Most of the existing atomistic kerogen models are made, by design, as assemblies of arbitrarily sized macromolecules, which question their ability to capture some of the intrinsic properties of the materials, like their stiffness, or their ability to sustain porosity under pressure. In contrast to these "molecular" models, here we describe in detail the properties of a database of 26 kerogen models made by simulating the natural evolution of type I and type III organic matter, from immature states up to far in the metagenesis stage, and for which the properties of the carbon skeleton, including stiffness and porosity, emerge from the simulations, without any a priori assumptions. The chemistry of these models is corrected with a simple algorithm, removing all possible radical sites, cumulene and triple bonds, to make them useable for extensive simulations with a suitable molecular mechanics forcefield, or for electronic structure calculations, which is demonstrated by the calculation of infrared spectra using density-functional tight binding molecular dynamics. The proposed forcefield is adapted for simulations of fluid adsorption or transport in a flexible kerogen framework, which accounts for any type of kerogen deformation, including for instance adsorption-induced deformations. All the models, including the forcefield parameters, are freely available for download.

The thermodynamic behavior of multi-component system, which includes sorbitol dissolved in water under CO2 and H-2 pressure, is investigated by in situ infrared spectroscopy. Our study focuses on the gas phase of binary, ternary, and quaternary systems at temperatures ranging from 40 degrees C to 220 degrees C and at CO2 pressures between 30 and 120 bar, while maintaining a constant pressure of H-2 at 30 or 60 bar. The influence of addition of sorbitol in the liquid aqueous phase and of H-2 in the CO2-rich gas phase on the mutual solubility of CO2 and water is evaluated. In our experimental conditions (T< 220 degrees C and P< 120 bar), it is found that in such multi-component system, a water-rich liquid phase always coexists with a CO2-rich gas phase. Presence of sorbitol in the water-rich phase and H-2 in the CO2-rich phase has a limited impact on the mutual solubility of water and CO2. Furthermore, sorbitol is not soluble in the CO2-rich phase and instead remains in the water-rich liquid phase over the thermodynamic range investigated.

The direct synthesis of glycerol carbonate from glycerol and CO2, using acetonitrile as a dehydration agent and DBU as a catalyst, was investigated to identify the mechanism involved during this reaction. DFT modeling revealed that the most efficient pathway involves forming a C-O bond between CO2 and glycerol's secondary alcohol. The catalyst reduces energy barriers across steps, particularly for the rate-limiting intramolecular ring closure, making the carbonyl substitution route more favorable than hydroxyl dehydration. However, acetonitrile's hydrolysis proved less effective as a dehydrating agent due to its higher energy barrier compared to direct carbonylation. While reaction parameters like CO2 pressure and acetonitrile volume had minimal impact on yield, they influenced glycerol conversion. Higher pressure and larger acetonitrile volumes reduced glycerol conversion without changing the yield of glycerol carbonate. Elevated temperatures and prolonged reaction times promoted the formation of side products, primarily monoacetin. The reaction's complex phase behavior, driven by pressure and temperature, revealed that glycerol and acetonitrile become fully miscible only under specific conditions (155 degrees C, 45 bar). In situ FTIR and HPLC analyses identified kinetic profiles for glycerol carbonate, acetins, and acetamide, with ammonia and urea detected in the gas phase. Complementary DFT calculations confirmed that monoacetin formation predominantly arises from the reaction of glycerol with acetamide, a pathway characterized by the lowest energy barriers, aligning with experimental findings.

The chlorine radical is a strong HAT (Hydrogen Atom Transfer) agent that is very useful for the functionalization of C(sp 3 )−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 f8 -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. Combining these two properties ultimately makes the self-assembled 8R f8 -4CzIPN •Cl − dual catalyst highly reactive in redox-neutral Giese-type C(sp 3 )−H bond alkylation reactions promoted by the chlorine radical. Additionally, because of its fluorous character, the efficient separation/recovery of 8R f8 -4CzIPN could be envisioned.

