Photogeneration of Chlorine Radical from a Self-Assembled Fluorous 4CzIPN•Chloride Complex: Application in C-H Bond Functionalization.

The chlorine radical is a strong HAT (Hydrogen Atom Transfer) agent that is very useful for the functionalization of C(sp)-H bonds. Albeit highly attractive, its generation from the poorly oxidizable chloride ion mediated by an excited photoredox catalyst is a difficult task. We now report that 8R-4CzIPN, an electron-deficient fluorous derivative of the benchmark 4CzIPN photoredox catalyst belonging to the donor-acceptor carbazole-cyanoarene family, is not only a better photooxidant than 4CzIPN, but also becomes an excellent host for the chloride ion.

Co-Localized Infrared-Raman Spectroscopy: An Innovative Approach for the Quantitative In Situ Analysis of Gas Mixtures at High Pressures.

This article spotlights the interest in using co-localized infrared (IR)-Raman spectroscopy as an innovative approach for the in situ monitoring of complex gas mixtures, e.g., hydrogen (H), nitrogen (N), carbon monoxide (CO), carbon dioxide (CO), and methane (CH), at elevated pressures.

Dual Photoredox Ni/Benzophenone Catalysis: A Study of the Ni Precatalyst Photoreduction Step.

The combination of NiX salts with a bipyridine-type ligand and aromatic carbonyl-based chromophores has emerged as a benchmark precatalytic system to efficiently conduct cross-couplings mediated by light. Mechanistic studies have led to two scenarios in which Ni is proposed as the catalytic species. Nonetheless, in none of these studies has a Ni to Ni photoreduction been evidenced.

One-pot synthesis of isosorbide from cellulose or lignocellulosic biomass: a challenge?

The catalytic conversion of (ligno)cellulose is currently subject of intense research. Isosorbide is one of the interesting products that can be produced from (ligno)cellulose as it can be used for the synthesis of a wide range of pharmaceuticals, chemicals, and polymers. Isosorbide is obtained after the hydrolysis of cellulose to glucose, followed by the hydrogenation of glucose to sorbitol that is then dehydrated to isosorbide.

Chemo- and Regioselective Additions of Nucleophiles to Cyclic Carbonates for the Preparation of Self-Blowing Non-Isocyanate Polyurethane Foams.

Polyurethane (PU) foams are indisputably daily essential materials found in many applications, notably for comfort (for example, matrasses) or energy saving (for example, thermal insulation). Today, greener routes for their production are intensively searched for to avoid the use of toxic isocyanates. An easily scalable process for the simple construction of self-blown isocyanate-free PU foams by exploiting the organocatalyzed chemo- and regioselective additions of amines and thiols to easily accessible cyclic carbonates is described.

Supercritical loading of gatifloxacin into hydrophobic foldable intraocular lenses - Process control and optimization by following in situ CO sorption and polymer swelling.

The supercritical impregnation process was used as a green technology for the elaboration of drug delivery intraocular lenses to mitigate the risk of post-operatory endophthalmitis after cataract surgery. Commercially available hydrophobic acrylic (copolymer of benzyl methacrylate and methyl methacrylate) intraocular lenses (IOLs) were impregnated with gatifloxacin, a fourth generation fluoroquinolone drug, using pure supercritical CO (scCO) to obtain solvent-free loaded implants. The interaction phenomena involved in the supercritical impregnation were studied by following in situ scCO sorption within the polymer support and the subsequent IOL swelling, and by taking into account drug solubility in the supercritical fluid phase.

CO -Sourced α-Alkylidene Cyclic Carbonates: A Step Forward in the Quest for Functional Regioregular Poly(urethane)s and Poly(carbonate)s.

Described is a robust platform for the synthesis of a large diversity of novel functional CO -sourced polymers by exploiting the regiocontrolled ring-opening of α-alkylidene carbonates by various nucleophiles. The reactivity of α-alkylidene carbonates is dictated by the exocyclic olefinic group. The polyaddition of CO -sourced bis(α-alkylidene carbonate)s (bis-αCCs) with primary and secondary diamines provides novel regioregular functional poly(urethane)s.

Current manufacturing processes of drug-eluting sutures.

Drug-eluting sutures represent the next generation of surgical sutures since they fulfill their mechanical functions but also deliver the drug in their vicinity after implantation. These implants are produced by a variety of manufacturing processes. Drug-eluting sutures represent the next generation of surgical sutures since they fulfill their mechanical functions but also deliver the drug in their vicinity after implantation.

Organocatalytic Coupling of CO with a Propargylic Alcohol: A Comprehensive Mechanistic Study.

The metal-free coupling of a propargylic alcohol with CO catalysed by guanidine derivatives was investigated in detail through the combination of online kinetic studies by in situ attenuated-total reflection IR (ATR-IR) spectroscopy and DFT calculations. Bicyclic guanidines, namely 1,5,7-triazabicyclo[4.4.

Organocatalytic Coupling of CO with Oxetane.

The organocatalytic coupling of CO with oxetanes is investigated under solvent-free conditions. The influence of the main reaction parameters (type of organocatalytic system, pressure, and temperature) on the yield, the product formed, and the selectivity of the reaction are discussed. An onium salt combined with a fluorinated alcohol promotes the efficient and selective organocatalytic synthesis of α,ω-hydroxyl oligocarbonates by coupling CO with oxetanes at 130 °C and at a CO pressure as low as 2 MPa.

Structure-Property Relationships in CO2-philic (Co)polymers: Phase Behavior, Self-Assembly, and Stabilization of Water/CO2 Emulsions.

