure collapses. Where acetonitrile is the minor co-solvent [Formula: see text] becomes more positive relative to the value found for hydrolysis in water until a value of about −40 cal deg−1 mol−1 is reached. The implication of these findings concerning the nature of solvation of weakly polar solutes in such mixtures is discussed.

Heat capacity of activation for the hydrolysis of methanesulfonyl chloride and benzenesulfonyl chloride in light and heavy water

1969 ◽  
Vol 47 (22) ◽  
pp. 4199-4206 ◽  
Author(s):  
R. E. Robertson ◽  
B. Rossall ◽  
S. E. Sugamori ◽  
L. Treindl
Keyword(s):  
Heat Capacity ◽  
Free Energy ◽  
Temperature Dependence ◽  
Heavy Water ◽  
Bond Formation ◽  
Sulfonyl Chlorides ◽  
Benzenesulfonyl Chloride ◽  
Methanesulfonyl Chloride ◽  
Hydrolysis Of ◽  
Parameter Temperature Dependence

Rates of solvolysis of methanesulfonyl chloride and benzenesulfonyl chloride have been determined in H2O and D2O. The free energy, enthalpy, entropy, and heat capacity of activation were calculated. The exceptional accuracy of the data permitted an estimation of dΔCp≠/dT from a four parameter temperature dependence of the kinetic rates.From these data we conclude that both sulfonyl chlorides hydrolyse by the same mechanism (Sn2) The change in R from CH3 to C6H5 in RSO2Cl did not alter ΔCp≠ but ΔS≠ (20°) was changed from −8.32 to −13.25 cal deg−1 mole−1, respectively. The significance of this difference is attributed to the probability of bond formation rather than to differences in solvent reorganization.

Studies in Solvolysis. Part VII. The Neutral Hydrolysis of Methyl Perchlorate

1975 ◽  
Vol 53 (20) ◽  
pp. 3106-3115 ◽  
Author(s):  
Ross Elmore Robertson ◽  
Adrianna Annesa ◽  
John Marshall William Scott
Keyword(s):  
Heat Capacity ◽  
Carbon Atom ◽  
Temperature Dependence ◽  
Thermodynamic Parameters ◽  
Isotope Effect ◽  
Perchlorate Ion ◽  
Rate Of Hydrolysis ◽  
Leaving Groups ◽  
Hydrolysis Of

The temperature dependence of the rate of hydrolysis of methyl perchlorate has been measured and the entropy (ΔS≠), enthalpy (ΔH≠), and heat capacity (ΔCp≠) of activation calculated. The measurements confirm that the perchlorate ion is superior to all other leaving groups in water. The isotope effect related to the hydrolysis of methyl-d3 perchlorate has been measured at three temperatures and shown to be inverse. The thermodynamic parameters and the isotope effect were examined with respect to the mechanism of substitution at a primary carbon atom.

An Examination of the Heat Capacity of Activation for the Hydrolysis of t-Butyl Chloride in Water

1972 ◽  
Vol 50 (2) ◽  
pp. 167-175 ◽  
Author(s):  
J. M. W. Scott ◽  
R. E. Robertson
Keyword(s):  
Heat Capacity ◽  
Alternative Hypothesis ◽  
Ion Pairs ◽  
Heat Capacities ◽  
Butyl Chloride ◽  
Methyl Halides ◽  
Displacement Reactions ◽  
Arrhenius Temperature Dependence ◽  
Hydrolysis Of ◽  
Arrhenius Temperature

The influence of ion-pair intermediates on solvolytic displacement reactions is considered for cases where the observed rate constant is complex.Such complex and composite rate constants under certain conditions may show deviations from the Arrhenius temperature dependence law. The deviations will manifest themselves as "spurious" positive and/or negative heat capacities of activation, superimposed on the real heat capacity terms.The hypothesis of Albery and Robinson (1) which proposes that the heat capacity of activation for t-butyl chloride is entirely "spurious" in the sense outlined above, is critically evaluated and rejected. An alternative hypothesis that considers the heat capacity to be a manifestation of solvation effects is retained.The mechanism of the hydrolysis of both the methyl and t-butyl halides in water is discussed and the kinetic laws appropriate to each are shown to be consistent with real heat capacities of activation. The mechanism proposed differs from the classical SN1–SN2 description. Both series of substrates are considered to give rise to intimate-ion-pairs but in the case of the methyl halides these react further by a path which involves the nucleophilicity of the solvent in a kinetically significant way. In the cases of the tertiary compounds, solvent separation of ion-pairs becomes kinetically significant. The nucleophilic component which characterizes the destruction of the solvent-separated ion-pairs for the tertiary compounds is kinetically insignificant.

