Presence Of Phosphomolybdic Acid Research Articles

An Efficient Rapid Synthesis of Benzoxazoles and Benzothiazoles Using PMA.SiO2 at Room Temperature under Heterogeneous Conditions

: Treatment of 2-aminophenol (or 2-aminothiophenol) with aromatic aldehydes in the presence of phosphomolybdic acid on silica at room temperature affords the corresponding benzoxazoles (or benzothiazoles) in excellent yields (88- 96%) under heterogeneous conditions. Benzoxazoles and benzothiazoles are formed less than 10 min.

Synthesis of pomegranate-like Mo2C@C nanospheres for highly efficient microwave absorption

Transition metal carbides/carbon composites are appearing as attractive microwave absorption materials (MAMs) due to their positive synergistic effects as well as good chemical stability. In this study, we trigger the polymerization of pyrrole monomer in the presence of phosphomolybdic acid (PMo12) at room temperature, and then convert the homogeneous PMo12/polypyrrole (PMo12/PPy) nanospheres into Mo2C@C nanospheres under high-temperature inert atmosphere. The carbonization of PPy conjugated chains also induces the in situ formation of Mo2C nanoparticles, resulting in a unique pomegranate-like microstructure. The pyrolysis temperature plays important roles in determining the size and crystalline phase of Mo2C nanoparticles, chemical composition, and the relative graphitization degree of carbon framework. As a dual dielectric system, conductivity loss is primarily responsible for the consumption of electromagnetic energy in Mo2C@C nanospheres, and dipole orientation polarization and interfacial polarization provide auxiliary contribution in this process. It is found that high pyrolysis temperature favors powerful dielectric loss capability. However, the desirable microwave absorption is established in the composite from moderate pyrolysis temperature (700 °C), where the strongest reflection loss reaches −48.0 dB at 12.5 GHz and the integrated qualified bandwidth covers the frequency range of 3.5–18.0 GHz. This is because moderate pyrolysis temperature endows Mo2C@C nanospheres with proper attenuation capability and matched characteristic impedance. In view of its excellent microwave absorption performance and simple preparation method, such Mo2C@C nanospheres with pomegranate-like heterostructure will be a kind of promising candidate for lightweight and broadband MAMs in the future.

Phosphomolybdic Acid-Assisted Growth of Ultrathin Bismuth Nanosheets for Enhanced Electrocatalytic Reduction of CO2 to Formate.

Oxides containing two-dimensional metallic catalysts have shown enhanced catalytic activity, stability, and product selectivity. Porous three-dimensional structures maximize the accessibility of the active sites, thus enhancing the catalytic performance of the catalysts. By integrating these desirable features in a single catalyst, further improvement in catalytic activity and selectivity is expected. In this study, oxide-containing bismuth (Bi) nanosheets of about 4 nm thickness interconnected to form a porous three-dimensional structure were synthesized by electrodeposition in the presence of phosphomolybdic acid under hydrogen evolution conditions. These Bi nanosheets catalyze CO2 reduction in a CO2 -saturated 0.5 m NaHCO3 solution to formate with a faradaic efficiency of 93±2 % at -0.86 V vs. RHE with a formate partial current density as high as 30 mA cm-2 . The Tafel slope of about 78 mV dec-1 suggests that the protonation of the adsorbed CO2 .- is the rate-limiting step.

Green synthesis of silver nanowires via ultraviolet irradiation catalyzed by phosphomolybdic acid and their antibacterial properties

In this study, we have fabricated well-defined silver nanowires by an ultraviolet (UV) irradiation technique in the presence of phosphomolybdic acid (PMo), which acted as a catalyst and stabilizing agent. The effect of fabrication parameters on the morphology of silver nanowires, such as initial concentrations of reactants, AgNO3 : PMo ratio, UV irradiation time, and temperature, are presented in detail. This suggests that the appropriate amount of PMo plays a relevant role in the formation of the silver nanowires, and temperature is another important factor determining the morphology of the silver nanowires. Furthermore, the antibacterial properties of silver nanowires was investigated against Escherichia coli, Staphylococcus aureus and Bacillus subtilis, and the mean diameters of the inhibition zones are 15.4 mm, 20.9 mm and 26.7 mm, respectively. This work provides a simple and green method for the synthesis of silver nanowires in aqueous solution with promising antibacterial properties.

