Pub Date : 2018-10-01DOI: 10.3184/146867818X15319903829218
Osman Asheri, S. Habibi‐Khorassani, M. Shahraki
The kinetics of the reaction between para-substituted anilines and dimethyl acetylenedicarboxylate (DMAD) with derivatives of benzaldehyde for the one-pot formation of 3,4,5-substituted furan-2(5H)-ones in the presence of lactic acid as a catalyst have been studied spectrophotometrically at different temperatures. A mechanism involving four steps was proposed for the reactions, all of which followed second-order kinetics. The partial orders with respect to substituted aniline and DMAD were one and one and the reactions revealed zero-order kinetics for benzaldehyde and its derivatives. Changing of substituents on benzaldehyde left rates of reaction unaffected. However, various substituents on aniline showed that para electron-withdrawing groups decreased the rate of reaction. According to investigation of an isokinetic relationship, a common mechanism exists for all studied substituents and a general mechanism can be formulated. Kinetic values (k and Ea) and associated activation parameters (ΔG‡, ΔS‡ and ΔH‡) of the reactions were determined.
{"title":"A Study on the Kinetics and Mechanism of the One-Pot Formation of 3,4,5-Substituted Furan-2(5H)-Ones in the Presence of Lactic Acid: Effect of Different Substituents","authors":"Osman Asheri, S. Habibi‐Khorassani, M. Shahraki","doi":"10.3184/146867818X15319903829218","DOIUrl":"https://doi.org/10.3184/146867818X15319903829218","url":null,"abstract":"The kinetics of the reaction between para-substituted anilines and dimethyl acetylenedicarboxylate (DMAD) with derivatives of benzaldehyde for the one-pot formation of 3,4,5-substituted furan-2(5H)-ones in the presence of lactic acid as a catalyst have been studied spectrophotometrically at different temperatures. A mechanism involving four steps was proposed for the reactions, all of which followed second-order kinetics. The partial orders with respect to substituted aniline and DMAD were one and one and the reactions revealed zero-order kinetics for benzaldehyde and its derivatives. Changing of substituents on benzaldehyde left rates of reaction unaffected. However, various substituents on aniline showed that para electron-withdrawing groups decreased the rate of reaction. According to investigation of an isokinetic relationship, a common mechanism exists for all studied substituents and a general mechanism can be formulated. Kinetic values (k and Ea) and associated activation parameters (ΔG‡, ΔS‡ and ΔH‡) of the reactions were determined.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"48 1","pages":"286 - 299"},"PeriodicalIF":0.7,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86854019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.3184/146867818X15319903829173
Chengyang Li, Libo Zhang, Yubo Ma, Tianfu Wang
The hydroformylation of monoformyltricyclodecenes (MFTD) to diformyltricyclodecanes (DFTD) was studied systematically. A series of 0.006 wt% Rh–0.006 wt% Co catalysts supported on commercially available nanopowders such as Al2O3, ZnO, TiO2 and CeO2 was prepared by the incipient wetness method and used to catalyse the hydroformylation of MFTD to DFTD. The 0.006 wt% Rh–0.006 wt% Co/ZnO catalyst showed the highest catalytic performance among the catalysts investigated, thus 41.8% DFTD yield with 100% DFTD selectivity could be achieved. This suggested that there may be a key role of the carrier on the catalytic performance in MFTD hydroformylation. Furthermore, the kinetic profiles for MFTD hydroformylation over the 0.006 wt% Rh–0.030 wt% Co/ZnO catalyst have been examined systematically to explore the effect of reaction temperature on the catalytic performance. These results collectively suggested that a particular reaction temperature might benefit MFTD hydroformylation. There may be some agglomeration of the active sites at higher reaction temperatures.