Herein, the long-standing challenge of the ring-opening aminolysis of CO2-derived tetrasubstituted cyclic carbonates at room temperature (r.T) is overcome under catalyst-free conditions. Molecular design of the cyclic carbonate by substitution of an alkyl group by a thioether unlocks quantitative conversion at r.T and ensures total regioselectivity toward highly substituted oxazolidone scaffolds. An in-depth rationalization of the high reactivity of these cyclic carbonate structures and of the aminolysis reaction mechanism is provided by a computational study supporting experimental observations. The high efficiency of the reaction is then translated to the deconstruction of high-performance thermoplastics containing tetrasubstituted cyclic carbonate linkages to deliver building blocks that are reused for designing recyclable thermosets bearing dynamic N,S-acetal linkages.

This study presents a one-pot process to obtain sorbitans directly from glucose. Sorbitans are composed of mainly 1,4-sorbitan and are usually in a mixture with isosorbide using mineral acid. The challenge is to be highly selective in sorbitans by developing a more sustainable process. The one-pot strategy allows us to avoid extra energy cost of separation, while the replacement of mineral acid by CO2 as a catalyst seems more sustainable due to the easy recovery. The proposed approach integrates the conversion of glucose into sorbitol via hydrogenation followed by sorbitol dehydration into sorbitans. This study focuses on experimentally investigating sorbitol dehydration to refine reaction conditions and employing molecular modeling to elucidate the catalytic role of CO2. The one-pot synthesis involves sequential reactions within a complex system comprising glucose, H-2, CO2, and a Ru catalyst. By replacement of mineral acids with CO2 as a catalyst, the process seems to improve sustainability, facilitated by the straightforward recovery of CO2. Through operando spectroscopy, the impact of CO2 pressure on the hydrogenation reaction as well as the influence of H-2 pressure and the Ru catalyst on the dehydration reaction are meticulously examined to propose an efficient one-pot synthesis route.

In this study, catalytic H/D exchange experiments have been performed between H2 and D2O catalyzed by supported metal catalysts, namely, Ru/Al2O3, Pt/Al2O3 and Pd/Al2O3 in order to unveil the reaction mechanism at work in the glucose hydrogenation reaction on these supported metal catalysts. The conversion of H2 and D2O towards the formation of the exchange species namely HOD, HD and D2 was investigated using in operando simultaneous ATR-IR/Raman spectroscopy allowing the monitoring of the liquid/gas phase respectively. After 24 h of reaction at 22 degrees C under 30 bar of H2, it is found that Pt/Al2O3 has the highest efficiency for the H/D exchange between H2 and D2O, followed by Ru/Al2O3 and then Pd/Al2O3. On the other hand, the enhanced activity of Ru/Al2O3 for the hydrogenation of glucose is tentatively assigned to H atoms adsorbed and activated on the Ru surface leading to an Ru-H infrared band located around 1940-1970 cm-1, that is observed only with Ru/Al2O3. This activated H* could be directly added to the carbon atom of the carbonyl of glucose to give sorbitol in a more efficient way compared to the other metals.

