Isabella Chiarotto

Electropolymerization of hydroxybenzene and aminobenzene isomers on platinum electrodes to assemble interference-free electrochemical biosensors

Abstract Hydroxybenzene and aminobenzene isomers have been electropolymerized on platinum electrodes together with oxidase enzymes for preparation and analytical evaluation of electrochemical biosensors. A conventional three electrode system was assembled for the electropolymerization of these compounds which led to the formation of poly(hydroxybenzene) and poly(aminobenzene). Different scan rates and scan ranges of potential were investigated and selected according to the monomer used. The time of electropolymerization was from 7 min to 4h. All the electrodes with the polymer films formed were tested for H 2 O 2 by cyclic voltammetry. Compounds as ascorbate, urate and acetaminophen, which are a common source of interferences in electrochemical biosensors analysis, based on H 2 O 2 detection, were tested. Results showed an oxidation peak of H 2 O 2 at the bare electrode and in all the electropolymerized probes, whereas for the interfering compounds the oxidation peak at electropolymerized probes was considerably reduced or not observed. When the electropolymerization was carried out in presence of the enzyme glucose oxidase, again the probe did not respond to the interferents, but gave a current signal to glucose in the range of 0.05 to 5mmol/L.

Isopropenyl acetate, a remarkable, cheap and acylating agent of amines under solvent- and catalyst-free conditions: a systematic investigation

Isopropenyl acetate was proved to be an efficient reagent for acetylation of amine in the absence of solvent and catalyst. The corresponding acetamides were obtained in very high yields without any purification.

Palladium-catalyzed electrochemical carbonylation of 2-amino-1-alkanols to oxazolidin-2-ones under very mild conditions

Abstract A new procedure for an efficient synthesis of oxazolidin-2-ones was developed. 2-Amino-1-alkanols undergo oxidative carbonylation under atmospheric pressure of carbon monoxide at room temperature using Pd(II) catalyst in combination with its anodic recycling at a graphite electrode.

Electrosynthesis of Aromatic Aldehydes by Palladium-Catalyzed Carbonylation of Aryl Iodides in the Presence of Formic Acid

The palladium-catalyzed electrocarbonylation of aryl halides performed in the presence of formic acid under one atmosphere of carbon monoxide affords aromatic aldehydes in good to high yields.

Electrochemical behaviour of PdII(PPh3)2Cl2 in the presence of carbon monoxide and its use in the palladium-catalyzed electrochemical formylation of iodoanisole

Abstract “Pd °(PPh 3 ) 2 ” generated by electroreduction of Pd II (PPh 3 ) 2 Cl 2 in the presence of carbon monoxide exists mainly in the form of low-ligated zerovalent palladium complex Pd °(PPh 3 ) 2 CO. On the basis of the experimental results, a mechanism is proposed for its formation. The oxidative addition of 4-iodoanisole to zerovalent palladium centre to afford a cyclic palladium(II) centre seems to be very efficient, but the 4-anisaldehyde formation undergoes severe competition with the two-electron reduction yielding anisole.

Direct vs indirect route in the activation of aroylpalladium(II) complexes by electron transfer

Abstract Based on mechanistic investigations, it is established that it is not possible to invert the reactivity of aroyl halides, ArCO-X, and make them react with electrophiles, in the presence of a palladium catalyst and a source of electron. Indeed, the key intermediate ArCO-Pd-XL 2 (L = PPh 3 ) whose activation by electron transfer in the presence of an electrophile would produce the coupling product ArCO-E, is less easily reduced than the corresponding aroyl halide. However, an indirect palladium catalyzed process for the synthesis of ArCO-E derivatives is proposed, from aryl halides, carbon monoxide and an electron source. The efficiency of the second process comes from the fact that the intermediate ArCO-Pd-XL 2 , formed by reaction of CO with Ar-Pd-XL 2 , is more easily reduced than the aryl halide and the transient Ar-Pd-XL 2 complex.

First direct evidence of N-heterocyclic carbene in BMIm acetate ionic liquids. An electrochemical and chemical study on the role of temperature

Cyclic voltammetry provides the first direct evidence of N-heterocyclic carbene (NHC) presence in neat 1-butyl-3-methylimidazolium acetate ionic liquid (BMImAcO) at 120 °C. The NHC existence, proved by its oxidation current in cyclic voltammetry, was confirmed by the formation of a PhCHO–NHC adduct in the pure ionic liquid. The role of the temperature was considered.

PALLADIUM-CATALYZED ELECTROCHEMICAL CARBONYLATION OF ALKYNES UNDER VERY MILD CONDITIONS

ABSTRACT Terminal alkynes were carbonylated under very mild conditions to yield acetylenecarboxylates under atmospheric pressure of carbon monoxide at room temperature using palladium(II) catalyst in combination with its anodic recycling at a graphite electrodes.

Palladium-catalysed electrochemical reduction of vinyl and aryl triflates

Abstract The reduction of vinyl and aryl triflates 1 , in the presence of stoichiometric amounts of benzoic acid and catalytic amounts of PdCl 2 (PPh 3 ) 2 results in the formation of the corresponding alkenes and arenes 2 . Most probably, the reaction proceeds via a catalytic cycle initiated by the one-step two-electron reduction of the palladium complex followed by oxidative addition of unsaturated triflates to the low-ligated zerovalent palladium complex Pd 0 (PPh 3 ) 2 Cl − . The resultant σ-vinyl and σ-arylpalladium(II) intermediate undergoes a one-step two-electron reduction to afford 2 in moderate to good yield, regenerating the low-ligated zerovalent palladium complex.

Characterization of naproxen-polymer conjugates for drug-delivery.

Abstract The synthesis and the characterization of three new naproxen decorated polymers are described. A versatile and general approach is employed to link the drug to polymers, affording the derivatives with a very high degree of purity. The release of the drug from the conjugates proved to be exceptionally slow, even in acidic aqueous media, and the kinetic of the process seems to be triggered by their solubility in water. On the other hand, the interesting outcome of the first ex vivo drug release experiments on human blood samples makes this preliminary study valuable for future investigations on the use of these polymeric prodrugs in in vivo treatment of inflammatory states.