{"title":"Nanopowder-Supported Ultra-Low Content Co–Rh Bimetallic Catalysts for Hydroformylation of Monoformyltricyclodecenes to Value-Added Fine Chemicals","authors":"Chengyang Li, Libo Zhang, Yubo Ma, Tianfu Wang","doi":"10.3184/146867818X15319903829173","DOIUrl":"https://doi.org/10.3184/146867818X15319903829173","url":null,"abstract":"The hydroformylation of monoformyltricyclodecenes (MFTD) to diformyltricyclodecanes (DFTD) was studied systematically. A series of 0.006 wt% Rh–0.006 wt% Co catalysts supported on commercially available nanopowders such as Al2O3, ZnO, TiO2 and CeO2 was prepared by the incipient wetness method and used to catalyse the hydroformylation of MFTD to DFTD. The 0.006 wt% Rh–0.006 wt% Co/ZnO catalyst showed the highest catalytic performance among the catalysts investigated, thus 41.8% DFTD yield with 100% DFTD selectivity could be achieved. This suggested that there may be a key role of the carrier on the catalytic performance in MFTD hydroformylation. Furthermore, the kinetic profiles for MFTD hydroformylation over the 0.006 wt% Rh–0.030 wt% Co/ZnO catalyst have been examined systematically to explore the effect of reaction temperature on the catalytic performance. These results collectively suggested that a particular reaction temperature might benefit MFTD hydroformylation. There may be some agglomeration of the active sites at higher reaction temperatures.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"52 1","pages":"254 - 261"},"PeriodicalIF":0.7,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88967977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.3184/146867818X15319903829191
Animesh Chattopadhyay, A. Dey, P. Karmakar, S. Ray, D. Nandi, Roshni Sarkar(Sain), A. K. Ghosh
The synthesis and interactions of the cis-diaqua-chloro-tris(dimethyl sulfoxide)ruthenium(II) complex with selected sulfur-containing ligands such as 2-thiouracil, glutathione and L-cysteine have been studied by UV-Vis spectrophotometry in aqueous medium at pH 4.5. From experimental data it is clear that all three reactions proceed via two steps: the first one being a rate-limiting ligand-dependent replacement of one water molecule, followed by a ligand-independent ring closure step with the expulsion of the second water molecule. The substituted products have been characterised by Job's method, FTIR spectroscopy and electrospray ionisation mass spectrometry. Activation parameters (ΔH≠ and ΔS≠) and thermodynamic parameters (ΔH0 and ΔS0, from the temperature dependence of the outer-sphere association equilibrium constant) are presented. Consistent with the experimental findings, an associative interchange mechanism is proposed.
{"title":"Mechanistic Aspects of Ligand Substitution on the Cis-Diaqua-Chloro-Tris(Dimethyl Sulfoxide)Ruthenium(II) Complex by Some Sulfur-Containing Bioactive Ligands in Aqueous Medium","authors":"Animesh Chattopadhyay, A. Dey, P. Karmakar, S. Ray, D. Nandi, Roshni Sarkar(Sain), A. K. Ghosh","doi":"10.3184/146867818X15319903829191","DOIUrl":"https://doi.org/10.3184/146867818X15319903829191","url":null,"abstract":"The synthesis and interactions of the cis-diaqua-chloro-tris(dimethyl sulfoxide)ruthenium(II) complex with selected sulfur-containing ligands such as 2-thiouracil, glutathione and L-cysteine have been studied by UV-Vis spectrophotometry in aqueous medium at pH 4.5. From experimental data it is clear that all three reactions proceed via two steps: the first one being a rate-limiting ligand-dependent replacement of one water molecule, followed by a ligand-independent ring closure step with the expulsion of the second water molecule. The substituted products have been characterised by Job's method, FTIR spectroscopy and electrospray ionisation mass spectrometry. Activation parameters (ΔH≠ and ΔS≠) and thermodynamic parameters (ΔH0 and ΔS0, from the temperature dependence of the outer-sphere association equilibrium constant) are presented. Consistent with the experimental findings, an associative interchange mechanism is proposed.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"23 1","pages":"274 - 285"},"PeriodicalIF":0.7,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85219114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.3184/146867818X15161889114466
Djilali Bassou, A. Ghomri, A. Atmani
A new, practical, synthesis of pyruvic orthoesters relying on the conversion of β-substituted phosphoenol pyruvates by the action of alkoxides is described. Our study of the reaction mechanism was done experimentally and also theoretically. Density functional theory calculations were used to explain the major reaction products found experimentally. Geometry optimisations and atomic charges obtained using different population analyses and the global and local reactivity indices, namely global electrophilicity and the Parr function, were obtained at the B3LYP/6-311G(d) level of theory. The experimental reactivity was correctly reproduced using the Parr function.
