Search results for "CARBONYLATION"
showing 10 items of 72 documents
3D Ruthenium Nanoparticle Covalent Assemblies from Polymantane Ligands for Confined Catalysis
2020
International audience; The synthesis of metal nanoparticle (NP) assemblies stabilized by functional molecules is an important research topic in nanoscience, and the ability to control interparticle distances and positions in NP assemblies is one of the major challenges in designing and understanding functional nanostructures. Here, two series of functionalized adamantanes, bis-adamantanes, and diamantanes, bearing carboxylic acid or amine functional groups, were used as building blocks to produce, via a straightforward method, networks of ruthenium NPs. Both the nature of the ligand and the Ru/ligand ratio affect the interparticle distance in the assemblies. The use of 1,3-adamantanedicarb…
Catalytic systems based on transition metals for the carbonylation of methanol to dimethylcarbonate
1997
Abstract The results of an investigation on catalytic systems arising from the electrochemical activation of salts and complexes of several transition metals for the carbonylation of methanol to dimethylcarbonate (DMC) are reported. Metals were tested as inorganic salts or complexes with ligands such as 2,2′-bipyridine (bipy), 1,6-bis (2-oxyphenyl)-2,5-diaza-1,5-hexadiene (salen), 2,4-pentanedionate (acac), triphenylphosphine (TPP) in methanol at room temperature saturated with carbon monoxide at atmospheric pressure. Best faradic yields vs DMC were observed as follows: CuCl(bipy): 84.8%; PdCl 2 (bipy): 64.0%; CoCl 2 : 26.0%; RhCl 3 : 25.0%; AgBF 4 (bipy): 10.2%; AuCl 3 : 9.4%; Cr(acac) 3 :…
Oxidative stress is related to frailty, not to age or sex, in a geriatric population: lipid and protein oxidation as biomarkers of frailty.
2014
Objectives: To ascertain whether indicators of oxidative damage to lipids (malondialdehyde (MDA)) and proteins (protein carbonylation) are biomarkers of frailty, after adjusting for age, sex, and other possible confounders. Design: Cross-sectional cohort study. Setting: Community. Participants: Toledo Study for Healthy Aging participants (N = 742, aged 65–95), classified as frail (n = 54), prefrail (n = 278) and nonfrail (n = 410) according to the Fried criteria. Measurements: Blood plasma was obtained using centrifugation (1,500 G, 15 minutes) and immediately frozen at −80°C. Plasma lipid peroxidation was determined by measuring the MDA formed from lipoperoxides using high-performance liqu…
Oxidative stress is related to frailty, not to age or sex, in a geriatric population
2017
Age-associated frailty is a geriatric syndrome. Frail individuals are vulnerable and lack capacity to manage external stressors. Frailty is associated with oxidative stress, but it has not been addressed in a large controlled human cohort. We aimed to ascertain whether indicators of oxidative damage to lipids and proteins are biomarkers of frailty, after adjusting for age, sex, and other possible confounders. We measured lipid and protein oxidation in the Toledo Study for Healthy Aging participants (N=742, aged 65–95), classified as frail, prefrail and nonfrail according to the Fried criteria. We found that age- and sex-adjusted levels of MDA and protein carbonylation in plasma proved to be…
Heterogenizing palladium tetraiodide catalyst for carbonylation reactions
2022
We report the first example of successful heterogenization of the classical PdI42- carbonylation catalyst, achieved in two simple steps from ionic liquid-functionalized multi-walled carbon nanotubes (MWCNTs). The newly developed materials (PdI4@MWCNT-imi-X, X = Br, I) present the PdI42- anion supported on an imidazolium network (imi) grown on MWCNTs and have been fully characterized. The activity of PdI4@MWCNT-imi-X has been successfully tested in a paradigmatic carbonylation reaction, the oxidative monoaminocarbonylation of 1-alkynes with amines to give high value added 2-ynamides (obtained in good yields, 50–84%, starting from various substrates). The heterogeneous catalyst could be easil…