In this study, a series of new Deep Eutectic Solvents (DESs) composed of phenol as the HBD (Hydrogen Bond Donor) and tetrabutyl ammonium (TBA) salts with different molecular anions as HBA (Hydrogen Bond Acceptor) were prepared and investigated using ATR-IR spectroscopy and DFT calculations in order to understand the solvation mechanism at work in these DESs. In particular, the OH stretching mode of phenol is significantly shifted to lower frequencies in the DESs in comparison with that reported for pure phenol. Similarly, characteristic vibrational modes of the anions in the investigated DESs display significant shifts in frequency in comparison with that measured for the pure TBA salt. As a representative example, the frequency shifts observed for the azide anion as a function of the HBA:HBD molar ratio were fully interpreted by the DFT calculations putting in evidence strong hydrogen bonding interactions that occurs between the anion and the phenol molecules. Interestingly, a minimum of the calculated free energy interaction of -25.9 kcal/mol was found at a 1:3 HBA: HBD molar ratio that is consistent with thermodynamic results reported for the Choline-chloride/Phenol DES for which the lowest freezing temperature was reported at this ratio.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Organocatalysis has been widely developed over the past decades as an alternative to metal-based catalysis. The actual concerns have also promoted the development of sustainable and degradable polymers. In this context, gamma-lactones are an interesting class of monomers that count many bio-based monomers, yielding polyesters that can be readily depolymerized. Also, the use of functional substituted lactones such as the alpha-hydroxy-gamma-butyrolactone (HBL) affords polyesters with pendant groups offering possible postmodification reactions. This article focuses on the ring-opening copolymerization (ROCP) of alpha-hydroxy-gamma-butyrolactone (HBL) and epsilon-caprolactone (epsilon-CL) in the presence of phosphazene P-4 base (tert-BuP4) as catalyst. The bulk copolymerization at high temperature (80 degrees C) yielded fast kinetics (5 min) and high monomer conversions (98% for epsilon-CL; 88% for HBL) and molar masses (14900 g/mol with (sic) = 3.8). A kinetics study at 80 degrees C revealed a partial HBL depolymerization over time. This phenomenon induced changes in the microstructures of the copolymers. Similar high conversions and molar masses could be also achieved at room temperature for 6 h without any depolymerization. Various monomer feed ratios were also evaluated affording copolyesters with up to 31% of incorporated HBL. In addition, DFT calculations with respect to the HBL homopolymerization revealed similar activation energies between different possible reactions, which include ring-opening polymerization, branching, and backbiting reactions.

In switchable molecular recognition, 1 O2 stimulus responsive receptors offer a unique structural change that is rarely exploited. The employed [4+2] reaction between 1 O2 and anthracene derivatives is quantitative, reversible and easily implemented. To evaluate the full potential of this new stimulus, a non-macrocyclic anthracene-based host was designed for the modular binding of cations. The structural investigation showed that 1 O2 controlled the atropisomerism in an on/off fashion within the pair of hosts. The binding studies revealed higher association constants for the endoperoxide receptor compared to the parent anthracene, due to a more favoured preorganization of the recognition site. The fatigue of the 1 O2 switchable hosts and their complexes was monitored over five cycles of cycloaddition/cycloreversion.

This review is dedicated to the state-of-the art routes used for the synthesis of CO2-based (a)cyclic carbonates and polycarbonates from alcohol substrates, with an emphasis on their respective main advantages and limitations. The first section reviews the synthesis of organic carbonates such as dialkyl carbonates or cyclic carbonates from the carbonation of alcohols. Many different synthetic strategies have been reported (dehydrative condensation, the alkylation route, the "leaving group" strategy, the carbodiimide route, the protected alcohols route, etc.) with various substrates (mono-alcohols, diols, allyl alcohols, halohydrins, propargylic alcohols, etc.). The second section reviews the formation of polycarbonates via the direct copolymerization of CO2 with diols, as well as the ring-opening polymerization route. Finally, polycondensation processes involving CO2-based dimethyl and diphenyl carbonates with aliphatic and aromatic diols are described.

The inherent skeletal and thermal features to forge polymers by step-growth polymerization are conflicting with any depolymerization strategies via cascade back-biting reactions that necessitate adequate ceiling temperature, spacers, and functionalities to create cyclic compounds. Here, we report the edition of step-growth poly(carbonate-urea)s and poly(carbonate-amide)s that are depolymerized on demand into their native precursor or added-value offspring oxazolidinones, together with a hemiacetal cyclic carbonate. The unprotected in-chain secondary amide or urea functionalities of the polymers trigger their degradation via cascade ring-closing events upon a thermal switch (from 25 to 80 degrees C) in the presence of an organic base as a catalyst. Although most studies are realized in solution for understanding the deconstruction process, the polymers are also fully degraded in 2 h in neat conditions without any catalyst at 150 degrees C. At 80 degrees C, the organic base is required to accelerate the process. On the road to sustainability and circularity, we validate the concept by exploiting monomers designed from waste CO2 and upcycled commodity plastics. Ultimately, these polymers are selectively depolymerized from plastic mixtures composed of commodity poly(ethylene terephthalate) and polycaprolactone, offering new options for recycling plastic waste mixtures while delivering high-value-added chemicals.

