共查询到20条相似文献,搜索用时 31 毫秒
1.
Chaza Darwich ThomasM. Klaptke CarlesMir Sabat 《Propellants, Explosives, Pyrotechnics》2008,33(5):336-346
Two new highly stable energetic salts were synthesized in reasonable yield by using the high nitrogen‐content heterocycle 3,4,5‐triamino‐1,2,4‐triazole and resulting in its picrate and azotetrazolate salts. 3,4,5‐Triamino‐1,2,4‐triazolium picrate (1) and bis(3,4,5‐triamino‐1,2,4‐triazolium) 5,5′‐azotetrazolate (2) were characterized analytically and spectroscopically. X‐ray diffraction studies revealed that protonation takes place on the nitrogen N1 (crystallographically labelled as N2). The sensitivity of the compounds to shock and friction was also determined by standard BAM tests revealing a low sensitivity for both. B3LYP/6–31G(d, p) density functional (DFT) calculations were carried out to determine the enthalpy of combustion (ΔcH (1) =−3737.8 kJ mol−1, ΔcH (2) =−4577.8 kJ mol−1) and the standard enthalpy of formation (ΔfH° (1) =−498.3 kJ mol−1, (ΔfH° (2) =+524.2 kJ mol−1). The detonation pressures (P (1) =189×108 Pa, P (2) =199×108 Pa) and detonation velocities (D (1) =7015 m s−1, D (2) =7683 m s−1) were calculated using the program EXPLO5. 相似文献
2.
Alessandro E. Contini Anthony J. Bellamy Leila N. Ahad 《Propellants, Explosives, Pyrotechnics》2012,37(3):320-328
Low‐melting paraffin wax was successfully used as a phlegmatizing agent to perform semi‐micro oxygen bomb calorimetry of spectroscopically pure samples of the sensitive explosive peroxides TATP and DADP. The energies of combustion (ΔcU) were measured and the standard enthalpies of formation (ΔfH°) were derived using the CODATA values for the standard enthalpies of formation of the combustion products. Whilst the measured ΔfH° of DADP (ΔfH°=−598.5 ± 39.7 kJ mol−1) could not be compared to any existing literature value, the measured ΔfH° value of TATP (ΔfH°=+151.4 ± 32.7 kJ mol−1) did not correlate well with the only existing experimental value and confirmed that TATP is an endothermic cyclic peroxide. 相似文献
3.
Janna Geith ThomasM. Klaptke Jan Weigand Gerhard Holl 《Propellants, Explosives, Pyrotechnics》2004,29(1):3-8
The enthalpies of combustion (ΔcombH) of dinitrobiuret (DNB) and diaminotetrazolium nitrate (HDAT‐NO3) were determined experimentally using oxygen bomb calorimetry: ΔcombH(DNB)=5195±200 kJ kg−1, ΔcombH(HDAT‐NO3)=7900±300 kJ kg−1. The standard enthalpies of formation (ΔfH°) of DNB and HDAT‐NO3 were obtained on the basis of quantum chemical computations at the electron‐correlated ab initio MP2 (second order Møller‐Plesset perturbation theory) level of theory using a correlation consistent double‐zeta basis set (cc‐pVTZ): ΔfH°(DNB)=−353 kJ mol−1, −1 829 kJ kg−1; ΔfH°(HDAT‐NO3)=+254 kJ mol−1, +1 558 kJ kg−1. The detonation velocities (D) and detonation pressures (P) of DNB and HDAT‐NO3 were calculated using the empirical equations by Kamlet and Jacobs: D(DNB)=8.66 mm μs−1, P(DNB)=33.9 GPa, D(HDAT‐NO3)=8.77 mm μs−1, P(HDAT‐NO3)=33.3 GPa. 相似文献
4.
