Tag: M.W=300-350

Fernandez, Sergio published the artcileA Unified Electro- and Photocatalytic CO₂ to CO Reduction Mechanism with Aminopyridine Cobalt Complexes, Recommanded Product: Tetrabutylammonium hydrogencarbonate, the publication is Journal of the American Chemical Society (2020), 142(1), 120-133, database is CAplus and MEDLINE.

A mechanistic understanding of electro- and photocatalytic CO₂ reduction is crucial to develop strategies to overcome catalytic bottlenecks. In this regard, for a new CO₂-to-CO reduction cobalt aminopyridine catalyst, a detailed exptl. and theor. mechanistic study is herein presented toward the identification of bottlenecks and potential strategies to alleviate them. The combination of electrochem. and in situ spectroelectrochem. together with spectroscopic techniques led us to identify elusive key electrocatalytic intermediates derived from complex [L^N4Co(OTf)₂] (1) (L^N4 = 1-[2-pyridylmethyl]-4,7-dimethyl-1,4,7-triazacyclononane) such as a highly reactive cobalt(I) (1^(I)) and a cobalt(I) carbonyl (1^(I)-CO) species. The combination of spectroelectrochem. studies under CO₂, ¹³CO₂, and CO with DFT disclosed that 1^(I) reacts with CO₂ to form the pivotal 1^(I)-CO intermediate at the 1^(II/I) redox potential. However, at this reduction potential, the formation of 1^(I)-CO restricts the electrocatalysis due to the endergonicity of the CO release step. In agreement with the exptl. observed CO₂-to-CO electrocatalysis at the Co^I/0 redox potential, computational studies suggested that the electrocatalytic cycle involves striking metal carbonyls. In contrast, under photochem. conditions, the catalysis smoothly proceeds at the 1^(II/I) redox potential. Under the latter conditions, it is proposed that the electron transfer to form 1^(I)-CO from 1^(II)-CO is under diffusion control. Then, the CO release from 1^(II)-CO is kinetically favored, facilitating the catalysis. Finally, we have found that visible-light irradiation has a pos. impact under electrocatalytic conditions. We envision that light irradiation can serve as an effective strategy to circumvent the CO poisoning and improve the performance of CO₂ reduction mol. catalysts.

Journal of the American Chemical Society published new progress about 17351-62-1. 17351-62-1 belongs to catalysis-chemistry, auxiliary class Salt,Amine, name is Tetrabutylammonium hydrogencarbonate, and the molecular formula is C17H37NO3, Recommanded Product: Tetrabutylammonium hydrogencarbonate.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Penney, Dp published the artcileStain and dye stability over a 30-year period: a comparison of certified dye powders by the Biological Stain Commission, Application In Synthesis of 10510-54-0, the publication is Biotechnic & Histochemistry (2009), 84(1), 11-15, database is CAplus and MEDLINE.

The Biol. Stain Commission (BSC) Assay Laboratory has received numerous inquiries during the past several years regarding the long-term stability of stain and dye powders, particularly since packaging requirements call for expiration dates on reagents. We have conducted a study to examine the long-term stability of selected dye powders. We used the standard procedures of the BSC for testing biol. stains for certification to give an indication of the long-term chem. stability as well as staining performance of the dye powders. An earlier study by Emmel and Stotz examined the stability of various dye powders after a five-year storage period. The present study is a follow-up project covering the same dyes after storage for 30 years. The dye samples chosen for the study are the same samples used in the five-year storage period study and give comparative results for all three time periods. The results of this study affirm the generally held speculation that dye powders are stable for many years and thus have a substantial shelf-life.

Biotechnic & Histochemistry published new progress about 10510-54-0. 10510-54-0 belongs to catalysis-chemistry, auxiliary class Other Aromatic Heterocyclic,Salt,Amine,Inhibitor,Inhibitor, name is 5,9-Diaminobenzo[a]phenoxazin-7-ium acetate, and the molecular formula is C18H15N3O3, Application In Synthesis of 10510-54-0.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Akhmetov, Vladimir published the artcileAcenaphthenoannulation Induced by the Dual Lewis Acidity of Alumina, Category: catalysis-chemistry, the publication is Chemistry – A European Journal (2022), 28(31), e202200584, database is CAplus and MEDLINE.