{"title":"Reactivity of β-Substituted Phosphoenol Pyruvates towards Alkoxides: A Theoretical and Experimental Study","authors":"Djilali Bassou, A. Ghomri, A. Atmani","doi":"10.3184/146867818X15161889114466","DOIUrl":"https://doi.org/10.3184/146867818X15161889114466","url":null,"abstract":"A new, practical, synthesis of pyruvic orthoesters relying on the conversion of β-substituted phosphoenol pyruvates by the action of alkoxides is described. Our study of the reaction mechanism was done experimentally and also theoretically. Density functional theory calculations were used to explain the major reaction products found experimentally. Geometry optimisations and atomic charges obtained using different population analyses and the global and local reactivity indices, namely global electrophilicity and the Parr function, were obtained at the B3LYP/6-311G(d) level of theory. The experimental reactivity was correctly reproduced using the Parr function.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"70 1","pages":"211 - 218"},"PeriodicalIF":0.7,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82125283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.3184/146867818X15233705894428
Hao Meng, Xuanwei Wu, Chao Ci, Qian Zhang, Zhe Li
The adsorption of NH3 and NO on the β-MnO2 (1 1 0) surface has been investigated by density functional theory using periodic models. The energetically favourable sites of adsorption of the gases on the β-MnO2 surface are 4-fold coordinate Mn (Mn4-top) and 5-fold coordinate Mn (Mn5-top). The relative adsorption energies (Eads) of these gases on the Mn4-top site and Mn5-top site are in the orders NH3 (Eads = −1.02 eV) > NO (Eads = −0.96 eV) and NH3 (Eads = −0.63 eV) > NO (Eads = −0.49 eV). The N-H and N–O bond lengths, Mulliken charges and the densities of states of the NH3 and NO molecules are discussed after adsorption. The calculated results indicate that the coordination number of surface Mn ions has a significant influence on the adsorption capacity. Furthermore, the analysis of the results of the density of states determinations shows that when NH3 and NO are adsorbed with the NH3-Mn and NO-Mn configurations, the bonding mechanism is mainly from the interaction between the NH3 or NO molecule and the Mn d orbital, which is the major reason for the strong chemical adsorption of NH3 and NO.