Mohammad Hossein Keshavarz Karim Esmailpour Mehdi Zamani Akbar Gholami Roknabadi 《Propellants, Explosives, Pyrotechnics》2015,40(6):886-891
The M06‐2X/6‐311G(d,p) and B3LYP/6‐311G(d,p) density functional methods and electrostatic potential analysis were used for calculation of enthalpy of sublimation, crystal density and enthalpy of formation of some thermally stable explosives in the gas and solid phases. These data were used for prediction of their detonation properties including heat of detonation, detonation pressure, detonation velocity, detonation temperature, electric spark sensitivity, impact sensitivity and deflagration temperature using appropriate methods. The range of different properties for these compounds are: crystal density 1.51–2.01 g cm−3, enthalpy of sublimation 346.4–424.7 kJ mol−1, the solid phase enthalpy of formation 500.4–860.6 kJ mol−1, heat of detonation 13.64–17.57 kJ g−1, detonation pressure 33.0–37.0 GPa, detonation velocity 8.5–9.5 km s−1, detonation temperature 5488–6234 K, electric spark sensitivity 7.89–9.47 J, impact sensitivity 21–38 J, deflagration temperature 560–586 K and power [%TNT] 207–276. The results show that two novel energetic compounds N,N′‐(diazene‐1,2‐diylbis(2,3,5,6‐tetranitro‐4,1‐phenylene))bis(5‐nitro‐4H‐1,2,4‐triazol‐3‐amine) (DDTNPNT3A) and 1,1′‐(diazene‐1,2‐diylbis(2,3,5,6‐tetranitro‐4,1‐phenylene))bis(3‐nitro‐1H‐1,2,4‐triazol‐5‐amine) (DDTNPNT5A) can be introduced as thermally explosives with high detonation performance. 相似文献
5.
Mohammad Hossein Keshavarz Hamid Reza Pouretedal Ali Reza Ghaedsharafi Seyed Ehsan Taghizadeh 《Propellants, Explosives, Pyrotechnics》2014,39(6):815-818
A reliable simple method for prediction of the standard Gibbs energy of formation (ΔfGθ) of energetic compounds containing nitroaromatic, acyclic, and cyclic nitramine, nitrate ester, and nitroaliphatic compounds is introduced herein. The method is based on the contribution of elemental composition (ΔfGelemθ) and the correcting function for the presence of additive and non‐additive molecular fragments (ΔfGcorrθ). In presence of some molecular moieties, ΔfGcorrθ may increase or decrease the value of ΔfGelemθ, depending on the intermolecular interactions. The experimental root‐mean‐square error (RMSE) of the novel correlation (22.7 kJ mol−1) is quite good. For some energetic compounds, where the computed values of two complex models of the quantitative structure‐property relationship (QSPR) theory were available, the experimental RMSE developed by the new method is smaller than the values obtained by QSPR method. 相似文献
6.
Xin Liao Xue‐Hai Ju Feng‐Qi Zhao Jian‐Hua Yi 《Propellants, Explosives, Pyrotechnics》2010,35(6):567-571
Density functional theory (DFT) calculations were performed for a series of polynitrobenzene derivatives. Some nitrobenzenes with amino groups attached were also investigated as a benchmark or as a precursor. Heats of formation (HOF) were evaluated. The isodesmic reactions used for the prediction of HOFs are of permutation type in terms of the substituents. The HOFs increase non‐additively with increasing number of nitro groups. The attachment of the amino groups to polynitrobenzenes dramatically decreases the HOF. The HOF of hexanitrobenzene (HNB) is 344.05 kJ mol−1 at the B3LYP/6‐311+G** level. This value is much larger than that of the widely used 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB), which engenders HNB a large chemical energy of detonation. The strengths of the group interactions were analyzed according to the disproportionation energy. The nearest‐neighbor interactions in polynitrobenzenes are in the range of 27.20–55.90 kJ mol−1. The energy barrier for the internal rotation of nitro group in nitrobenzene is 24.6 kJ mol−1. However, the energy barrier for the internal rotation of 2‐position nitro group of 1,2,3‐trinitrobenzene is as large as 216.3 kJ mol−1. The chemical energies of detonation for polynitrobenzenes with three or more nitro groups are over 6000 J g−1. Pentanitroaniline and HNB have good performances in terms of detonation velocity and pressure. 相似文献
7.
