The Reaction of 2,4,6-Trinitrotoluene and 2,4,6-Trinitrotoluene-d3 with Sodium Isopropoxide in Isopropyl Alcohol

1974 ◽  
Vol 52 (9) ◽  
pp. 1750-1759 ◽  
Author(s):  
E. Buncel ◽  
A. R. Norris ◽  
K. E. Russell ◽  
P. Sheridan ◽  
H. Wilson
Keyword(s):  
Complex Formation ◽  
Low Temperatures ◽  
Isopropyl Alcohol ◽  
Initial Rate ◽  
Ion Pairs ◽  
Stopped Flow ◽  
Rate Data ◽  
Methyl Group ◽  
Free Ions ◽  
Deuteron Transfer

The reaction of sodium isopropoxide with 2,4,6-trinitrotoluene (TNT) and TNT-d3 (deuterated methyl group) in isopropanol has been investigated using stopped-flow techniques. Two absorbing species, identified as a σ-complex and the TNT anion (TNT−) are formed in this reaction. The formation of TNT− involves a rate determining proton transfer as shown by the observation of an isotope effect[Formula: see text] A spectrum of the σ-complex was calculated from initial rate data and was observed experimentally at low temperatures (λmax = 435, 495 nm). The effects of added salts on rates and equilibria of σ-complex and TNT− formation have been determined.In this study the possible involvement of free alkoxide ions and ion-pairs in the reactions has been evaluated. The free alkoxide ion is the more reactive species in deuteron transfer whilst in σ-complex formation the free ions and ion-pairs have comparable reactivity. A rationale of this behavior is presented.The kinetic parameters are, for deuteron transfer: kiD = 850 ± 100 M−1s−1 at 30 °C, ΔH≠ = 14.9 ± 1.1 kcal mol−1, ΔS≠ = 5.1 ± 2.9 cal deg−1 mol−1; for σ-complex formation: k′ = 1870 ± 150 M−1 s−1 at 30 °C, ΔHσ≠ = 10.2 ± 0.3 kcal mol−1, ΔSσ≠ = −9.8 ± 1.1 cal deg−1 mol−1.

scholarly journals Thermodynamic and detailed kinetic study of the formation of orthophthalaldehyde-agmatine complex by fluorescence intensities

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Khémesse Kital ◽  
Moumouny Traoré ◽  
Diégane Sarr ◽  
Moussa Mbaye ◽  
Mame Diabou Gaye Seye ◽  
...  
Keyword(s):  
Complex Formation ◽  
Thermodynamic Parameters ◽  
Initial Rate ◽  
Reaction Medium ◽  
Standard Entropy ◽  
Step Size ◽  
Formation Reaction ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Complex Formation Process

Abstract The aim of this work is to determine the thermodynamic parameters and the kinetics of complex formation between orthophthalaldehyde (OPA) and agmatine (AGM) in an alkaline medium (pH 13). Firstly, the association constant (Ka) between orthophthalaldehyde and agmatine was determined at different temperatures (between 298 K and 338 K) with a step size of 10 K. Secondly, the thermodynamic parameters such as standard enthalpy (ΔH°), standard entropy (ΔS°),and Gibbs energy (∆G) were calculated, where a positive value of ΔH° (+45.50 kJ/mol) was found, which shows that the reaction is endothermic. In addition, the low value of ΔS°(+0.24 kJ/mol) indicates a slight increase in the disorder in the reaction medium. Furthermore, the negative values of ΔG between −35.62 kJ/mol and −26.02 kJ/mol show that the complex formation process is spontaneous. Finally, the parameters of the kinetics of the reaction between OPA and AGM were determined as follows: when the initial concentration of AGM (5 × 10−6 M) is equal to that of the OPA, the results show that the reaction follows an overall 1.5 order kinetics with an initial rate of 5.1 × 10−7Mmin−1 and a half-life of 8.12 min. The partial order found in relation to the AGM is 0.8. This work shows that the excess of OPA accelerates the formation reaction of the complex.