ChemInform Abstract: Phosphomolybdic Acid: An Efficient and Recyclable Solid Acid Catalyst for the Synthesis of 4,4′‐(Arylmethylene)bis(1H‐pyrazol‐5‐ols).

Abstract An efficient and environmentally friendly method has been developed for synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ols) by condensation reaction of aromatic aldehydes with 3-methyl-l-phenyl-5-pyrazolone in the presence of phosphomolybdic acid as a recyclable catalyst in ethanol at ambient temperature in excellent yields.

A facile route for rapid synthesis of cubic mesoporous silica

Ordered SBA-16-type mesoporous silica materials (MSMs) have been rapidly synthesized under weak acidic media in the presence of phosphomolybdic acid (abbreviated to HPMo) and inorganic salts (NaCl, Na2SO4, KCl and K2SO4) by using nonionic triblock copolymer F127 as a structure directing agent and tetraethylorthosilicate (TEOS) as a silica source. Both HPMo and inorganic salts play a crucial role in promoting SBA-16-type MSMs formation, and the reaction products have still retained an ordered body-centered cubic (Im3m) mesostructure after treated with 100°C water for 120h. The high hydrothermal stability of reaction products might be attributed to the higher degree of polymerization and condensation of silanol groups, arisen from the synergistic effect of rapid nucleation with the aid of HPMo and salt effect during the crystallization process.

Phosphomolybdic Acid: An Efficient and Recyclable Solid Acid Catalyst for the Synthesis of 4,4′-(Arylmethylene)bis(1H-pyrazol-5-ols)

An efficient and environmentally friendly method has been developed for synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ols) by condensation reaction of aromatic aldehydes with 3-methyl-l-phenyl-5-pyrazolone in the presence of phosphomolybdic acid as a recyclable catalyst in ethanol at ambient temperature in excellent yields.

Investigation on the Synthesis of α-Terpinene and Maleic Anhydride Adduct Catalyzed by Heteropolyacid

α-pinene was isomerized in the presence of phosphomolybdic acid. One of the products, α-terpinene, can react with maleic anhydride to form α-terpinene and maleic anhydride adduct (TMA). The optimum conditions for the synthesis of TMA have been investigated. The yield of 83% can be attained with the heterogeneous catalyst phosphomolybdic acid on active carbon (PMA/C), and can maintain ~67% after the catalyst was used for 5 times.

Novel Conducting Polymer-Heteropoly Acid Hybrid Material for Artificial Photosynthetic Membranes

Artificial photosynthetic (AP) approaches to convert and store solar energy will require membranes capable of conducting both ions and electrons while remaining relatively transparent and chemically stable. A new approach is applied herein involving previously described in situ chemical polymerization of electronically conducting poly(3,4-ethylenedioxythiophene) (PEDOT) in the presence of proton conducting heteropoly acid (HPA) phosphomolybdic acid (PMA). The electrochemical behaviour of the PEDOT/PMA hybrid material was investigated and it was found that the conducting polymer (CP) is susceptible to irreversible oxidative processes at potentials where water is oxidized. This will be problematic in AP devices should the process occur in very close proximity to a conducting polymer-based membrane. It was found that PEDOT grants the system good electrical performance in terms of conductivity and stability over a large pH window; however, the presence of PMA was not found to provide sufficient proton conductivity. This was addressed in an additional study by tuning the ionic (and in turn, electronic) conductivity in creating composites with the proton-permselective polymer Nafion. It was found that a material of this nature with near-equal conductivity for optimal chemical conversion efficiency will consist of roughly three parts Nafion and one part PEDOT/PMA.

