Antonino Morvillo

Ruthenium-catalyzed oxygenation of saturated hydrocarbons by t-butylhydroperoxide

Abstract Saturated hydrocarbons such as adamantane, cyclooctane, cyclohexane, hexane and heptane are oxygenated by t-butylhydroperoxide (TBHP) or hypochlorite in the presence of the homogeneous catalysts K5[Ru(H2O)PW11O39] and cis-[Ru(H2O)2(dmso)4](BF4)2. With the latter a free-radical mechanism appears to dominate when TBHP is employed, thus accounting for the remarkably high rates of alkane conversions (up to ca. 8 turnovers per minute). Hypochlorite oxygenations proceed via oxo—metal species.

Oxidative addition of alkanenitriles to nickel(0) complexes via π-intermediates

Abstract The alkanenitriles R(C 6 H 5 )CHCN (R = H, CH 3 ) coordinate rapidly and quantitatively through the CN group to the complexes [Ni(PCy 3 ) 2 ] or [{Ni(PCy 3 ) 2 } 2 N 2 ]. Both the end-on [Ni(PCy 3 ) 2 (σ-R′CN)] and the edge-on [Ni(PCy 34 )(π-R′CN)] adducts are formed,and are present in an equilibrium the position of which is governed by the amount of added PCy 3 . The π-complexes react to give the cyano-organometal complexes [Ni(PCy 3 ) n (R′)(CN)] through an oxidative addition involving splitting of the CCN bond. The complexes obtained are unstable and slowly decompose under the reaction conditions to give the coupling R′-R′ (R = H) or the β-elimination R′(-H) (R = CH 3 ) products. The kinetics of the reaction and the stereochemical result suggest a template mechanism in agreement with the findings above.

Cationic complexes of rhodium(I) as catalysts in the homogeneous O2-oxidation of terminal alkenes to methyl ketones

Abstract [Rh(LL) 2 ] + , [Rh(LL)(diene)] + and [Rh(LL)S 2 ] + complexes are effective as catalysts for the oxidation by dioxygen of terminal olefins to methyl ketones. The complexes act as monooxygenases, the second oxygen atom being transferred to the alcohol solvent.

Oxidation of dibenzothiophene by hydrogen peroxide or monopersulfate and metal–sulfophthalocyanine catalysts: an easy access to biphenylsultone or 2-(2′-hydroxybiphenyl)sulfonate under mild conditions

A catalytic system consisting of metal–sulfophthalocyanines (MPcS) and monopersulfate or hydrogen peroxide as oxidants was effective in the dibenzothiophene oxidative desulfurization with various yields and selectivities. Oxidations were conducted at room temperature in acetonitrile–water mixed solvent. The dibenzothiophene oxidation involved the step by step formation of dibenzothiophene dioxide and biphenylsultone (dibenzo-1,2-oxathiine 2,2-dioxide), followed by hydrolysis to 2(2′-hydroxybiphenyl)sulfonate and finally catalytic desulfurization to 2-hydroxybiphenyl (2-phenylphenol) and sulfuric acid; all the intermediate compounds were identified. Moreover, catalytic over-oxidation of 2-hydroxybiphenyl, with ring fission and formation of various oxidation products, among them carbon dioxide, oxalic and benzoic acid, was also observed. Among the various MPcS catalysts examined (M = Fe, Co and Ru), the ruthenium derivative exhibited the best performances with persulfate and iron derivative with hydrogen peroxide; in both cases the slow step of the process consisted in the oxidation of dibenzothiophene dioxide to biphenylsultone.

Ruthenium-catalyzed oxidative dehalogenation of organics

Abstract Water-soluble ruthenium(II) complexes are effective catalysts for the deep oxidation of chlorinated organics in the presence of hydrogen peroxide or mono-persulfate at room temperature. Reactions are conducted either in nitromethane–water two phase or in water–acetonitrile mixtures or in water alone, in the presence of a surfactant agent (if the case) with the ruthenium(II) catalysts [Ru(H 2 O) 2 (dmso) 4 ](BF 4 ) 4 , [RuCl 2 (dmso) 4 ] or [RuPcS] (dmso=dimethylsulfoxide; PcS=tetra-sulfo-phthalocyaninate). The oxidation of various chlorinated organics (chloro, bromo-, iodo- and nitro-benzene, polychlorobenzenes, polychlorophenols) was followed by monitoring the nature and the relative amounts of the final products: chlorinated substrates are often converted into hydrochloric acid and carbon dioxide. Factors such as solvent and oxidant affect the reactions, the most favorable conditions being achieved in aqueous media. Substituted benzenes are oxidized via an initial electrophilic attack followed by a series of faster steps, whereas with polychlorophenols, which are more sensitive to oxidation than substituted benzenes, the reaction is also radical in character.

