PRESSURE EFFECT AND MECHANISM IN THE ACID-CATALYZED HYDRATION OF PROPYLENE AND ISOBUTYLENE

1964 ◽  
Vol 42 (5) ◽  
pp. 1019-1026 ◽  
Author(s):  
B. T. Baliga ◽  
E. Whalley
Keyword(s):  
Molecular Structure ◽  
Strong Evidence ◽  
Pressure Effect ◽  
Transition States ◽  
Effect Of Temperature ◽  
Kcal Mole ◽  
Effect Of Pressure ◽  
Entropy Of Activation ◽  
Acid Catalyzed ◽  
Arrhenius Energy

The effect of pressure up to 3 kbar on the rate of the acid-catalyzed hydration of propylene and isobutylene has been measured. The volumes of activation are: for propylene at 100 °C−9.6 ± ~1.0 cm3 mole−1, and for isobutylene at 35 °C− 11.5 ± ~1.0 cm3 mole−1. The effect of temperature in the range 90–120 °C on the rate of hydration of propylene at 100 bar was measured. At 100 °C the Arrhenius energy is 27.1 ± ~1.0 kcal mole−1 and the entropy of activation is −5.4 ± ~2.5 cal deg−1 mole−1. Both the volumes and entropies of activation strongly indicate that a molecule of water is present in the transition states, which can therefore be represented as [olefin. H+•H2O]≠. There appears to be no strong evidence regarding the molecular structure of the transition states.

EFFECT OF PRESSURE AND TEMPERATURE ON THE RATE OF THE ACID-CATALYZED HYDRATION OF ETHYLENE

1965 ◽  
Vol 43 (9) ◽  
pp. 2453-2456 ◽  
Author(s):  
B. T. Baliga ◽  
E. Whalley
Keyword(s):  
Transition State ◽  
Perchloric Acid ◽  
Kcal Mole ◽  
Effect Of Pressure ◽  
Energy Entropy ◽  
Acid Catalyzed ◽  
Aqueous Perchloric Acid

The rate of hydration of ethylene in dilute aqueous perchloric acid has been measured in the range 170–190 °C at 100 bars and 100 to 3 000 bars at 180 °C. The energy, entropy, and volume of activation are 33.3 ± ~1 kcal mole−1, −5.7 ± ~2.5 cal deg−1 mole−1, and − 15.5 ± ~1.5 cm3 mole−1 respectively. The volume of activation shows that at least one molecule of water is strongly bound in the transition state.

scholarly journals The effect of pressure on reactions in solution I—Sodium ethoxide and ethyl iodide to 3000 kg/cm 2 II—Pyridine and ethyl iodide to 8500 kg/cm 2

1935 ◽  
Vol 150 (869) ◽  
pp. 223-240 ◽  
Keyword(s):  
Atmospheric Pressure ◽  
Pressure Effect ◽  
Sodium Ethoxide ◽  
Ethyl Iodide ◽  
Effect Of Temperature ◽  
Reaction Velocity ◽  
Velocity Constant ◽  
Effect Of Pressure ◽  
Different Temperatures ◽  
Arrhenius Expression

Previous work has shown that pressure has an accelerating effect on a large number of chemical reactions in the liquid phase. The rates of the reaction between pyridine and cetyl halides have been studied at different temperatures and pressures, but it was not found possible to interpret the results by means of the ordinary reaction velocity equations, and no conclusions could be drawn as to the mechanism of the pressure effect. In making a further attempt to determine this mechanism, it seemed desirable to take reactions which have already been studied at atmospheric pressure and are known to follow the simple velocity equations, and to investigate the effect of pressure on the velocity con­stants. The effect of temperature on the velocity constant of a reaction k , can be expressed by the Arrhenius expression k = A e -E/RT . A knowledge of the variation of the velocity constant with pressure at different temperatures would show whether this change is due to a change in the value of the constants A or E, or of both.

