Sommaire. 2014 Étude expérimentale (chambre d'ionisation et amplification linéaire) des groupes d... more Sommaire. 2014 Étude expérimentale (chambre d'ionisation et amplification linéaire) des groupes discrets de particules de désintégration de l'azote produits par les neutrons rapides (source radon et béryllium). Mise en évidence de 14 groupes énergétiques compris entre 0,5 et 3,3 x 106 eV. Discussion de la réaction (14N, n ~ 11B, 03B1). Niveaux nucléaires possibles du noyau intermédiaire 15N entre 11 et 14 x 206 eV. Dans ce domaine l'écartement moyen des niveaux consécutifs serait de 0,2 x 106 eV.
N-dodecil-N,N-dimethyl-3-amino-1-propan sulphonate was used for stabilizing gold nanoparticles in... more N-dodecil-N,N-dimethyl-3-amino-1-propan sulphonate was used for stabilizing gold nanoparticles in water that afforded Au/C (SB-Au/C) when immobilized on activated carbon. Characterization by XPS revealed a high atomic percentage of superficial gold (% at. Au(4f)/C(2s)), compared with other Au/C catalysts prepared by the immobilization of different sols. The activity of the SB-Au/C catalyst was found to be superior to that observed in the liquid-phase oxidation of ethylene glycol using other gold-on-carbon catalysts.
The present invention relates to the use of raw glycerine as a cement additive in order to improv... more The present invention relates to the use of raw glycerine as a cement additive in order to improve the compression strength thereof
As a result of the booming biodiesel and oleochemicals manufacturing taking place worldwide since... more As a result of the booming biodiesel and oleochemicals manufacturing taking place worldwide since more than a decade, 2 million tonnes of glycerol consistently reach the market every year, even though after a decade of growth the total glycerol supply is expected to slightly decrease in 2014. Today the supply of glycerol is entirely independent of its demand, as there is as much glycerol as the amount of vegetable oils and animal fats are hydrolyzed to make oleochemicals, or transesterified to produce biodiesel. This unique situation has led to consistently low glycerol prices, which initiated both the market penetration of glycerol in countries where it was not used due to traditional high price, as well as new uses of glycerol as raw material for the production of value added chemicals. This article sheds light on the market of this uniquely versatile chemical whose number of applications is unique amid all existing chemicals.
One of the most exciting and unforeseen developments of the chemical research has been the recent... more One of the most exciting and unforeseen developments of the chemical research has been the recent application of gold in catalysis. In fact, this metal has become an important tool in organic synthesis several years after the first reports on ethyne hydrochlorination and CO oxidation and now it is w...
Au (0) sols were obtained in aqueous solutions by reduction of NaAuCl4 with NaBH4 in the presence... more Au (0) sols were obtained in aqueous solutions by reduction of NaAuCl4 with NaBH4 in the presence of protective agents [the long chain compound poly (oxyethylene (23) lauryl ether (C12E23), the polymer poly {bis (2-chloroethyl) ether-alt-1, 3-bis [3-(dimethylamino) propyl ...
Gold on carbon oxidizes aldehydes to carboxylic acids in water solution under mild conditions wit... more Gold on carbon oxidizes aldehydes to carboxylic acids in water solution under mild conditions without loss of activity on recycling, as does not occur for platinum on carbon. Also scarcely soluble aldehydes can be oxidized but the reaction rate is slower. Experiments carried out in an organic solvent such as CCl 4 show a speed up of the reaction, in this solvent being recyclable both Au/C and Pt/C. Another explored possibility was represented by carrying out the reaction in the absence of solvent. However, for solid aldehydes like p-and o-OH-PhCHO the water solvent represent the unique alternative.