ThomasM. Klaptke F.Xaver Steemann Muhamed Sueska 《Propellants, Explosives, Pyrotechnics》2008,33(3):213-218
Some thermodynamic and explosive properties of the recently reported 1‐azido‐2‐nitro‐2‐azapropane (ANAP) have been determined in a combined computational ab initio (MP2/aug‐cc‐pVDZ) and EXPLO5 (Becker–Kistiakowsky–Wilson's equation of state, BKW EOS) study. The enthalpy of formation of ANAP in the liquid phase was calculated to be ΔfH°, ANAP(l)=+297.1 kJ mol−1. The heat of detonation (Qv), the detonation pressure (P), and the detonation velocity of ANAP were calculated to be Qv=−6088 kJ kg−1, P=23.8 GPa, D=8033 m s−1. A mixture of ANAP and tetranitromethane (TNM) was investigated in an attempt to tailor the impact sensitivity of ANAP, but results obtained indicate that the mixture is almost as sensitive as pure ANAP. On the other hand, ANAP and TNM were found to be chemically compatible (1H, 13C, 14N NMR; DSC) and a 1 : 1 mixture (by weight) of both components was calculated to have superior explosive properties than either of the individual components: Qv=−6848 kJ kg−1, P=27.0 GPa, D=8284 m s−1. 相似文献
8.
《分离科学与技术》2012,47(4):705-722
Abstract The sorption behavior of 3.18×10?6 mol l?1 solution of Tm(III) metal ions onto 7.25 mg l?1 of 1‐(2‐pyridylazo)‐2‐naphthol (PAN) loaded polyurethane foam (PUF) has been investigated at different temperatures i.e. 303 K, 313 K, and 323 K. The maximum equilibration time of sorption was 30 minutes from pH 7.5 buffer solution at all temperatures. The various rate parameters of adsorption process have been investigated. The diffusional activation energy (ΔEads) and activation entropy (ΔSads) of the system were found to be 22.1±2.6 kJ mol?1 and 52.7±6.2 J mol?1 K?1, respectively. The thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG) were calculated and interpreted. The positive value of ΔH and negative value of ΔG indicate that sorption is endothermic and spontaneous in nature, respectively. The adsorption isotherms such as Freundlich, Langmuir, and Dubinin–Radushkevich isotherm were tested experimentally at different temperatures. The changes in adsorption isotherm constants were discussed. The binding energy constant (b) of Langmuir isotherm increases with temperature. The differential heat of adsorption (ΔHdiff), entropy of adsorption (ΔSdiff) and adsorption free energy (ΔGads) at 313 K were determined and found to be 38±2 kJ mol?1, 249±3 J mol?1 K?1 and –40.1±1.1 kJ mol?1, respectively. The stability of sorbed complex and mechanism involved in adsorption process has been discussed using different thermodynamic parameters and sorption free energy. 相似文献
9.
Moritz vonDenffer ThomasM. Klaptke Gernot Kramer Gunnar Spieß JanM. Welch Gerhard Heeb 《Propellants, Explosives, Pyrotechnics》2005,30(3):191-195
5‐Aminotetrazolium nitrate was synthesized in high yield and characterized using Raman and multinuclear NMR spectroscopy (1H, 13C, 15N). The molecular structure of 5‐aminotetrazolium nitrate in the crystalline state was determined by X‐ray crystallography: monoclinic, P 21/c, a=1.05493(8) nm, b=0.34556(4) nm, c=1.4606(1) nm, β=90.548(9)°, V=0.53244(8) nm3, Z=4, ϱ=1.847 g cm−3, R1=0.034, wR2 (all data)=0.090. The thermal stability of 5‐aminotetrazolium nitrate was determined using differential scanning calorimetry; the compound decomposes at 167 °C. The enthalpy of combustion (ΔcombH) of 5‐aminotetrazolium nitrate ([CH4N5]+[NO3]−) was determined experimentally using oxygen bomb calorimetry: ΔcombH([CH4N5]+[NO3]−)=−6020±200 kJ kg−1. The standard enthalpy of formation (ΔfH°) of [CH4N5]+[NO3]− was obtained on the basis of quantum chemical computations at the electron‐correlated ab initio MP2 (second order Møller‐Plesset perturbation theory) level of theory using a correlation consistent double‐zeta basis set (cc‐pVTZ): ΔfH°([CH4N5]+[NO3]−(s))=+87 kJ mol−1=+586 kJ kg−1. The detonation velocity (D) and the detonation pressure (P) of 5‐aminotetrazolium nitrate were calculated using the empirical equations by Kamlet and Jacobs: D([CH4N5]+[NO3]−)=8.90 mm μs−1 and P([CH4N5]+[NO3]−)=35.7 GPa. 相似文献
10.