In this study, the solvation of H2 in supercritical CO2 was investigated by co-localized infrared absorption/ Raman scattering spectroscopies. The Fermi dyad and combinations of vibrational modes of CO2 were detected by Raman and infrared spectroscopy respectively, with increasing intensities according to CO2 concentrations varying from 1 to 15 mol.L-1. H2 rotational bands and vibrons with almost constant intensities were detected by Raman spectroscopy according to a constant H2 pressure of 3 MPa. In contrast, a collision-induced infrared band of H2 was reported for the first time in supercritical CO2 and its intensity was found to be directly proportional to the intensity of the CO2 bands. In addition, the intensities of the H2 and CO2 contributions were found to be sensitive to the local density fluctuations existing near the critical temperature of CO2 (Tc = 31 degrees C, Pc = 7.4 MPa).

Chiral trifluoromethyl alcohol groups were introduced at the hindered ortho positions of 9,10-diphenylanthracenes to investigate their effects on the physical properties and reactivity towards oxidative dearomatization. In such compact structures, the position in different quadrants and the preferred orientation of the -CH(OH)CF3 groups were determined by the relative and absolute configurations of each stereoisomer, respectively. As a consequence, the stereochemistry governs the organization of the H-bonded molecules in single crystals (homochiral dimers vs ribbon), whereas in chlorinated solvents, they all behave as discrete compounds. Concerning their reactivity, the stereospecific dearomative oxidation of these molecules leads to 9,10-bis-spiro-isobenzofuran-anthracenes, when using organic single-electron transfer oxidants. The chiroptical properties of the alcohols and the corresponding dearomatized products were compared and showed an important modulation of the intensity.

Designing easily degradable polymers has become anew challenge to overcome the post-consumer plastic waste accumulation in the environment. Polycarbonates are important polymers that can be chemically recycled; however, most often, their degradation requires high temperatures and/or the use of catalysts. In this work, we report the facile chemical recycling of regio regular polycarbonates prepared by the organocatalyzed copolymerization of CO2-sourced exovinylene biscyclic carbonates(Bis alpha CC) with diols derived from biomass. These polymers ,thanks to their pending ketone groups, are rapidly (< 30 min) andtotally deconstructed into the parent diol and a bis(oxazolidinone)by catalyst-free aminolysis at 25 degrees C. By using 3-propanolamine forthe aminolysis, a hydroxy-functionalized bis(oxazolidinone) isrecovered, which can be copolymerized with Bis alpha CC to yield a polymer alternating carbonate and oxazolidinone linkages.Importantly, the same bis(oxazolidinone) scaffold is recovered as the main product by aminolysis of this copolymer, offering a close-loop recycling scenario for this polymer. This work illustrates that these polycarbonates are prone to facile and complete aminolysisunder mild and catalyst-free conditions, but can also be exploited to prepare new building blocks for the synthesis of noveldegradable polymers. The mechanism of formation of these heterocycles is studied by model reactions and rationalized by densityfunctional theory (DFT) calculations.

The glassy ternary system Ge-Te-Se is currently receiving an increased attention due to its extended range of transmission in the infrared opening the way to various potential applications in photonics. In this study, a multi-techniques approach combining solid-state NMR, Raman and infrared spectroscopies and DFT calculations provides insight into the organization of the GeSe4-GeTe4 glassy network and allows to clarify a whole structural description of the glassy system. A particular attention is devoted to the presence of mixed GeTe8-xSex structural units and to the type of interconnections forming the glass networks. Such experimental/theoretical approach is provided both for the selenium and the tellurium rich part of the glassy system.