Catalytic oxidation of vicinal diols to α-hydroxy carboxylates with dioxygen in alkaline solution... more Catalytic oxidation of vicinal diols to α-hydroxy carboxylates with dioxygen in alkaline solution has been performed by using gold based catalysts. The optimization of the catalytic system has highlighted the influence of the support and preparation method on both activity and selectivity. Under mild conditions (T = 343-363 K, pO 2 = 300 kPa (absolute)) high selectivities (90-100%) toward monooxygenation in the cases of ethane-1,2-diol and propane-1,2-diol were achieved at high diol conversions (80-94%). The racemization of optically active propane-1,2-diol during its oxidation as well as isotopic H-D exchange experiments allowed us to deduce new features in the mechanism of diol oxidation and concerning the dependence of selectivity on reaction conditions. The recycling of gold on carbon catalyst revealed its good resistance toward deactivation, greater than palladium or platinum on carbon catalysts which were respectively affected by metal leaching and a considerable loss of selectivity.
The selective oxidation of D-glucose to D-gluconic acid was performed at both controlled (7-9.5) ... more The selective oxidation of D-glucose to D-gluconic acid was performed at both controlled (7-9.5) and free pH values in an aqueous solution in the presence of a gold on carbon catalyst using dioxygen as the oxidant under mild conditions (323-373 K, pO 2 = 100-300 kPa). No isomerization of glucose to fructose was observed during the reaction, and total selectivity to D-gluconate was obtained. A comparative study of gold and commercial palladium and platinum-derived catalysts highlighted the unique property of supported gold, i.e., it is active at low pH (2.5), whereas at a buffered higher pH (9.5), gold and bismuth-doped platinumpalladium on carbon catalysts show comparable selectivity, though gold has a higher activity. Moreover, upon recycling, gold is more stable toward deactivation, although this also depends on the operative pH.
The progressive poisoning effect of different molecules on carbon supported gold catalysts has be... more The progressive poisoning effect of different molecules on carbon supported gold catalysts has been evaluated during the aerobic oxidation of glucose. A geometrical model has been derived for describing the morphological properties of two catalysts made of carbon supported gold particles having a known size distribution centered at 3.30 and 7.89 nm respectively. The observed deactivation trend follows the order thiocyanate > cyanide ≈ cysteine > thiourea and it obeys an exponential law. The kinetics of catalyst deactivation has been interpreted by considering the important contribute of electronic factors which overlap the space shielding of active sites, due to long range poison-catalyst interaction influencing the entire metal particle. Considering the nature of the molecules showing a high poisoning effect and the promoting effect of OH − , a molecular model for electronic interactions in gold nanoparticles during the aerobic oxidation of glucose has been proposed where the dioxygen reduction step is differently influenced by soft and hard-nucleophiles.
One of the strategic building blocks in organic synthesis is 3-hydroxypropionic acid, which is pa... more One of the strategic building blocks in organic synthesis is 3-hydroxypropionic acid, which is particularly important for the manufacture of high performance polymers. However, to date, despite many attempts using both biological and chemical routes, no large scale effective process for manufacturing 3-hydroxypropionic acid has been developed. One potentially useful starting point is from allyl alcohol, as this can be obtained in principle from the dehydration of glycerol, thereby presenting a bio-renewable green pathway to this important building block. The catalytic transformation of allyl alcohol to 3-hydroxypropionic acid presents interesting challenges in catalyst design, particularly with respect to the control of selectivity among the products that can be expected, as acrylic acid, acrolein and glyceric acid can also be formed. In this paper, we present a novel eco-sustainable catalytic pathway leading to 3-hydroxypropionic acid, which highlights the outstanding potential of gold-based and bimetallic catalysts in the aerobic oxidation of allyl alcohol.
An environmentally benign oxidation of benzyl alcohol to benzaldehyde with hydrogen peroxide as o... more An environmentally benign oxidation of benzyl alcohol to benzaldehyde with hydrogen peroxide as oxidant and metal dodecanesulfonate salts as catalysts was conducted under solvent-free condition by biphasic catalysis. Ferric tridodecanesulfonate showed excellent catalytic activity exhibiting complete conversion of benzyl alcohol with 194.4 mol/mol cat turnover number (TON) and nearly 100% selectivity to benzaldehyde at ambient pressure and 90 • C. This catalyst can be recovered and reused for three times without a significant loss in its activity and selectivity.