Catalytic aerobic oxidation of allylic alcohols to carbonyl compounds under mild conditions

A new catalytic aerobic oxidation of alcohols to aldehydes under green conditions was developed (room temperature and pressure, water solution, open vials). The water-soluble platinum(II) tetrasulfophthalocyanine (PtPcS) catalyst showed the best selectivity for carbonyl derivatives, and in particular for α,β-unsaturated alcohols; the reactions are slow.

Direct synthesis of adipic acid by mono-persulfate oxidation of cyclohexane, cyclohexanone or cyclohexanol catalyzed by water-soluble transition-metal complexes

A catalytic system consisting of water-soluble metal sulfophthalocyanines (MPcS) or various ruthenium complexes and mono-persulfate as the oxidant was effective in the oxidation of cyclohexanone, cyclohexanol and cyclohexane to adipic acid with different yields and selectivity. Oxidations were conducted at room temperature and under atmospheric pressure in aqueous media (or, in the case of cyclohexane, in a water–neat substrate double phase). The oxidation of cyclohexanol involved step-by-step formation of cyclohexanone, e-caprolactone and 6-hydroxyhexanoic acid, all of which have been identified in the reaction mixtures; in selected cases moderate over-oxidation of adipic acid to glutaric and succinic acid was also observed. Various MPcS catalysts were examined (M = Fe, Co, Ni, Cu and Ru), and the ruthenium derivative exhibited the best performances in terms of rate and selectivity. Mono-persulfate was found to be a more convenient oxidizing reagent than hydrogen peroxide; related patterns were observed when H2O2 was used, however extended dismutation of the oxidant limited the overall yields. Cyclohexane underwent slow oxidation when reacted with persulfate (water–substrate double phase) in the presence of the water-soluble metal catalysts; adipic acid was selectively produced (95%) in the presence of RuPcS catalyst with yields as high as 21% (48 h). The catalytic performance of simpler ruthenium derivatives, such as [RuCl2(DMSO)4] (RuDMS) and K5[Ru(H2O)P11O39] (RuPW), was also examined for comparison purposes. A kinetic scheme for cyclohexane oxidation is proposed.

Ruthenium sulfophthalocyanine catalyst for the oxidation of chlorinated olefins with hydrogen peroxide

Abstract In aqueous solution and at room temperature, various α-chloro-alkenes are effectively dechlorinated by hydrogen peroxide oxidation using a water-soluble ruthenium(II)-tetrasulfophthalocyanine catalyst, RuPcS. The molecular structure of RuPcS has been elucidated by ESI-mass spectroscopy. In the reaction conditions, and specifically in acidic media, the complex rapidly gives rise to a novel species, most likely catalytically active, whose nature is investigated.

Cationic cobalt(I) carbonyl complexes containing secondary or tertiary phosphines. A direct synthesis from cobalt(II) salts.

Abstract Cobalt(I) carbonyl complexes of formula [Co(CO)n(P)5−n]ClO4 (n = 1, 2, 3; P = secondary or tertiary phosphine) have been prepared by reaction of CO under ambient conditions with Co(ClO4)2 · 6H2O and phosphine in isopropyl alcohol. The chemical and spectroscopic properties of these complexes are described and the stoichiometry and mechanism of the carbonylation reaction discussed.

Oxidation of C1–C4 alcohols by iron- and ruthenium-sulfophthalocyanine precatalysts with hydrogen peroxide or mono-persulfate in water

Abstract A catalytic system consisting of iron- or ruthenium-sulfophthalocyanine and hydrogen peroxide or mono-persulfate was effective in the oxidation of simple primary and secondary alcohols as well as of simple ketones. The oxidation reactions were conducted in aqueous media with turnover rates, defined as moles of product per mole of catalyst per minute, up to 5. Primary alcohols, including methanol, were selectively oxidized into the corresponding carboxylic acids. Secondary alcohols were transformed into the corresponding ketones, which were found to undergo further oxidation to esters via Baeyer–Villiger reaction, followed by hydrolysis or alternatively in the case of acetone via direct oxidation to acetic acid and CO 2 . Moreover, t -butyl alcohol was also found to be slowly oxidized into acetone and methanol. Analysis of the oxidation reaction of cyclobutanol indicated an ionic mechanism; no deuterium kinetic isotope effect was measured in the cases of methanol and ethanol. The mechanistic origin of the catalytic efficiency is also discussed.