13 research outputs found
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Continuous-Flow Synthesis and Derivatization of Aziridines through Palladium-Catalyzed C(sp 3 )âH Activation
A continuousâflow synthesis of aziridines by palladiumâcatalyzed C(sp3)âH activation is described. The new flow reaction could be combined with an aziridineâringâopening reaction to give highly functionalized aliphatic amines through a consecutive process. A predictive mechanistic model was developed and used to design the CâH activation flow process and illustrates an approach towards firstâprinciples design based on novel catalytic reactions.We are grateful to the Department of Chemical Engineering and Biotechnology (J.Z.) and the EPSRC (A.P.S.) for studentships, and to the ERC and EPSRC (EP/100548X/1) for fellowships (M.J.G.). Mass spectroscopy data were acquired at the EPSRC UK National Mass Spectroscopy Facility at Swansea Universit
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Scalable Palladium-Catalyzed C(sp3)-H Carbonylation of Alkylamines in Batch and Continuous Flow
Development of scalable processes for CÂ(sp3)âH oxidative carbonylation of alkylamines is reported to provide convenient access to the ÎČ-lactam scaffol d. A study of the kinetics of the process revealed that the reaction is CO-limited even at elevated pressures and that there is an optimal CO concentration for the most effective outcomethis understanding led to an increase in the turnover number from 7 to 420 in the optimized process. Two scalable processes were then developed: a batch process, characterized by a very low catalyst loading, and a continuous process for an oxidative CâH carbonylation reaction that uses a copper-tube-flow reactor as a heterogeneous source of Cu2+ oxidant. The continuous process was tested on oxidative carbonylation of several alkylamines, yielding very good results with virtually no optimization required. This study thereby builds upon the utility of flow chemistry applications to oxidative carbonylations and scalable metal-catalyzed processes more generally
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The effect of chemical representation on active machine learning towards closed-loop optimizationâ
Multivariate chemical reaction optimization involving catalytic systems is a non-trivial task due to the high number of tuneable parameters and discrete choices.Alexande
Effects of composition variations and curing conditions on the gloss of water reducible clear coatings prepared from palm stearin alkyds
Survey of artemisinin production by diverse <it>Artemisia </it>species in northern Pakistan
<p>Abstract</p> <p>Background</p> <p>Artemisinin is the current drug of choice for treatment of malaria and a number of other diseases. It is obtained from the annual herb, <it>Artemisia annua </it>and some microbial sources by genetic engineering. There is a great concern that the artemisinin production at current rate will not meet the increasing demand by the pharmaceutical industry, so looking for additional sources is imperative.</p> <p>Methods</p> <p>In current study, artemisinin concentration was analysed and compared in the flowers, leaves, roots and stems of <it>Artemisia annua </it>and 14 other <it>Artemisia </it>species including two varieties each for <it>Artemisia roxburghiana </it>and <it>Artemisia dracunculus </it>using high performance liquid chromatography (HPLC).</p> <p>Results</p> <p>The highest artemisinin concentration was detected in the leaves (0.44 ± 0.03%) and flowers (0.42 ± 0.03%) of <it>A. annua</it>, followed by the flowers (0.34 ± .02%) of <it>A. bushriences </it>and leaves (0.27 ± 0%) of <it>A. dracunculus var dracunculus</it>. The average concentration of artemisinin varied in the order of flowers > leaves > stems > roots.</p> <p>Conclusion</p> <p>This study identifies twelve novel plant sources of artemisinin, which may be helpful for pharmaceutical production of artemisinin. This is the first report of quantitative comparison of artemisinin among a large number of <it>Artemisia </it>species.</p