Pub Date : 2020-04-04DOI: 10.29356/jmcs.v64i2.1126
J. A. González-Calderón, G. Mendoza, M. G. Peña-Juárez, E. Pérez
In this work, the effect of the chemical modification of titanium dioxide particles on the nonisothermal crystallization process of polylactic acid (PLA) was studied. Cold crystallization in some polymers occurs above the glass transition temperature (Tg) when the polymer chains gain sufficient mobility to organize themselves into the ordered structure (i.e. the crystal structure) by folding the chains. Cold crystallization in general is caused by the ordering of the molecular chains in the crystalline PLA due to the increased mobility during heating. Through an analysis of the cool crystallization process in DSC at different cooling rates, it was observed that the behavior of PLA and its composites made with titanium dioxide, neat and functionalized with dicarboxylic acids, can be described through the models used for crystallization of the polymer carrying out during cooling, such as Mo’s and Jeziorny’s model. In addition, it was determined that the chemical modification of TiO2 performed with silane increases the crystallization rate in the last step of the process; while the chemical modification with dicarboxylic acid has an accelerated effect on the crystal formation process attributed to the affinity between the aliphatic part of this group and the polymer chains. Also, it was shown that the inclusion of the silanized particles has no effect on the energy requirement compared to the pure PLA process; however, the addition of particles with the dicarboxylic acid decreases the energy value required to complete the crystalline state due to affinity at the surface to immobilize the polymer chains. Finally, it is emphasized that the activation energy required to perform the crystallization of PLA and its composites has positive values, which is an indicator that the crystallization was performed while heating, after reaching and passing the glass transition temperature and before melting.
{"title":"Used of Chemically Modified Titanium Dioxide Particles to Mediate the Non-isothermal Cold Crystallization of Poly(latic acid)","authors":"J. A. González-Calderón, G. Mendoza, M. G. Peña-Juárez, E. Pérez","doi":"10.29356/jmcs.v64i2.1126","DOIUrl":"https://doi.org/10.29356/jmcs.v64i2.1126","url":null,"abstract":"In this work, the effect of the chemical modification of titanium dioxide particles on the nonisothermal crystallization process of polylactic acid (PLA) was studied. Cold crystallization in some polymers occurs above the glass transition temperature (Tg) when the polymer chains gain sufficient mobility to organize themselves into the ordered structure (i.e. the crystal structure) by folding the chains. Cold crystallization in general is caused by the ordering of the molecular chains in the crystalline PLA due to the increased mobility during heating. Through an analysis of the cool crystallization process in DSC at different cooling rates, it was observed that the behavior of PLA and its composites made with titanium dioxide, neat and functionalized with dicarboxylic acids, can be described through the models used for crystallization of the polymer carrying out during cooling, such as Mo’s and Jeziorny’s model. In addition, it was determined that the chemical modification of TiO2 performed with silane increases the crystallization rate in the last step of the process; while the chemical modification with dicarboxylic acid has an accelerated effect on the crystal formation process attributed to the affinity between the aliphatic part of this group and the polymer chains. Also, it was shown that the inclusion of the silanized particles has no effect on the energy requirement compared to the pure PLA process; however, the addition of particles with the dicarboxylic acid decreases the energy value required to complete the crystalline state due to affinity at the surface to immobilize the polymer chains. Finally, it is emphasized that the activation energy required to perform the crystallization of PLA and its composites has positive values, which is an indicator that the crystallization was performed while heating, after reaching and passing the glass transition temperature and before melting.","PeriodicalId":21347,"journal":{"name":"Revista de la Sociedad Química de Mexico","volume":"87 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84251988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-04DOI: 10.29356/JMCS.V64I2.1079
Safaa S. Hassan, M. Shoukry, A. A. Jbarah
The formation equilibria of the dimethyltin(IV) complexes with of N,N,N’,N’tetraethylethylenediamine (Et4en) in solution were investigated. The stoichiometry and stability constants of the complexes formed in solution phase were determined at different temperatures (15 oC – 35 oC) and in solutions of dioxane-water mixtures of different compositions (15% 62.5%). The accepted model is composed of the 110, 111, 11-1 and 11-2 species. The thermodynamic parameters ∆H° and ∆S° associated with the protonation of N,N,N`,N`-tetraethylethylendiamine (Et4en) and its complex formation with the dimethyltin(IV) species were determined. The complex formation reaction is exothermic. The equilibrium constant for the displacement of N,N,N’,N’-tetraethylethylenediamine coordinated to dimethyltin(IV) by some selected DNA constituents was calculated. The Keq values clearly indicate the ability of DNA to displace the coordinated Et4en from its dimethyltin(IV) complex. The nucleotides IMP and GMP have the highest values. The DFT/B3LYP method was used for geometric optimization of the ligand and the complex using the Gaussian 09 program. Also the vibrational frequencies of the ligands and complexes were computed for the optimized geometries. The results shows that there is no imaginary frequencies as found in the calculated vibrational frequencies. The binding energies of the dimethyltin(IV) complexes were calculated. All calculated binding energy values are negative.