PRESSURE EFFECT AND MECHANISM IN ACID CATALYSIS: IV. THE HYDROLYSIS OF DIETHYL ETHER

1959 ◽  
Vol 37 (4) ◽  
pp. 788-794 ◽  
Author(s):  
J. Koskikallio ◽  
E. Whalley
Keyword(s):  
Diethyl Ether ◽  
Acid Catalysis ◽  
Pressure Effect ◽  
Slow Step ◽  
Acidity Function ◽  
Temperature Range ◽  
Entropy Of Activation ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The acid-catalyzed hydrolysis of diethyl ether has been measured in the temperature range 120–160 °C at low acid concentrations; the entropy of activation is −9.0 ± ~2.5 cal deg−1 mole−1. The effect of pressures up to 3000 atm has been measured at 161.2 °C; the volume of activation at 1 atm is −8.5 ± ~2 cm3 mole−1. These two results show that the slow step is bimolecular. The rate in concentrated acids was measured at 119 °C; the rate was much more nearly proportional to the acidity function h0 than to concentration of acid. This is contrary to the predictions of the Zucker–Hammett hypothesis, which is therefore not valid for the hydrolysis of diethyl ether.

PRESSURE EFFECT AND MECHANISM IN ACID CATALYSIS: V. THE HYDROLYSIS OF ACETIC ANHYDRIDE

1959 ◽  
Vol 37 (8) ◽  
pp. 1360-1366 ◽  
Author(s):  
J. Koskikallio ◽  
D. Pouli ◽  
E. Whalley
Keyword(s):  
Acetic Anhydride ◽  
Acid Catalysis ◽  
Pressure Effect ◽  
Valid Method ◽  
Acetone Water ◽  
Entropy Of Activation ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The spontaneous and the acid-catalyzed hydrolyses of acetic anhydride have been measured as a function of temperature over the range 0 to 40 °C, as a function of pressure over the range 0 to 3 kb at 0 °C, and as a function of solvent over the range 0 to 70.3% w/w acetone–water at 0 °C. The results are discussed with reference to the mechanisms of the hydrolyses. The volume and entropy of activation of the acid-catalyzed hydrolysis are −17.1 ± ~1.3 cm3 mole−1 and ~ −20 cal deg−1 mole−1, showing that the mechanism[Formula: see text]suggested because the rate was proportional to Hammett's h0, is not correct. It follows that the Zucker–Hammett hypothesis is invalid for this reaction, as we have shown previously for other reactions, and hence that it does not provide a valid method of distinguishing between the A-1 and A-2 mechanisms.

scholarly journals Pressure-induced monotonic enhancement of Tc to over 30 K in the superconducting Pr0.82Sr0.18NiO2 thin films

2021 ◽  
Author(s):  
Ningning Wang ◽  
Mingwei Yang ◽  
Keyu Chen ◽  
Zhen Yang ◽  
Hua Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Resistivity ◽  
Pressure Effect ◽  
Ambient Pressure ◽  
Strain Engineering ◽  
Superconducting Properties ◽  
Liquid Pressure ◽  
Infinite Layer ◽  
Effect Of Pressure ◽  
First Time

Abstract The successful synthesis of superconducting nickelate thin films with the highest Tc ~ 15 K has reignited great enthusiasms on this class of potential analogue to high-Tc cuprates suggested decades ago. To pursue higher Tc is always an important task in studying new superconductors. Here we report for the first time the effect of pressure on the superconducting properties of infinite-layer Pr0.82Sr0.18NiO2 thin films by measuring electrical resistivity under various pressures in a cubic anvil cell apparatus. We find that the onset of superconductivity, Tconset, can be enhanced monotonically from ~ 18 K at ambient pressure to ~ 31 K without showing signatures of saturation upon increasing pressure to 12.1 GPa in the presence of liquid pressure transmitting medium. This encouraging result indicates that the Tc of infinite-layer nickelates superconductors can be further raised up by applying higher pressures or strain engineering in the heterostructure films. In addition to the pressure effect, we also discussed the influence of stress/strain on the superconducting properties of the nickelate thin films.