Kinetic solvent isotope effect, solvent reorganization, and the SN1–SN2 mechanism

1969 ◽  
Vol 47 (18) ◽  
pp. 3397-3404 ◽  
Author(s):  
L. Treindl ◽  
R. E. Robertson ◽  
S. E. Sugamori
Keyword(s):  
Heat Capacity ◽  
Probable Mechanism ◽  
Activation Process ◽  
Solvent Structure ◽  
Butyl Chloride ◽  
Solvent Isotope Effect ◽  
Mechanism Of Reaction ◽  
Wide Range ◽  
Two Temperatures ◽  
Solvent Isotope

The temperature dependence of the rates of solvolysis have been determined in D2O for t-butyl chloride, 2,2-dibromopropane, 2-bromo-2-chloropropane, and 2-chloro-2-methyl propyl methyl ether, and corresponding values of ΔH≠, ΔS≠, and ΔCp≠ are derived. Values of ΔH≠ and ΔS≠ from the solvolysis of seven other halides and two benzenesulfonates have been estimated from rate determinations at two temperatures in D2O.A comparison of these values with terms from corresponding experiments in H2O provides values of δIΔG≠, δIΔH≠, and δIΔS≠ characterizing the kinetic solvent isotope effect.While δIΔG≠ appears to have about the same value for a wide range of halides of different structure irrespective of the probable mechanism of reaction, systematic differences in δIΔH≠ and δIΔS≠ differentiate those reacting by an SN2 mechanism from those reacting by an SN1 mechanism. This difference is in the direction suggesting a loosening of solvent structure in the activation process in agreement with indications obtained from the corresponding values of the heat capacity of activation.

ABOUT HEAT CAPACITY OF TITANIUM CARBIDE TiCx

2019 ◽  
pp. 56-66
Author(s):  
I. Khidirov ◽  
V. V. Getmanskiy ◽  
A. S. Parpiev ◽  
Sh. A. Makhmudov
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Titanium Carbide ◽  
Temperature Dependence ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Thermodynamic Characteristics ◽  
Liquid Nitrogen Temperature ◽  
Analysis Data ◽  
Thermal Excitation

This work relates to the field of thermophysical parameters of refractory interstitial alloys. The isochoric heat capacity of cubic titanium carbide TiCx has been calculated within the Debye approximation in the carbon concentration  range x = 0.70–0.97 at room temperature (300 K) and at liquid nitrogen temperature (80 K) through the Debye temperature established on the basis of neutron diffraction analysis data. It has been found out that at room temperature with decrease of carbon concentration the heat capacity significantly increases from 29.40 J/mol·K to 34.20 J/mol·K, and at T = 80 K – from 3.08 J/mol·K to 8.20 J/mol·K. The work analyzes the literature data and gives the results of the evaluation of the high-temperature dependence of the heat capacity СV of the cubic titanium carbide TiC0.97 based on the data of neutron structural analysis. It has been proposed to amend in the Neumann–Kopp formula to describe the high-temperature dependence of the titanium carbide heat capacity. After the amendment, the Neumann–Kopp formula describes the results of well-known experiments on the high-temperature dependence of the heat capacity of the titanium carbide TiCx. The proposed formula takes into account the degree of thermal excitation (a quantized number) that increases in steps with increasing temperature.The results allow us to predict the thermodynamic characteristics of titanium carbide in the temperature range of 300–3000 K and can be useful for materials scientists.