{"title":"Cordination Compound of Dimethyltin(IV) with N,N,N’N’-Tetraethylethylenediamine: Speciation and Theoretical approach","authors":"Safaa S. Hassan, M. Shoukry, A. A. Jbarah","doi":"10.29356/JMCS.V64I2.1079","DOIUrl":"https://doi.org/10.29356/JMCS.V64I2.1079","url":null,"abstract":"The formation equilibria of the dimethyltin(IV) complexes with of N,N,N’,N’tetraethylethylenediamine (Et4en) in solution were investigated. The stoichiometry and stability constants of the complexes formed in solution phase were determined at different temperatures (15 oC – 35 oC) and in solutions of dioxane-water mixtures of different compositions (15% 62.5%). The accepted model is composed of the 110, 111, 11-1 and 11-2 species. The thermodynamic parameters ∆H° and ∆S° associated with the protonation of N,N,N`,N`-tetraethylethylendiamine (Et4en) and its complex formation with the dimethyltin(IV) species were determined. The complex formation reaction is exothermic. The equilibrium constant for the displacement of N,N,N’,N’-tetraethylethylenediamine coordinated to dimethyltin(IV) by some selected DNA constituents was calculated. The Keq values clearly indicate the ability of DNA to displace the coordinated Et4en from its dimethyltin(IV) complex. The nucleotides IMP and GMP have the highest values. The DFT/B3LYP method was used for geometric optimization of the ligand and the complex using the Gaussian 09 program. Also the vibrational frequencies of the ligands and complexes were computed for the optimized geometries. The results shows that there is no imaginary frequencies as found in the calculated vibrational frequencies. The binding energies of the dimethyltin(IV) complexes were calculated. All calculated binding energy values are negative.","PeriodicalId":21347,"journal":{"name":"Revista de la Sociedad Química de Mexico","volume":"65 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73223046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-12DOI: 10.29356/JMCS.V52I4.1131
I. Gavilán-García, Elvira Santos-Santos, L. R. Tovar-Gálvez, A. Gavilán-García, Sara Suarez, J. Olmos
Amalgamation was heavily used in mining since 1557 in Spanish Colonies. In Mexico and other parts of Latin-America, this process generated tailings which were left aside in the mine backyards. In the valley of Zacatecas, tailings were carried out of the mines due to the run-off from the mountains and contaminated most of the Zacatecan Valley which most important economic activ- ity is agricultural (crop and livestock raising). The main concern in this area is the high level of total mercury found in previous studies. So far, various research studies have been conducted in Mexico to identify the contamination by total mercury in contaminated soils. However, research has not been developed to determine the available fraction by an analysis of the chemical species present in contaminat- ed sites, which represent a risk to human health and the environment. The aim of this study is to develop a mercury sequential chemical extraction methodology with appropriate conditions for identifying: 1) water-soluble fraction, 2) elemental fraction, 3) interchangeable fraction, 4) strongly bound fraction, 5) organic fraction, 6) fraction as sulphides and 7) residual fraction. With this, it might be determined if the mercury species present in mining soils in the state of Zacatecas, Mexico represent a potential risk because of its mobility in the differ- ent environmental compartments. Results show that chemical species in the towns of Osiris and La Zacatecana (HgS and amalgamated mercury) have high stability and low mobility.
