STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: XI. THE DECOMPOSITION OF BENZYLIDENE DIACETATE, o-CHLOROBENZYLIDENE DIACETATE AND BENZYLIDENE DIBUTYRATE

1940 ◽  
Vol 18b (8) ◽  
pp. 223-230 ◽  
Author(s):  
N. A. D. Parlee ◽  
J. C. Arnell ◽  
C. C. Coffin
Keyword(s):  
Double Bond ◽  
Steric Factor ◽  
Reverse Reaction ◽  
Breaking Point ◽  
Reaction Velocity ◽  
First Order ◽  
Gas Reactions

Benzylidene diacetate, o-chlorobenzylidene diacetate, and benzylidene dibutyrate decompose unimolecularly at rates given by the equation previously found for crotonylidene diacetate and furfurylidene diacetate, viz., [Formula: see text]. The fact that these esters all have a double bond at the same distance from the breaking point of the molecule is considered significant in connection with their identical reaction velocity, which is about six times that of ethylidene diacetate. Benzylidene diacetate decomposes at the same rate in both the liquid and vapour states to reach an equilibrium given by the equation [Formula: see text]. The reverse reaction with a rate given by [Formula: see text] is characterized by a steric factor of 10−4.

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: VII. THE DECOMPOSITION OF ETHYLIDENE DIBUTYRATE AND HEPTYLIDENE DIACETATE

1937 ◽  
Vol 15b (6) ◽  
pp. 247-253 ◽  
Author(s):  
C. C. Coffin ◽  
J. R. Dacey ◽  
N. A. D. Parlee
Keyword(s):  
Activation Energy ◽  
Homologous Series ◽  
Reaction Velocity ◽  
Vapor State ◽  
Specific Reaction ◽  
First Order ◽  
Gas Reactions

Ethylidene dibutyrate and heptylidene diacetate decompose in the vapor state at temperatures between 200° and 300 °C. to form an aldehyde and an anhydride. The reactions are homogeneous, unimolecular, and complete. The activation energy is the same as that previously found for other members of this homologous series. Ethylidene dibutyrate decomposes at the same rate as ethylidene diacetate, and thus provides further evidence that the specific reaction velocity is independent of the size of the anhydride radicals. Heptylidene diacetate decomposes at the same rate as butylidene diacetate. This indicates that after the aldehyde radical has attained a certain size (three or four carbon atoms) the addition of –CH2− groups leaves the specific reaction velocity unchanged. The velocity constants are given by the equations[Formula: see text]

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: III. THE DECOMPOSITION OF PARALDEHYDE

1932 ◽  
Vol 7 (1) ◽  
pp. 75-80 ◽  
Author(s):  
C. C. Coffin
Keyword(s):  
Activation Energy ◽  
Total Pressure ◽  
Mercury Vapor ◽  
Constant Volume ◽  
Reverse Reaction ◽  
First Order ◽  
Partial Pressures ◽  
Gas Reactions ◽  
Points Of View

The gaseous decomposition of paraldehyde to acetaldehyde has been studied from points of view already outlined. The reaction, which was followed by increase of pressure at constant volume, is homogeneous, accurately first order, and is presumably uncatalyzed. Its velocity has been measured between 209° and 270 °C. at initial pressures of from 1.18 to 52.0 cm. of mercury. It goes to completion under these conditions of pressure and temperature at a rate which is independent of the total pressure and of the partial pressures of paraldehyde, acetaldehyde and mercury vapor. The activation energy is 44160 cal. per mol. The velocity constants are given by the equation [Formula: see text]. The bearing of the data on the probably trimolecular reverse reaction as well as on work already reported is discussed.

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: VIII. THE DECOMPOSITION OF TRICHLORETHYLIDENE DIACETATE AND TRICHLORETHYLIDENE DIBUTYRATE

1937 ◽  
Vol 15b (6) ◽  
pp. 254-259 ◽  
Author(s):  
N. A. D. Parlee ◽  
J. R. Dacey ◽  
C. C. Coffin
Keyword(s):  
Activation Energy ◽  
Experimental Error ◽  
Acid Anhydride ◽  
Exchange Energy ◽  
Reaction Velocity ◽  
First Order ◽  
Measurable Rate ◽  
Gas Reactions

Trichlorethylidene diacetate and trichlorethylidene dibutyrate have been found to decompose at temperatures between 200° and 290 °C. at a measurable rate to give chloral and an acid anhydride. The reactions are homogeneous and of the first order, and have the same specific velocity in both the liquid and vapor states. The activation energy is identical (within experimental error) with that previously found for non-chlorinated members of this series of esters. The two compounds decompose at the same rate, in agreement with the hypothesis that the anhydride radicals do not easily exchange energy with the bonds that break. This reaction velocity, which is somewhat smaller than that of ethylidene diacetate at any temperature, is given by the equation [Formula: see text].

