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Blitz MA, Pilling MJ, Robertson SH, Seakins PW, Speak TH. Global Master Equation Analysis of Rate Data for the Reaction C 2H 4 + H ⇄ C 2H 5: Δ fH0⊖C 2H 5. J Phys Chem A 2021; 125:9548-9565. [PMID: 34704447 DOI: 10.1021/acs.jpca.1c05911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
While forward and reverse rate constants are frequently used to determine enthalpies of reaction and formation, this process is more difficult for pressure-dependent association/dissociation reactions, especially since the forward and reverse reactions are usually studied at very different temperatures. The problems can be overcome by using a data-fitting procedure based on a master equation model. This approach has been applied to existing experimental pressure-dependent forward and reverse rate coefficients for the reaction C2H4 + H ⇄ C2H5 (k1, k-1) using the MESMER code to determine ΔfH0⊖C2H5 from the enthalpy of the reaction. New measurements of k1, k-1 were included in analysis. They are based on laser flash photolysis with direct observation of H atom time profiles by vacuum ultraviolet laser-induced fluorescence under conditions where the approach to equilibrium could be observed. Measurements were made over the temperature range 798-828 K and with [He] from 2.33 to 7.21 × 1018 molecule cm-3. These data were then combined with a wide range of existing experimental data with helium as the bath gas (112 measurements of k1 and k-1, covering the temperature range 285-1094 K, and [He] = 7.1 × 1015-1.9 × 1019 molecule cm-3) and fitted using the master equation solver MESMER. The required vibrational frequencies and rotational constants of the system were obtained from ab initio calculations, and the activation threshold for association (ΔEthresh), enthalpy of reaction (ΔrH0⊖), imaginary frequency (υimag), and helium energy-transfer parameters (⟨ΔE⟩d,298(T/298)n) were optimized. The resulting parameters (errors are 2σ) are ΔEthresh = 11.43 ± 0.34 kJ mol-1, ΔrH0⊖ = -145.34 ± 0.60 kJ mol-1, υimag = 730 ± 130 cm-1, ⟨ΔE⟩d,298 = 54.2 ± 7.6 cm-1, and n = 1.17 ± 0.12. A value of ΔfH298.15⊖(C2H5) = 120.49 ± 0.57 kJ mol-1 is obtained by combining ΔrH0⊖ with standard enthalpies of formation for H and C2H4 and making the appropriate temperature corrections. The dependence of these parameters on how the internal rotor and CH2 inversion modes are treated has been explored. The experimental data for other bath gases have been analyzed, and data sets compatible with the potential energy surface parameters determined above have been identified. The parameters are virtually identical but with slightly smaller error limits. Parameterization of k1, k-1 using the Troe formalization has been used to investigate competition between ethyl decomposition and reaction with oxygen under combustion conditions.
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Affiliation(s)
- Mark A Blitz
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K.,National Centre for Atmospheric Science (NCAS), University of Leeds, Leeds LS2 9JT, U.K
| | | | | | - Paul W Seakins
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
| | - Thomas H Speak
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
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Uspenskaya EV, Pleteneva TV, Kazimova IV, Syroeshkin AV. Evaluation of Poorly Soluble Drugs' Dissolution Rate by Laser Scattering in Different Water Isotopologues. Molecules 2021; 26:601. [PMID: 33498881 PMCID: PMC7866158 DOI: 10.3390/molecules26030601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 12/29/2020] [Accepted: 01/19/2021] [Indexed: 11/24/2022] Open
Abstract
The most important task in the design of dosage forms is to modify the pharmaceutical substances structure in order to increase solubilization, targeted delivery, controlled rate of drug administration, and its bioavailability. Screening-laboratory (in vitro) or computer (in silico)-as a procedure for selecting a prototype for the design of a drug molecule, involves several years of research and significant costs. Among a large number of solvents and diluents (alcohol, ether, oils, glycerol, Vaseline) used in the pharmaceutical industry for the manufacture of drugs water finds the greatest application. This is because all biological reactions (reactions in living systems) take place in water and distribution of the fluid in the body and the substances found within is critical for the maintenance of intracellular and extracellular functions. Modern studies in the field of the stable isotopic compositions of natural water and its structure and properties make it possible to use isotopic transformations of the water to improve the pharmacokinetic properties of medicinal substances without previous structural modification. It is known that by replacing any of the atoms in the reacting substance molecule with its isotope, it is possible to record changes in the reactivity, which are expressed as a change in the reaction rate constant, i.e., in the manifestation of the kinetic isotope effect (KIE). The article presents the results of studies on the effect of the kinetic isotope effect of a solvent-water-on increasing the solubility and dissolution rate constants of poorly soluble drugs using laser diffraction spectroscopy. The results of the studies can be successfully implemented in pharmaceutical practice to overcome the poor solubility of medicinal substances of classes II and IV, according to the biopharmaceutical classification system (BCS), in water for pharmaceutical purposes by performing its preliminary and safe isotopic modification.