This Review provides comprehensive guidelines for the design of CO2-philic copolymers through an exhaustive and precise coverage of factors governing the solubility of different classes of polymers. Starting from computational calculations describing the interactions of CO2 with various functionalities, we describe the phase behavior in sc-CO2 of the main families of polymers reported in literature. The self-assembly of amphiphilic copolymers of controlled architecture in supercritical carbon dioxide and their use as stabilizers for water/carbon dioxide emulsions then are covered.

Fluorinated Alcohols as Activators for the Solvent-Free Chemical Fixation of Carbon Dioxide into Epoxides.

The addition of fluorinated alcohols to onium salts provides highly efficient organocatalysts for the chemical fixation of CO2 into epoxides under mild experimental conditions. The combination of online kinetic studies, NMR titrations and DFT calculations allows understanding this synergistic effect that provides an active organocatalyst for CO2 /epoxides coupling.

Enhanced Solubility of Polyvinyl Esters in scCO by Means of Vinyl Trifluorobutyrate Monomer.

The novel monomer, vinyl trifluorobutyrate (VTFBu), when polymerized in a controlled fashion by RAFT/MADIX polymerization with a xanthate transfer agent, yields poly(vinyl ester)s with improved solubility in supercritical carbon dioxide. The thermodynamic parameters controlling the solubility of VTFBu/vinyl acetate statistical copolymers are discussed based on ab initio calculations, glass transition temperatures of the copolymers, and surface tension measurements. The enhanced solubility of this new class of CO-philic polymer combined with its good chemical stability render it attractive for the preparation of next-generation macromolecular surfactants for the formation of water-scCO emulsions.

Enhancement of poly(vinyl ester) solubility in supercritical CO2 by partial fluorination: the key role of polymer-polymer interactions.

An enhancement of poly(vinyl ester) solubility in supercritical carbon dioxide (sc-CO(2)) can be achieved by decreasing the strength of the polymer-polymer interactions. To demonstrate this, a library of statistical copolymers of vinyl acetate and vinyl trifluoroacetate was synthesized by RAFT/MADIX polymerization with varying compositions at a given number-average molecular weight. These copolymers exhibited unprecedentedly low cloud-point pressures in sc-CO(2) at 40 °C compared with previously reported poly(vinyl esters).

On the interaction between supercritical CO2 and epoxides combining infrared absorption spectroscopy and quantum chemistry calculations.

The nature and strength of the interactions occurring between epoxides and CO(2) have been investigated by combining infrared spectroscopy with quantum chemistry calculations. A series of infrared absorption experiments on four model epoxide molecules highly diluted in supercritical CO(2) have been performed at constant temperature T = 40 °C for various CO(2) pressures varying from 1 to 30 MPa. Then, we carried out a theoretical analysis based on quantum chemistry calculations using Density Functional Theory (B3PW91 and CAM-B3LYP) and ab initio (MP2) computational methods.

Elucidating the association of water in wet 1-octanol from normal to high temperature by near- and mid-infrared spectroscopy.

Near- (NIR) and mid-infrared (MIR) absorption spectra of pure and water-saturated 1-octanol were measured along the liquid-gas coexistence curve from ambient temperature and pressure up to 300 degrees C and 10 MPa. Density of the mixture as a function of temperature was assessed by spectral analysis in the NIR region. Two distinct regimes of temperature were identified in the evolution of solvent-subtracted spectra: at normal conditions and up to 180 degrees C, water is organized in multimeric H-bonded aggregates, while at higher temperature, mainly dimers and monomers exist.

Substituent effect on the interaction of aromatic primary amines and diamines with supercritical CO(2) from infrared spectroscopy and quantum calculations.

The nature and the strength of the interactions occurring between aromatic primary amines and CO(2) have been investigated by combining infrared spectroscopy with molecular modelling. A series of infrared absorption experiments on various aromatic mono- and diamines in supercritical CO(2) have been performed at constant temperature (T = 40 degrees C) for various CO(2) pressures varying from 6 to 30 MPa. Then, we carried out a theoretical analysis based on quantum calculations using both density functional (B3LYP) and ab initio (MP2) computational methods.

In situ IR spectroscopy and ab initio calculations to study polymer swelling by supercritical CO(2).

The CO(2) sorption and polymer swelling of hydroxytelechelic polybutadiene (HTPB) and poly(ethylene glycol) (PEG) have been investigated as a function of temperature and CO(2) pressure by combining in situ near-infrared spectroscopy with molecular modeling. The results reported here for the PEG-CO(2) system are in a very good agreement with literature data hence validating our experimental procedure. It has been found that CO(2) sorption and swelling effect is more important for PEG than for HTPB.

A combined spectroscopic and theoretical study of dibutyltin diacetate and dilaurate in supercritical CO2.

Two organotin catalysts, namely, dibutyltin dilaurate (DBTDL) and dibutyltin diacetate (DBTDA), commonly used in the synthesis of polyurethanes, have been investigated combining vibrational spectroscopic measurements with molecular modeling. The structure and vibrational spectra of the DBTDA molecule have been simulated using density functional theory. Thus, because of the Sn.

On the perturbation of the intramolecular H-bond in diols by supercritical CO2: a theoretical and spectroscopic study.

The role played by supercritical carbon dioxide used as a dispersant medium in the synthesis of polyurethane particles has been investigated. High-temperature-high-pressure in situ infrared spectroscopic measurements combined with ab initio calculations were performed to investigate the hydroxyl stretching vibrations of ethylene glycol (EG) and 1,4-butanediol (BD), two monomers commonly used in the field of step growth polymerization. Specific interactions between the diols and CO2 have been put in evidence.