Liquefaction of almond husk for assessment as feedstock to obtain valuable bio-oils

2019 ◽  
Vol 91 (7) ◽  
pp. 1177-1190
Author(s):  
Maria Margarida Mateus ◽  
Sandro Matos ◽  
Dinis Guerreiro ◽  
Paulo Debiagi ◽  
Daniela Gaspar ◽  
...  
Keyword(s):  
Lignocellulosic Biomass ◽  
Reaction Model ◽  
Effect Of Temperature ◽  
Acid Catalyzed ◽  
Face Centered ◽  
Liquefaction Process ◽  
Favorable Conditions ◽  
Almond Husk ◽  
Composite Face ◽  
Central Composite

Abstract Almond husk liquefaction can be envisaged as an alternative to fossil sources which are becoming exhausted. Lately, the polyols obtain from the lignocellulosic biomass have been under investigation for the production of sustainable chemicals, fuel, materials or other commodities. Within this context, acid-catalyzed liquefaction of such lignocellulosic biomass has been successfully used to access highly functionalized compounds that can be used to replace those produced from petroleum. Almond shells waste can be considered to be part of the lignocellulosic biomass. Its main constituents of are cellulose, hemicellulose, and lignin. In this assay, the biochemical composition of almond husk was estimated based on atomic mass balances, and at the same time, the pyrolysis outcome was also estimated using a kinetic model using some reference compounds. In order to evaluate the use of almond waste as a substrate for acid-catalyzed liquefaction, the most favorable conditions of the liquefaction process were investigated. To better understand the liquefaction process, response surface methodology, in particular, central composite face-centered factorial design was used to set an array of 17 experiments including three replications at the center point leading to the development of a reaction model for further prediction and optimization of the liquefaction outcome. The effect of temperature (120–150 °C), time (20–200 min) and catalyst amount (0.5–5 wt. %) was investigated and a predictive model established.

Bisulfite Degrades Aflatoxin: Effect of Temperature and Concentration of Bisulfite

1978 ◽  
Vol 41 (10) ◽  
pp. 774-780 ◽  
Author(s):  
M. P. DOYLE ◽  
E. H. MARTH
Keyword(s):  
Rate Constant ◽  
Aflatoxin B1 ◽  
Reaction Rate ◽  
Reaction Rates ◽  
Reaction Rate Constant ◽  
Effect Of Temperature ◽  
Kcal Mole ◽  
First Order ◽  
Potassium Acid Phthalate ◽  
Acid Phthalate

Bisulfite reacted with aflatoxin B1 and G1 resulting in their loss of fluorescence. The reaction was first order with rate depending on bisulfite (or the bisulfite and sulfite) concentration(s). Aflatoxin G1 reacted more rapidly with bisulfite than did aflatoxin B1. In the presence of 0.035 M potassium acid phthalate-NaOH buffer (pH 5.5) plus 1.3% (vol/vol) methanol at 25 C, the reaction rate constant for degradation of aflatoxin G1 was 2.23 × 10−2h− and that for aflatoxin B1 was 1.87 × 10−2h− when 50 ml of reaction mixture contained 1.60 g of K2SO3. Besides bisulfite concentrations, temperature influenced reaction rates. The Q10 for the bisulfite-aflatoxin reaction was approximately 2 while activation energies for degrading aflatoxin B1 and aflatoxin G1 were 13.1 and 12.6 kcal/mole, respectively. Data suggest that treating foods with 50 to 500 ppm SO2 probably would not effectively degrade appreciable amounts of aflatoxin. Treating foods with 2000 ppm SO2 or more and increasing the temperature might reduce aflatoxin to an acceptable level.

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