Authors have discovered a dual (i. e., soft and hard) Lewis acidity of alumina that enables rapid one-pot ¦Ð-extension through the activation of terminal alkynes followed by C-F activation. The tandem reaction introduces an acenaphthene fragment – an essential moiety of geodesic polyarenes. This reaction provides quick access to elusive non-alternant polyarenes such as ¦Ð-extended buckybowls and helicenes through three-point annulation of the 1-(2-ethynyl-6-fluorophenyl)naphthalene moiety. The versatility of the developed method was demonstrated by the synthesis of unprecedented structural fragments of elusive geodesic graphene nanoribbons.

Chemistry – A European Journal published new progress about 191-07-1. 191-07-1 belongs to catalysis-chemistry, auxiliary class Electronic Materials, name is Coronene, and the molecular formula is C24H12, Category: catalysis-chemistry.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Woods, Caleb M. published the artcileAllosteric Activation of Cytochrome P450 3A4 by ¦Á-Naphthoflavone: Branch Point Regulation Revealed by Isotope Dilution Analysis, Application of 5,9-Diaminobenzo[a]phenoxazin-7-ium acetate, the publication is Biochemistry (2011), 50(46), 10041-10051, database is CAplus and MEDLINE.

Cytochrome P 450 3A4 (CYP3A4) is the dominant xenobiotic metabolizing CYP. Despite great interest in CYP enzymol., two in vitro aspects of CYP3A4 catalysis are still not well understood, namely, sequential metabolism and allosteric activation. We have therefore investigated such a system in which both phenomena are present. Here we report that the sequential metabolism of Nile Red (NR) is accelerated by the heterotropic allosteric effector ¦Á-naphthoflavone (ANF). ANF increases the rates of formation for NR metabolites M1 and M2 and also perturbs the metabolite ratio in favor of M2. Thus, ANF has as an allosteric effect on a kinetic branch point. Co-incubating deuterium-labeled NR and unlabeled M1, we show that ANF increases k_cat/k_off ?1.8-fold in favor of the k_cat of M2 production Steady-state metabolic experiments are analyzed using a kinetic model in which the enzyme and substrates are not in rapid equilibrium, and this distinction allows for the estimation of rates of catalysis for the formation of both the primary (M1) and secondary (M2) products, as well as the partitioning of enzyme between these states. These results are compared with those of earlier spectroscopic investigations of NR and ANF cooperativity, and a mechanism of ANF heteroactivation is presented that involves effects on substrate off rate and coupling efficiency.

Biochemistry published new progress about 10510-54-0. 10510-54-0 belongs to catalysis-chemistry, auxiliary class Other Aromatic Heterocyclic,Salt,Amine,Inhibitor,Inhibitor, name is 5,9-Diaminobenzo[a]phenoxazin-7-ium acetate, and the molecular formula is C4H6BrFO2, Application of 5,9-Diaminobenzo[a]phenoxazin-7-ium acetate.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Hu, Mingyuan published the artcilePolyunsaturated fatty acid intake and incidence of type 2 diabetes in adults: a dose response meta-analysis of cohort studies, Quality Control of 6217-54-5, the publication is Diabetology & Metabolic Syndrome (2022), 14(1), 34, database is CAplus and MEDLINE.

Meta-anal. of relationship between polyunsaturated fatty acid (PUFA) intake and incidence of type 2 diabetes (T2D) in adults. PubMed, Embase, Cochrane Library, and Web of Science databases were searched for cohort studies that examined the association between PUFA and T2D incidence published up to Sept. 6, 2021. Relative risk (RR) or hazard ratio (HR) was used as the effect indicator, each effect size was expressed by 95% confidence interval (CI). The presence of heterogeneity of effect size between studies was assessed by the Q-test and I2 statistics. If I2 ¡Ý 50%, the random-effects model was applied, otherwise the fixed effects model was used. Sensitivity anal. was performed for all models. Potential publication bias was assessed. We conducted linear and nonlinear dose-response meta-analyses, calculated summary relative risk (SRR). Twenty-five articles were selected including 54,000 patients in this study. Our estimates observed no linear associations between total PUFA and the incidence of T2D. However, the summary dose-response curve of T2D risk increased in a nonlinear pattern with the consumption of omega-3 PUFA (Pnonlinearity < 0.001) and docosahexaenoic acid (DHA) (Pnonlinearity = 0.040). Our subgroup anal. showed that total PUFA intake was associated with increased incidence of T2D in Europe (RR: 1.040, 95% CI 1.009 to 1.072), and Australia (RR: 1.188, 95% CI 1.113 to 1.269). However, total PUFA intake was associated with decreased T2D incidence in Asia (RR: 0.897, 95% CI 0.860 to 0.936). Subgroup anal. based on PUFA types showed that DHA intake was associated with decreased T2D incidence (RR: 1.164, 95% CI 1.048 to 1.294) while linoleic acid (LA) decreased T2D incidence (RR: 0.956, 95% CI 0.930 to 0.983). Regarding the sex subgroup, women¡äs intake of total PUFA would increase the risk of T2D (RR: 1.049, 95% CI 1.019 to 1.079) while total PUFA intake decreased the risk of T2D in men (RR: 0.955, 95% CI 0.913 to 0.999). For specific PUFA, dose-response curves show nonlinear significant associations between PUFA intakes and T2D. It may be necessary to pay attention to the effects of PUFA and type of intake on T2D.

