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Organocatalysts are increasingly gaining attention for the ring opening polymerization (ROP) of lactones due to numerous advantages. In this work, the goal is to expand the scope of catalysts for the ROP of alkyl substituted caprolactones: a mixture of beta,delta-trimethyl-epsilon-caprolactones (TMCL). Several organocatalysts were evaluated, with a focus on bifunctional organophosphorus catalysts including two novel categories, namely phosphonic acids and phosphinic acids. The effects of initial monomer concentration, temperature, catalyst loading and catalyst type on the monomer conversion at equilibrium and the reaction kinetics were addressed. The ceiling temperature of TMCL is 302 degrees C in bulk and 34 degrees C at 1 M, as determined experimentally. During polymerization, higher conversion and reaction rates were observed for the most substituted lactone ( proximal lactone). This difference of reactivity between the two regio-isomeric lactones was greater for lower reaction temperatures. Density functional theory (DFT) calculations on the ring opening of the lactones demonstrated that the difference of reactivity can be attributed to a lower enthalpic contribution of the proximal lactone making the ring opening of this lactone more energetically favored. The difference in calculated Gibbs free energy was found to increase with lower temperature.

An alkaline-earth metal catalytic system for environmentally benign allylic alkylation was developed. Allylic alcohols can be utilized directly at room temperature in this transition-metal-free process, producing water as the only byproduct. A variety of allylic compounds, including the ones containing all-carbonyl quaternary centers, can be obtained with high yields. Ministry of Education (MOE) We gratefully acknowledge the financial support from the National Natural Science Foundation of China (21702108), the Natural Science Foundation of Jiangsu Province, China (BK20160977), the Six Talent Peaks Project in Jiangsu Province (YY-033), the grant from Ministry of Education of Singapore MOE2016-T1-002-043 (RG111/16), and Nanjing Tech University (39837101).

RATIONALE For clumped isotope analysis (Δ47 ), hydrocarbon and organic molecules present an important contaminant that cannot always be removed by CO2 purification through a Porapak-Q trap. Low-temperature oxygen plasma ashing (OPA) is a quick and easy approach for treatment; however, the impact of this treatment on the original carbonate clumped isotope values has never been fully studied. METHODS We tested the isotopic impact of OPA using three natural samples with a large range of initial Δ47 values. Crushed and sieved (125 μm mesh) samples were placed into a Henniker Plasma HPT-100 plasma system and treated at a flow rate of 46 mL/min and a power of 100 W at a vacuum of 0.2 mbar for 10, 20, 30 and 60 min before clumped isotope analysis using two MAT 253 isotope ratio mass spectrometers modified to measure masses 44-49. RESULTS OPA treatment for 30 min or more on calcite powder samples has the potential to alter the clumped isotopic composition of the samples beyond analytical error. A systematic positive offset is observed in all samples. The magnitude of this alteration translates to a temperature offset from known values ranging from 4°C to 13°C. We postulate that the observed positive offset in Δ47 occurs because the bonds within lighter isotopologues are preferentially broken by plasma treatment, leading to an artificial increase in the 'clumping' value of the sample. CONCLUSIONS We recommend that any laboratory performing OPA treatments should reduce the runs to 10-20 min or carry out successive runs of 10 min followed by sample stirring, as this procedure showed no alteration in the initial Δ47 values. Our results validate the use of OPA for clumped isotope applications and will allow future research to use clumped isotopes for challenging samples such as oil-stained carbonates, bituminous shales or host rocks with very high organic carbon content.

Mechanistic insights gained through density functional theory (DFT M06 and B3LYP) computations on a three-component cooperative asymmetric catalytic reaction between a diazo ester, a carbamate, and an imine, catalyzed by dirhodium acetate and chiral phosphoric acid (Bronsted acid), are presented. The addition of the dirhodium-bound enol to the imine yielding an alpha,beta-diamino ester is energetically more preferred over a potentially competitive protonation of the same enol leading to an alpha-amino ester.

Building up on an available synthetic methodology, phosphate monoesters ROPO3H2 have been synthesized in good yields. The synthetic procedure employed features acetic anhydride mediated activation of phosphoric acid in the presence of alcohols, leading to the formation of phosphate monoesters. The products have been isolated as their cyclohexyl amine salts, [CyNH3](2)[(MeO)PO3]center dot 3H(2)O (1) and [CyNH3][(RO)PO3H] (Cy = cyclohexyl; R = Et (2), iPr (3), or tBu (4)). Neutralization of 1-4 by readily available inexpensive ion exchange resin Amberlite produces monoalkylphosphates (RO)P(O).OH)(2) (R = Me (5), Et (6), iPr (7), or tBu (8)). Thermally labile 1-4 and 7 have been structurally characterized by single crystal X-ray diffraction studies. Due to their intrinsic thermal instability due to beta-H elimination, these compounds can be used as ligands for the preparation of single-source precursors for ceramic phosphates by reacting them with suitable metals ions. It is also possible to isolate co-crystals of the anionic and neutral forms of these phosphates as it has been demonstrated in the isolation and structural characterization of [(iPrO)PO3H2]center dot{[CyNH3][(iPrO)PO3H]} (9). To demonstrate the utility of these monoalkylphosphates in the low-temperature synthesis of metal phosphate bioceramics, isopropyl phosphate 7 has been employed to prepare calcium phosphate [{Ca((iPrO)PO3)(OH2)}center dot H2O] n (10), which undergoes neat thermal decomposition in two stages to lose water and propene to yield beta-Ca2P2O7 at low temperatures (280 degrees C).

