Mirari Ayerbe - Academia.edu (original) (raw)
Papers by Mirari Ayerbe
The inclusion of technology in the teaching and learning processes in Higher Education has always... more The inclusion of technology in the teaching and learning processes in Higher Education has always posed difficulties. The pandemic caused by COVID19 has forced the use of technology to maintain emergency remote teaching, but it has also helped to give a boost to the aforementioned aspect. This paper presents a project carried out at the UPV/EHU (Spain) for the progressive inclusion of technology in a pedagogical model based on active and cooperative methodologies. This project contributes to the development of the digital teaching competence of university teachers and the development of professional skills based on autonomy, responsibility and critical decision-making by students.
The Journal of Physical Chemistry, 1995
ABSTRACT Ab initio molecular orbital calculations on the ion-molecule reactions of the tripler P+... more ABSTRACT Ab initio molecular orbital calculations on the ion-molecule reactions of the tripler P+ with ClH and FH have been performed at the G1*, G2* (G1 and G2 methodologies with MP2/6-31G(d,p) base geometries), MCSCF, and QCISD(T) levels of theory. Two reaction mechanisms leading to PX(+) + H (X = Cl, F) products have been investigated. Both of them proceed through the formation of an ion-molecule complex, in the first step of the reaction, without energy barrier. Reaction pathway I involves the abstraction of hydrogen from the X atom. A significant configuration mixing is found to take place for this abstaction, and we have found that it is energetically unfavored with respect to the reactants. Reaction pathway II consists of the transposition of the hydrogen from the X atom to P, to form the HPX(+) intermediate, and then abstraction of the hydrogen from P. Reaction pathway II, which is energetically more favorable than pathway I, could be a likely source of P-Cl (X = F, Cl) bond containing compounds in the interstellar medial however, it is predicted to be an unlikely source for P-F compounds.
Tetrahedron Letters, 1995
The Journal of Physical Chemistry A, 1997
ABSTRACT A study of both the singlet and triplet potential energy surfaces of the [H3, P2]+ syste... more ABSTRACT A study of both the singlet and triplet potential energy surfaces of the [H3, P2]+ system has been carried out using the G2 procedure. Various stable structures along with a number of reaction mechanisms for the reaction of both the 1D and 3P electronic states of P+ with phosphine have been elucidated. The most stable isomer on the singlet potential energy surface, which corresponds to the species resulting from a hydrogen migration in the P+−PH3 complex, lies 127.3 kcal/mol below the reactants level, P+(1D) + PH3(1A1). On the triplet surface, on the other hand, the P+−PH3 ion−molecule complex is the most stable isomer, 84.4 kcal/mol below P+(3P) + PH3(1A1). Various reaction paths for both the molecular and atomic hydrogen elimination have been fully characterized. For both spin multiplicities the H2 abstraction is found to be favored with respect to H abstraction, in full agreement with available experimental data. Finally, we have also discussed the hydrogen and/or charge-transfer reaction between singlet 1D and triplet 3P states of P+ with phosphine.
Journal of Polymer Science Part A: Polymer Chemistry, 2006
The synthesis of new polymer colloids based on renewable resources, such as sugar-derived monomer... more The synthesis of new polymer colloids based on renewable resources, such as sugar-derived monomers, is nowadays a matter of interest. These new polymeric particles should be useful in biomedical applications, such as drug delivery, because of their assumed biodegradability. In this work, two new families of polymer latex particles, based on a sugar-derived monomer, 3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-a-D-glucofuranose (3-MDG), were produced and characterized. The syntheses of poly(3-MDG) crosslinked particles and those obtained by copolymerization with methacrylic acid (MAA), poly(3-MDG-co-MAA) crosslinked particles, were prepared by surfactant-free emulsion polymerization in a batch reactor. The average particle diameter evolutions, the effect of pH of the dispersion medium on the final average diameters, together with the microscopic and morphological analysis of the particle's surface and inner dominium, were analyzed. Poly(3-MDG-co-EGDMA) stable particles were obtained by adding low amounts of initiator. The surface-charge density of these particles corresponded to the sulfate groups coming from the initiator. In the second family of latices, poly(3-MDG-co-MAA-co-EGDMA) particles, DCP measurements and SEM and TEM observations showed that the sizes and surface characteristics depended on the amounts of MAA and crosslinker used in the reaction mixture.