{"title":"A Density Functional Theory Study of NH3 and NO Adsorption on the β-MnO2 (110) Surface","authors":"Hao Meng, Xuanwei Wu, Chao Ci, Qian Zhang, Zhe Li","doi":"10.3184/146867818X15233705894428","DOIUrl":"https://doi.org/10.3184/146867818X15233705894428","url":null,"abstract":"The adsorption of NH3 and NO on the β-MnO2 (1 1 0) surface has been investigated by density functional theory using periodic models. The energetically favourable sites of adsorption of the gases on the β-MnO2 surface are 4-fold coordinate Mn (Mn4-top) and 5-fold coordinate Mn (Mn5-top). The relative adsorption energies (Eads) of these gases on the Mn4-top site and Mn5-top site are in the orders NH3 (Eads = −1.02 eV) > NO (Eads = −0.96 eV) and NH3 (Eads = −0.63 eV) > NO (Eads = −0.49 eV). The N-H and N–O bond lengths, Mulliken charges and the densities of states of the NH3 and NO molecules are discussed after adsorption. The calculated results indicate that the coordination number of surface Mn ions has a significant influence on the adsorption capacity. Furthermore, the analysis of the results of the density of states determinations shows that when NH3 and NO are adsorbed with the NH3-Mn and NO-Mn configurations, the bonding mechanism is mainly from the interaction between the NH3 or NO molecule and the Mn d orbital, which is the major reason for the strong chemical adsorption of NH3 and NO.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"28 1","pages":"219 - 228"},"PeriodicalIF":0.7,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81306526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.3184/146867818X15233705894374
Mengzhi Yang, Meiling Wang
This study investigated the adsorption process of p-nitrophenol (p-NP) onto partially reduced graphene oxide (prGO) using both experiment and theoretical calculations. The maximum adsorption capacity of prGO at pH 6.0 and 293 K for p-NP was 29.94 mg g−1 which was significantly higher than previously reported using a metal-doped reduced graphene oxide composite. Systematic, comparative theoretical calculations were used to investigate the adsorption mechanism of p-NP onto graphene oxide, prGO and graphene nanosheet (GN). Calculations revealed three types of adsorption site and indicated that the adsorption force and sites were significantly affected by the quantity and type of oxygen-containing functional groups on the GN. The adsorption affinity was mainly derived from hydrogen bonds and π-π stacking which was further demonstrated by FTIR analysis. Due to its excellent adsorption performance, good recyclability and easy separation, prGO can be a promising adsorbent for the efficient elimination of p-NP from wastewater in the future.
本研究通过实验和理论计算研究了对硝基苯酚(p-NP)在部分还原氧化石墨烯(prGO)上的吸附过程。在pH 6.0和293 K条件下，prGO对p-NP的最大吸附量为29.94 mg g - 1，显著高于先前报道的金属掺杂还原氧化石墨烯复合材料。采用系统的、比较的理论计算研究了p-NP在氧化石墨烯、氧化石墨烯和石墨烯纳米片(GN)上的吸附机理。计算发现了三种类型的吸附位点，并表明吸附力和吸附位点受GN上含氧官能团数量和类型的显著影响。吸附亲合力主要来源于氢键和π-π堆积，FTIR分析进一步证实了这一点。由于其优异的吸附性能，良好的可回收性和易于分离，prGO有望成为未来有效去除废水中p-NP的吸附剂。
{"title":"Adsorption of P-Nitrophenol Onto Partially Reduced Graphene Oxide: An Experimental and Theoretical Study","authors":"Mengzhi Yang, Meiling Wang","doi":"10.3184/146867818X15233705894374","DOIUrl":"https://doi.org/10.3184/146867818X15233705894374","url":null,"abstract":"This study investigated the adsorption process of p-nitrophenol (p-NP) onto partially reduced graphene oxide (prGO) using both experiment and theoretical calculations. The maximum adsorption capacity of prGO at pH 6.0 and 293 K for p-NP was 29.94 mg g−1 which was significantly higher than previously reported using a metal-doped reduced graphene oxide composite. Systematic, comparative theoretical calculations were used to investigate the adsorption mechanism of p-NP onto graphene oxide, prGO and graphene nanosheet (GN). Calculations revealed three types of adsorption site and indicated that the adsorption force and sites were significantly affected by the quantity and type of oxygen-containing functional groups on the GN. The adsorption affinity was mainly derived from hydrogen bonds and π-π stacking which was further demonstrated by FTIR analysis. Due to its excellent adsorption performance, good recyclability and easy separation, prGO can be a promising adsorbent for the efficient elimination of p-NP from wastewater in the future.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"1 1","pages":"189 - 200"},"PeriodicalIF":0.7,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89639535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.3184/146867818X15233705894347
Shrivanand M. Pai, B. L. Newalkar, P. Parikh
As bifunctional catalysts, metal-supported zeolites play an important role in refining and petrochemical processes, e.g. isomerisation, alkylation, etc. Reduction in acidity and acid strength of zeolites upon their impregnation with metals have been widely reported. Also hydrogen spillover vis-a-vis the closeness of two catalyst functions (acid and metal) has been discussed at length. Hydrogen spillover has been claimed to give rise to formation of additional acid sites on supports. Here quantification of acid sites for two zeolites, zeolite Y and ZSM-5, impregnated with different metals in various proportions after exposing them to hydrogen, has been attempted using ammonia temperature programmed desorption. The observed acidity values have been explained on the basis of metal cluster size.
