Comparison between phosphine and NHC-modified Pd catalysts in the telomerization of butadiene with methanol – a kinetic study combined with model-based experimental analysis

The authors thank the European Community within its project SYNFLOW (FP7; grant agreement n8 NMP2-LA-2010-246461) for financial support.The telomerization of butadiene with methanol was investigated in the presence of different palladium catalysts modified either with triphenylphosphine (TPP) or 1,3-dimesityl-imidazol-2-ylidene (IMes) ligand. When pure butadiene was used as substrate, a moderate selectivity for the Pd-TPP catalyst toward the desired product 1-methoxy-2,7-octadiene (1-Mode) of around 87 % was obtained, while the IMes carbene ligand almost exclusively formed 1-Mode with 97.5 % selectivity. The selectivity remained unchanged when the pure butadiene feed was replaced by synthetic crack-C4 (sCC4), a technical feed of 45 mol% butadiene and 55 mol% inerts (butenes and butanes). The TPP-modified catalyst showed a lower reaction rate, which was attributed to the expected dilution effect caused by the inerts. Surprisingly, the IMes-modified catalyst showed a higher rate with sCC4 compared to the pure feed. By means of a model-based experimental analysis, kinetic rate equations could be derived. The kinetic modeling supports the assumption that the two catalyst systems follow different kinetic rate equations. For the Pd-TPP catalyst, the reaction kinetics were related to the Jolly mechanism. In contrast, the Jolly mechanism had to be adapted for the Pd-IMes catalyst as the impact of the base seems to differ strongly from that for the Pd-TPP catalyst. The Pd-IMes system was found to be zero order in butadiene at moderate to high butadiene concentrations and first order in base while the nucleophilicity of the base is influenced by the methanol amount resulting in a negative reaction order for methanol.PostprintPeer reviewe

Tracing Active Sites in Supported Ni Catalysts during Butene Oligomerization by Operando Spectroscopy under Pressure

Supported Ni catalysts have been studied during the dimerization of butenes by operando electron paramagnetic resonance (EPR) and in situ X-ray absorption spectroscopy (XAS) at 353 K and up to 16 bar. Single NiI/NiII shuttles were identified as active sites, whereby the conversion of initial NiI to NiII by oxidative addition of butene is obviously faster than the re-reduction of NiII to NiI by reductive elimination of the C8 product, rendering the equilibrium percentage of NiI small. At p ≤ 2 bar, NiI single sites form inactive Ni0 aggregates, while this is suppressed at higher pressure (∼12 bar). A reaction mechanism is proposed

Comparison between phosphine and NHC-modified Pd catalysts in the telomerization of butadiene with methanol – a kinetic study combined with model-based experimental analysis

The telomerization of butadiene with methanol was investigated in the presence of different palladium catalysts modified either with triphenylphosphine (TPP) or 1,3-dimesityl-imidazol-2-ylidene (IMes) ligand. When pure butadiene was used as substrate, a moderate selectivity for the Pd-TPP catalyst toward the desired product 1-methoxy-2,7-octadiene (1-Mode) of around 87 % was obtained, while the IMes carbene ligand almost exclusively formed 1-Mode with 97.5 % selectivity. The selectivity remained unchanged when the pure butadiene feed was replaced by synthetic crack-C4 (sCC4), a technical feed of 45 mol% butadiene and 55 mol% inerts (butenes and butanes). The TPP-modified catalyst showed a lower reaction rate, which was attributed to the expected dilution effect caused by the inerts. Surprisingly, the IMes-modified catalyst showed a higher rate with sCC4 compared to the pure feed. By means of a model-based experimental analysis, kinetic rate equations could be derived. The kinetic modeling supports the assumption that the two catalyst systems follow different kinetic rate equations. For the Pd-TPP catalyst, the reaction kinetics were related to the Jolly mechanism. In contrast, the Jolly mechanism had to be adapted for the Pd-IMes catalyst as the impact of the base seems to differ strongly from that for the Pd-TPP catalyst. The Pd-IMes system was found to be zero order in butadiene at moderate to high butadiene concentrations and first order in base while the nucleophilicity of the base is influenced by the methanol amount resulting in a negative reaction order for methanol

