In order to teach students,the importance of conductometric titrations in this work,we present a laboratory experiment to quantify the amount of metformin hydrochloride in a tablet.The quantification was carried out t...In order to teach students,the importance of conductometric titrations in this work,we present a laboratory experiment to quantify the amount of metformin hydrochloride in a tablet.The quantification was carried out through the evaluation of the chloride by silver nitrate.The titration and the end point were followed by conductometric titration,as well as by potentiometric and visually by the Volhard method.In addition,the theoretical conductivities of the metformin hydrochloride solution were calculated when known volumes of titrant are added,using the limit conductivity data for each of the ions present in the literature.To simulate the conductometric titration,the calculated conductivity values were plotted based on the volume of silver nitrate added.A comparison between techniques is made in order to determine the best monitoring method,being this one conductimetry to detect the equivalence point for metformin hydrochloride with 0.99±0.03,according to relative standard deviation(%RSD).Simulated titration curves adequately describe obtained results in an experimental way.The conductometric titration is the best method for quantification since it shows less dispersion between obtained results and has the highest concordance among results.Their application is shown through the analysis and conductometric titration simulations.展开更多
We study the decay t →cγ?with flavor-changing neutral interactions in scalar sector of the type III Two Higgs Doublet Model (THDM-III) with mixing between neutral scalar fields as a result of consid...We study the decay t →cγ?with flavor-changing neutral interactions in scalar sector of the type III Two Higgs Doublet Model (THDM-III) with mixing between neutral scalar fields as a result of considering the most general scalar potential. The branching ratio of the decay Br (t?→cγ) is calculated as function of the mixing parameters and masses of the neutral scalar fields. We obtain a Br (t?→cγ) of the order of 10−8 for the considered regions of the mixing parameters. Finally, one upper bound for the possible events is estimated to be n=18 by assuming an expected luminosity of the order of 300 fb−1.展开更多
Carbamates are molecules that have different types of biological activities and provide a particular chemical control against ticks. The new structures of the proposed compounds were optimized and synthetized respecti...Carbamates are molecules that have different types of biological activities and provide a particular chemical control against ticks. The new structures of the proposed compounds were optimized and synthetized respectively, through a molecular model using the methods:PM3, HF and DFT applying the B3LYP functional, with the basis 6-31+G(d) and 6-311+G(d,p), BVP86 and PBEPBE with 6-31+G(d) and the vibrational frequencies computed. These calculated frequencies were compared with the experimental ones to determine the most accurate level of theory for the prediction of vibrational frequencies of the compounds. The best results were obtained through HF/631+G(d). Additionally, we report a modification to obtain this type of compounds, and based on the amino-dehalogenation of ethyl chloroformate, different benzyl ethyl carbamates were synthesized modifying the base molecule. The performances obtained were compared to others already reported. The methodology used allowed us to synthesize new carbamates using benzylamine derivatives through a modification on the basic catalysis of the addition-elimination reaction.展开更多
文摘In order to teach students,the importance of conductometric titrations in this work,we present a laboratory experiment to quantify the amount of metformin hydrochloride in a tablet.The quantification was carried out through the evaluation of the chloride by silver nitrate.The titration and the end point were followed by conductometric titration,as well as by potentiometric and visually by the Volhard method.In addition,the theoretical conductivities of the metformin hydrochloride solution were calculated when known volumes of titrant are added,using the limit conductivity data for each of the ions present in the literature.To simulate the conductometric titration,the calculated conductivity values were plotted based on the volume of silver nitrate added.A comparison between techniques is made in order to determine the best monitoring method,being this one conductimetry to detect the equivalence point for metformin hydrochloride with 0.99±0.03,according to relative standard deviation(%RSD).Simulated titration curves adequately describe obtained results in an experimental way.The conductometric titration is the best method for quantification since it shows less dispersion between obtained results and has the highest concordance among results.Their application is shown through the analysis and conductometric titration simulations.
文摘We study the decay t →cγ?with flavor-changing neutral interactions in scalar sector of the type III Two Higgs Doublet Model (THDM-III) with mixing between neutral scalar fields as a result of considering the most general scalar potential. The branching ratio of the decay Br (t?→cγ) is calculated as function of the mixing parameters and masses of the neutral scalar fields. We obtain a Br (t?→cγ) of the order of 10−8 for the considered regions of the mixing parameters. Finally, one upper bound for the possible events is estimated to be n=18 by assuming an expected luminosity of the order of 300 fb−1.
基金Proyect:PAPIIT IT200817PAPIIT No 202015Catedra PIAPI1607:Diseno de moleculas bioativas.
文摘Carbamates are molecules that have different types of biological activities and provide a particular chemical control against ticks. The new structures of the proposed compounds were optimized and synthetized respectively, through a molecular model using the methods:PM3, HF and DFT applying the B3LYP functional, with the basis 6-31+G(d) and 6-311+G(d,p), BVP86 and PBEPBE with 6-31+G(d) and the vibrational frequencies computed. These calculated frequencies were compared with the experimental ones to determine the most accurate level of theory for the prediction of vibrational frequencies of the compounds. The best results were obtained through HF/631+G(d). Additionally, we report a modification to obtain this type of compounds, and based on the amino-dehalogenation of ethyl chloroformate, different benzyl ethyl carbamates were synthesized modifying the base molecule. The performances obtained were compared to others already reported. The methodology used allowed us to synthesize new carbamates using benzylamine derivatives through a modification on the basic catalysis of the addition-elimination reaction.