The Journal of Organic Chemistry, 2006
Aza-Wittig reaction of N-vinylic phosphazenes (1,2 addition), derived from diphenylmethylphosphin... more Aza-Wittig reaction of N-vinylic phosphazenes (1,2 addition), derived from diphenylmethylphosphine or derived from trimethylphosphine with alpha,beta-unsaturated aldehydes, leads to the formation of 3-azatrienes through a [2 + 2]-cycloaddition-cycloreversion sequence. The presence of an alkyl substituent in position 3 of N-vinylic phosphazenes increases the steric interactions, and [4 + 2] periselectivity (1,4 addition) is observed. Reaction of azatrienes with alpha,beta-unsaturated aldehydes yields pyridines.
The Journal of Organic Chemistry, 2007
The mechanism and the origins of the stereocontrol observed in the reaction between differently s... more The mechanism and the origins of the stereocontrol observed in the reaction between differently substituted alkenes and stable (phosphino)(silyl)carbenes giving cyclopropanes have been studied computationally. These cyclopropanation reactions proceed via asynchronous concerted mechanisms involving early transition structures with a significant charge transfer from the carbene to the alkene moiety. The geometric features of these transition structures preclude a significant overlap between the orbitals required for secondary orbital interactions between the reactants. The stereoselectivity observed experimentally stems from favorable electrostatic and steric interactions between the reactants leading to the stereoisomers in which the phosphanyl and carbonyl or aryl groups are cis to each other.
The Journal of Organic Chemistry, 1998
ABSTRACT
Acta Crystallographica Section E Structure Reports Online, 2001
Journal of Organic Chemistry, 2006
The mechanism of the aza-Wittig reaction between phosphazenes and aldehydes has been studied comp... more The mechanism of the aza-Wittig reaction between phosphazenes and aldehydes has been studied computationally, using DFT methods (B3LYP/6-31G level), and experimentally. It has been found that the reaction consists of a tandem [2+2] cycloaddition-cycloreversion sequence in which pi and sigma orbitals as well as lone pairs are involved. Both [2+2] processes take place via thermally allowed supra-supra mechanisms. P-trimethyl-lambda(5)-phosphazenes are predicted to be more reactive than their P-triphenyl analogues. The stereochemical outcome of the whole reaction depends only on the second step, because conformational changes in the intermediate 1,3,2-lambda(5)-oxazaphosphazetidines have a much lower activation energy than the second [2+2] cycloreversion reaction. Preferential or exclusive formation of the corresponding (E)-imines is predicted.
The inclusion of technology in the teaching and learning processes in Higher Education has always... more The inclusion of technology in the teaching and learning processes in Higher Education has always posed difficulties. The pandemic caused by COVID19 has forced the use of technology to maintain emergency remote teaching, but it has also helped to give a boost to the aforementioned aspect. This paper presents a project carried out at the UPV/EHU (Spain) for the progressive inclusion of technology in a pedagogical model based on active and cooperative methodologies. This project contributes to the development of the digital teaching competence of university teachers and the development of professional skills based on autonomy, responsibility and critical decision-making by students.
The Journal of Physical Chemistry, 1995
ABSTRACT Ab initio molecular orbital calculations on the ion-molecule reactions of the tripler P+... more ABSTRACT Ab initio molecular orbital calculations on the ion-molecule reactions of the tripler P+ with ClH and FH have been performed at the G1*, G2* (G1 and G2 methodologies with MP2/6-31G(d,p) base geometries), MCSCF, and QCISD(T) levels of theory. Two reaction mechanisms leading to PX(+) + H (X = Cl, F) products have been investigated. Both of them proceed through the formation of an ion-molecule complex, in the first step of the reaction, without energy barrier. Reaction pathway I involves the abstraction of hydrogen from the X atom. A significant configuration mixing is found to take place for this abstaction, and we have found that it is energetically unfavored with respect to the reactants. Reaction pathway II consists of the transposition of the hydrogen from the X atom to P, to form the HPX(+) intermediate, and then abstraction of the hydrogen from P. Reaction pathway II, which is energetically more favorable than pathway I, could be a likely source of P-Cl (X = F, Cl) bond containing compounds in the interstellar medial however, it is predicted to be an unlikely source for P-F compounds.
