Palladium Nanoparticles–Polypyrrole Composite as Effective Catalyst for Fluoroalkylation of Alkenes

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Abstract: Palladium nanoparticles–polypyrrole composite (Pd/PPy) catalyzes the addition of perfluoroalkyl halides to olefins to produce a variety of products with good yields. An effective fluoroalkylation technique tested with various olefins, fluoroalkyl halides and Pd/PPy was developed. The reaction proceeds highly efficient under mild phosphine-free reaction conditions with different substrates, easy catalyst recycling and provides a general and straightforward access to fluoroalkylated products. Furthermore, we were able to control whether the addition of perfluoroalkyl occurs with various monomer (fluoroalkylated alkene or alkane with RF and OH moieties) or dimer formation (under electrochemical conditions). Graphical Abstract: [Figure not available: see fulltext.]

A Ni(III) complex stabilized by silica nanoparticles as an efficient nanoheterogeneous catalyst for oxidative C-H fluoroalkylation

© The Royal Society of Chemistry 2016.We have developed NiIII-doped silica nanoparticles ([(bpy)xNiIII]@SiO2) as a recyclable, low-leaching, and efficient oxidative functionalization nanocatalyst for aromatic C-H bonds. The catalyst is obtained by doping the complex [(bpy)3NiII] on silica nanoparticles along with its subsequent electrooxidation to [(bpy)xNiIII] without an additional oxidant. The coupling reaction of arenes with perfluoroheptanoic acid occurs with 100% conversion of reactants in a single step at room temperature under nanoheterogeneous conditions. The catalyst content is only 1% with respect to the substrates under electrochemical regeneration conditions. The catalyst can be easily separated from the reaction mixture and reused a minimum of five times. The results emphasize immobilization on the silica support and the electrochemical regeneration of NiIII complexes as a facile route for developing an efficient nanocatalyst for oxidative functionalization

Seeding time on irrigated rice

Em seis experimentos de campo, semeados em outubro, novembro e dezembro de 1978 e 1979, foram estudados os efeitos da brusone (Pyricularia oryzae Cav.) e de temperatura baixas (frio) sobre a produção das cultivares de arroz (Oryza sativa L.) Bluebelle, EEA 406, IRGA 408, Dawn e Caloro. Os resultados permitiram concluir que a época de semeadura influi na produtividade do arroz e que a produção das épocas tardias (dezembro) é mais prejudicada pelos danos da brusone e do frio, simultaneamente. Determinou-se, também, que as cultivares estudadas apresentam comportamentos diversos quanto à sua sensibilidade a esses fatores, e que a semeadura em épocas precoces - outubro e novembro - oferece à cultura maiores possibilidades de escapar desses danos. A brusone foi mais danosa sobre as cultivares Caloro e EEA 406, enquanto que o frio prejudicou mais a produção de IRGA 408 e Dawn. A cultivar Bluebelle, de ciclo precoce, sofreu os efeitos de ambos os fatores de maneira mais suave e apresentou maiores chances de escape. Não foram obtidas correlações satisfatórias entre os danos da brusone e as condições meteorológicas.At six field experiments, seeded in October, November and December of 1978 and 1979, the rice blast disease (Pyricularia oryzae Cav.) and low temperature effects on the grain yield of the rice cultivars Bluebelle, EEA 406, IRGA 408, Dawn, and Caloro, were studied. The results showed that seeding time had effect on rice yield, and in the later seeding times, in December the yield was reduced simultaneously by the rice blast disease and cold. It was also determinated that the rice cultivars show differences on susceptibility to these factors, and that the early seeding, at October and November, gives the cultivation more chances for the rice crop lo escape from both blast and cold damages. The rice blast disease attack was more severe on the rice cultivars Caloro and EEA 406. On the other hand, the low temperatures injured more the rice cultivars IRGA 408 and Dawn. The Bluebelle, a short growth duration variety has more chances lo escape from these losses. No satisfactory correlation was obtained between the rice blast disease losses and the metheorological conditions

Unexpected ligand effect on the catalytic reaction rate acceleration for hydrogen production using biomimetic nickel electrocatalysts with 1,5-diaza-3,7-diphosphacyclooctanes

© 2015 Elsevier B.V. All rights reserved. The two new nickel complexes [Ni(PR2NPh(CH)Ph2)2]2+ (where R = Ph or o-Py) with cyclic 1,5-diaza-3,7-diphosphacyclooctane ligands have been synthesized. All complexes are effective electrocatalysts for hydrogen production using [(DMF)H]+ as proton source in acetonitrile. The bulky benzhydryl substituent at nitrogen atom leads to higher catalytic activity comparison to benzyl. The introduction o-Py substituents at phosphorus as additional basic center is caused by the changing of voltage-current picture and significantly catalytic current enhancement. TOFs being 100 and 15200 s-1 for R = Ph and o-Py, respectively

Palladium Nanoparticles–Polypyrrole Composite as Effective Catalyst for Fluoroalkylation of Alkenes

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Abstract: Palladium nanoparticles–polypyrrole composite (Pd/PPy) catalyzes the addition of perfluoroalkyl halides to olefins to produce a variety of products with good yields. An effective fluoroalkylation technique tested with various olefins, fluoroalkyl halides and Pd/PPy was developed. The reaction proceeds highly efficient under mild phosphine-free reaction conditions with different substrates, easy catalyst recycling and provides a general and straightforward access to fluoroalkylated products. Furthermore, we were able to control whether the addition of perfluoroalkyl occurs with various monomer (fluoroalkylated alkene or alkane with RF and OH moieties) or dimer formation (under electrochemical conditions). Graphical Abstract: [Figure not available: see fulltext.]