Hydrogenation of sugar monomers to sugars alcohols was performed in the presence of a commercial Ru/Al2O3 catalyst. It was shown that glucose (10 wt %) was selectively converted to sorbitol with a yield around 97% under optimized conditions (100 degrees C, 30 bar, 150 min of reaction and 5 wt % of catalyst). The reaction pathway was determined by the analysis of intermediate compounds. This catalyst was stable up to 10 reaction cycles due to alumina phases of the support and the Ru particle sizes. Moreover, it was shown that during the reaction the catalyst is reactivate under hydrogen explaining its stability, helping to maintain its activity by avoiding its poisoning. The Ru leaching was rather low and the particle sizes were still around 2 nm after several cycles showing that the catalyst morphology was similar to the fresh one. This catalyst was also active in the hydrogenation of sugars such as fructose, mannose, galactose, and xylose to sugar alcohols. This commercial catalyst is a stable catalyst that can be used in the hydrogenation of various sugars exhibiting an outstanding stability.

Visible light promoted perfluoroalkylation reactions initiated via halogen bonding interactions between perfluoroalkyl iodides (Rf-I, Rf = Cr,F2,i) and Lewis bases have been recognized as a powerful tool in the field of radical synthetic chemistry. In order to provide some insights into the nature, strength and role in the activation process of halogen bonding interactions, we have performed a combined UV-Visible/ Raman/DFT study on a model Rf-I (C4F9I) and a series of Lewis bases (LB) frequently used for the activation of perfluoroalkylation reactions, including DBU, MTBD, TMG, TMEDA and Et3N. Raman studies conducted in acetonitrile solutions show that the band at 279 cm 1 associated with the C I stretching normal mode of C4F9I shifts about 20 cm 1 towards lower wavenumbers upon formation of the halogen-bonded complexes. Additionally, the Raman study revealed that at concentrations typically used for perfluoroalkylation reactions, the [C4F9I-LB] complexes are the main species present in solution. UVVis spectroscopy revealed that complex formation is characterized by a strong increase in absorption from 225 to 350 nm. The higher the basicity of the Lewis base, the higher the increase of the UV absorbance. (C) 2021 Elsevier B.V. All rights reserved.

We have explored the domino reaction between propargylic alcohols, carbon dioxide, and various alcohols with the double objective to prepare oxo-alkyl carbonates with a high yield and selectivity under mild conditions and to extend the process to the synthesis of phosgene-free polycarbonates. We first searched for a common catalytic system that was highly selective for the two reactions involved in the domino process, i.e., the cycloaddition of CO2 to propargylic alcohol to yield a-alkylidene cyclic carbonate (alpha CC) and the alcoholysis of alpha CC to furnish oxo-alkyl carbonate. Kinetics studies monitored by operando IR spectroscopy and supported by H-1 NMR analyses and DFT modeling have permitted us to identify an efficient binary catalytic system composed of a combination of tetrabutylammonium phenolate [TBA] [OPh] and silver iodide (AgI) (or copper iodide (CuI)) and to understand its action mode. The [TBA] [OPh]/ AgI catalytic system (5 mol %) was then successfully implemented for the selective preparation of a range of oxo-alkyl carbonates by the domino reaction with alcohols and propargylic alcohols of different structures. Most of these oxo-alkyl carbonates were produced at a high yield (>= 97%) under mild operating conditions, i.e., at 60 degrees C and 1 bar of CO2. The one-pot synthesis of various poly(beta-oxo-carbonate)s from bis(propargylic alcohol)s, diols, and CO2 was finally investigated, and the best operating conditions ([TBA][OPh]/AgI (10 mol %), 60 degrees C, 15 bar) afforded polycarbonate oligomers with weight-average molar masses of 4300 g/mol. Although the system should be optimized to produce longer polymer chains, this process offers a new phosgene-free alternative to the synthesis of functional polycarbonates poly(beta-oxo-carbonate)s) under mild conditions.