Tetrahedron Letters, 1995
The Journal of Physical Chemistry A, 1997
ABSTRACT A study of both the singlet and triplet potential energy surfaces of the [H3, P2]+ syste... more ABSTRACT A study of both the singlet and triplet potential energy surfaces of the [H3, P2]+ system has been carried out using the G2 procedure. Various stable structures along with a number of reaction mechanisms for the reaction of both the 1D and 3P electronic states of P+ with phosphine have been elucidated. The most stable isomer on the singlet potential energy surface, which corresponds to the species resulting from a hydrogen migration in the P+−PH3 complex, lies 127.3 kcal/mol below the reactants level, P+(1D) + PH3(1A1). On the triplet surface, on the other hand, the P+−PH3 ion−molecule complex is the most stable isomer, 84.4 kcal/mol below P+(3P) + PH3(1A1). Various reaction paths for both the molecular and atomic hydrogen elimination have been fully characterized. For both spin multiplicities the H2 abstraction is found to be favored with respect to H abstraction, in full agreement with available experimental data. Finally, we have also discussed the hydrogen and/or charge-transfer reaction between singlet 1D and triplet 3P states of P+ with phosphine.
Journal of Polymer Science Part A: Polymer Chemistry, 2006
The synthesis of new polymer colloids based on renewable resources, such as sugar-derived monomer... more The synthesis of new polymer colloids based on renewable resources, such as sugar-derived monomers, is nowadays a matter of interest. These new polymeric particles should be useful in biomedical applications, such as drug delivery, because of their assumed biodegradability. In this work, two new families of polymer latex particles, based on a sugar-derived monomer, 3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-a-D-glucofuranose (3-MDG), were produced and characterized. The syntheses of poly(3-MDG) crosslinked particles and those obtained by copolymerization with methacrylic acid (MAA), poly(3-MDG-co-MAA) crosslinked particles, were prepared by surfactant-free emulsion polymerization in a batch reactor. The average particle diameter evolutions, the effect of pH of the dispersion medium on the final average diameters, together with the microscopic and morphological analysis of the particle's surface and inner dominium, were analyzed. Poly(3-MDG-co-EGDMA) stable particles were obtained by adding low amounts of initiator. The surface-charge density of these particles corresponded to the sulfate groups coming from the initiator. In the second family of latices, poly(3-MDG-co-MAA-co-EGDMA) particles, DCP measurements and SEM and TEM observations showed that the sizes and surface characteristics depended on the amounts of MAA and crosslinker used in the reaction mixture.
The Journal of Organic Chemistry, 2006
Aza-Wittig reaction of N-vinylic phosphazenes (1,2 addition), derived from diphenylmethylphosphin... more Aza-Wittig reaction of N-vinylic phosphazenes (1,2 addition), derived from diphenylmethylphosphine or derived from trimethylphosphine with alpha,beta-unsaturated aldehydes, leads to the formation of 3-azatrienes through a [2 + 2]-cycloaddition-cycloreversion sequence. The presence of an alkyl substituent in position 3 of N-vinylic phosphazenes increases the steric interactions, and [4 + 2] periselectivity (1,4 addition) is observed. Reaction of azatrienes with alpha,beta-unsaturated aldehydes yields pyridines.
The Journal of Organic Chemistry, 2007
The mechanism and the origins of the stereocontrol observed in the reaction between differently s... more The mechanism and the origins of the stereocontrol observed in the reaction between differently substituted alkenes and stable (phosphino)(silyl)carbenes giving cyclopropanes have been studied computationally. These cyclopropanation reactions proceed via asynchronous concerted mechanisms involving early transition structures with a significant charge transfer from the carbene to the alkene moiety. The geometric features of these transition structures preclude a significant overlap between the orbitals required for secondary orbital interactions between the reactants. The stereoselectivity observed experimentally stems from favorable electrostatic and steric interactions between the reactants leading to the stereoisomers in which the phosphanyl and carbonyl or aryl groups are cis to each other.
The Journal of Organic Chemistry, 1998
ABSTRACT
Acta Crystallographica Section E Structure Reports Online, 2001
Journal of Organic Chemistry, 2006
The mechanism of the aza-Wittig reaction between phosphazenes and aldehydes has been studied comp... more The mechanism of the aza-Wittig reaction between phosphazenes and aldehydes has been studied computationally, using DFT methods (B3LYP/6-31G level), and experimentally. It has been found that the reaction consists of a tandem [2+2] cycloaddition-cycloreversion sequence in which pi and sigma orbitals as well as lone pairs are involved. Both [2+2] processes take place via thermally allowed supra-supra mechanisms. P-trimethyl-lambda(5)-phosphazenes are predicted to be more reactive than their P-triphenyl analogues. The stereochemical outcome of the whole reaction depends only on the second step, because conformational changes in the intermediate 1,3,2-lambda(5)-oxazaphosphazetidines have a much lower activation energy than the second [2+2] cycloreversion reaction. Preferential or exclusive formation of the corresponding (E)-imines is predicted.