Enamides with a free NH group have been evaluated as nucleophiles in chiral Bronsted acid-catalyzed enantioselective alpha-amidoalkylation reactions of bicyclic hydroxylactams for the generation of quaternary stereocenters. A quantitative structure-reactivity relationship (QSRR) method has been developed to find a useful tool to rationalize the enantioselectivity in this and related processes and to orient the catalyst choice. This correlative perturbation theory (PT)-QSRR approach has been used to predict the effect of the structure of the substrate, nucleophile, and catalyst, as well as the experimental conditions, on the enantioselectivity. In this way, trends to improve the experimental results could be found without engaging in a long-term empirical investigation. Ministerio de Economia y Competitividad (CTQ2013-41229-P), IKERBASQUE foundation, Gobierno Vasco (IT-623-13) and Universidad del Pais Vasco/Euskal Herriko Unibertsitatea UPV/EHU are gratefully acknowledged for their financial support. Technical and human support provided by Servicios Generales de Investigacion SGIker (UPV/EHU, MINECO, GV/EJ, ERDF and ESF) is also acknowledged.

Polybenzimidazole (PBI) has become a popular polymer of choice for the preparation of membranes for potential use in high-temperature proton exchange membrane polymer fuel cells. Phosphoric acid-doped composite membranes of poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (PBI4N) impregnated with hafnium oxide nanofiller with varying content levels (0-18 wt %) have been prepared. The structureproperty relationships of both the undoped and acid-doped composite membranes are studied using thermogravimetric analysis, modulated differential scanning calorimetry, dynamic mechanical analysis, wide-angle X-ray scattering, infrared spectroscopy, and broadband electrical spectroscopy. Results indicate that the presence of nanofiller improves the thermal and mechanical properties of the undoped membranes and facilitates a greater level of acid uptake. The degree of acid dissociation within the acid-doped membranes is found to increase with increasing nanofiller content. This results in a conductivity, at 215 degrees C and a nanofiller level x = 0.04, of 9.0 x 10(-2) S cm(-1) for [PBI4N(HfO2)(x)](H3PO4)(y). This renders nanocomposite membranes of this type as good candidates for use in high temperature proton exchange membrane fuel cells (HT-PEMFCs).

2-(tert-butyldimethylsilyl)-5-(10-bromodecyl)-1-(N,N-dimethylsulfamoyl)-imidazole and NaPO3 Et2 react at room temperature to yield the corresponding imidazole diethyl phosphonate, which when reflux...

International audience; Activated carbons were prepared from biomass of Algerian date pits for developing efficient and cheap adsorbents in the aim to remove heavy metals from waste water. Carbon adsorbents were obtained following two successive treatments: pyrolysis under dry nitrogen flow and physical activation under wet nitrogen flow. Pyrolysis process was optimized by varying some operating parameters such as temperature, nitrogen flow, heating rate and pyrolysis hold time in order to determine their effects on the porous structure development of date pits activated carbon. Chars obtained from pyrolysis process were activated with the same operating conditions (activation temperature of 700 degrees C, 50% nitrogen + 50% water flow rate of 150 cm(3)/min and heating rate of 10 degrees C/min) except for the activation hold time which varied from 0.5 to 4h. Experimental results showed that pyrolysis conditions have significant effects on the chars and activated carbons properties prepared from date pits. The best rnicroporous activated carbon (surface area of 464 m(2)/g, microporous volume of 0.203 cm(3)/g and total pore volume of 0.220 cm(3)/g) was obtained by pyrolysis at 10 degrees C/min up to 700 degrees C for 1 h under 150 cm(3)/min of nitrogen. Activation hold time has also an impact on activated carbons porosity. The best surface area. microporous volume and total pore volume were obtained after activation for 4 h: 1467 m(2)/g. 0.711 cm(3)/g and 0.725 cm(3)/g respectively. The best adsorbents prepared from date pits were then tested for the removal of Fe3+ and Cu2+ from aqueous solutions. Results show that these adsorbents have higher metallic cation adsorption capacities than usual commercial activated carbons because of the presence of both carboxylic and phenolic groups at the surface witch improves the cation-exchange and complexation properties of these adsorbents in addition of the greater specific surface area. Adsorption data were analyzed with Langmuir and Freundlich isotherms. The better fit is obtained with the Langmuir model.

A novel one-pot, three-component synthesis of N-acyl or N-carbamoyl-alpha-amidosulfides 4 is described. The three-component reaction of aldehydes 1, primary carbamates (or amides) 2 and phenylsulfinic acid (6a) afforded alpha-amidosulfones 7, which after addition of sodium thiolate were in situ transformed into stable alpha-amidosulfides 4 in good to excellent yields. We demonstrated that silver salts or Bronsted acids were able to promote the formation of aliphatic and aromatic N-acylimines from 4 in quantitative yield under mild conditions. The phosphoric acid catalyzed Friedel-Crafts alkylation of 3-substituted indoles with alpha-amidosulfides 4 leading to 2,3-disubstitued indoles was also documented.