Potenzo Giannoccaro

Pd–benzothiazole carbene catalysed carbonylation of aryl halides in ionic liquids

Abstract The carbonylations of aryl halides with the Pd–carbene catalyst 1 were studied both in molecular solvents and in ionic liquids (ILs). Among the ILs, tetrabutylammonium bromide (TBAB) was found to give better results. Under these conditions the catalyst, when recovered and reused, did not show a significant decrease of activity. The role of TBAB on the catalyst stability is discussed.

Hidrido-complexes of iron(IV) and iron(II)

Abstract The preparation and properties are described of hydrido-complexes of iron(IV), FeH 4 L 3 (L=PetPh 2 , PBuPh 2 ) and of iron(II), FeH 2 (PEtPh 2 ) 3 , FeHCl(dp) 2 , FeH 2 (dp) 2 [dp=C 2 H 4 (PPh 2 ) 2 ].

Palladium-catalysed N,N′-disubstituted urea synthesis by oxidative carbonylation of amines under CO and O2 at atmospheric pressure

Abstract N,N′-disubstituted ureas have been obtained in good yields by reaction of aromatic and aliphatic primary amines in alcohol solution with CO and O2 under mild conditions (70–90°C, 1 atm) and in the presence of catalytic amounts of PdCl2 or a palladium(II) complex. Under more drastic temperature and pressure conditions carbamate esters were obtained instead. In the aniline carbonylation, the catalysis involves the following reactions: Reaction (1) occurs at room temperature but more drastic conditions (70–90°C) are necessary for reaction (2). The influence of onium salts, such as PhNH3+X− (X = Cl, I) or CuCl2, on the catalytic activity has also been studied and the best results obtained with CuCl2. A side reaction involving carbon monoxide oxidation was almost suppressed when the reactions were carried out in alcohol, but enhanced when THF or dimethoxypropane was used as solvent.

Oxidative carbonylation of aniline catalyzed by Pd(II)-2,2'-bipyridyl complex intercalated in α-zirconium-phosphate

Abstract Palladium(II) and palladium(II)-copper(II) complexes (with N-donor ligands intercalated between the layers of α-zirconium phosphate) have been employed in the oxidative carbonylation of aniline. The catalytic activity of the materials has been studied together with the properties of α-zirconium phosphate as a supporting agent. Their very low activity observed in an initial induction period slowly increases to more marked levels in mild working conditions (80 °C, atmospheric pressure); in more drastic conditions diphenylurea and methyl carbamate are produced in a non-selective way due to a concomitant oxidation of aniline. By pre-heating the materials at 130 °C under CO or CO/O2, an increase of the catalytic activity is obtained, and the treated systems are able to catalyze selectively the carbonylation of aniline in mild conditions. By submitting the pretreated systems to a series of catalytic cycles and by re-employing the same catalyst in each cycle, a decrease in activity is observed until complete deactivation of the catalyst, when Pd is almost completely eliminated by the solid. On the basis of the analysis of the pretreated sample before and after deactivation, this behaviour is ascribed to migration of the Pd from the inner layers to the surface of the solid matrix and to its subsequent solubilization in the reaction medium.

Nitrogen fixation. : II. Dinitrogen-complexes of iron

Abstract The preparation and properties of dihydridodinitrogen complexes of iron(II), FeH 2 (N 2 )L 3 (L=PetPh 2 , PBuPh 2 ) are described. FeH 2 (N 2 )(PEtPh 2 ) 3 reacts with CO, to give the very stable FeH 2 (CO)(PEtPh 2 ) 3 . Both these complexes react in a 1:1 ration with AlEt 3 and possible routes of reaction are discussed.

New cationic hydrido and hydrido-dinitrogen complexes of iron

A number of catlonic hydrldo complexes of transitmn metals, stabilized by tertiary phosphmes, have been described in the last few years Among the metals of the nickel and of the cobalt group, many very stable derlvatlves of platmtim’-6 and lr~dmm7-*0, but only a few of palladmm” , nickel’*, rhodmm13 and cobalt I4 are known Among the metals of the iron group, only a series of catlonlc hydrldo complexes of general formula trans-[MH(L)(depe)2]BPh4 (M = Fe, Ru, OS, L = CO, p-Me0 C6H4 NC, N,, PhCN, depe = Et2P CH2 CH, PEt,) has been described”” We have now prepared a new, very stable catlomc hydrldo complex of formula [FeH(dppe)* ] Y (dppe = Ph, P-CH, CH, PPh2 , Y = BPh,, C104) This coordmatlvely unsaturated complex of Iron (II) reacts very easily with a number of neutral hgands to gve a new series of catromc hydrldo complexes of general formula trarzs-[FeH(L)(dppe),]Y (L = Me2 CO, N2, CO, NHs, Py, MeCN, PhCN), with H2 to gve the new catlomc hydrldo complex of iron [FeH3(dppe)2] Y, and with CO*, CS2, O2 and olefins to @ve compounds wluch have not yet been fully characterized The pentacoordmated catromc hydrldo complex of iron(H) has been obtained both by exchange under argon from FeHCl(dppe), (ref 16) according to the reaction

New catalytic system for the hydrogenation of ketones

Abstract Alcohols are produced in high yield by hydrogenation of several aliphatic and aromatic ketones with rhodium complexes as catalysts in the presence of strong alkali.

Methylchloroformate synthesis via direct interaction of palladium di(methoxycarbonyl) complexes with CuCl2: Utilization in the synthesis of carbonates and carbamates

Abstract ClCOOCH 3 has been obtained in very good yield by reaction of [PdL 2 (COOCH 3 ) 2 ] [L 2 = 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen)] with CuCl 2 . The in situ reaction of ClCOOCH 3 with alcohols or amines produces carbonates or carbamates.

Synthesis and reactivity toward gas molecules of chloro 2,6-di(diphenylphosphinomethyl)pyridine rhodium(I)

Abstract The synthesis of the title compound and of its adducts with O 2 , CO, CO 2 , SO 2 , tertiary phosphines is described. The reactions of the dioxygen adduct with sulfur dioxide and carbon monoxide are also reported.

Oxidative carbonylation of aliphatic amines catalysed by nickel-complexes

Abstract The catalytic activity of some nickel-complexes in the dioxygen-induced carbonylation of amines has been studied. N,N′-oxamides expected on the basis of a previous report. The study of the reaction mechanism shows that amines are carbonylated in a reductive step, during which either ureas or oxamides can be obtained depending on the amount of water present. When dioxygen is used as the oxidant the oxidative step produces water, which promotes the urea formation. The oxygen is also responsible for the low yields owing to a side reaction involving amine oxidation. These conclusions were confirmed when the carbonylations were carried out under pseudo-catalysis conditions, or when oxidants which do not produce water in the oxidative step were used.