The mechanism of the oxidation of thiocyanate ion by peroxomonosulphate in aqueous solution. II. Kinetics of the reaction

1966 ◽  
Vol 19 (8) ◽  
pp. 1365 ◽  
Author(s):  
RH Smith ◽  
IR Wilson
Keyword(s):  
Aqueous Solution ◽  
Initial Rate ◽  
Stopped Flow ◽  
Thiocyanate Ion ◽  
First Order ◽  
Conductance Method ◽  
Rate Of Reaction ◽  
Kinetics Of

Initial rates of reaction for the above oxidation have been measured by a stopped-flow conductance method. Between pH 2 and 3.6, the initial rate of reaction, R, is given by the expression R{[HSO5-]+[SCN-]} = {kb+kc[H+]}[HSO5-]0[SCN-]20+ka[H+]-1[HSO5]20[SCN-]0 As pH increases, there is a transition to a pH-independent rate, first order in each thiocyanate and peroxomonosulphate concentrations.

Isotope effects and activation parameters for the proton transfer reaction from 1-(4-nitrophenyl)-1-nitroethane to free anions and ion pairs of cesium n-propoxide in n-propanol solvent

1986 ◽  
Vol 64 (6) ◽  
pp. 1021-1025 ◽  
Author(s):  
Arnold Jarczewski ◽  
Grzegorz Schroeder ◽  
Przemyslaw Pruszynski ◽  
Kenneth T. Leffek
Keyword(s):  
Proton Transfer ◽  
Rate Constants ◽  
Isotope Effects ◽  
Ion Pairs ◽  
Activation Parameters ◽  
Solvation Shell ◽  
Ion Pair ◽  
Initial State ◽  
Free Ion ◽  
Deuteron Transfer

Rate constants for the proton and deuteron transfer from 1-(4-nitrophenyl)-1-nitroethane to cesium n-propoxide in n-propanol have been measured under pseudo-first-order conditions with an excess of base for four temperatures between 5 and 35 °C. Using literature values of the fraction of cesium n-propoxide ion pairs that are dissociated into free ions, separate second-order rate constants for the proton and deuteron transfer to the ion pair and to the free ion have been calculated. The cesium n-propoxide ion pair is about 2.8 times more reactive than the free n-propoxide ion. The primary kinetic isotope effects for the two reactions are the same (kH/kD = 6.1–6.3 at 25 °C) within experimental error. The enthalpy of activation is smaller for the ion-pair reaction and the entropy of activation more negative than for the free-ion reaction. For proton transfer, ΔH±ion pair = 8.3 ± 0.2 kcal mol−1, ΔH±ion = 9.6 ± 1.0 kcal mol−1, ΔS±ion pair = −12.3 ± 0.6 cal mol−1 deg−1, ΔS±ion = −10.1 ± 3.4 cal mol−1 deg−1. The greater reactivity of the ion pair relative to the free ion is interpreted in terms of the weaker solvation shell of the ion pair in the initial state.

scholarly journals The quantitative analysis of ligand binding and initial-rate data for allosteric and other complex enzyme mechanisms

1976 ◽  
Vol 153 (1) ◽  
pp. 101-117 ◽  
Author(s):  
W G Bardsley
Keyword(s):  
Kinetic Data ◽  
Quantitative Data ◽  
Initial Rate ◽  
Graphical Methods ◽  
Enzyme Kinetic ◽  
Rate Data ◽  
Curve Shape ◽  
High Substrate Concentration ◽  
Complex Curve ◽  
Complex Curves

1. The eight methods for plotting enzyme kinetic data are classified and analysed, and it is shown how, in each case, it is only possible to obtain quantitative data on the coefficients of the lowest- and highest-degree terms in the rate equation. 2. The combinations of coefficients that are accessible experimentally from limiting slopes and intercepts at both low and high substrate concentration are stated for all the graphical methods and the precise effects of these on curve shape in different spaces is discussed. 3. Ambiguities arising in the analysis of complex curves and certain special features are also investigated. 4. Four special ordering functions are defined and investigated and it is shown how knowledge of these allows a complete description of all possible complex curve shapes.