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: IX. THE DECOMPOSITION OF FURFURYLIDENE DIACETATE AND CROTONYLIDENE DIACETATE

1937 ◽  
Vol 15b (6) ◽  
pp. 260-263 ◽  
Author(s):  
J. R. Dacey ◽  
C. C. Coffin
Keyword(s):  
Activation Energy ◽  
Double Bond ◽  
Acetic Anhydride ◽  
Vapor Phase ◽  
Reaction Rates ◽  
Phase Decomposition ◽  
Specific Reaction ◽  
First Order ◽  
Gas Reactions

The vapor phase decomposition of furfurylidene diacetate and crotonylidene diacetate to acetic anhydride and their respective aldehydes is homogeneous, first order, and complete. The activation energy is that characteristic of the series, viz., 33,000 cal. The specific reaction rates of the two esters are the same, and are about six times as great as that of ethylidene diacetate at any temperature. It is suggested that the increased velocity is due to the presence of the double bond. Velocity constants are given by the equation [Formula: see text].

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: V. THE DECOMPOSITION OF PARACETALDEHYDE AT HIGH PRESSURES

1934 ◽  
Vol 11 (2) ◽  
pp. 180-189 ◽  
Author(s):  
A. L. Geddes ◽  
C. C. Coffin
Keyword(s):  
Liquid Phase ◽  
Critical Point ◽  
Vapor Phase ◽  
High Pressures ◽  
Heterogeneous Systems ◽  
Homogeneous Reaction ◽  
Reaction Velocity ◽  
First Order ◽  
Gas Reactions ◽  
Liquid Vapor

The homogeneous first order gaseous decomposition of paraldehyde to acetaldehyde has been studied at temperatures from 230 to 254 °C. up to pressures at which the liquid phase makes its appearance, i.e., 12 atm. at 230° and 18 atm. at 254 °C. Over-all velocity constants for the homogeneous reaction in the heterogeneous liquid-vapor system have been determined from these pressures up to the critical point. The data confirm results already published. It is found that in the purely gaseous system increase of pressure tends to diminish the reaction velocity. That the specific reaction velocity in the liquid phase is greater than that in the vapor phase is shown by the fact that the velocity constants of the heterogeneous systems increase progressively with the liquid-vapor ratio. Extrapolation to 100% of liquid gives velocity constants about five times as great as those characteristic of the vapor phase. Peculiarities in the behavior of the system at the critical point and preliminary measurements of the velocity of the trimolecular reverse reaction are described.

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: VI. THE DECOMPOSITION OF METHYLENE DIACETATE, METHYLENE DIPROPIONATE, AND METHYLENE DIBUTYRATE

1937 ◽  
Vol 15b (5) ◽  
pp. 229-236 ◽  
Author(s):  
C. C. Coffin ◽  
W. B. Beazley
Keyword(s):  
Activation Energy ◽  
Experimental Error ◽  
Pressure Change ◽  
Reaction Rates ◽  
Reaction Velocity ◽  
First Order ◽  
Exact Position ◽  
Gas Reactions ◽  
Homogeneous Decomposition ◽  
Large Experimental Error

The homogeneous decomposition of methylene diacetate vapor to formaldehyde and acetic anhydride at temperatures between 220° and 305 °C. and at pressures ranging from several centimetres of mercury to several atmospheres has been studied. Reaction rates were determined by analytical and by pressure change methods. The first order decomposition is opposed by a second order recombination. A secondary reaction makes it impossible to determine the exact position of the resulting equilibrium. Within the rather large experimental error, methylene diacetate has the same activation energy (33,000 cal.) as its homologues. Its specific reaction velocity is smaller than that of the ethylidene esters. Methylene dipropionate and dibutyrate decompose at the same rate as the diacetate. These facts are in accord with the hypothesis that the extent to which a radical can contribute to the energy of activation is dependent upon its position in the molecule. Veolcity constants are given by the equation [Formula: see text]

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: II. THE DECOMPOSITION OF THE ISOMERIC ESTERS BUTYLIDENE DIACETATE AND ETHYLIDENE DIPROPIONATE

1932 ◽  
Vol 6 (4) ◽  
pp. 417-427 ◽  
Author(s):  
C. C. Coffin
Keyword(s):  
Activation Energy ◽  
Degrees Of Freedom ◽  
Maximum Energy ◽  
Velocity Measurements ◽  
First Order ◽  
Gas Reactions ◽  
Points Of View ◽  
The Stability ◽  
Future Work ◽  
Internal Degrees Of Freedom

The gaseous decompositions of the esters butylidene diacetate and ethylidene dipropionate have been studied from points of view previously outlined in papers on the decomposition of ethylidene diacetate (2, 3). The decomposition velocities have been measured at initial pressures of from 5 to 56 cm. of mercury and at temperatures between 211 and 265 °C. The reactions are homogeneous and of the first order. They agree with the Arrhenius equation and give 100% yields (within experimental error) of an aldehyde and an anhydride. The preparation of the compounds and improvements in the technique of the velocity measurements are described.While the specific velocities of the three reactions at any temperature are somewhat different, their activation energies are the same. It is suggested that in the case of such simple reactions, which are strictly localized within the molecular structure, the activation energy can be identified as the maximum energy that the reactive bonds may possess and still exist; i.e., it may be taken as a measure of the stability of the bonds which are broken in the reaction. The suggestion is also made that for a series of reactions which have the same activation energy, the specific velocities can be taken as a relative measure of the number of internal degrees of freedom that contribute to the energy of activation. On the basis of these assumptions it becomes possible to use reaction-velocity measurements for the investigation of intramolecular energy exchange. The theoretical significance of the data is further discussed and the scope of future work in this connection is indicated.The monomolecular velocity constants (sec−1) of the decomposition of ethylidene diacetate, ethylidene dipropionate and butylidene diacetate are given respectively by the equations [Formula: see text], [Formula: see text], and [Formula: see text].