Salt effect in hydrolysis of 3-acyl-1,3-diphenyltriazenes

1981 ◽  
Vol 46 (12) ◽  
pp. 3104-3109 ◽  
Author(s):  
Miroslav Ludwig ◽  
Oldřich Pytela ◽  
Miroslav Večeřa
Keyword(s):  
Sodium Chloride ◽  
Temperature Dependence ◽  
Potassium Chloride ◽  
Rate Constants ◽  
Zinc Sulphate ◽  
Salt Effect ◽  
Sodium Sulphate ◽  
Potassium Sulphate ◽  
Lithium Sulphate ◽  
Hydrolysis Of

Rate constants of non-catalyzed hydrolysis of 3-acetyl-1,3-diphenyltriazene (I) and 3-(N-methylcarbamoyl)-1,3-diphenyltriazene (II) have been measured in the presence of salts (ammonium chloride, potassium chloride, lithium chloride, sodium chloride and bromide, ammonium sulphate, potassium sulphate, lithium sulphate, sodium sulphate and zinc sulphate) within broad concentration ranges. Temperature dependence of the hydrolysis of the substrates studied has been measured in the presence of lithium sulphate within temperature range 20° to 55 °C. The results obtained have been interpreted by mechanisms of hydrolysis of the studied substances.

On Temperature Dependence of Excess Gibbs Energy

1999 ◽  
Vol 64 (7) ◽  
pp. 1093-1099 ◽  
Author(s):  
Ivona Malijevská ◽  
Anatol Malijevský
Keyword(s):  
Heat Capacity ◽  
Gibbs Energy ◽  
Temperature Dependence ◽  
Excess Gibbs Energy ◽  
Excess Enthalpy ◽  
Excess Heat Capacity ◽  
Wilson Equation ◽  
Excess Heat ◽  
Energy Excess ◽  
Wilson And Nrtl Equations

Temperature dependence of GE is discussed for three widely used equations linear and nonlinear in parameters. It is shown that the Wilson equation predicts always positive excess heat capacity regardless of values of its parameters. Several temperature modifications of the Redlich-Kister, Wilson and NRTL equations are discussed with respect to the sign of the excess Gibbs energy, excess enthalpy and excess heat capacity.

scholarly journals The Water Footprint of Primary and Secondary Processing of Beef from Different Cattle Breeds: A Value Fraction Allocation Model

2021 ◽  
Vol 13 (12) ◽  
pp. 6914
Author(s):  
Frikkie Alberts Maré ◽  
Henry Jordaan
Keyword(s):  
Water Footprint ◽  
Negative Relationship ◽  
High Water ◽  
Allocation Model ◽  
Cattle Breeds ◽  
A Value ◽  
Average Production ◽  
High Water Intake ◽  
The Difference ◽  
By Products

The high water intake and wastewater discharge of slaughterhouses have been a concern for many years. One neglected factor in previous research is allocating the water footprint (WF) to beef production’s different products and by-products. The objective of this article was to estimate the WF of different cattle breeds at a slaughterhouse and cutting plant and allocate it according to the different cuts (products) and by-products of beef based on the value fraction of each. The results indicated a negative relationship between the carcass weight and the processing WF when the different breeds were compared. Regarding a specific cut of beef, a kilogram of rib eye from the heaviest breed had a processing WF of 614.57 L/kg, compared to the 919.91 L/kg for the rib eye of the lightest breed. A comparison of the different cuts indicated that high-value cuts had higher WFs than low-value cuts. The difference between a kilogram of rib eye and flank was 426.26 L/kg for the heaviest breed and 637.86 L/kg for the lightest breed. An option to reduce the processing WF of beef is to lessen the WF by slaughtering heavier animals. This will require no extra investment from the slaughterhouse. At the same time, the returns should increase as the average production inputs per kilogram of output (carcass) should reduce, as the slaughterhouse will process more kilograms.

A kinetic standard for precise calibration of spectrophotometer cell temperature.

1981 ◽  
Vol 27 (5) ◽  
pp. 753-755 ◽  
Author(s):  
P A Adams ◽  
M C Berman
Keyword(s):  
Temperature Dependence ◽  
Rate Constants ◽  
Cell Temperature ◽  
First Order ◽  
Order Rate ◽  
Acid Catalyzed ◽  
Pseudo First Order ◽  
Hydrolysis Of

Abstract We describe a simple, highly reproducible kinetic technique for precisely measuring temperature in spectrophotometric systems having reaction cells that are inaccessible to conventional temperature probes. The method is based on the temperature dependence of pseudo-first-order rate constants for the acid-catalyzed hydrolysis of N-o-tolyl-D-glucosylamine. Temperatures of reaction cuvette contents are measured with a precision of +/- 0.05 degrees C (1 SD).

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