ABSTRACT This article reviews the metal catalyzed syntheses of aniline and pyrrole leading to con... more ABSTRACT This article reviews the metal catalyzed syntheses of aniline and pyrrole leading to conductive polymers. Considering that these materials are commonly produced via electrochemical or chemical processes, catalytic methods could represent a strategic tool for improved technologies based on the use of clean reagents, such as dioxygen and hydrogen peroxide. The advantage of avoiding either the use of a large amount of reagents or the formation of unsustainable amounts of by-products is highlighted. Beside synthetic and mechanistic aspects of the catalytic preparation of polyaniline and polypyrrole, a critical description of the morphological properties, related to the choice of the catalytic system, is presented.
Differently stabilised metal sols have been used as precursors in the preparation of heterogeneou... more Differently stabilised metal sols have been used as precursors in the preparation of heterogeneous gold catalysts for liquid phase oxidation in water solution. The methodology of sols generation appears to be fundamental to obtaining nanoparticles; the support, instead, plays an important role in maintaining particle dimension and morphology. Three different materials (␥-Al 2 O 3 , SiO 2 and activated carbon) have been used as the supporting agents for different gold sols that were obtained by reducing HAuCl 4 with NaBH 4 in the presence of polyvinylalcohol (PVA) or polyvinylpirrolidone (PVP) and with the tetrakis(hydroxymethyl)phosphonium chloride (THPC)/NaOH system. During the immobilisation step, the maintenance of the particle dimension observed in solution depends on both the support and the type of sol. The gold particle mean size of the colloidal suspension is more easily maintained on oxidic supports than on carbon, the latter apparently needing both steric and polar stabilisation of the gold particle. Comparison of Au/␥-Al 2 O 3 and Au/C catalyst activity in the liquid phase oxidation of ethylene glycol to glycolate highlighted the peculiarity of gold on carbon catalysts; in fact, the normally observed trend of reactivity is partially reversed, medium sized gold particle being the most active.
Dedicated to the humanity and scientific creativity of Prof. Mauro Graziani in the occasion of hi... more Dedicated to the humanity and scientific creativity of Prof. Mauro Graziani in the occasion of his 75th birthday.
Sommaire. 2014 Étude expérimentale (chambre d'ionisation et amplification linéaire) des groupes d... more Sommaire. 2014 Étude expérimentale (chambre d'ionisation et amplification linéaire) des groupes discrets de particules de désintégration de l'azote produits par les neutrons rapides (source radon et béryllium). Mise en évidence de 14 groupes énergétiques compris entre 0,5 et 3,3 x 106 eV. Discussion de la réaction (14N, n ~ 11B, 03B1). Niveaux nucléaires possibles du noyau intermédiaire 15N entre 11 et 14 x 206 eV. Dans ce domaine l'écartement moyen des niveaux consécutifs serait de 0,2 x 106 eV.
N-dodecil-N,N-dimethyl-3-amino-1-propan sulphonate was used for stabilizing gold nanoparticles in... more N-dodecil-N,N-dimethyl-3-amino-1-propan sulphonate was used for stabilizing gold nanoparticles in water that afforded Au/C (SB-Au/C) when immobilized on activated carbon. Characterization by XPS revealed a high atomic percentage of superficial gold (% at. Au(4f)/C(2s)), compared with other Au/C catalysts prepared by the immobilization of different sols. The activity of the SB-Au/C catalyst was found to be superior to that observed in the liquid-phase oxidation of ethylene glycol using other gold-on-carbon catalysts.
The present invention relates to the use of raw glycerine as a cement additive in order to improv... more The present invention relates to the use of raw glycerine as a cement additive in order to improve the compression strength thereof
As a result of the booming biodiesel and oleochemicals manufacturing taking place worldwide since... more As a result of the booming biodiesel and oleochemicals manufacturing taking place worldwide since more than a decade, 2 million tonnes of glycerol consistently reach the market every year, even though after a decade of growth the total glycerol supply is expected to slightly decrease in 2014. Today the supply of glycerol is entirely independent of its demand, as there is as much glycerol as the amount of vegetable oils and animal fats are hydrolyzed to make oleochemicals, or transesterified to produce biodiesel. This unique situation has led to consistently low glycerol prices, which initiated both the market penetration of glycerol in countries where it was not used due to traditional high price, as well as new uses of glycerol as raw material for the production of value added chemicals. This article sheds light on the market of this uniquely versatile chemical whose number of applications is unique amid all existing chemicals.
