The moduli space of holomorphic differentials on curves of genus
g
admits a natural action of the group
. The study of orbits of this action and their closures has attracted the interest of a wide ...range of researchers in the last few decades. In the 2000s, C. McMullen described an infinite family of orbifolds that are closures of such orbits in the space of holomorphic differentials on curves of genus 2. In spaces of holomorphic differentials on curves of higher genera, well-known examples of orbifolds that are unions of
-orbit closures are Prym eigenform loci. They are nonempty for surfaces of genus at most 5. This paper presents the first nontrivial calculations of the number of connected components in Prym eigenform loci for surfaces of maximum possible genus.
Hydroformylation is an important industrial process applied for the production of many highly-demanded chemicals. For now, only the Co/phosphine, Rh/phosphine, or ligand-free systems are used in ...industry. Although most of the research dealing with hydroformylation also considers systems with phosphorus-containing ligands or heterogeneous materials, the interest in developing phosphorus-free nitrogen-containing systems tends to grow during the last decade. N-ligands can be easier to synthesize, more stable towards oxidation, and at the same time add some useful features, such as the higher activity in the tandem hydroformylation-based reactions. The review is focused on the progress made in the design of N-ligands for homogeneous and biphasic hydroformylation of unsaturated compounds, as well as N-containing heterogeneous catalysts for the process. In addition, the data on tandem reactions, such as reductive hydroformylation and hydroaminomethylation, are systematized and discussed.
Display omitted
•Publications on N-containing phosphorus-free systems in hydroformylation are reviewed.•Rh/N systems are useful for applied hydroformylation-based reactions.•Rh/NR3 systems are effective for reductive hydroformylation.•Prospects of biphasic and heterogeneous Rh/N systems are discussed.
The feature of hydroformylation of model gas mixtures with different ethylene, hydrogen, and methane concentrations in the presence of rhodium catalysts have been studied. The effect of the initial ...pressure in the reactor and the reaction temperature on the reaction rate and selectivity has been determined. It has been shown that ethylene hydroformylation occurs with a high propanal selectivity (up to 99%), with the turnover frequency of the reaction reaching 9500 h
–1
. It has been proposed that various phosphine ligands should be used to implement alternative methods of separating the catalyst system from the reaction products.
In view of the growing environmental concerns and the need to involve alternative sources of raw materials in the chemical industry, intensive research efforts in the last decades have focused on ...carbon dioxide reactions. In this context, the present review discusses prior studies that were aimed at producing commercially important compounds, such as acids, alcohols, organic carbonates, and polycarbonates, in homogeneous catalytic systems that contain transition-metal complexes. Such systems have been traditionally valued for their high activity and selectivity under relatively mild conditions. The review provides systematized information both on CO
2
reactions with hydrogen to produce C
1
chemicals such as formic acid and methanol, and on CO
2
interactions with organics (e.g., olefins, alcohols, and epoxides) to produce valuable chemical compounds.
A series of heterogeneous phosphine-containing rhodium hydroformylation catalysts based on porous aromatic frameworks (PAFs) were prepared. The catalysts PAF30-MDEA-TPPTS-Rh (TPPTS is trisodium ...triphenylphosphine-3,3',3''-trisulfonate, MDEA is methyldiethanolamine fragment) and PAF-30-Im-TPPTS-Rh (Im is imidazole fragment) showed the highest stability in repeated use in 1-hexene hydroformylation. The catalyst PAF-30-MDEA-TPPTS-Rh before and after use in hydroformylation was characterized by elemental C,N,H,S analysis, inductively coupled plasma atomic absorption spectroscopy, low-temperature nitrogen adsorption–desorption, transmission electron microscopy, IR spectroscopy, and X-ray photoelectron spectroscopy. The effect of temperature, pressure, and solvent on the course of hydroformylation in the presence of PAF-30-MDEA-TPPTS-Rh was studied. The catalyst is active in hydroformylation of a series of unsaturated compounds, including functionalized substrates and olefins with internal double bond.
Hydroformylation reactions and related tandem reactions (hydroformylation—hydrogenation, hydroaminomethylation) proceeding without introduction of syngas were considered. Reaction systems, in which ...other gases or liquid-dissolved reagents were used as a formyl group source, were described and systematized.
A phosphine-containing porous polymer (TPDB), and a rhodium catalyst based on it, were synthesized. Proceeding from the relevant TEM, NMR, IR spectroscopy, and XPS data obtained, it was assumed that ...both the Rh(I) complexes and the Rh(0) nanoparticles that are stabilized in the polymer pores act as the catalyst’s active phase. The size of the nanoparticles (2–6 nm) is consistent with that of the polymer pores. The catalyst was tested in a model reaction of octene-1 hydroformylation at 2.0 MPa (CO : H
2
= 1 : 1) in the temperature range of 60–120°C. It was demonstrated that the catalyst can be used repeatedly, and its activity remains constant from the third cycle of its use (aldehyde yield about 30% for 5 h,
n
/
iso
2.5).
