| 1. |
- Kleimark, Jonatan, 1982, et al.
(författare)
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Low Temperature Studies of Iron-Catalyzed Cross-Coupling of Alkyl Grignard Reagents with Aryl Electrophiles
- 2012
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Ingår i: Advanced Synthesis & Catalysis. - 1615-4169. ; 354:2-3, s. 448-456
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Tidskriftsartikel (refereegranskat)abstract
- The title reaction has been studied under low temperature conditions. Coupling with active substrates can be done even at dry ice temperature. Initial rate studies at −25°C indicate that high concentrations of any reagent can lead to either complete or partial catalyst deactivation. Under strongly reducing conditions, iron seems to form less active complexes that only slowly re-enter the catalytic cycle, possibly through bimolecular coupling of iron(II) complexes. Computational studies support the experimental observations, and indicate that oxidation states below +I cannot be reached by reductive elimination.
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| 2. |
- Kleimark, Jonatan, 1982, et al.
(författare)
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Mechanistic Investigation of Iron-Catalyzed Coupling Reactions
- 2009
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Ingår i: ChemCatChem. - : Wiley. - 1867-3880 .- 1867-3899. ; 1:1, s. 152-161
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Tidskriftsartikel (refereegranskat)abstract
- The mechanism of the iron-catalyzed cross-coupling of aryl electrophiles with alkyl Grignard reagents is studied by a combination of GC monitoring, Hammett competition experiments, and DFT calculations. The reaction follows a pathway where an FeI complex, formed in situ, reacts in a rate-limiting oxidative addition with the aryl electrophile. A rapid thermoneutral transmetalation from a Grignard reagent occurs either before or after the oxidative addition, with little to differentiate between the two pathways. A reductive elimination of the resulting alkyl aryl FeIII complex closes the catalytic cycle. Iron in lower oxidation states can act as a competent precatalyst by oxidation into the FeI-FeIII cycle. FeII complexes can give FeI catalysts through reductive elimination of a bimetallic complex. Added ligands, dilution, and powerful aryl electrophiles all serve to increase the stability of the active catalyst, presumably by counteracting oligomerization of low-valent iron.
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| 3. |
- Larsson, Per-Fredrik, 1983, et al.
(författare)
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Copper-catalyzed cross-couplings with part-per-million catalyst loadings.
- 2009
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Ingår i: Angewandte Chemie (International ed. in English). - : Wiley. - 1521-3773. ; 48:31, s. 5691-3
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Tidskriftsartikel (refereegranskat)abstract
- Homeopathic doses: The presence of 0.001 mol % of a copper salt can be sufficient to catalyze arylation reactions of various nucleophiles with phenyl iodide. The two most important factors governing the reaction outcome are the ligand quantity and the temperature.
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| 4. |
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| 5. |
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| 6. |
- Larsson, Per-Fredrik, 1983, et al.
(författare)
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Mechanistic Aspects of Submol% Copper-Catalyzed C-N Cross-Coupling
- 2014
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Ingår i: Chemcatchem. - : Wiley. - 1867-3880. ; 6:5, s. 1277-1282
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Tidskriftsartikel (refereegranskat)abstract
- Carbonnitrogen bond formation can be catalyzed by copper in very low concentrations (approximate to 100ppm), with mechanistic features that are distinct from those in the high-concentration regime. The reaction was studied by initial rate kinetics, competitive Hammett studies, and DFT calculations. The deprotonation of the model nucleophile, pyrrole, is limited by mass transfer with the heterogeneous base. The positive reaction order in dimethylethylenediamine was explained by this reagent working not only as a ligand to Cu, but also as a facilitator for mass transfer. The selectivity-determining step in the competitive Hammett study is oxidative addition. Alternative mechanisms for this step, such as single-electron transfer, atom transfer, or sigma-bond metathesis, can be excluded based on the observed Hammett behavior and DFT calculations.
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| 7. |
- Larsson, Per-Fredrik, 1983, et al.
(författare)
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New efficient ligand for sub-mol % copper-catalyzed C-N cross-coupling reactions running under air
- 2012
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Ingår i: Beilstein Journal of Organic Chemistry. - : Beilstein Institut. - 1860-5397. ; 8, s. 1909-1915
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Tidskriftsartikel (refereegranskat)abstract
- A new efficient ligand, N,N ''-dimethyldiethylene triamine (DMDETA), has been synthesized and evaluated for sub-mol % copper-catalyzed C-N cross-coupling reactions. The efficiency of the ligand was determined by kinetic methods. DMDETA proved to display efficiency similar to DMEDA and, in addition, the resulting catalyst was tolerant to air.
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| 8. |
- Andersson, Niklas, et al.
(författare)
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Calibration of a polyethylene plant for grade change optimisations
- 2011
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Ingår i: 21ST European Symposium on Computer Aided Process Engineering. - 1570-7946. - 9780444538956 ; 29, s. 673-677
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Konferensbidrag (refereegranskat)abstract
- A polyethylene plant model coded in Modelica and based on a nonlinear MPC model currently used at Borealis AB is considered for calibration. A case study of model calibration at steady-state for four different operating points are analysed, both when looking at one operating point separately, but also to calibrate several simultaneously. Both model parameters and reactor inputs are calibrated for true plant measurement data. To solve the parameter estimation problem, the JModelica.org platform is used, offering tools to express and solve calibration problems. Calibration was obtained with narrow confidence intervals and shows a potential to improve the model accuracy by changing the parameter values. The results will be used for dynamic optimisations of grade changes.
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| 9. |
- Andersson, Niklas, et al.
(författare)
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Parameter Selection in the Parameter Estimation of Grade Transitions in a Polyethylene Plant
- 2015
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Ingår i: Studies in Engineering and Technology. - : Redfame Publishing. - 2330-2038 .- 2330-2046. ; 3:1, s. 1-18
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Tidskriftsartikel (refereegranskat)abstract
- A polyethylene plant at Borealis AB is modelled in the Modelica language and considered for parameter estimations at grade transitions. Parameters have been estimated for both the steady-state and the dynamic case using the JModelica.org platform, which offers tools for steady-state parameter estimation and supports simulation with parameter sensitivies. The model contains 31 candidate parameters, giving a huge amount of possible parameter combinations. The best parameter sets have been chosen using a parameter-selection algorithm that identified parameter sets with poor numerical properties. The parameter-selection algorithm reduces the number of parameter sets that is necessary to explore. The steady-state differs from the dynamic case with respect to parameter selection. Validations of the parameter estimations in the dynamic case show a significant reduction in an objective value used to evaluate the quality of the solution from that of the nominal reference, where the nominal parameter values are used.
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| 10. |
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