Gilles Boni

Organo-catalyzed synthesis of aliphatic polycarbonates in solvent-free conditions

A new efficient and expeditious route to the synthesis of aliphatic polycarbonates, in solvent-free conditions and using 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO2) as a catalyst precursor, is described. The protocol consists of a two-step polymerization process involving the transesterification of dimethyl carbonate (DMC) with linear alkane diols and leading to high molecular weight homopolymers. The reaction went to completion quantitatively with the liberation of methanol as the only by-product. The in situ formation of N-heterocyclic carbene species resulting from BMIM-2-CO2 decarboxylation is suggested to be a key feature of the condensation process. The protocol was then applied to the copolymerization of diverse diols leading to the synthesis of polycarbonates with average segment lengths and random sequences.

Mono- and di-bridged heterobimetallic systems from group 5 hydride phosphido and hydride phosphino metalloligands. Crystal structure of Cp2Ta(H)( μ-H)( μ-PMe2)Cr(CO)4

The trihydrides Cp 2 MH 3 (M  Nb, Ta) react with chlorophosphines PR 2 Cl (R  Me, Ph) affording phosphonium salts [Cp 2 MH 2 (PR 2 H)] + , Cl − ( 2 (a, b) 2′ (a, b)) . Depending on the metal (Nb or Ta) and on the nature of the phosphine substituent (Me or Ph), deprotonation of these salts leads to hydride phosphino Cp 2 MH(PR 2 H) ( 3 (a, b) 3′a) or hydrided phosphido Cp 2 TaH 2 (PPh 2 ) ( 4′b ) metalloligands. These two kinds of complexes are able to bind [M′(CO) 5 ] or [M′(CO) 4 ] (M′  Cr, Mo, W) organometallic fragments to give mono- or di-bridged heterobimetallic systems. The crystallographic analysis of Cp 2 Ta(H)(μ-H)(μ-PMe 2 )Cr(CO) 4 ( 7′aCr ) is reported and discussed.

Diglycidylether of iso-eugenol: a suitable lignin-derived synthon for epoxy thermoset applications

A novel lignin-based synthon, diglycidylether of iso-eugenol (DGE-isoEu) is used as a prepolymer for the preparation of thermosetting resins. DGE-isoEu is synthesized in a two-step procedure with a satisfactory yield from bio-based iso-eugenol (isoEu, 2-methoxy-4-(1-propenyl)phenol) catalytically fragmented from lignin in an organosolv process. DGE-isoEu was fully characterized by NMR, MS and FTIR. Curing of the DGE-isoEu monomer has then been investigated in the presence of several carboxylic acid derivatives hardeners. The thermal and mechanical properties of each material were recorded showing, in particular, a high Tg and instantaneous modulus values in the range of 78–120 °C and 4.6–5.5 GPa, respectively. The lignin derived new materials give very attractive thermo-mechanical properties comparable to that of common BPA-containing epoxy resins.

1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solvent-free conditions

Summary The ring-opening polymerization of ε-caprolactone (ε-CL) and rac-lactide (rac-LA) under solvent-free conditions and using 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO2) as precatalyst is described. Linear and star-branched polyesters were synthesized by successive use of benzyl alcohol, ethylene glycol, glycerol and pentaerythritol as initiator alcohols, and the products were fully characterized by 1H and 13C{1H} NMR spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). BMIM-2-CO2 acts as an N-heterocyclic carbene precursor, resulting from in situ decarboxylation, either by heating under vacuo (method A) or by addition of NaBPh4 (method B). Possible catalytic and deactivation mechanisms are proposed.

Tantalocenehydridephosphorus chemistry.: Some new complexes and crystal structures of [CpCp′TaH2(PMe2H)]PF6 (Cp=C5H5, Cp′=C5H2tBu(Me)2) and Cp2Ta(H)(μ-PPh2,H)Fe(CO)3

Abstract The aim of this paper is to look for a better knowledge of the behaviour of bent tantalocenes that bear hydrides, phosphorus PR2X (R=Me, Ph; X=H, lone pair) and cyclopentadienyl (Cp=C5H5, Cp′=C5H2tBu(Me)2, Cp*=C5Me5) ligands. An orbital control of regioselectivity of insertion of the PR2 phosphide fragment of chlorophosphines PR2Cl into the central TaH bond of trihydrides Cp2TaH3 leading to the formation of metallophosphonium cations is discussed. Neutralisation of cationic complexes with strong bases leads either to the Ta(V)–phosphide or to the Ta(III)–phosphine species depending on the nature of the cyclopentadienyl ligand; good electron donor Cp′ and Cp* rings favour the formation of Ta(V)–phosphide species, while C5H5 orients neutralisation towards Ta(III)–phosphine ones. These trends are roughly confirmed by DFT calculations. The X-ray structure of the first tantalocene phosphonium ionic compound [CpCp′TaH2(PMe2H)]PF6 (Cp′=C5H2tBu(Me)2) as well as that of the bimetallic complex Cp2Ta(H)(μ-PPh2,H)Fe(CO)3 are also reported.