Allogeneic transplantation in multiple myeloma: long-term follow-up and cytogenetic subgroup analysis

This phase 3 trial compared tandem autologous stem cell transplantation (autoSCT) versus autoSCT followed by reduced-intensity conditioning allogeneic stem cell transplantation (auto/alloSCT) in patients with newly diagnosed multiple myeloma (MM) with deletion of (del) chromosome 13q (del13q). The availability/absence of a human leukocyte antigen-matched-related or matched-unrelated donor (MUD) determined the nature of the second SCT. The primary endpoint was progression-free survival (PFS) in the intention-to-treat population (n = 199). Auto/alloSCT was performed in 126 patients; 74 received MUD allografts. After 91 months median follow-up, median PFS with auto/allo versus tandem autoSCT was 34.5 versus 21.8 months (P = 0.003; adjusted hazard ratio 0.55, 95% confidence interval 0.36-0.84). Median overall survival (OS) was 70.2 versus 71.8 months (P = 0.856). Two-year non-relapse mortality with auto/allo versus tandem autoSCT was 14.3% versus 4.1% (P = 0.008). In patients harboring both del13q and del17p, median PFS and OS were 37.5 and 61.5 months with auto/allo (n = 19) versus 6.1 and 23.4 months with tandem autoSCT (n = 6) (P = 0.0002 and 0.032). Our findings suggest that auto/alloSCT significantly extends PFS versus tandem autoSCT in del13q MM, and indicate some survival benefit for first-line alloSCT in high-risk MM

Allogeneic transplantation in multiple myeloma: long-term follow-up and cytogenetic subgroup analysis

This phase 3 trial compared tandem autologous stem cell transplantation (autoSCT) versus autoSCT followed by reduced-intensity conditioning allogeneic stem cell transplantation (auto/alloSCT) in patients with newly diagnosed multiple myeloma (MM) with deletion of (del) chromosome 13q (del13q). The availability/absence of a human leukocyte antigen-matched-related or matched-unrelated donor (MUD) determined the nature of the second SCT. The primary endpoint was progression-free survival (PFS) in the intention-to-treat population (n = 199). Auto/alloSCT was performed in 126 patients; 74 received MUD allografts. After 91 months median follow-up, median PFS with auto/allo versus tandem autoSCT was 34.5 versus 21.8 months (P = 0.003; adjusted hazard ratio 0.55, 95% confidence interval 0.36-0.84). Median overall survival (OS) was 70.2 versus 71.8 months (P = 0.856). Two-year non-relapse mortality with auto/allo versus tandem autoSCT was 14.3% versus 4.1% (P = 0.008). In patients harboring both del13q and del17p, median PFS and OS were 37.5 and 61.5 months with auto/allo (n = 19) versus 6.1 and 23.4 months with tandem autoSCT (n = 6) (P = 0.0002 and 0.032). Our findings suggest that auto/alloSCT significantly extends PFS versus tandem autoSCT in del13q MM, and indicate some survival benefit for first-line alloSCT in high-risk MM

Diagnosis of invasive fungal diseases in haematology and oncology: 2018 update of the recommendations of the infectious diseases working party of the German society for hematology and medical oncology (AGIHO)

Invasive fungal diseases (IFD) are a primary cause of morbidity and mortality in patients with haematological malignancies. These infections are mostly life-threatening and an early diagnosis and initiation of appropriate antifungal therapy are essential for the clinical outcome. Most commonly, Aspergillus and Candida species are involved. However, other Non-Aspergillus moulds are increasingly identified in case of documented IFD. For definite diagnosis of IFD, a combination of diagnostic tools have to be applied, including conventional mycological culture and non-conventional microbiological tests such as antibody/antigen and molecular tests, as well as histopathology and radiology. Although varying widely in cancer patients, the risk of invasive fungal infection is highest in those with allogeneic stem cell transplantation and those with acute leukaemia and markedly lower in patients with solid cancer. Since the last edition of Diagnosis of Invasive Fungal Diseases recommendations of the German Society for Hematology and Oncology in 2012, integrated care pathways have been proposed for the management and therapy of IFDs with either a diagnostic driven strategy as opposed to a clinical or empirical driven strategy. This update discusses the impact of this additional evidence and effective revisions