David Adam Konstantin Karaghiosoff ThomasM. Klaptke Gerhard Holl Manfred Kaiser 《Propellants, Explosives, Pyrotechnics》2002,27(1):7-11
Triazidotrinitro benzene, 1,3,5‐(N3)3‐2,4,6‐(NO2)3C6 ( 1 ) was synthesized by nitration of triazidodinitro benzene, 1,3,5‐(N3)3‐2,4‐(NO2)2C6H with either a mixture of fuming nitric and concentrated sulfuric acid (HNO3/H2SO4) or with N2O5. Crystals were obtained by the slow evaporation of an acetone/acetic acid mixture at room temperature over a period of 2 weeks and characterized by single crystal X‐ray diffraction: monoclinic, P 21/c (no. 14), a=0.54256(4), b=1.8552(1), c=1.2129(1) nm, β=94.91(1)°, V=1.2163(2) nm3, Z=4, ϱ=1.836 g⋅cm−3, Rall =0.069. Triazidotrinitro benzene has a remarkably high density (1.84 g⋅cm−3). The standard heat of formation of compound 1 was computed at B3LYP/6‐31G(d, p) level of theory to be ΔH°f=765.8 kJ⋅mol−1 which translates to 2278.0 kJ⋅kg−1. The expected detonation properties of compound 1 were calculated using the semi‐empirical equations suggested by Kamlet and Jacobs: detonation pressure, P=18.4 GPa and detonation velocity, D=8100 m⋅s−1. 相似文献
11.
The thermodynamic properties of 136 polychlorinated phenarsazines (PCPAZs) have been calculated by density functional theory at the B3LYP/6‐31G* level. Then, isodesmic reactions are designed to calculate ΔfH° and ΔfG° of PCPAZs. The relations of these thermodynamic parameters with the number and position of Cl atom substitution (NPCS) are discussed and a relative stability order of PCPAZs is theoretically proposed according to the relative magnitude of their ΔfG°. In addition, the values of molar heat capacities at constant pressure from 200 to 1000 K for PCPAZs are calculated, and the temperature dependence relations of this parameter are obtained using the least‐squares method. 相似文献
12.
Weiwei Wang Jianjun Liu Wenwei He Deqian Li 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2007,82(8):705-710
The kinetics of ytterbium(III) extraction from sulfate medium with Cyanex 923 in heptane has been investigated with a constant interfacial cell with laminar flow, which aimed to identify the extraction regime, reaction zone and rate equations. It was found that the extraction rate of ytterbium(III) increased linearly with stirring speed and specific interfacial area. The activation energy Ea (9.56 kJ mol?1), activation enthalpy ΔH± (7.05 kJ mol?1), activation entropy ΔS±298 (?0.31 kJ mol?1) and Gibbs free energy of activation ΔG±298 (98.3 kJ mol?1) were calculated from the dependence of extraction rate on temperature. The experiential rate equations were obtained by investigating the influence of the concentration of various species on the extraction rate. A diffusion regime has been deduced from evidence of the linear dependence of extraction rate on stirring speed and the low value of the activation energy. The liquid–liquid interface is most probably the reaction zone in view of the linear dependence of extraction rate on specific interfacial area, the high interfacial activity and low water‐solubility of extractant. Thus the mass transfer rate is controlled by interfacial film diffusion of species. Copyright © 2007 Society of Chemical Industry 相似文献
13.