Reactions of (η5-C5H5)(CO)2Fe-Substituted N-Sulfonyl Azadienes with C-Nucleophiles. A Route to 5-Substituted Dihydropyrrolones
2000
A variety of cyclic β-[(η5-C5H5)(CO)2Fe]-substituted N-sulfonyl azadienes 4 were prepared: e.g., from the corresponding iron-substituted (Z)-enals and benzenesulfonamide. Reactions of these iron compounds with Grignard reagents or organolithiums gave 5-substituted α,β-unsaturated N-sulfonyl γ-lactams 5. In some cases the corresponding non-N-protected 5-substituted γ-lactams 6 were isolated as well. Key steps of these reaction cascades are the initial 1,2-addition to the imine moiety and the subsequent carbonylation step. The reaction of the chromene−iron complex 4e with (allyl)MgCl gave the (η3-allyl)iron−γ-lactam complex 8a with a ring-opened chromene framework. This complex was structura…
A Combined Theoretical and Experimental Approach for Platinum Catalyzed 1,2-Propanediol Aqueous Phase Reforming
2017
Decomposition pathways of 1,2-propanediol (1,2-PDO) on platinum were investigated by means of experiments and quantum-mechanical calculations. Different reaction paths on a Pt(111) model surface were computationally screened. Gas and liquid phase products distribution for aqueous phase reforming of 1,2-PDO solutions was experimentally analyzed. A mechanistic approach was used to trace the preferred paths according to calculated activation barriers of the elementary steps; in this way, the presence or absence of some hypothesized intermediates in the experiments was computationally rationalized. Hydroxyacetone was demonstrated to be among the most favored decomposition products. The competit…
Effect of oxidative stress on UDP-glucuronosyltransferases in rat astrocytes.
2012
WOS:000309170300003; International audience; The present work reports data regarding effects of an induced oxidative stress on the mainly expressed isoforms of UDP-glucuronosyltransferases (UGTs) in the brain. UGT1A6 and UGT1A7 expression and enzymatic activities toward the 1-naphthol were analyzed in rat cultured astrocytes following the exposure for 48 h to redox-cycling xenobiotic compounds such as quinones and bipyridinium ions. The expression of NADPH:cytochrome P450 reductase and NAD(P)H:quinone oxidoreductase 1 (NQO1) was also investigated. Oxidative stress induced significant deleterious changes in astrocyte morphology, decreased cell viability and inhibited catalytic function of UG…
Hemostatic, inflammatory, and oxidative markers in pesticide user farmers
2016
Research Article; International audience; The aim of this work was to investigate inflammatory, oxidative, and thrombotic parameters as biomarkers in farmers exposed to pesticides. Fifty farmers using chemical pesticides and 60 unexposed control men participated in this study. The Mediterranean diet compliance, the duration of pesticide use, and personal protection for pesticides handling were recorded using self-administered questionnaires. Serum biochemical parameters, oxidant/antioxidant, inflammatory, and thrombosis markers were determined. Our findings showed oxidative stress reflected by an increase in malondialdehyde, carbonyl proteins and superoxide anion levels and a decrease in vi…
Is obesity associated with oxidative stress in children?
2009
We evaluated the presence of oxidative stress in obese children without co-morbidities.The study population included 68 children (30 girls, 38 boys), between 6 and 14 years of age. The levels of markers of oxidative damage (malondialdehyde [MDA], and plasma carbonyl groups [CG]) and measures of antioxidant defense, such as the enzyme glutathione peroxidase (GPx) and low molecular scavengers (erythrocyte-reduced glutathione [GSH], alpha-tocopherol and beta-carotene) were determined. Children were categorized in groups by the standard deviation score of body mass index (SDS-BMI). Twenty children were non-obese (SDS-BMIor =1.33), and the 48 obese children (SDS-BMIor =2) were further divided in…