{"title":"Quantifying Enhancement of Metal-Supported Zeolites Due to Hydrogen Spillover","authors":"Shrivanand M. Pai, B. L. Newalkar, P. Parikh","doi":"10.3184/146867818X15233705894347","DOIUrl":"https://doi.org/10.3184/146867818X15233705894347","url":null,"abstract":"As bifunctional catalysts, metal-supported zeolites play an important role in refining and petrochemical processes, e.g. isomerisation, alkylation, etc. Reduction in acidity and acid strength of zeolites upon their impregnation with metals have been widely reported. Also hydrogen spillover vis-a-vis the closeness of two catalyst functions (acid and metal) has been discussed at length. Hydrogen spillover has been claimed to give rise to formation of additional acid sites on supports. Here quantification of acid sites for two zeolites, zeolite Y and ZSM-5, impregnated with different metals in various proportions after exposing them to hydrogen, has been attempted using ammonia temperature programmed desorption. The observed acidity values have been explained on the basis of metal cluster size.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"20 1","pages":"157 - 165"},"PeriodicalIF":0.7,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84535822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.3184/146867818X15161889114493
M. Tasviri, Samin Bargozideh
BiVO4/InVO4 and BiVO4/InVO4/g-C3N4 were prepared by hydrothermal and ultrasonic-assisted hydrothermal methods respectively. All prepared samples were characterised by X-ray diffraction, scanning electron microscopy and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activity of the prepared catalysts was determined by degradation of Acid Blue 92 (AB92) under visible light. The rate constant and efficiency of AB92 degradation over BiVO4/InVO4/g-C3N4 was higher than that over BiVO4/InVO4 which indicates better photocatalytic activity of BiVO4/InVO4/g-C3N4. This enhancement can be attributed to the suitable dispersion of BiVO4 and InVO4 particles on the g-C3N4 surface. Furthermore, the conduction band and valence band edge potentials of InVO4, BiVO4 and g-C3N4 extend the life-time of electron–hole pairs which is beneficial for the improvement of photocatalytic efficiency.
{"title":"Fabricating Nano-Sized BiVO4/InVO4/g-C3N4 Photocatalysts for Efficient Degradation of Acid Blue 92 Azo Dye","authors":"M. Tasviri, Samin Bargozideh","doi":"10.3184/146867818X15161889114493","DOIUrl":"https://doi.org/10.3184/146867818X15161889114493","url":null,"abstract":"BiVO4/InVO4 and BiVO4/InVO4/g-C3N4 were prepared by hydrothermal and ultrasonic-assisted hydrothermal methods respectively. All prepared samples were characterised by X-ray diffraction, scanning electron microscopy and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activity of the prepared catalysts was determined by degradation of Acid Blue 92 (AB92) under visible light. The rate constant and efficiency of AB92 degradation over BiVO4/InVO4/g-C3N4 was higher than that over BiVO4/InVO4 which indicates better photocatalytic activity of BiVO4/InVO4/g-C3N4. This enhancement can be attributed to the suitable dispersion of BiVO4 and InVO4 particles on the g-C3N4 surface. Furthermore, the conduction band and valence band edge potentials of InVO4, BiVO4 and g-C3N4 extend the life-time of electron–hole pairs which is beneficial for the improvement of photocatalytic efficiency.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"49 1","pages":"112 - 120"},"PeriodicalIF":0.7,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72866888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.3184/146867818X15161889114484
Anes El-Hadj Saïd, S. Mekelleche
The antioxidant properties of the synthesised 5-tert-butylbenzene-1,2,3-triol (system A) and the designed 3,5-di-tert-butylbenzene-1,2-diol (system B) have been explored through density functional theory at the M05-2X/6-31+G(d,p) level of theory. The quantum mechanics-based test for overall free radical scavenging activity (QM- ORSA) protocol has been employed to account for their radical-scavenging capacity against the hydroperoxyl radical (HOO•) in the gas phase and in toluene solvent as a mimic lipid medium. The different mechanisms of the chemical reactions of the studied systems with HOO• have been considered, namely (i) the hydrogen atom transfer (HAT), (ii) the single electron transfer followed by proton transfer and (iii) the radical adduct formation. Our calculations provide evidence that HAT is the most favoured reaction mechanism in both the gas phase and in lipid media and the calculated thermodynamic and kinetic parameters indicate that the designed compound is more efficient than the synthesised system A and the reference system (α-tocopherol).