{"title":"Mercury Speciation in Contaminated Soils from Old Mining Activities in Mexico Using a Chemical Selective Extraction","authors":"I. Gavilán-García, Elvira Santos-Santos, L. R. Tovar-Gálvez, A. Gavilán-García, Sara Suarez, J. Olmos","doi":"10.29356/JMCS.V52I4.1131","DOIUrl":"https://doi.org/10.29356/JMCS.V52I4.1131","url":null,"abstract":"Amalgamation was heavily used in mining since 1557 in Spanish Colonies. In Mexico and other parts of Latin-America, this process generated tailings which were left aside in the mine backyards. In the valley of Zacatecas, tailings were carried out of the mines due to the run-off from the mountains and contaminated most of the Zacatecan Valley which most important economic activ- ity is agricultural (crop and livestock raising). The main concern in this area is the high level of total mercury found in previous studies. So far, various research studies have been conducted in Mexico to identify the contamination by total mercury in contaminated soils. However, research has not been developed to determine the available fraction by an analysis of the chemical species present in contaminat- ed sites, which represent a risk to human health and the environment. The aim of this study is to develop a mercury sequential chemical extraction methodology with appropriate conditions for identifying: 1) water-soluble fraction, 2) elemental fraction, 3) interchangeable fraction, 4) strongly bound fraction, 5) organic fraction, 6) fraction as sulphides and 7) residual fraction. With this, it might be determined if the mercury species present in mining soils in the state of Zacatecas, Mexico represent a potential risk because of its mobility in the differ- ent environmental compartments. Results show that chemical species in the towns of Osiris and La Zacatecana (HgS and amalgamated mercury) have high stability and low mobility.","PeriodicalId":21347,"journal":{"name":"Revista de la Sociedad Química de Mexico","volume":"65 1","pages":"263-271"},"PeriodicalIF":0.0,"publicationDate":"2019-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75212475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-12DOI: 10.29356/jmcs.v64i1.1031
A. Aydın, Cemil Keskinoğlu, U. Kökbaş, A. Tuli
Ultrasound is used in many analysis studies, including liquid mixtures. Many mixtures are analyzed to understand their contents or properties in different situations. One of these mixtures is the ethanol-water combination. In this study, the amount of ethanol in the liquid mixture was determined noninvasively by the ultrasonic method using a microcontroller-based system. The results show that the measurements obtained were within the p<0.05 confidence interval. The characteristics evaluation of the system shows that the system can detect ethanol concentration as low as 0.552 g/L, thus the system has a broad and linear determination range for ethanol. Although the system is calibrated and tested with ethanol-water mixture, it can be used for any mixture that changes density related to the substance concentration, including different alcohols which are soluble in water (glycols, glycoethers, etc.) or any other material (solid or liquid) which is soluble in alcohol or different liquid solvent. The system has so many advantages that make it possible to use comfortably in many areas where the amount of ethanol contained in the mixture is essential. These advantages are the high accuracy and sensitivity, being noninvasive, portable, and not having a destructive effect on the substance.
{"title":"Noninvasive Determination of the Amount of Ethanol in Liquid Mixtures by Ultrasound Using Bilinear Interpolation Method","authors":"A. Aydın, Cemil Keskinoğlu, U. Kökbaş, A. Tuli","doi":"10.29356/jmcs.v64i1.1031","DOIUrl":"https://doi.org/10.29356/jmcs.v64i1.1031","url":null,"abstract":"Ultrasound is used in many analysis studies, including liquid mixtures. Many mixtures are analyzed to understand their contents or properties in different situations. One of these mixtures is the ethanol-water combination. In this study, the amount of ethanol in the liquid mixture was determined noninvasively by the ultrasonic method using a microcontroller-based system. The results show that the measurements obtained were within the p<0.05 confidence interval. The characteristics evaluation of the system shows that the system can detect ethanol concentration as low as 0.552 g/L, thus the system has a broad and linear determination range for ethanol. Although the system is calibrated and tested with ethanol-water mixture, it can be used for any mixture that changes density related to the substance concentration, including different alcohols which are soluble in water (glycols, glycoethers, etc.) or any other material (solid or liquid) which is soluble in alcohol or different liquid solvent. The system has so many advantages that make it possible to use comfortably in many areas where the amount of ethanol contained in the mixture is essential. These advantages are the high accuracy and sensitivity, being noninvasive, portable, and not having a destructive effect on the substance.","PeriodicalId":21347,"journal":{"name":"Revista de la Sociedad Química de Mexico","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87260157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-12DOI: 10.29356/jmcs.v64i1.1034
Tengfei Zhang, W. Zhang, Dongning Hao, Qing Liu
The three-dimensional and networked SBA-15 (3D-SBA-15) supported phosphotungstic acid (PW) was used as heterogeneous catalyst for the one-pot three-components Mannich reaction at room temperature. The H3PW12O40/3D-SBA-15 catalyst was prepared using an impregnation method and confirmed by series of characterizations such as Fourier-transform infrared spectra (FT-IR), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 physisorption and thermogravimetric (TG) analysis. 50PW/3D-SBA-15 catalyst with H3PW12O40 loading of 50 wt% showed the highest yield of 93% in 1.8 h for the Mannich reaction of benzaldehyde, aniline and acetophenone under solvent-free condition. A series of β-aminoketone derivatives were synthesized successfully in the presence of this catalyst. In addition, H3PW12O40/3D-SBA-15 catalyst can be easily recovered and reused four times without significant decrease of the activity. This work provides an improved modification of the three-component Mannich reaction in terms of mild reaction conditions, clean reaction profiles, small quantity of catalyst and a simple workup procedure.