One of the most exciting and unforeseen developments of the chemical research has been the recent... more One of the most exciting and unforeseen developments of the chemical research has been the recent application of gold in catalysis. In fact, this metal has become an important tool in organic synthesis several years after the first reports on ethyne hydrochlorination and CO oxidation and now it is w...
Au (0) sols were obtained in aqueous solutions by reduction of NaAuCl4 with NaBH4 in the presence... more Au (0) sols were obtained in aqueous solutions by reduction of NaAuCl4 with NaBH4 in the presence of protective agents [the long chain compound poly (oxyethylene (23) lauryl ether (C12E23), the polymer poly {bis (2-chloroethyl) ether-alt-1, 3-bis [3-(dimethylamino) propyl ...
Gold on carbon oxidizes aldehydes to carboxylic acids in water solution under mild conditions wit... more Gold on carbon oxidizes aldehydes to carboxylic acids in water solution under mild conditions without loss of activity on recycling, as does not occur for platinum on carbon. Also scarcely soluble aldehydes can be oxidized but the reaction rate is slower. Experiments carried out in an organic solvent such as CCl 4 show a speed up of the reaction, in this solvent being recyclable both Au/C and Pt/C. Another explored possibility was represented by carrying out the reaction in the absence of solvent. However, for solid aldehydes like p-and o-OH-PhCHO the water solvent represent the unique alternative.
Catalytic oxidation of vicinal diols to α-hydroxy carboxylates with dioxygen in alkaline solution... more Catalytic oxidation of vicinal diols to α-hydroxy carboxylates with dioxygen in alkaline solution has been performed by using gold based catalysts. The optimization of the catalytic system has highlighted the influence of the support and preparation method on both activity and selectivity. Under mild conditions (T = 343-363 K, pO 2 = 300 kPa (absolute)) high selectivities (90-100%) toward monooxygenation in the cases of ethane-1,2-diol and propane-1,2-diol were achieved at high diol conversions (80-94%). The racemization of optically active propane-1,2-diol during its oxidation as well as isotopic H-D exchange experiments allowed us to deduce new features in the mechanism of diol oxidation and concerning the dependence of selectivity on reaction conditions. The recycling of gold on carbon catalyst revealed its good resistance toward deactivation, greater than palladium or platinum on carbon catalysts which were respectively affected by metal leaching and a considerable loss of selectivity.
The selective oxidation of D-glucose to D-gluconic acid was performed at both controlled (7-9.5) ... more The selective oxidation of D-glucose to D-gluconic acid was performed at both controlled (7-9.5) and free pH values in an aqueous solution in the presence of a gold on carbon catalyst using dioxygen as the oxidant under mild conditions (323-373 K, pO 2 = 100-300 kPa). No isomerization of glucose to fructose was observed during the reaction, and total selectivity to D-gluconate was obtained. A comparative study of gold and commercial palladium and platinum-derived catalysts highlighted the unique property of supported gold, i.e., it is active at low pH (2.5), whereas at a buffered higher pH (9.5), gold and bismuth-doped platinumpalladium on carbon catalysts show comparable selectivity, though gold has a higher activity. Moreover, upon recycling, gold is more stable toward deactivation, although this also depends on the operative pH.
The progressive poisoning effect of different molecules on carbon supported gold catalysts has be... more The progressive poisoning effect of different molecules on carbon supported gold catalysts has been evaluated during the aerobic oxidation of glucose. A geometrical model has been derived for describing the morphological properties of two catalysts made of carbon supported gold particles having a known size distribution centered at 3.30 and 7.89 nm respectively. The observed deactivation trend follows the order thiocyanate > cyanide ≈ cysteine > thiourea and it obeys an exponential law. The kinetics of catalyst deactivation has been interpreted by considering the important contribute of electronic factors which overlap the space shielding of active sites, due to long range poison-catalyst interaction influencing the entire metal particle. Considering the nature of the molecules showing a high poisoning effect and the promoting effect of OH − , a molecular model for electronic interactions in gold nanoparticles during the aerobic oxidation of glucose has been proposed where the dioxygen reduction step is differently influenced by soft and hard-nucleophiles.
