114 research outputs found
A Suzuki Coupling Based Route to 2,2'-Bis(2-indenyl)biphenyl Derivatives
Because of the promising performance in olefin polymerization of 2,2'-bis(2-indenyldiyl)biphenyl zirconium dichloride, we developed a new and broadly applicable route to 2,2'-bis(2-indenyl)biphenyl derivatives. Reaction of the known 2,2'-diiodobiphenyl with the new 2-indenyl boronic acid did not result in the desired 2,2'-bis(2-indenyl)biphenyl (10); instead an isomer thereof, (spiro-1,1-(2,2'-biphenyl)-2-(2-indenyl)indane), was obtained. It was found that compound 10 could be made via a palladium-catalyzed reaction of 2,2-biphenyldiboronic acid with 2-bromoindene under standard Suzuki reaction conditions. However, the yield of this reaction was low at low palladium catalyst loadings, due to a competitive hydrolysis reaction of 2,2-biphenyldiboronic acid. HTE techniques were used to find an economically viable protocol. Thus, use of the commercially available 1.0 molar solution of (n-Bu)4NOH in methanol with cosolvent toluene led to precipitation of the pure product in a fast and clean reaction, using only 0.7 mol % (0.35 mol % per C-C) of the expensive palladium catalyst.
Oxalic acid hydrogenation to glycolic acid:heterogeneous catalysts screening
To meet our ambitions of a future circular economy and drastically reduce CO2 emissions, we need to make use of CO2 as a feedstock. Turning CO2 into monomers to produce sustainable plastics is an attractive option for this purpose. It can be achieved by electrochemical reduction of CO2 to formic acid derivatives, that can subsequently be converted into oxalic acid. Oxalic acid can be a monomer itself and it is a potential new platform chemical for material production, as useful monomers such as glycolic acid and ethylene glycol can be derived from it. Today the most common route from oxalic acid to glycolic acid requires multiple steps as it proceeds via oxalic acid di-esters as intermediates. In this work, we aim to avoid the extra reaction step of esterification. We explore the direct conversion of oxalic acid to glycolic acid in a two-step approach. In the first step, we define the ideal reaction conditions and test commercially available catalysts. We show that the reduction of oxalic acid can be performed at much lower temperatures and glycolic acid yields higher than those reported previously can be obtained. In the second step, we explore the design principles required for ideal catalysts which avoid the formation of acetic acid and ethylene glycol as side products. We show that ruthenium is the most active metal for the reaction and that carbon appears the most suitable support for these catalysts. By adding tin as a promotor, we could increase the selectivity and yield further whilst maintaining high activity of the resulting catalyst. This research lays the foundation for the efficient direct reduction of oxalic acid to glycolic acid and defines the design parameters for even better catalysts and the ideal process and conditions.</p
Cathodic Disintegration as an Easily Scalable Method for the Production of Sn- and Pb-Based Catalysts for CO<sub>2</sub> Reduction
Infrared Properties of QCD from Dyson-Schwinger equations
I review recent results on the infrared properties of QCD from
Dyson-Schwinger equations. The topics include infrared exponents of
one-particle irreducible Green's functions, the fixed point behaviour of the
running coupling at zero momentum, the pattern of dynamical quark mass
generation and properties of light mesons.Comment: 47 pages, 19 figures, Topical Review to be published in J.Phys.G, v2:
typos corrected and some references adde
Condensation and interaction range in harmonic boson traps: a variational approach
For a gas of N bosons interacting through a two-body Morse potential a
variational bound of the free energy of a confined system is obtained. The
calculation method is based on the Feynman-Kac functional projected on the
symmetric representation. Within the harmonic approximation a variational
estimate of the effect of the interaction range on the existence of
many-particle bound states, and on the N-T phase diagram is obtained.Comment: 14 pages+4 figures, submitted to phys.rev.
Configural and featural processing in humans with congenital prosopagnosia.
Prosopagnosia describes the failure to recognize faces, a deficiency that can be
devastating in social interactions. Cases of acquired prosopagnosia have often
been described over the last century. In recent years, more and more cases of
congenital prosopagnosia (CP) have been reported. In the present study we tried
to determine possible cognitive characteristics of this impairment. We used
scrambled and blurred images of faces, houses, and sugar bowls to separate
featural processing strategies from configural processing strategies. This
served to investigate whether congenital prosopagnosia results from
process-specific deficiencies, or whether it is a face-specific impairment.
Using a delayed matching paradigm, 6 individuals with CP and 6 matched healthy
controls indicated whether an intact test stimulus was the same identity as a
previously presented scrambled or blurred cue stimulus. Analyses of
dÂŽ values indicated that congenital prosopagnosia
is a face-specific deficit, but that this shortcoming is particularly pronounced
for processing configural facial information
Degradation of YRA1 Pre-mRNA in the Cytoplasm Requires Translational Repression, Multiple Modular Intronic Elements, Edc3p, and Mex67p
The yeast YRA1 pre-mRNA contains multiple intronic elements that regulate transcript decay and translatability via the Edc3p decapping activator and the Mex67p/Mtr2p export receptor
Stoma-free survival after anastomotic leak following rectal cancer resection : worldwide cohort of 2470 patients
Funding Information: The TENTACLE-Rectum study was funded by Medtronic External Research Program. The authors declare no other conflict of interest.Peer reviewedPublisher PD
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