Claucia Fernanda Volken de Souza Débora Jung Luvizetto Faccin Omar Mertins Júlio Xandro Heck Nádya Pesce da Silveira Argimiro Resende Secchi Marco Antônio Záchia Ayub 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(10):1567-1575
BACKGROUND: This paper describes the modeling of the kinetics of thermal inactivation of transglutaminase (TGase) from a newly isolated Bacillus circulans BL32, isolated from the Amazon environment. The purified enzyme was incubated at temperatures ranging from 30 to 70 °C and values of the thermodynamic inactivation parameters, such as activation energy (ΔE), activation enthalpy (ΔH), activation entropy (ΔS), and free energy (ΔG) for thermal inactivation, were calculated. RESULTS: The kinetics of TGase thermo‐inactivation followed a Lumry–Eyring model. The enzyme was very stable up to 50 °C, with approximately 50% of activity remaining after heating for 12 h. It was completely inactivated by incubation at 70 °C for 2 min. ΔE for TGase was 350.5 kJ mol?1. ΔH and ΔS for thermo‐inactivation of the TGase were 347.8 kJ mol?1 and 744 J mol?1 K?1 at 50 °C, respectively. Dynamic light scattering measurements suggest that the thermal inactivation of this microbial TGase can be partially attributed to the formation of aggregates. CONCLUSION: These results provide useful information about the thermal characteristics of the microbial TGase from B. circulans BL32 and indicate that this enzyme could be a good candidate for industrial applications. Copyright © 2009 Society of Chemical Industry 相似文献
14.
Martina Spaeth Peter Plischka Frank-Michael Bohnen Regine Herbst-Irmer Hartmut Laatsch 《Advanced Synthesis \u0026amp; Catalysis》1997,339(1):243-249
Conformation and Rotation Barriers of Substituted Glyoxylic Acid Amides Semiempirical calculations predict an orthogonal orientation of the carbonyl groups in tertiary glyoxylic acid amides, which is in good agreement with an X-ray structure analysis of 5 . Due to the influence of the α-carbonyl group, the rotation barrier in the substituted glyoxylic acid amides 2a–d, 3a, 3b , and 4–6 (ΔG#c = 84–92 kJ mol−1) is about 10 kJ/mol higher than in simple acid amides, as was found by dynamic NMR line shape analysis. 相似文献
15.
Taking the solvent water into account, the energetics of the reactions of O3 with Br? leading to BrO3 ? have been calculated by Density Functional Theory at the B3LYP/6–311+G(d)/SCRF =COSMO level. Br? reversibly forms an adduct, BrOOO?, (ΔG?=?+6 kJ mol?1) that decays spin allowed into BrO? and O2(1Δg) (ΔG?=?+13 kJ mol?1). BrO? undergoes an oxidation to BrO2 ? and a reduction to Br?. This may be accounted for if two different adducts, OBrOOO? and BrOOOO?, decay into BrO? plus O2 and Br? plus 2 O2. After cyclization, OBrOOO? may also lead to Br? plus 2 O2. 相似文献
16.
Simple protocols to convert molecular mechanics (MMX/PCMODEL), semiempirical PM3, and HF ab initio energies to accurate heats of formation for hydrocarbons with benzene rings are described. The data set consists of every hydrocarbon benzene derivative with an experimentally determined ΔHfo (g), and the ΔHfo (g)'s cover a range of -140 to +410 kJ/mol. The molecular structures are comprised of numerous structural types. Hierarchical sets of molecular structure parameters are defined to describe these molecules. The independent variables include atom types (level 1), group and ring terms (level 2), nonbonded atom interactions (level 3), and the calculated MMX, PM3 or ab initio HF energies, which contribute a final level 4 parameter for rectification of the ΔHfo (g) data. The additivity, level 1-3 parameters give an excellent correlation of the experimental ΔHfo (g)'s, average error = 3.4 kJ, and maximum error = 12.1 kJ. However, the correlations are further enhanced by addition of any level 4 parameter, with maximum improvement coming at the 6-31G*//STO-3G HF level of calculation. 相似文献
17.
Sergey P. Verevkin Barbara Dogan Johannes Hdrich Hans-Dieter Beckhaus Christoph Rüchardt 《Advanced Synthesis \u0026amp; Catalysis》1995,337(1):93-98
Geminal Substituent Effects. VIII. Enthalpies of Formation of Acetals The standard enthalpies of combustion ΔHc° (1 or c) of the α-phenyl-substituted acetals ( 1 ) and diacetals ( 2 ) were measured calorimetrically. The enthalpies of vaporisation or sublimation ΔHvap or ΔHsub of 1–2 were obtained from the temperature function of the vapor pressure measured in a flow system, and the standard enthalpies of formation are obtained thereof: ΔH°f (1 or c) and ΔHf° (g) (in kJ mol−1) for 1a = −308.40 ± 0.52(1), −248.94 ± 0.88; 1b = −343.48 ± 0.72 (1), −288.5 ± 1.5; 1c = −267.4 ± 1.3 (1), −205.3 ± 1.3; 1d = −343.8 ± 2.1 (c), −261.9 ± 2.2; 1e = −397.02 ± 0.86 (c), −311.3 ± 1.2; 1f = −414.52 ± 0.80 (1), −350.68 ± 0.86; 2a = −564.8 ± 2.4 (c), −467.1 ± 2.5; 2b = −547.6 ± 1.6 (c), −414.9 ± 2.7; 2c = −717.1 ± 7.5 (c), −587.0 ± 8.0. The results are combined into values of two strain free group increments CH[20, CPh] = −59.7 and C[20, CPh, C] = −71.3 kJ mol−1; and compared to the aliphatic series of acetals. 相似文献
18.
