The use of NIR-FT-Raman spectroscopy for the characterization of polymer-supported reagents and catalysts

Synergy between supported ionic liquid-like phases and immobilized palladium N-heterocyclic carbene-phosphine complexes for the Negishi reaction under flow conditions

The combination of supported ionic liquids and immobilized NHC-Pd-RuPhos led to active and more stable systems for the Negishi reaction under continuous flow conditions than those solely based on NHC-Pd-RuPhos. The fine tuning of the NHC-Pd catalyst and the SILLPs is a key factor for the optimization of the release and catch mechanism leading to a catalytic system easily recoverable and reusable for a large number of catalytic cycles enhancing the long-term catalytic performance.

A cross-sectional survey based on blood VOCs, hematological parameters and urine indicators in a population in Jilin, Northeast China

The objective of this study was to examine whether long-term exposure to low-dose volatile organic compounds (VOCs) will have an effect on the health of non-occupational population. A total of 499 non-occupational participants aged more than 18 that live around Jilin Petrochemical Industrial Zone were chosen by stratified cluster random sampling. Their blood VOCs' levels, hematological parameters and urine indicators together with detailed questionnaire data were used to find possible relationships using binary logistic regression analysis. The detection rate of benzene in the blood was high in the non-occupational population around the industrial area, and it even reached 82.3% in males but no significant difference was recorded between male and female population. In addition, trichloroethane (male: 33.2% V female: 21.7%; p = 0.002), carbon tetrachloride (males: 20.3% V females: 7.5%; p < 0.001) and trichlorethylene (male: 34.9% V female: 24.7%; p = 0.004) all showed significant differences in gender, and without exception, the prevalence of males was higher in these three VOCs than of females. The changes in red blood cell (RBC), hematocrit (HCT) and basophils are correlated with carbon tetrachloride, trichloroethylene and chloroform, respectively. And RBC, HCT and basophils are statistically significant in male compared with female of the study population. The increase in trichlorethylene was associated with an increase of 1.723% (95% CI 1.058-2.806) in HCT. The increase in carbon tetrachloride showed a more significant correlation with an increase of 2.638% in RBC count (95% CI 1.169-5.953). And trichloromethane led to a 1.922% (95% CI 1.051-3.513) increase in basophils. The changes in urinary WBC, urine ketone (KET) and urinary bilirubin (BIL) showed significant correlation with benzene, carbon tetrachloride and dibromochloromethane, respectively. The correlation in females is more significant than in males. The increase of benzene in the female population increased urinary leukocyte count by 2.902% (95% CI 1.275-6.601). The effect of carbon tetrachloride on KET was particularly pronounced, resulting in an increase of 7.000% (95% CI 1.608-30.465). Simultaneously, an increase in dibromochloromethane caused an increase of 4.256% (95% CI 1.373-13.192) in BIL. The changes in RBC, HCT and basophils can only serve as an auxiliary indicator for disease diagnosis, so they have no significant clinical significance. However, the alteration of urinary WBC, KET and BIL has great clinical significances, and it is suggested that the monitoring of the above indicators from low-dose long-term exposure be strengthen in this area.

Polymer immobilized tantalum(v)–amino acid complexes as selective and recyclable heterogeneous catalysts for oxidation of olefins and sulfides with aqueous H2O2

Polymer supported peroxotantalate based heterogeneous catalysts served as highly efficient, selective and recyclable catalysts for alkene epoxidation and sulfide oxidation with green oxidant aqueous H₂O₂ under mild reaction conditions.

Chiral catalysts immobilized on achiral polymers: effect of the polymer support on the performance of the catalyst

Achiral polymeric supports can have important positive effects on the activity, stability and selectivity of supported chiral catalysts.

New porous monolithic membranes based on supported ionic liquid-like phases for oil/water separation and homogenous catalyst immobilisation

Membranes based on supported ionic liquid-like phase (SIILP) systems with tunable properties allowed oil/water separation and reaction/separation integration in biphasic systems.