Hybrid organic–inorganic materials based on poly(o-phenylenediamine) and polyoxometallate functionalized carbon nanotubes

The chemical polymerization of o-phenylenediamine (OPD) on single-walled carbon nanotubes (SWCNTs) in the presence of phosphomolybdic acid (H 3PMo 12O 40 xH 2O) has been studied by surface enhanced resonant Raman scattering (SERRS) spectroscopy. One demonstrates that an organic–inorganic hybrid composite of the type poly(o-phenylenediamine)/polyoxometallate-functionalized SWCNTs is produced by the chemical interaction between polyoxometallate-functionalized SWCNTs and poly(o-phenylenediamine) (POPD) doped with [H 2PMo 12O 40] − ions. According to TEM investigations, a result of the chemical interaction of SWCNT with H 3PMo 12O 40 xH 2O is the formation into the composite mass of tube fragments of shorter length, which behave like closed shell fullerenes since Raman fingerprint is given by lines situated at 240–275 and 1450–1472 cm −1. The chemical polymerization of OPD on SWCNTs achieved in the absence of H 3PMo 12O 40 xH 2O leads to a covalent functionalization of the wall side of the tubes, which is revealed in Raman spectra, recorded at the excitation wavelength of 514 nm, by an enhancement of the lines associated with the tangential vibrational modes of SWCNTs. Using FTIR spectroscopy, significant hindrance steric effects are evidenced in the POPD/polyoxometallate-functionalized SWCNT composite.

Rapid Synthesis of Mesoporous SBA-16 Silica in Weakly Acidic Media

Abstract Well-ordered mesoporous SBA-16 (with Im3m symmetry) has been synthesized within 6 h in weakly acidic media in the presence of phosphomolybdic acid and inorganic salts. The aforementioned materials were characterized by XRD, N2 adsorption–desorption, and TG-DTA.

Aerobic Oxidation of 3-Iodomethyl-Δ3-cephem-4-carboxylate to 3-Formyl-Δ3-cephem-4-carboxylate through 3-Hydroperoxymethyl-Δ3-cephem-4-carboxylate

Abstract Aerobic oxidation of p-methoxybenzyl 3-iodomethyl-8-oxo-7-phenylacetamido-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate (3-iodomethyl-7-phenylacetamido-Δ3-cephem-4-carboxylate) in N-methyl-2-pyrrolidone in the presence of phosphomolybdic acid mainly afforded the corresponding 3-formyl-Δ3-cephem-4-carboxylate, while similar aerobic oxidation in the presence of potassium iodide gave 3-hydroxymethyl-Δ3-cephem-4-carboxylate as a major product. 3-Hydroperoxymethyl-Δ3-cephem-4-carboxylate was isolated as a primary product in the aerobic oxidation, which was subsequently converted to either 3-formyl-Δ3-cephem-4-carboxylate by dehydration with phosphomolybdic acid or 3-hydroxymethyl-Δ3-cephem-4-carboxylate by reduction with potassium iodide.

17α-Acyloxy-3,5-pregnadien-20-one誘導体の合成

In order to examine their oral progestational activity, some 17α-acyloxy-3, 5-pregnadien-20-one derivatives (IIIa, IIIb, IIIc, IIId, IIIe, VI, VII, VIII, and IX) were synthesized. III, VI, and VII were obtained by dehydration of 4-en-3-ol derivatives, which were obtained by selective reduction of 17α-acyloxyprogesterone derivatives with sodium borohydride, in the presence of phosphomolybdic acid in acetone solution at room temperature or boiling temperature. VIII and IX were obtained by the reaction of 17α-acyloxyprogesterone derivatives with acetyl chloride at room temperature. The effect of substituents in 3, 5-diene derivatives on the oral progestational activity was discussed.

The extraction of caesium with nitrobenzene in the presence of phosphomolybdic acid

The main factors controlling the distribution of caesium between the aqueous phase and a nitrobenzene phase in presence of phosphomolybdic acid were investigated. Data on the distribution of the heteropolyacid are given. The selectivity of caesium extraction was evaluated. The possibility of separating caesium by this method for analytical purposes was demonstrated in isolating caesium from a mixture of long-lived fission products and in isolating caesium from rubidium by repeated extraction.