A kinetic study of the reaction between a hydroxyl-terminated polybutadiene (HTPB) and isophorone diisocyanate (IPDI) was carried out in the bulk state by using quantitative Fourier transform infrared (FTIR) spectroscopy. The reaction is shown to obey a second-order rate law, being first order in both the HTPB and IPDI concentrations. The activation parameters obtained from the evaluation of kinetic data are ΔH‡ = 41.1 ± 0.4 kJ mol, ΔS‡ = −198 ± 2 J K−1 mol−1 and Ea = 43.8 ± 0.4 kJ mol−1, which are quite different from the solution values. However, they are in agreement with the results obtained on propellants by torsional braid measurements. The large negative value of the activation entropy is indicative of an associative mechanism, which is in accord with the second-order rate law for the polyurethane formation. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1979–1983, 1997 相似文献
19.
A series of low‐cost, pyridinium cation‐based hypergolic ionic liquids (HIL) containing amine, butyl, or allyl substituents with cyanoborohydride [BH3CN]− and dicyanamide [DCA]− anions were developed and characterized. The investigated physicochemical properties include melting and decomposition temperature, viscosity, density, heat of formation (ΔHf) and specific impulse (Isp). The ignition delay (ID) of all HILs was tested with the oxidizer RFNA. The HIL, 1‐allyl 4‐amino pyridinium dicyanamide, exhibited highest density (1.139 g cm−3) amongst the known pyridinium HILs. The heats of formation predicted on the basis of Gaussian 09 suit programs were within the range of − 30 to 356 kJ mol−1. The structure of HIL, 1‐butyl 4‐aminopyridinium cyanoborohydride, was examined by single‐crystal X‐ray diffraction, which revealed hydrogen bonding between anion and cation as N1−H1N ⋅⋅⋅ N3=2.07 Å, N1−H2N ⋅⋅⋅ H1B1=2.18 Å, and N1−H2N ⋅⋅⋅ H2B1=2.21 Å, respectively. HIL (1‐allyl 4‐aminopyridiniun cyanoborohydride) exhibited highest Isp of 228 s amongst the designed series. 相似文献
20.
The reaction enthalpy and rate of reduction of 1,1-diphenylethylene (DPE) by the frustrated Lewis pair formed between tris-pentafluorophenylborane (BCF) and diethyl ether (Et2O) in dichloromethane have been determined by mixing calorimetry. At 50 °C and 13.6 atm hydrogen, a 0.08 M solution of DPE is reduced to 1,1-diphenylethane, in the presence of 1 equivalent BCF and 0.8 equivalents Et2O, in 40 minutes. NMR spectroscopy showed>99 % conversion to the reduced product. The rate of conversion of the olefin to the alkane, as monitored by the time-dependent heat flow, showed a linear dependence on the free Et2O and BCF concentration. Integration of the heat flux provides a measurement of the reaction enthalpy, ΔH, of ca. −116±4 kJ mol−1 for the reaction Ph2C=CH2+H2→Ph2CHCH3. The equilibrium constant for dative adduct formation, Et2O+BCF↔Et2O−BCF, was determined as a function of temperature by 19F NMR spectroscopy, and provided an experimental measurement of the enthalpy, ΔH=−54.6±3.3 kJ mol−1, and entropy, ΔS=−154±13 J mol−1 K−1, for dative bond formation in DCM. Extrapolation of the Van’t Hoff plot to 50 °C provides Keq, which is used to estimate the concentration of free BCF and Et2O available to activate hydrogen. 相似文献