Synthesis of C2-Symmetric Diphosphormonoamidites and Their Use as Ligands in Rh-Catalyzed Hydroformylation: Relationships between Activity and Hydrolysis Stability

A series of diphosphoramidites has been synthetized with a piperazine, homopiperazine, and an acyclic 1,2-diamine unit in the backbone. New compounds were tested alongside related N-acyl phosphoramidites as ligands in the Rh-catalyzed hydroformylation of n-octenes to investigate their influence on the activity and regioselectivity. A subsequent study of their hydrolysis stability revealed that the most stable ligands induced the highest activity in the catalytic reaction

Confidence limits associated with values of the Earth’s magnetic field used for directional drilling

This paper describes updated uncertainties for use with predicted geomagnetic parameters within magnetic measurement-while-drilling (MWD) survey-tool-error models. These models are used to define positional-error ellipsoids along the wellbore, which assist in hitting geological targets and avoiding collisions with existing wellbores. The declination, dip angle, and total field strength of the Earth’s magnetic field are used with magnetic-survey tools for surveying the wellbore. These values are often obtained from mathematical models such as the British Geological Survey (BGS) global-geomagnetic model (BGGM). As the Earth’s magnetic field is continually varying with time, the BGGM is updated annually to maintain accuracy. However, a global predictive model cannot capture all sources of the Earth’s magnetic field, which results in uncertainties of the predicted parameters. The Industry Steering Committee on Wellbore Surveying Accuracy (ISCWSA) published an MWD-error model in 2000 (Williamson 2000). The geomagnetic-field uncertainties that are part of this model were derived from work conducted by the BGS in the early 1990s. Since then, more-accurate data from magnetic-survey satellites have been introduced into the BGGM, and the uncertainty of the predicted geomagnetic-field parameters has been reduced. The original approach to deriving the uncertainties involved separating the various error sources in the magnetic field and assessing them individually. This paper uses a simpler approach where clean orientated magnetic downhole data are simulated using geomagnetic-observatory data. Spot absolute measurements of the magnetic field made at observatories around the world are adjusted for the crustal magnetic field to make them more representative of hydrocarbon geology. The adjusted observatory data are then compared with the predicted values from the BGGM to assess the uncertainty. The uncertainties do not fit a normal distribution, so they are expressed as limits for various confidence levels. They vary with location and, in their derivation, do not assume any underlying empirical error distribution. While they also vary with time, we provide time-averaged look-up tables which should be valid for as long as there are good-quality satellite data on which to base global magnetic-field models. Options to reduce the uncertainties further using data from local magnetic surveys [in-field referencing (IFR)] and observatories (interpolation IFR) are also described. The use of the revised geomagnetic uncertainty values in the MWD-error model will reduce wellbore-position uncertainty to reflect the increased accuracy from recent improvements in geomagnetic modeling. This is demonstrated using results for the ellipsoids of uncertainty output by an MWD error model for three standard ISCWSA well profiles

A magnetic field model with daily variations of the magnetospheric field and its induced counterpart in 2001

Using geomagnetic data from the Ørsted satellite and observatories, two models of the Earth's magnetic field during 2001 have been produced. The two models differ in the time dependence of the spherical harmonic degree 1 magnetospheric field and its internally induced counterpart. The first model uses B-spline basis functions in time, with one node per day. The second uses a more common representation in which the hourly Dst index controls the rapid variations of the magnetospheric field. The solution of the first model shows that the amplitude of the magnetospheric field correlates well with the Dst index even for relatively active days. However, it shows much more variability in field direction than the magnetospheric field solution of the second model. In particular, this variability allows a better fit to the Y-components at magnetic observatories situated close to the meridian of the magnetic poles. For both models, the residuals of the fits to the observatory and satellite Y-component data have an unusual periodicity that is anticorrelated with the Y-component of the interplanetary magnetic field (IMF). This is possibly due to inter-hemispheric currents that flow in the upper ionosphere on the night-side of the Earth, but is more likely to be due to a direct penetration of the magnetosphere by the IMF

Influence of the bite natural angle of bidentate diphosphine ligands in the syngas-free branched hydroformylation of Β-functionalized olefins

© 2018 Elsevier B.V. The correlation between the activity, regio- and chemoselectivity of Rh-diphosphine catalyst and the ligand bite natural angle (βn) in the syngas-free hydroformylation of allyl cyanide was investigated. A screening of Xantphos type and diphosphine alkyl ligands with different bite natural angles was studied. Interesting, a switch in the linear to the branch regioselectivity was found. Wide βn favour a linear regioselectivity whereas smaller βn allow the formation of the branched aldehyde as the major product. Modification of the substituents at the phosphorus atoms of the diphosphine ligands produced a dramatic change in the hydroformylation. Others β-functionalized olefins were also branched hydroformylated

The Swarm Satellite Constellation Application and Research Facility (SCARF) and Swarm data products

Swarm, a three-satellite constellation to study the dynamics of the Earth's magnetic field and its interactions with the Earth system, is expected to be launched in late 2013. The objective of the Swarm mission is to provide the best ever survey of the geomagnetic field and its temporal evolution, in order to gain new insights into the Earth system by improving our understanding of the Earth's interior and environment. In order to derive advanced models of the geomagnetic field (and other higher-level data products) it is necessary to take explicit advantage of the constellation aspect of Swarm. The Swarm SCARF (Satellite Constellation Application and Research Facility) has been established with the goal of deriving Level-2 products by combination of data from the three satellites, and of the various instruments. The present paper describes the Swarm input data products (Level-1b and auxiliary data) used by SCARF, the various processing chains of SCARF, and the Level-2 output data products determined by SCARF

The Swarm Satellite Constellation Application and Research Facility (SCARF) and Swarm data products

International audiencewith the Earth system, is expected to be launched in late 2013. The objective of the Swarm mission is to providethe best ever survey of the geomagnetic field and its temporal evolution, in order to gain new insights into theEarth system by improving our understanding of the Earth’s interior and environment. In order to derive advancedmodels of the geomagnetic field (and other higher-level data products) it is necessary to take explicit advantageof the constellation aspect of Swarm. The Swarm SCARF (Satellite Constellation Application and ResearchFacility) has been established with the goal of deriving Level-2 products by combination of data from the threesatellites, and of the various instruments. The present paper describes the Swarm input data products (Level-1band auxiliary data) used by SCARF, the various processing chains of SCARF, and the Level-2 output data productsdetermined by SCARF