Giuseppe Filardo

Electrochemical carboxylation of aldehydes and ketones with sacrificial aluminum anodes.

Abstract The electrocarboxylation of aldehydes to the corresponding α-hydroxyacids was described as impossible with conventional electrochemical systems. It is reported here that it is possible to realize it in diaphragmless cells making of sacrificial aluminum anodes. The method can be used also for the electrocarboxylation of ketones with good yields.

A new simple static method for the determination of solubilities of condensed compounds in supercritical fluids

Abstract A simple static method based on gravimetric measurements has been adopted to measure the solubility of benzenecarboxylic acid, 2-hydroxy-benzenecarboxylic acid, 4-hydroxy-benzenecarboxylic acid and 1,8-dihydroxyanthraquinone along several isotherms in the temperature range 318–357 K and the pressure interval 7–23 MPa. Solubility data have been correlated with the Zieger–Eckert approach, using the Fedor atomic and group contribution method to estimate the solubility parameter and the molar volume of the solutes. A good agreement was obtained between data reported in the literature and those determined using the proposed method which allows one to measure solubility mole fraction as low as 10 −5 . Provided that a suitable analytical technique is adopted the method can be extended also to multicomponent systems.

Electrochemical carboxylation of benzal chloride

Abstract The clectrocarboxylation of benzal chloride to -chlorophenylacetic and phenylmalonic acids is realized in diaphragmless cells with aluminium sacrificial anodes. Yields respectively up to 50% and 30% can be obtained. Phenylacetic acid is always present among the products.

Electrochemical carboxylation of organic substrates. Synthesis of carboxylic derivatives of acenaphthylene

The electrochemical carboxylation of acenaphthylene totrans-acenaphthene-1,2-dicarboxylic acid and acenaphthene-1-carboxylic acid has been investigated. The yields of the synthesis are influenced by the cathode material by the current density and, in the case of acenaphthene-1-carboxylic acid, by the pressure of carbon dioxide. In preparative experiments, performed in a ‘gas lift’ electrochemical cell, up to 100 g oftrans-acenaphthene-1,2-dicarboxylic acid were obtained at cathodic current densities of 40 mA cm−2 and with current yields greater than or equal to 80%.

The electrochemistry of carbon monoxide reductive cyclotetramerization to squarate anion

Abstract The electrochemical reduction, of carbon monoxide to C4O2−4 squarate anion is investigated. Particular attention is devoted to the influence that solvents, electrolytes, electrodes and carbon monoxide pressure have on the yields. The main feature appears to be that strictly controlled conditions are not necessary for cyclotetramerization. In dmf — Bu4NBr the following yields vs reacted CO and circulated charge were obtained with different cathodes: Pt(49%, 34%); Au(48%, 29%); Al(47%, 38%); stainless steel (36%, 33%); graphite (39%, 31%). A distinct influence of the supporting electrolyte (inorganic and tetraalkylammonium halides) was however observed.

Catalytic systems based on transition metals for the carbonylation of methanol to dimethylcarbonate

Abstract The results of an investigation on catalytic systems arising from the electrochemical activation of salts and complexes of several transition metals for the carbonylation of methanol to dimethylcarbonate (DMC) are reported. Metals were tested as inorganic salts or complexes with ligands such as 2,2′-bipyridine (bipy), 1,6-bis (2-oxyphenyl)-2,5-diaza-1,5-hexadiene (salen), 2,4-pentanedionate (acac), triphenylphosphine (TPP) in methanol at room temperature saturated with carbon monoxide at atmospheric pressure. Best faradic yields vs DMC were observed as follows: CuCl(bipy): 84.8%; PdCl 2 (bipy): 64.0%; CoCl 2 : 26.0%; RhCl 3 : 25.0%; AgBF 4 (bipy): 10.2%; AuCl 3 : 9.4%; Cr(acac) 3 : 6.7%; PtCl 2 (bipy): 2.1%; NiCl 2 : 1.8%. The influence of the ligand on faradic yields has been also investigated.

Electrochemical activation of transition metal complexes for the carbonylation of methanol to dimethylcarbonate

Abstract The preliminary results on the electrochemical activation of catalytic systems based on copper and cobalt complexes for the carbonylation of methanol to dimethylcarbonate at room temperature and atmospheric pressure are reported. Faradic yields up to 70%, with very high selectivity towards dimethylcarbonate, were observed with CuCl(2,2′-bipyridine). Positive results were also obtained, although with poorer catalytic activity, with other complexes such as CuCl(tetramethylethylenediamine), [Co(1,6-bis(2-oxyphenyl)-2, 5-diaza-1,5-hexadiene)]0.5 H2O and Co(2,4-pentanedionate)2.

A one-pot method to enhance dissolution rate of low solubility drug molecules using dispersion polymerization in supercritical carbon dioxide

The surfactant assisted polymerization of 1-vinyl-2-pyrrolidone in supercritical carbon dioxide in the presence of Piroxicam, selected as a model of a low aqueous solubility drug, was studied in order to prepare in a single step a polymeric composite to enhance the rate of dissolution of the pharmaceutical compound. Reactive entrapping was carried out at 65 degrees C in the P range 21-38MPa. Under proper operative conditions we obtained the composite under the form of sub-micron spherical particles with relatively narrow particle size distribution. Drug loadings higher than 12% (w/w) were obtained and XRD and Raman spectroscopy suggest that the anti-inflammatory agent is dispersed in the matrix with a non-crystalline structure. The dissolution rate of the drug from the composites was significantly faster both than that of the pure compound and of its physical mixture with the polymer. Collected results suggest that the proposed one-pot process can be used to prepare polymer based composites to increase bioavailability of low solubility drugs without utilization of toxic solvents and under mild temperature conditions.

Electrochemical Syntheses Involving Carbon Dioxide

The recent developments of electrosynthetic processes involving carbon dioxide are reviewed. Both processes involving carbon dioxide alone and electrocarboxylations are taken under consideration. The first of these two fields, mainly projected towards the production of basic chemicals such as methanol or carbon monoxide, is at present at a stage of fundamental research. Some interesting developments have recently appeared in the literature, concerning the use of electrode materials, or of transition metal complexes with particular catalytic activity. Electrocarboxylations are at a stage of more applicative development: some processes have reached the stage of pilot plant, and other have interesting, perspectives of application. A considerable effort has been devoted to the development of processes in undivided cells, with anodic reactions involving the oxidation of oxalates or formates, or the dissolution of sacrificial anodes. Specially designed electrochemical reactors have also been developed. The proper application field for electrocarboxylation processes appears to be the production of fine chemicals.

Electrochemical production of initiators for polymerization processes

The most important technological interest in initiator production lies, in the electrosynthesis of complex catalytic systems, i. e. coordination compounds and Ziegler-Natta catalysts, although the choice of olefins to be polymerized with these electrosynthesized complexes is still limited to ethylene and to very few other monomers.