An assessment of emerging C-H activation catalysts of the type [(COD)Ir(IMes)(PR3)]PF6 in the deuteration of N-heterocycles is divulged. Substrate scope, competition experiments, and labelling of drug type molecules have revealed PR3 = PPh3 provides a broadly more applicable and widely effective catalyst system compared to other available complexes in the present series.
The first examples of selective ortho-directed C-H activation with unprotected 2-aryltetrazoles are described. A new base-assisted protocol for iridium(i) hydrogen isotope exchange catalysis allows access to ortho-deuterated and tritiated tetrazoles, including the tetrazole-containing pharmaceutical, Valsartan. Preliminary mechanistic studies are also presented.
The mixing performance of a distributed-feed plate-type reactor equipped with curved channel design and microstructured multinozzle injectors was investigated. Almost ideal plug flow behavior with 300 < Bo < 2000 for Re numbers between 338 and 3610 and total flow up to 240 L/h was ascribed to bend-induced vortices in combination with modulated flow velocities along the flow path. The micromixing performance of multinozzle jet injectors which consisted of round nozzles with 100 and 140 μm diameters in a circular pattern was studied using a decolorization reaction and the Villermaux-Dushman reaction in conjunction with the IEM model. Mixing times as obtained by the first method were generally higher than that obtained by the second method but both were in the range of milliseconds. The dependence of respective mixing times on the energy dissipation rate was found to scale with power-law exponents of −0.58 and −0.43, respectively, and suggested engulfment as the limiting mixing mechanism.
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