{"title":"H3PW12O40 Anchored on the Three-Dimensional and Networked SBA-15 as an Efficient and Recyclable Catalyst for Mannich Reaction","authors":"Tengfei Zhang, W. Zhang, Dongning Hao, Qing Liu","doi":"10.29356/jmcs.v64i1.1034","DOIUrl":"https://doi.org/10.29356/jmcs.v64i1.1034","url":null,"abstract":"The three-dimensional and networked SBA-15 (3D-SBA-15) supported phosphotungstic acid (PW) was used as heterogeneous catalyst for the one-pot three-components Mannich reaction at room temperature. The H3PW12O40/3D-SBA-15 catalyst was prepared using an impregnation method and confirmed by series of characterizations such as Fourier-transform infrared spectra (FT-IR), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 physisorption and thermogravimetric (TG) analysis. 50PW/3D-SBA-15 catalyst with H3PW12O40 loading of 50 wt% showed the highest yield of 93% in 1.8 h for the Mannich reaction of benzaldehyde, aniline and acetophenone under solvent-free condition. A series of β-aminoketone derivatives were synthesized successfully in the presence of this catalyst. In addition, H3PW12O40/3D-SBA-15 catalyst can be easily recovered and reused four times without significant decrease of the activity. This work provides an improved modification of the three-component Mannich reaction in terms of mild reaction conditions, clean reaction profiles, small quantity of catalyst and a simple workup procedure.","PeriodicalId":21347,"journal":{"name":"Revista de la Sociedad Química de Mexico","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81460399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-12DOI: 10.29356/JMCS.V52I4.1132
D. Quintanar-Guerrero, Briza Nadyr Zorraquín-Cornejo, A. Ganem-Rondero, E. Piñón-Segundo, M. G. Nava-Arzaluz, J. Cornejo-Bravo
pH-Sensitive hydrogels of the poly(methacrylic acid-co- methyl methacrylate) (MAA/MMA) type, 22/78 molar % with differ- ent cross-linking percentages (0.3 and 0.5%) were synthesized. These gels were loaded with a model hydrophilic compound (dichlorobro- mophenol blue dye, DCBFB) with the aim of evaluating its release at different pH values (1.2, 5.0, 6.8, 7.4). The swelling degree and the release from these hydrogels are highly dependent on the pH of the dissolution medium and on the cross-linking degree. Scanning electron microscopy and differential scanning calorimetry studies demonstrated that part of the dye is embedded in crystal form within the hydrogel. The release profiles of the hydrogels assessed at pH = 6.8 and 7.4 were adjusted to the Higuchi model, regarding them as
{"title":"Controlled Release of Model Substances from pH-Sensitive Hydrogels","authors":"D. Quintanar-Guerrero, Briza Nadyr Zorraquín-Cornejo, A. Ganem-Rondero, E. Piñón-Segundo, M. G. Nava-Arzaluz, J. Cornejo-Bravo","doi":"10.29356/JMCS.V52I4.1132","DOIUrl":"https://doi.org/10.29356/JMCS.V52I4.1132","url":null,"abstract":"pH-Sensitive hydrogels of the poly(methacrylic acid-co- methyl methacrylate) (MAA/MMA) type, 22/78 molar % with differ- ent cross-linking percentages (0.3 and 0.5%) were synthesized. These gels were loaded with a model hydrophilic compound (dichlorobro- mophenol blue dye, DCBFB) with the aim of evaluating its release at different pH values (1.2, 5.0, 6.8, 7.4). The swelling degree and the release from these hydrogels are highly dependent on the pH of the dissolution medium and on the cross-linking degree. Scanning electron microscopy and differential scanning calorimetry studies demonstrated that part of the dye is embedded in crystal form within the hydrogel. The release profiles of the hydrogels assessed at pH = 6.8 and 7.4 were adjusted to the Higuchi model, regarding them as","PeriodicalId":21347,"journal":{"name":"Revista de la Sociedad Química de Mexico","volume":"6 1","pages":"272-278"},"PeriodicalIF":0.0,"publicationDate":"2019-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86824498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-12DOI: 10.29356/JMCS.V52I4.1130
Javier Audry Sánchez, Francisco Javier Garfias y Ayala
Ozone concentration in the atmosphere of Mexico City is analyzed for the period 2000-2006, finding an average reduction of 24%, in spite of not meeting the norm of 110 ppb in more than 42% of the days in Pedregal. The maximum ozone levels in the last three years were 250 ppb well above the norm of 110 ppb. The number of vehicles registered in the Federal District has increased in the period by an average of 35%. Notwithstanding the increase in vehicular fleet, improvement of air quality is ascribed to the replacement of old cars by more efficient and less contaminating new cars. To decrease even more the ozone concentration, it is suggested to decrease further the Reid Vapor Pressure of gasoline to 7.0 psia to reduce the evapora- tion of light olefins.
