Carbonylation

Carbonylation reactions constitute potent methodologies for the synthesis of all kinds of carbonyl containing compounds. Such transformations, which require the presence of additional oxidants, are usually cataloged as so‐called “oxidative carbonylations”. This chapter examines the catalytic systems that have been used for reductive and oxidative carbonylation. In addition, it provides a detailed case study of the rapid formation of essentially pure methyl methacrylate (MMA) from the methoxycarbonylation of propyne. The chapter also gives a case study that describes the development of a highly efficient class of homogeneous catalysts for the carbonylation of alkynes, which makes possible an economically competitive and environmentally benign process for MMA production. The chapter further reviews the synthesis of ethylene/CO copolymer with discussion of the reaction mechanisms. Finally, it also reviews the copolymerization of unfunctionalized and functionalized monosubstituted‐ethenes as well as imines

First application of the Laser Ion Source and Trap (LIST) for on-line experiments at ISOLDE

International audienceThe Laser Ion Source and Trap (LIST) provides a new mode of operation for the resonance ionization laser ion source (RILIS) at ISOLDE/CERN, reducing the amount of surface-ionized isobaric contaminants by up to four orders of magnitude. After the first successful on-line test at ISOLDE in 2011 the LIST was further improved in terms of efficiency, selectivity, and reliability through several off-line tests at Mainz University and at ISOLDE. In September 2012, the first on-line physics experiments to use the LIST took place at ISOLDE. The measurements of the improved LIST indicate more than a twofold increase in efficiency compared to the LIST of the 2011 run. The suppression of surface-ionized francium contaminants has enabled the first in-source laser spectroscopy of 217Po and 219Po

High-resolution laser spectroscopy with the Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at CERN-ISOLDE

International audienceThe Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at CERN has achieved high-resolution resonance ionisation laser spectroscopy with a full width at half maximum linewidth of 20(1) MHz for 219,221219,221Fr, and has measured isotopes as short lived as 5 ms with 214214Fr. This development allows for greater precision in the study of hyperfine structures and isotope shifts, as well as a higher selectivity of single-isotope, even single-isomer, beams. These achievements are linked with the development of a new laser laboratory and new data-acquisition systems

High-resolution laser spectroscopy with the Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at CERN-ISOLDE

The Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at CERN has achieved high-resolution resonance ionisation laser spectroscopy with a full width at half maximum linewidth of 20(1) MHz for 219,221Fr, and has measured isotopes as short lived as 5 ms with 214Fr. This development allows for greater precision in the study of hyperfine structures and isotope shifts, as well as a higher selectivity of single-isotope, even single-isomer, beams. These achievements are linked with the development of a new laser laboratory and new data-acquisition systems

Effect of alloy composition on the dendrite arm spacing of multicomponent aluminum alloys

Predictions of secondary dendrite arm spacing (SDAS) for multicomponent aluminum alloys using a dendrite ripening model are compared with experimental observations. For six of the seven alloys studied, the predicted SDAS was within 20 pct of the measured SDAS. It was found that the final SDAS was dependent upon both the solidification time and the solute profile of the solidifying alloys. It is interesting that while the solidification times and the solute segregation during solidification varied significantly over the range of alloys, these two factors largely canceled each other out so that the predicted SDAS did not vary much between the alloys. The experimental and modeling results show that elements causing high constitutional undercooling near the beginning of solidification, e.g., Ti, which reduces the grain size substantially, have little effect on the SDAS. Instead, it was found that elements that strongly partitioned toward the end of solidification were more effective at restricting SDAS coarsening