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Affiliation(s)
- Elena V. Uspenskaya
- Department of Pharmaceutical and Toxicological Chemistry, Medical Institute, RUDN University, 6 Miklukho-Maklaya Street, 117198 Moscow, Russia; (T.V.P.); (I.V.K.); (A.V.S.)
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Harman CE, Schwieterman EW, Schottelkotte JC, Kasting JF. ABIOTIC O2LEVELS ON PLANETS AROUND F, G, K, AND M STARS: POSSIBLE FALSE POSITIVES FOR LIFE? ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-637x/812/2/137] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Salter RJ, Blitz MA, Heard DE, Kovács T, Pilling MJ, Rickard AR, Seakins PW. Quantum yields for the photolysis of glyoxal below 350 nm and parameterisations for its photolysis rate in the troposphere. Phys Chem Chem Phys 2013; 15:4984-94. [DOI: 10.1039/c3cp43597k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lee PF, Matsui H, Chen WY, Wang NS. Production of H and O(3P) Atoms in the Reaction of CH2 with O2. J Phys Chem A 2012; 116:9245-54. [DOI: 10.1021/jp307140z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Pei-Fang Lee
- Department of Applied Chemistry, National Chiao Tung University, 1001, Ta Hsueh Road, Hsinchu
30010, Taiwan
| | - Hiroyuki Matsui
- Department of Applied Chemistry, National Chiao Tung University, 1001, Ta Hsueh Road, Hsinchu
30010, Taiwan
| | - Wei-Yu Chen
- Department of Applied Chemistry, National Chiao Tung University, 1001, Ta Hsueh Road, Hsinchu
30010, Taiwan
| | - Niann-Shiah Wang
- Department of Applied Chemistry, National Chiao Tung University, 1001, Ta Hsueh Road, Hsinchu
30010, Taiwan
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Lee PF, Matsui H, Wang NS. Study on the Reaction of CH2 with H2 at High Temperature. J Phys Chem A 2012; 116:1891-6. [DOI: 10.1021/jp211849h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pei-Fang Lee
- Department
of Applied Chemistry, National Chiao Tung University, 1001,
Ta Hsueh Road, Hsinchu 30010, Taiwan
| | - Hiroyuki Matsui
- Department
of Applied Chemistry, National Chiao Tung University, 1001,
Ta Hsueh Road, Hsinchu 30010, Taiwan
| | - Niann-Shiah Wang
- Department
of Applied Chemistry, National Chiao Tung University, 1001,
Ta Hsueh Road, Hsinchu 30010, Taiwan
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Blitz MA, Seakins PW. Laboratory studies of photochemistry and gas phase radical reaction kinetics relevant to planetary atmospheres. Chem Soc Rev 2012; 41:6318-47. [DOI: 10.1039/c2cs35204d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gannon KL, Blitz MA, Liang CH, Pilling MJ, Seakins PW, Glowacki DR. Temperature Dependent Kinetics (195−798 K) and H Atom Yields (298−498 K) from Reactions of 1CH2 with Acetylene, Ethene, and Propene. J Phys Chem A 2010; 114:9413-24. [DOI: 10.1021/jp102276j] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- K. L. Gannon
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - M. A. Blitz
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - C. H. Liang
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - M. J. Pilling
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - P. W. Seakins
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - D. R. Glowacki
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, U.K., and School of Chemistry, Centre for Computational Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
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Lu KW, Matsui H, Huang CL, Raghunath P, Wang NS, Lin MC. Shock Tube Study on the Thermal Decomposition of CH3OH. J Phys Chem A 2010; 114:5493-502. [DOI: 10.1021/jp100535r] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ku-We Lu
- Department of Applied Chemistry, National Chiao Tung University, 1001, Ta Hsuch Road, Hsinchu 30010 Taiwan
| | - Hiroyuki Matsui
- Department of Applied Chemistry, National Chiao Tung University, 1001, Ta Hsuch Road, Hsinchu 30010 Taiwan
| | - Ching-Liang Huang
- Department of Applied Chemistry, National Chiao Tung University, 1001, Ta Hsuch Road, Hsinchu 30010 Taiwan
| | - P. Raghunath