Diabetology & Metabolic Syndrome published new progress about 6217-54-5. 6217-54-5 belongs to catalysis-chemistry, auxiliary class Alkenyl,Carboxylic acid,Aliphatic hydrocarbon chain,Metabolic Enzyme,RAR/RXR,Natural product, name is Docosahexaenoic Acid, and the molecular formula is C22H32O2, Quality Control of 6217-54-5.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Li, Xinling published the artcileSize-fractionated nonpolar organic compounds of traffic aerosol emissions in a highway tunnel, Related Products of catalysis-chemistry, the publication is Environmental Pollution (Oxford, United Kingdom) (2022), 118501, database is CAplus and MEDLINE.

Size-fractionated aerosol samples (PM0.25, PM0.25-1, PM1-2.5, and PM2.5-10) were collected in a highway tunnel in Shanghai, China. The concentrations of nonpolar organic compounds (NPOCs), i.e., n-alkanes, polycyclic aromatic hydrocarbons (PAHs) and hopanes in the aerosol samples at the tunnel inlet and outlet, emission factors (EFs) of individual NPOCs in PM10, and EFs of size-fractionated individual NPOCs were analyzed comprehensively. NPOC concentrations in this tunnel were lower than the earlier tunnel results, which might be attributed to the tunnel configuration effect on the pollution dilution along the tunnel, in addition to the improvement of engine technol. and fuel quality during past decades. n-Alkane homologs for C14-C35 exhibited a smooth hump-like distribution pattern with the most abundance at C22 and 1-2 carbon number shifts of Cmax in comparison to those in other tunnels due to different fleet and fuel compositions The most abundant PAHs from diesel (e.g., Nap, Phe, Flu and Pyr) and gasoline (e.g., BghiF, BbkF, BeP, DBA and BghiP) vehicle emissions presented concentration increases of 1.8-5.8 times from the tunnel inlet to outlet. The individual n-alkane and PAH distributions exhibited obvious size dependence, while it was expected that the relative abundances and homolog distributions of hopanes were very similar for different size stages. Several diagnostic ratios, e.g., fossil/plant n-alkanes and LMW/HMW PAHs, were evidently size dependent, indicating different sources of size-fractionated n-alkanes and PAHs.

Environmental Pollution (Oxford, United Kingdom) published new progress about 191-07-1. 191-07-1 belongs to catalysis-chemistry, auxiliary class Electronic Materials, name is Coronene, and the molecular formula is C24H12, Related Products of catalysis-chemistry.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Nikoorazm, Mohsen published the artcileFe₃O₄@MCM-41@Zn-Arg: as a novel, magnetically recoverable and ecofriendly nanocatalyst for the synthesis of disulfides, sulfoxides and 2,3-dihydroquinazolin-4(1H)-ones, Formula: C14H10O4S2, the publication is Inorganic and Nano-Metal Chemistry (2021), 51(5), 642-655, database is CAplus.

The direct supporting of Zn-arginine complex on magnetic core-shell nanostructures (Fe₃O₄@MCM-41@Zn-Arg) was reported as a novel, heterogeneous and excellent nanocatalyst, which was applied for the oxidation reaction of sulfides to sulfoxides, oxidative coupling of thiols to their corresponding disulfides and the synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives under mild conditions. The simple exptl. procedure, very good catalytic activity, low cost, and excellent recycling are the noteworthy features of the currently employed heterogeneous catalytic system.

Inorganic and Nano-Metal Chemistry published new progress about 119-80-2. 119-80-2 belongs to catalysis-chemistry, auxiliary class sulfides,Carboxylic acid,Benzene, name is 2,2′-Dithiodibenzoic acid, and the molecular formula is C14H10O4S2, Formula: C14H10O4S2.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Castillo Melean, Johnny published the artcileEnantiospecific synthesis of 2-[¹⁸F]fluoro-L-phenylalanine and 2-[¹⁸F]fluoro-L-tyrosine by isotopic exchange, Category: catalysis-chemistry, the publication is Organic & Biomolecular Chemistry (2011), 9(3), 765-769, database is CAplus and MEDLINE.