One of the strategic building blocks in organic synthesis is 3-hydroxypropionic acid, which is pa... more One of the strategic building blocks in organic synthesis is 3-hydroxypropionic acid, which is particularly important for the manufacture of high performance polymers. However, to date, despite many attempts using both biological and chemical routes, no large scale effective process for manufacturing 3-hydroxypropionic acid has been developed. One potentially useful starting point is from allyl alcohol, as this can be obtained in principle from the dehydration of glycerol, thereby presenting a bio-renewable green pathway to this important building block. The catalytic transformation of allyl alcohol to 3-hydroxypropionic acid presents interesting challenges in catalyst design, particularly with respect to the control of selectivity among the products that can be expected, as acrylic acid, acrolein and glyceric acid can also be formed. In this paper, we present a novel eco-sustainable catalytic pathway leading to 3-hydroxypropionic acid, which highlights the outstanding potential of gold-based and bimetallic catalysts in the aerobic oxidation of allyl alcohol.
An environmentally benign oxidation of benzyl alcohol to benzaldehyde with hydrogen peroxide as o... more An environmentally benign oxidation of benzyl alcohol to benzaldehyde with hydrogen peroxide as oxidant and metal dodecanesulfonate salts as catalysts was conducted under solvent-free condition by biphasic catalysis. Ferric tridodecanesulfonate showed excellent catalytic activity exhibiting complete conversion of benzyl alcohol with 194.4 mol/mol cat turnover number (TON) and nearly 100% selectivity to benzaldehyde at ambient pressure and 90 • C. This catalyst can be recovered and reused for three times without a significant loss in its activity and selectivity.
ABSTRACT This article reviews the metal catalyzed syntheses of aniline and pyrrole leading to con... more ABSTRACT This article reviews the metal catalyzed syntheses of aniline and pyrrole leading to conductive polymers. Considering that these materials are commonly produced via electrochemical or chemical processes, catalytic methods could represent a strategic tool for improved technologies based on the use of clean reagents, such as dioxygen and hydrogen peroxide. The advantage of avoiding either the use of a large amount of reagents or the formation of unsustainable amounts of by-products is highlighted. Beside synthetic and mechanistic aspects of the catalytic preparation of polyaniline and polypyrrole, a critical description of the morphological properties, related to the choice of the catalytic system, is presented.
Differently stabilised metal sols have been used as precursors in the preparation of heterogeneou... more Differently stabilised metal sols have been used as precursors in the preparation of heterogeneous gold catalysts for liquid phase oxidation in water solution. The methodology of sols generation appears to be fundamental to obtaining nanoparticles; the support, instead, plays an important role in maintaining particle dimension and morphology. Three different materials (␥-Al 2 O 3 , SiO 2 and activated carbon) have been used as the supporting agents for different gold sols that were obtained by reducing HAuCl 4 with NaBH 4 in the presence of polyvinylalcohol (PVA) or polyvinylpirrolidone (PVP) and with the tetrakis(hydroxymethyl)phosphonium chloride (THPC)/NaOH system. During the immobilisation step, the maintenance of the particle dimension observed in solution depends on both the support and the type of sol. The gold particle mean size of the colloidal suspension is more easily maintained on oxidic supports than on carbon, the latter apparently needing both steric and polar stabilisation of the gold particle. Comparison of Au/␥-Al 2 O 3 and Au/C catalyst activity in the liquid phase oxidation of ethylene glycol to glycolate highlighted the peculiarity of gold on carbon catalysts; in fact, the normally observed trend of reactivity is partially reversed, medium sized gold particle being the most active.
Dedicated to the humanity and scientific creativity of Prof. Mauro Graziani in the occasion of hi... more Dedicated to the humanity and scientific creativity of Prof. Mauro Graziani in the occasion of his 75th birthday.
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