{"title":"Investigation of Reaction Mechanisms and Kinetics of the Radical Scavenging Ability of 5-Tert-Butylbenzene-1,2,3-Triol and 3,5-di-Tert-Butylbenzene-1,2-Diol Compounds Towards OOH Radical","authors":"Anes El-Hadj Saïd, S. Mekelleche","doi":"10.3184/146867818X15161889114484","DOIUrl":"https://doi.org/10.3184/146867818X15161889114484","url":null,"abstract":"The antioxidant properties of the synthesised 5-tert-butylbenzene-1,2,3-triol (system A) and the designed 3,5-di-tert-butylbenzene-1,2-diol (system B) have been explored through density functional theory at the M05-2X/6-31+G(d,p) level of theory. The quantum mechanics-based test for overall free radical scavenging activity (QM- ORSA) protocol has been employed to account for their radical-scavenging capacity against the hydroperoxyl radical (HOO•) in the gas phase and in toluene solvent as a mimic lipid medium. The different mechanisms of the chemical reactions of the studied systems with HOO• have been considered, namely (i) the hydrogen atom transfer (HAT), (ii) the single electron transfer followed by proton transfer and (iii) the radical adduct formation. Our calculations provide evidence that HAT is the most favoured reaction mechanism in both the gas phase and in lipid media and the calculated thermodynamic and kinetic parameters indicate that the designed compound is more efficient than the synthesised system A and the reference system (α-tocopherol).","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"1 1","pages":"101 - 111"},"PeriodicalIF":0.7,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82946246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-01DOI: 10.3184/146867818X15161889114475
Libo Zhang, Chengyang Li, Yubo Ma, Tianfu Wang
In this work, SiO2-supported Co–Rh bimetallic catalysts were prepared by adopting a method of impregnation and were used to catalyse the hydroformylation of dicyclopentadiene (DCPD) to diformyltricyclodecanes. Firstly, the hydroformylation of DCPD was carried out and three reaction stages were observed. In the first stage, a sharp decrease of reaction pressure was observed within 4 minutes. In the next stage, almost no reaction pressure decrease was detected over a relatively longer reaction time (70 minutes). In the final stage, the reaction pressure decreased at a relatively gentle rate, with barely any decrease of reaction pressure being observed at 460 minutes. Secondly, the hydroformylation of monoformyltricyclodecenes (MFTD) with various reaction times was carried out; the catalyst that was used at various reaction times was also recovered. Finally, the catalyst that had been used at various reaction times was characterised and analysed and the relationship between the catalytic performance and the structure of the catalysts was confirmed. In addition, combined with triphenylphosphine, the influence of pressure on the activity of Co–Rh bimetallic catalysts was investigated for the hydroformylation of MFTD.
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