2-[¹⁸F]Fluoro-L-phenylalanine and 2-[¹⁸F]fluoro-L-tyrosine have been developed as promising radiopharmaceuticals for mol. imaging using positron emission tomog. (PET). However, the lack of a convenient radiosynthetic pathway has limited their practical use. In this work a new three-step nucleophilic synthesis of these compounds starting from [¹⁸F]fluoride is described. Corresponding precursors (I) (R¹ = H or OCH₂Ph; Boc = tert-butoxycarbonyl) were ¹⁸F-fluorinated by isotopic exchange, followed by the removal of an activating formyl group with Rh(PPh₃)₃Cl and subsequent hydrolysis of protecting groups in acidic medium. All reactions were carried out using both conventional and microwave heating. Conventional heated reactions yielded the desired products 2-[¹⁸F]Fphe and 2-[¹⁸F]Ftyr in 43% and 49% whereas radiochem. yields of 34% and 43%, resp., were obtained when they were heated by microwaves. Under optimized conditions the enantiomeric purity was ¡Ý94% for both radiopharmaceuticals.

Organic & Biomolecular Chemistry published new progress about 17351-62-1. 17351-62-1 belongs to catalysis-chemistry, auxiliary class Salt,Amine, name is Tetrabutylammonium hydrogencarbonate, and the molecular formula is C17H37NO3, Category: catalysis-chemistry.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Castillo Melean, Johnny published the artcileA three-step radiosynthesis of 6-[¹⁸ F]fluoro-L-meta-tyrosine starting with [¹⁸ F]fluoride, COA of Formula: C17H37NO3, the publication is Journal of Labelled Compounds and Radiopharmaceuticals (2015), 58(3), 133-140, database is CAplus and MEDLINE.

The radiosynthesis of 6-[¹⁸ F]fluoro-L–m-tyrosine has generally been performed by electrophilic radiofluorination, which exhibits several drawbacks. In the present work, a three-step radiochem. synthesis is described starting from [¹⁸ F]fluoride. The synthetic sequence, including isotopic exchange, Baeyer-Villiger oxidation, and hydrolysis, were examined comparing four fluorobenzophenone derivatives as labeling precursors. Of those, (2S,5S)-tert-Bu 5-(5-acetyl-2-fluorobenzyl)-2-tert-butyl-3-methyl-4-oxoimidazolidine-1-carboxylate and (2S,5S)-tert-Bu 2-tert-butyl-5-(2-fluoro-5-(2,2,2-trifluoroacetyl)benzyl)-3-methyl-4-oxoimidazolidine-1-carboxylate proved to be the most suitable ones. 6-[¹⁸ F]Fluoro-L-m-tyrosine was obtained with overall radiochem. yields of 8-13% and an enantiomeric excess of up to 98%.

Journal of Labelled Compounds and Radiopharmaceuticals published new progress about 17351-62-1. 17351-62-1 belongs to catalysis-chemistry, auxiliary class Salt,Amine, name is Tetrabutylammonium hydrogencarbonate, and the molecular formula is C17H37NO3, COA of Formula: C17H37NO3.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia

Li, Xiaoman published the artcileCatalyst- and Metal-Free Photo-Oxidative Coupling of Thiols with BrCCl₃, Category: catalysis-chemistry, the publication is European Journal of Organic Chemistry (2022), 2022(23), e202200340, database is CAplus.

This paper reported a catalyst- and metal-free method to construct disulfide bond with BrCCl₃ under light irradiation This clean and mild reaction promoted the oxidative coupling of thiols with wide substrate scope, and was applicable to benzylic, aryl and aliphatic thiols, especially cysteine derivative The disulfides were obtained in high yields up to 98%, avoiding the use of heating, strong oxidant, metal reagent or catalyst. This facile strategy facilitated the synthesis of disulfide compounds

European Journal of Organic Chemistry published new progress about 119-80-2. 119-80-2 belongs to catalysis-chemistry, auxiliary class sulfides,Carboxylic acid,Benzene, name is 2,2′-Dithiodibenzoic acid, and the molecular formula is C14H10O4S2, Category: catalysis-chemistry.

Referemce:
https://courses.lumenlearning.com/boundless-chemistry/chapter/catalysis/,
Catalysis – Wikipedia