The Reactions of Organometallic Compounds Involving Silicon. Reactions of Triphenyl-, Diphenylmethyl-, and Phenyldimethylsilyl-lithium with 9-Phenylfluorene in Tetrahydrofuran

1972 ◽  
Vol 50 (23) ◽  
pp. 3761-3766 ◽  
Author(s):  
M. A. Hamid
Keyword(s):  
Low Temperatures ◽  
Initial Rate ◽  
Organometallic Compounds ◽  
Initial Reactant ◽  
Thermodynamic Constants ◽  
Rate Of Reaction ◽  
Stop Flow

Triphenyl-, diphenylmethyl-, and phenyldimethylsilyl-lithium react very rapidly with 9-phenylfluorene in tetrahydrofuran (THF) but the reaction can be followed spectroscopically using the stop-flow technique at low temperatures. The order of reaction, found from the dependence of the initial rate of reaction on the initial reactant concentrations, is unity in both 9-phenylfluorene and the relevant organosilyl-lithium reagent. The thermodynamic constants of activation for the reaction between 9-phenylfluorene and triphenylsilyl-lithium (Ph3SiLi), diphenylmethylsilyl-lithium (Ph2MeSiLi), and phenyldimethylsilyl-lithium (PhMe2SiLi), respectively, are: ΔH≠ = 4.5, 4.0, and 4.0 kcal mol−1; ΔG≠ = 13.0, 12.5, and 12.5 kcal mol−1; ΔS≠ = −34.9, −34.8, and −34.9 cal mol−1 deg−1

Gas Phase and Surface Reactions in Mocvd of GaAs from Triethylgallium, Trimethylgallium, and Organometallic Arsenic Precursors

1988 ◽  
Vol 131 ◽  
Author(s):  
Thomas R. Omstead ◽  
Penny M. Van Sickle ◽  
Klavs F. Jensen
Keyword(s):  
Gas Phase ◽  
Low Temperatures ◽  
Surface Reactions ◽  
Rate Data ◽  
Gas Phase Reactions ◽  
Heated Zone ◽  
Model Predictions ◽  
First Time ◽  
Good Agreement

ABSTRACTThe growth of GaAs from triethylgallium (TEG) and trimethylgallium (TMG) with tertiarybutylarsine (tBAs), triethylarsenic (TEAs), and trimethylarsenic (TMAs), has been investigated by using a reactor equipped with a recording microbalance for in situ rate measurements. Rate data show that the growth with these precursors is dominated by the formation of adduct compounds in the gas lines, by adduct related parasitic gas phase reactions in the heated zone, and by the surface reactions. A model is proposed for the competition between deposition reactions and the parasitic gas phase reactions. Model predictions are in very good agreement with experimental data for all combinations of precursors except for TEG/TMAs where extensive gallium droplet formation is observed at low temperatures. Growth of reasonable quality GaAs with Hall mobilities of 7600 cm2/Vs at 77 K using TEG and tBAs is reported for the first time.

STUDIES ON THE FORMATION OF HEXAMINE

1952 ◽  
Vol 30 (9) ◽  
pp. 687-693 ◽  
Author(s):  
T. R. Ingraham ◽  
C. A. Winkler
Keyword(s):  
Activation Energy ◽  
Acetic Acid ◽  
Acid Solution ◽  
Induction Period ◽  
Ammonium Nitrate ◽  
Sodium Acetate ◽  
Glacial Acetic Acid ◽  
Initial Rate ◽  
Acetic Acid Solution ◽  
Rate Data

Rate curves have been determined for the reaction of ammonium nitrate with formaldehyde in glacial acetic acid solution at 25 °C., 35 °C., 45 °C., and 55 °C. over a range of Initial mole ratios (formaldehyde: ammonia) of 0.75:1 to 9.0:1. Data obtained at 25 °C. show a definite induction period in the formation of hexamine. The length of the induction period is not changed by increasing ammonium nitrate concentrations above the theoretical (1.5:1), but may be appreciably shortened by initial additions of excess formaldehyde or of sodium acetate. From 35 °C. upward, the induction period is not apparent. The order of the reaction with respect to formaldehyde has been determined from initial rate data, and an activation energy calculated. The reactions in general appear analogous to those found in slightly acid aqueous systems.

Sign in / Sign up

Export Citation Format

Share Document