Characterizations of Thermoplastic Block Elastomers Based on Polybutadiene and ε -Caprolactone

A broad series of tri- and multiblock copolymers based on linear and branched oligomers of polybutadiene as central blocks and polycaprolactone (PCL) as block extremities are characterized by SEC, DSC, DMA, Dynamical Rheology and DRX. DSC analyses reveal phase separation between the two amorphous PB and PCL phases. By thermal analysis, the glass transition temperature of PCL is only detected for materials containing at least 80% w/w of PCL. This is attributed to the small length of the polyester blocks for copolymers containing less than 80% w/w of PCL. The increase of fusion heat with increasing PCL content in the copolymers is correlated to the greater ability of PCL chains to rearrange as HTPB amount decrease in the material. Regarding the evolution of the melting temperature of the various copolymers, the characterization by DMA and dynamical rheology confirms the behaviour observed by DSC. Mechanical and rheological properties (i.e., storage modulus and complex viscosities) were studied and reveal that the behavior of the copolymers depends on both the rate of PCL chains and on the nature of the elastomeric block.

Synthesis and Complexation of the Metalloligand {(η5‐C5H5)[η5‐C5Me3‐1,2‐(PPh2)2]TiCl2} (TiPHOS): The First Example of a 1,2‐Bis(diphenylphosphanyl)titanocene Derivative

The reaction of lithium 1,2-bis(diphenylphosphanyl)trimethylcyclopentadienide (1) with CpTiCl3 leads to the formation of the titanocene diphosphane {(η5-C5H5)[η5-C5Me3-1,2-(PPh2)2]TiCl2} (TiPHOS, 2). This metalloligand reacts readily with (NBD)Cr(CO)4 and W(CO)5(THF) to give, in both cases, the bimetallic chelate complexes (TiPHOS)Cr(CO)4 (3) and (TiPHOS)W(CO)4 (4). The structure of 4 has been determined by X-ray diffraction. The synthesis of a new early-late heterobimetallic complex (TiPHOS)Rh(CO)Cl (5) is reported.

Reactivity of bimetallic dibridged complexes Cp2Ta(H)(μ-H)(μ-PMe2)M′(CO)4 (M′ = Cr, Mo, W) toward two-electron donor ligands L (L = PR3, Me2P(CH2)nPMe2). Synthesis of linear trinuclear chain complexes Cp2Ta(H)2(μ-PMe2)M′(CO)4(Me2P(CH2)2PMe2)Cr(CO)5 (M′ = Mo, W)

Abstract The reaction of the heterobimetallic phosphido- and hydrido-bridged complexes Cp 2 TaH(μ-H)(μ-PMe 2 )M′(CO) 4 (M′ = Cr, Mo, W) ( 1–3 ) with phosphines (L = PPh 2 Me, PMe 2 Ph) or diphosphines (L = dmpm, dmpe) leads to Cp 2 Ta(H) 2 (μ-PMe 2 )M′(CO) 4 (L) ( 1a, 1b, c, d-3b, c, d ) with L regiospecifically coordinated to M′. Except for L = PPh 2 Me, the reaction is stereospecific, since a cis arrangement (with respect to the PMe 2 bridge) on the M′ site is obtained. The new compounds Cp 2 Ta(H) 2 (μ-PMe 2 )M′ (CO) 4 (Me 2 P(CH 2 ) 2 PMe 2 ) (M′ = Mo, W) are able to bind [Cr(CO) 5 ] fragments affording the linear trinuclear chain compounds Cp 2 Ta(H) 2 (μ-PMe 2 )M′(CO) 4 (Me 2 P(CH 5 ) ( 4,5 ). All new complexes have been fully characterized by NMR and IR spectroscopy, and by their elemental analyses.

Synthesis and reactivity of the phosphido-bridge complex [Cp2Ta(μ-CO)(μ-PMe2)Cr(CO)4]

Abstract The heterobimetallic complex [Cp2Ta(CO)(μ-PMe2)Cr(CO)5] 1 was prepared by reaction of [Cp2Ta(CO)(PMe2)] with [Cr(CO)5THF]. Irradiation of 1 afforded the dibridged compounf [Cp2Ta(μ-Pme2)Cr(CO)4] 2. Addition reactions between 2 and Lew is bases L (L  phosphines, or isonitriles) and produced [Cp2Ta(CO)(μ-PMe2)Cr(CO)4(L)] 3(a,b) with L regiospecifically coordinating to Cr. Depending on L, the reaction may be stereospecific, since the coordination of L can lead to cis or trans arrangements on the Cr site.

In Vitro Release of Local Anaesthetic and Anti-Inflammatory Drugs from Crosslinked Collagen Based Device

The drug delivery systems that are the object of this article take the form of a hydrophilic matrix (collagen or crosslinked collagen) containing a drug. These devices can be used as The model active agents, were chosen from the range of local anaesthetics (lidocaine hydrochloride), anti-inflammatory (diclofenac sodium salt) and antioxydant (caffeic acid). Whatever the drug affinity for water, in the first time of the experiments, the release appears to be systematically delayed when the matrix is crosslinked. For lidocaine hydrochloride based systems, as the amount of drug increases in the matrix, the high gap concentration between the matrix and the buffer solution promote the diffusion and a Fickian behavior is observed on the release curves. Depending on the chemical nature of the drug and its solubility, several interactions between the drug and the collagen matrix can be considered. A new drug delivery system containing caffeic acid as the anti-inflammatory and antioxydant molecule could be tested. This new system was able to release 95% of the drug in 5 h and the global release rate depends on the initial drug concentration in the device.