- Department of Applied Chemistry, National Chiao Tung University, 1001, Ta Hsuch Road, Hsinchu 30010 Taiwan
| | - Niann-Shiah Wang
- Department of Applied Chemistry, National Chiao Tung University, 1001, Ta Hsuch Road, Hsinchu 30010 Taiwan
| | - M. C. Lin
- Department of Applied Chemistry, National Chiao Tung University, 1001, Ta Hsuch Road, Hsinchu 30010 Taiwan
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Kovács T, Blitz MA, Seakins PW. H-Atom Yields from the Photolysis of Acetylene and from the Reaction of C2H with H2, C2H2, and C2H4. J Phys Chem A 2010; 114:4735-41. [DOI: 10.1021/jp908285t] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tamás Kovács
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Mark A. Blitz
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Paul W. Seakins
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
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Gannon KL, Blitz MA, Kovács T, Pilling MJ, Seakins PW. State resolved measurements of a (1)CH(2) removal confirm predictions of the gateway model for electronic quenching. J Chem Phys 2010; 132:024302. [PMID: 20095669 DOI: 10.1063/1.3263617] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Collisional quenching of electronically excited states by inert gases is a fundamental physical process. For reactive excited species such as singlet methylene, (1)CH(2), the competition between relaxation and reaction has important implications in practical systems such as combustion. The gateway model has previously been applied to the relaxation of (1)CH(2) by inert gases [U. Bley and F. Temps, J. Chem. Phys. 98, 1058 (1993)]. In this model, gateway states with mixed singlet and triplet character allow conversion between the two electronic states. The gateway model makes very specific predictions about the relative relaxation rates of ortho and para quantum states of methylene at low temperatures; relaxation from para gateway states leads to faster deactivation independent of the nature of the collision partner. Experimental data are reported here which for the first time confirm these predictions at low temperatures for helium. However, it was found that in contrast with the model predictions, the magnitude of the effect decreases with increasing size of the collision partner. It is proposed that the attractive potential energy surface for larger colliders allows alternative gateway states to contribute to relaxation removing the dominance of the para gateway states.
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Affiliation(s)
- K L Gannon
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
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Morales SB, Le Picard SD, Canosa A, Sims IR. Experimental measurements of low temperature rate coefficients for neutral–neutral reactions of interest for atmospheric chemistry of Titan, Pluto and Triton: Reactions of the CN radical. Faraday Discuss 2010; 147:155-71; discussion 251-82. [DOI: 10.1039/c004219f] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gannon KL, Blitz MA, Liang CH, Pilling MJ, Seakins PW, Glowacki DR, Harvey JN. An experimental and theoretical investigation of the competition between chemical reaction and relaxation for the reactions of 1CH2 with acetylene and ethene: implications for the chemistry of the giant planets. Faraday Discuss 2010; 147:173-88; discussion 251-82. [DOI: 10.1039/c004131a] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Harding LB, Georgievskii Y, Klippenstein SJ. Roaming Radical Kinetics in the Decomposition of Acetaldehyde. J Phys Chem A 2009; 114:765-77. [DOI: 10.1021/jp906919w] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Lawrence B. Harding
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Yuri Georgievskii
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439
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Kovács T, Blitz MA, Seakins PW, Pilling MJ. H atom formation from benzene and toluene photoexcitation at 248 nm. J Chem Phys 2009; 131:204304. [DOI: 10.1063/1.3262701] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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