Solventless, selective and catalytic oxidation of primary, secondary and benzylic alcohols by a Merrifield resin supported molybdenum(vi) complex with H2O2 as an oxidant

Here, we have described the synthesis, characterization and catalytic activity of a dioxo-molybdenum(vi) complex supported on functionalized Merrifield resin (MR-SB-Mo). The functionalization of Merrifield resin (MR) was achieved in two-steps viz. carbonylation (MR-C) and Schiff base formation (MR-SB). The compounds, MR-C, MR-SB and MR-SB-Mo, were characterized at each step of the synthesis by elemental, SEM, EDX, thermal, BET and different spectroscopic analysis. The catalyst, MR-SB-Mo, efficiently and selectively oxidized a wide variety of alcohols to aldehydes or ketones using 30% H₂O₂ as an oxidant with reasonably good TOF (660 h⁻¹ in case of benzyl alcohol). The catalyst acted heterogeneously under solventless reaction conditions and did not lead to over oxidized products under optimized conditions. The catalyst afforded regeneration and can be reused for at least five reaction cycles without loss of efficiency and product selectivity. A reaction mechanism for the catalytic activity of MR-SB-Mo was proposed and a probable reactive intermediate species isolated.

Synthesis of a Merrifield resin supported dioxomolybdenum(vi) complex. The compound was well characterized and it catalysed the oxidation of alcohols to aldehydes or ketones with high TOF.

Influence of Chemical Functionality on the Rate of Polymer-Induced Heteronucleation

Polymer-induced heteronucleation can dramatically increase the nucleation rate of pharmaceuticals. However, directly comparing the heteronucleation rates of different polymer functionalities is often convoluted with changing physical or structural aspects of heteronuclei. Here, we report a methodology for comparing nucleation efficiencies of different functionalities on polymer heteronuclei of uniform topology with the goal of identifying those functionalities that best accelerate nucleation of a model pharmaceutical. It was found that the previously employed design for additives to speed acetaminophen crystallization underperforms a modified framework that accounts for the effect of competitive solvent binding. These findings are informed by a survey of interactions from the CSD and not only serve to aid in the controlled crystallization of pharmaceuticals, but also provide insight into the mechanism of heteronucleation.

Dual stereocontrolled alkylation of aldehydes with polystyrene-supported nickel complexes derived from α-amino amides

Nickel(ii) complexes derived from α-amino amide ligands anchored to gel-type and monolithic polymers act as efficient catalysts for the enantioselective addition of dialkylzinc reagents to aldehydes.

Pd(0) supported onto monolithic polymers containing IL-like moieties. Continuous flow catalysis for the Heck reaction in near-critical EtOH

Long-term stable Pd(0) catalysts can be easily supported onto polymeric monoliths containing methyl-imidazole moieties and the corresponding reactors based on these materials can be applied for the continuous Heck reaction in near-critical EtOH.

Microscopic infrared mapping of chloromethylated polystyrene resin beads

In solid-phase combinatorial chemistry, analyses are performed using a wide range of analytical techniques ranging from gel-phase nuclear magnetic resonance (NMR) to colorimetric tests to elemental analysis. However, these techniques cannot be used to interrogate functional group distribution at the single-bead level. This paper explores the feasibility of using Fourier transform infrared (FT-IR) microscopy to examine site distribution on chloromethylated polystyrene resin beads and to quantify the loading after coupling with 4-cyanophenol, an IR tagging agent. FT-IR microscopy also provides a unique opportunity to better understand the reactivity of highly cross-linked polymer beads under a range of chemical conditions.

Improvement of ligand economy controlled by polymer morphology: the case of polymer-supported bis(oxazoline) catalysts

A functionalized chiral bis(oxazoline) is used as a chiral monomer in polymerization reactions leading to homo- and copolymers of different morphology. Polymers with a high content of chiral monomer lead to enantioselectivities that are higher than those obtained with the soluble ligand, but the chiral ligand is not used in an optimal way. A hyperbranched polymer, obtained by using a hexavinyldendrimer as the cross-linker, leads to the same enantioselectivities with a more efficient use of the chiral ligand.