{"title":"Recent Trend in Ozone Levels in the Metropolitan zone of Mexico City","authors":"Javier Audry Sánchez, Francisco Javier Garfias y Ayala","doi":"10.29356/JMCS.V52I4.1130","DOIUrl":"https://doi.org/10.29356/JMCS.V52I4.1130","url":null,"abstract":"Ozone concentration in the atmosphere of Mexico City is analyzed for the period 2000-2006, finding an average reduction of 24%, in spite of not meeting the norm of 110 ppb in more than 42% of the days in Pedregal. The maximum ozone levels in the last three years were 250 ppb well above the norm of 110 ppb. The number of vehicles registered in the Federal District has increased in the period by an average of 35%. Notwithstanding the increase in vehicular fleet, improvement of air quality is ascribed to the replacement of old cars by more efficient and less contaminating new cars. To decrease even more the ozone concentration, it is suggested to decrease further the Reid Vapor Pressure of gasoline to 7.0 psia to reduce the evapora- tion of light olefins.","PeriodicalId":21347,"journal":{"name":"Revista de la Sociedad Química de Mexico","volume":"54 1","pages":"256-262"},"PeriodicalIF":0.0,"publicationDate":"2019-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87162323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seven compounds were isolated from the leaves and fruits of Egyptian Withania somnifera dunal, (Family: Solanaceae). The identity of the compounds based on their spectroscopic data were as follows: two withanolides; withaperuvin C (1), phyperunolideF (2) and four lipids;1,2-di-O-palmitoyl-3-O-(6 ́ ́ ́-sulfo-α-Dquinovopyranosyl)-glycerol (3), vaccenic acid (5), 1,3 dicaproyl,2-vaccenoyl-glycerol (6), vaccenolymonoglyceride (7) and β-sitosterol glucoside (4). All the isolated metabolites except (4) were reported for the first time from this plant. Besides, this is the first report for isolation of compounds (6, 7) in a pure form from a natural source. Different fractions of the fruits of the Egyptian plant were investigated for their anticholinesterase activities where the most potent ones found to be the aqueous, the light petroleum fraction in addition to a mixture of lipids.
{"title":"Chemical Constituents of Egyptian Withania Somnifera Leaves and Fruits and their Anticholinesterase Activity","authors":"R. Mahrous, H. Fathy, R. M. El-Khair, A. A. Omar","doi":"10.29356/jmcs.v63i4.944","DOIUrl":"https://doi.org/10.29356/jmcs.v63i4.944","url":null,"abstract":"Seven compounds were isolated from the leaves and fruits of Egyptian Withania somnifera dunal, (Family: Solanaceae). The identity of the compounds based on their spectroscopic data were as follows: two withanolides; withaperuvin C (1), phyperunolideF (2) and four lipids;1,2-di-O-palmitoyl-3-O-(6 ́ ́ ́-sulfo-α-Dquinovopyranosyl)-glycerol (3), vaccenic acid (5), 1,3 dicaproyl,2-vaccenoyl-glycerol (6), vaccenolymonoglyceride (7) and β-sitosterol glucoside (4). All the isolated metabolites except (4) were reported for the first time from this plant. Besides, this is the first report for isolation of compounds (6, 7) in a pure form from a natural source. Different fractions of the fruits of the Egyptian plant were investigated for their anticholinesterase activities where the most potent ones found to be the aqueous, the light petroleum fraction in addition to a mixture of lipids.","PeriodicalId":21347,"journal":{"name":"Revista de la Sociedad Química de Mexico","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89803951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Bakherad, Ali Keivanloo, A. Amin, Amir Farkhondeh
In this paper, we report the catalyst-free three-component synthesis of 1,8-dioxooctahydroxanthenes in magnetized water as a green solvent. The reaction of aldehydes and 1,3-cyclohexanedione/dimedone in magnetized water gives the 9-substituted 1,8-dioxooctahydroxanthene derivatives. This green method offers the advantages of short reaction times, low-cost, simple work-up procedure, quantitative reaction yields, and no need for an organic solvent.