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: I. THE DECOMPOSITION OF ETHYLIDENE DIACETATE

1931 ◽  
Vol 5 (6) ◽  
pp. 636-647 ◽  
Author(s):  
C. C. Coffin
Keyword(s):  
Acetic Anhydride ◽  
Experimental Method ◽  
General Equation ◽  
Arrhenius Equation ◽  
Inert Gases ◽  
First Order ◽  
Theoretical Significance ◽  
Gas Reactions

The decomposition represented by the general equation[Formula: see text]has been found to take place according to the monomolecular law. In the case of the several homologous esters already investigated at pressures above 10 cm. of mercury the reaction is entirely homogeneous, is uninfluenced by the presence of inert gases and obeys the Arrhenius equation. This paper describes the experimental method and deals with the decomposition of ethylidene diacetate to acetaldehyde and acetic anhydride at temperatures of 220° to 268 °C. and at initial pressures of 11 to 46 cm. of mercury. The heat of activation is 32900 cal./mol and the velocity constants (sec−1) are given by the equation, ln [Formula: see text]. The theoretical significance of the data is discussed.

Aromatic oxidation by cobaltic acetate in acetic acid

1969 ◽  
Vol 47 (3) ◽  
pp. 387-392 ◽  
Author(s):  
Koichiro Sakota ◽  
Yoshio Kamiya ◽  
Nobuto Ohta
Keyword(s):  
Activation Energy ◽  
Electron Transfer ◽  
Acetic Acid ◽  
Bond Energy ◽  
Hydrogen Abstraction ◽  
Steric Factor ◽  
Benzyl Acetate ◽  
Kcal Mole ◽  
First Order ◽  
Reversible Electron Transfer

A detailed kinetic study of oxidation of toluene and its derivatives by cobaltic acetate in 95 vol% acetic acid is reported. The reaction was found to be profoundly affected by a steric factor and rather insensitive to the C—H bond energy. The order of reactivities of various alkylbenzenes is quite reversal to that of hydrogen abstraction reactions. The reaction was of first-order with respect to toluene, of second-order with respect to cobaltic ion and of inverse first-order with respect to cobaltous ion. The oxidation by cobaltic ion seems to proceed via an initial reversible electron transfer from toluene to cobaltic ion, yielding [Formula: see text] which is oxidized into benzyl acetate by another cobaltic ion. The apparent activation energy for toluene was found to be 25.3 kcal mole−1, and the same activation energy was found for ethylbenzene, cumene, diphenylmethane, and triphenylmethane.

Reaction of Glutathione with Conjugated Carbonyls

1975 ◽  
Vol 30 (7-8) ◽  
pp. 466-473 ◽  
Author(s):  
Hermann Esterbauer ◽  
Helmward Zöllner ◽  
Norbert Scholz
Keyword(s):  
Catalytic Effect ◽  
Biological Activities ◽  
Equilibrium Constants ◽  
Reverse Reaction ◽  
Mesityl Oxide ◽  
Forward Reaction ◽  
First Order ◽  
First Order Kinetics ◽  
Proton Donors ◽  
The Stability

Abstract 1. GSH reacts with conjugated carbonyls according to the equation: G SH+R-CH=CH-COR⇆R-CH(SG)-CH2-COR. The forward reaction follows second order, the reverse reaction first order kinetics. It is assumed that this reaction reflects best the ability of conjugated carbonyls to inactivate SH groups in biological systems. 2. The rate of forward reaction increases with pH approx. parallel with αSH. Besides OH- ions also proton donors (e. g. buffers) increase the rate. The catalytic effect of pH and buffer is inter­ preted in view of the reaction mechanism. 3. The equilibrium constants as well as the rate constants for forward (k1) and reverse reaction show an extreme variation depending on the carbonyl structure. Acrolein and methyl vinyl ketone (kt = 120 and 32 mol-1 sec-1 , resp.) react more rapidly than any other carbonyl to give very stable adducts (half-lives for reverse reaction 4.6 and 60.7 days, resp.). Somewhat less reactive are 4-hydroxy-2-alkenals and 4-ketopentenoic acid (k1 between 1 and 3 mol-1 sec-1), but they also form very stable adducts showing half-lives between 3.4 and 19 days. All other carbonyl studied react either very slowly (e. g. citral, ethly crotonate, mesityl oxide, acrylic acid) or form very labile adducts (crotonal, pentenal, hexenal, 3-methyl-butenone). Comparing biological activities of con­ jugated carbonyls their reactivity towards HS (k1) and the stability of the adducts must be considered.

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