This review deals with heterogeneous hydroformylation catalysts, specifically metal complexes fixed in an organic polymer structure. It describes the main catalyst synthesis methods, provides data on ...hydroformylation of unsaturated compounds (including asymmetric hydroformylation), and shows how those compounds can be used. The special focus is on the systematization of data on heterogeneous catalysts developed on the basis of porous organic polymers. Due to their porous structure, resistance to organic media and the high concentration of heteroatoms they contain, these materials can be considered promising for developing highly active, selective and stable heterogeneous catalysts for hydroformylation of unsaturated compounds, particularly higher linear olefins.
Three rhodium-containing catalytic systems active in tandem hydroformylation/hydrogenation of unsaturated substrates were developed based on polyethyleneimine (PEI): a homogeneous system with ...distillation of the product; a biphasic system with segregation of the product and catalyst into a non-polar phase and a polar phase, respectively; and a solid catalyst prepared from PEI and (3-chloropropyl)triethoxysilane with its centrifugation from the product mixture. All the systems were shown to be reusable over multiple cycles in hydroformylation/hydrogenation, with the catalytic activity being partially sustained in both steps of the tandem process. Methylation of PEI (or its NH and NH
2
moieties in the case of solid material) was found to be critical for the catalytic activity in hydroformylation.
Clinical trials have shown treatment benefits of dupilumab in patients with uncontrolled asthma for up to 1 year. This study aimed to evaluate the long-term safety and efficacy of dupilumab in ...patients with moderate-to-severe asthma, as data for extended treatment with dupilumab beyond 1 year are not available.
TRAVERSE was an open-label extension study in 362 hospitals and clinical centres across 27 countries that assessed the safety and efficacy of dupilumab 300 mg every 2 weeks up to 96 weeks in adults and adolescents (aged 12-84 years) with moderate-to-severe or oral-corticosteroid-dependent severe asthma who had completed a previous dupilumab asthma study (phase 2A EXPEDITION, phase 2B DRI P2b, phase 3 QUEST, or VENTURE). The primary endpoint was the number and percentage of patients with any treatment-emergent adverse events. Secondary endpoints included annualised exacerbation rate (AER) over the treatment period and change from parent study baseline in pre-bronchodilator FEV
, the five-item asthma control questionnaire (ACQ-5), the asthma quality of life questionnaire (AQLQ), type 2 biomarkers (blood eosinophils and serum total IgE), and anti-drug antibodies (ADAs). Statistical analyses were descriptive. We report safety in all enrolled patients, and efficacy in patients with non-oral-corticosteroid-dependent asthma and in subgroups, including patients with a type 2 inflammatory phenotype who received 148 weeks of treatment. This study is registered with ClinicalTrials.gov, NCT02134028.
Between Aug 5, 2014, and Oct 11, 2019, of 2302 patients assessed for eligibility, 2282 adults and adolescents were enrolled (median age 50 years, 62·1% female and 37·9% male). Safety during TRAVERSE was consistent with the known dupilumab safety profile. The proportion of patients reporting treatment-emergent adverse events throughout the study duration was similar to that observed in the parent studies and ranged from 76·3% to 94·7%. The most frequently reported treatment-emergent adverse events were nasopharyngitis (17·5-25·9%), injection-site erythema (2·2-23·4%), and bronchitis (9·3-19·0%). Serious asthma exacerbations (0·5-3·6%) and pneumonia (0·7-2·7%) were the most frequently reported serious adverse events. There were four treatment-emergent adverse events leading to death. Efficacy during TRAVERSE was also consistent with the results of parent studies. In patients who were non-oral-corticosteroid-dependent, AER remained low (0·277-0·327) across parent study and treatment groups, pre-bronchodilator FEV
improvements were sustained to the end of treatment at week 96 (mean changes from parent study baseline ranged from 0·22 L SD 0·44 to 0·33 L 0·44 across parent study and treatment groups), and improvements in ACQ-5 and AQLQ scores were sustained to the last timepoint assessed at week 48. Rapid improvements were observed in pre-bronchodilator FEV
and sustained improvements were seen in all outcome measures for patients given dupilumab who previously received placebo in parent studies; further improvements in AER, asthma control, and health-related quality of life were observed in patients who continued receiving dupilumab. Blood eosinophils and serum total IgE decreased progressively. ADA status had no effect on safety or efficacy. In the subgroup of patients with a type 2 inflammatory phenotype followed-up for 148 weeks, AER decreased progressively, and initial lung function improvements were sustained over 148 weeks.
Data show that safety and efficacy of dupilumab in adult and adolescent patients with moderate-to-severe asthma are sustained when treatment is extended up to 148 weeks. These findings therefore support the long-term use of dupilumab in this patient population.
Sanofi and Regeneron Pharmaceuticals.
PDF