{"title":"Catalyst-free, a Green, and Efficient Protocol for the Synthesis of 1,8-dioxooctahydroxanthenes in Magnetized Water","authors":"M. Bakherad, Ali Keivanloo, A. Amin, Amir Farkhondeh","doi":"10.29356/jmcs.v63i4.865","DOIUrl":"https://doi.org/10.29356/jmcs.v63i4.865","url":null,"abstract":"In this paper, we report the catalyst-free three-component synthesis of 1,8-dioxooctahydroxanthenes in magnetized water as a green solvent. The reaction of aldehydes and 1,3-cyclohexanedione/dimedone in magnetized water gives the 9-substituted 1,8-dioxooctahydroxanthene derivatives. This green method offers the advantages of short reaction times, low-cost, simple work-up procedure, quantitative reaction yields, and no need for an organic solvent.","PeriodicalId":21347,"journal":{"name":"Revista de la Sociedad Química de Mexico","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73902991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study shows that genetic algorithm (GA) is a suitable method for selecting wavelengths for partial least squares (PLS) calibration of mixtures with almost identical spectra without loss of prediction capacity employing spectrofluorimetric method. A training set of mixtures containing different concentrations of ofloxacin (OFL) and riboflavin (B2) were prepared to be used as calibration set to check the prediction ability of GA-PLS models due to spectral overlapping of these constituents. Each model was validated using a validation set and then real samples were analyzed. Linear calibration curves were obtained in the 0.5-5.0 and 2.0-10.0 μg mL-1 range for ofloxacin and riboflavin, respectively. To preprocess the data matrices, the orthogonal signal correction (OSC) was used and the analysis results were statistically compared. The methods accuracy for simultaneous determination of ofloxacin and riboflavin, were evaluated by the root mean square errors of prediction (RMSEP) which were 0.0868 and 0.158 for ofloxacin and riboflavin, respectively, and relative standard error of prediction (RSEP) which were 2.738 and 2.846 for ofloxacin and riboflavin, respectively using OSC-GA-PLS models. This procedure allows the simultaneous determination of OFL and B2 in human urine and serum samples with good reliability of the determination.
{"title":"Genetic Algorithms-Based Approach for Wavelength Selection in Simultaneous Spectrofluorimetric Determination of Ofloxacin and Riboflavin in biological samples by Partial Least-Squares","authors":"F. Assadian, A. Niazi","doi":"10.29356/jmcs.v63i4.704","DOIUrl":"https://doi.org/10.29356/jmcs.v63i4.704","url":null,"abstract":"This study shows that genetic algorithm (GA) is a suitable method for selecting wavelengths for partial least squares (PLS) calibration of mixtures with almost identical spectra without loss of prediction capacity employing spectrofluorimetric method. A training set of mixtures containing different concentrations of ofloxacin (OFL) and riboflavin (B2) were prepared to be used as calibration set to check the prediction ability of GA-PLS models due to spectral overlapping of these constituents. Each model was validated using a validation set and then real samples were analyzed. Linear calibration curves were obtained in the 0.5-5.0 and 2.0-10.0 μg mL-1 range for ofloxacin and riboflavin, respectively. To preprocess the data matrices, the orthogonal signal correction (OSC) was used and the analysis results were statistically compared. The methods accuracy for simultaneous determination of ofloxacin and riboflavin, were evaluated by the root mean square errors of prediction (RMSEP) which were 0.0868 and 0.158 for ofloxacin and riboflavin, respectively, and relative standard error of prediction (RSEP) which were 2.738 and 2.846 for ofloxacin and riboflavin, respectively using OSC-GA-PLS models. This procedure allows the simultaneous determination of OFL and B2 in human urine and serum samples with good reliability of the determination.","PeriodicalId":21347,"journal":{"name":"Revista de la Sociedad Química de Mexico","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80793210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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