Innentitelbild: Visuelle Beobachtung der Auflösung und Wiederablagerung von Palladium während der Suzuki‐Miyaura‐Reaktion (Angew. Chem. 17/2008)

MacQuarrie, Stephanie; Horton, J. Hugh; Barnes, Jack; McEleney, Kevin; Loock, Hans‐Peter; Crudden, Cathleen M.

doi:10.1002/ange.200890074

Cited by 2 publications

(2 citation statements)

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“…Work by Organ and coworkers has demonstrated, that these Pd-on-glass films (and other metal-coated glass capillaries) can be used for a variety of synthetically important flow chemistry applications in an elevated temperature regime [63–64], including Mizoroki–Heck chemistry [62]. It should be emphasized that our interest in this steel-based immobilized catalytic Pd system was mainly to demonstrate reactor contamination/fouling and not of a preparative nature.…”

Section: Resultsmentioning

confidence: 99%

“…We suspect that the Pd metal inside the steel coil is present in the form of a thin film of nanometer-sized Pd crystallites, very similar to the highly porous and catalytically active Pd films that can be generated very easily inside glass capillaries by the decomposition of Pd(OAc) 2 under somewhat similar elevated temperature conditions [ 62 ]. Work by Organ and coworkers has demonstrated, that these Pd-on-glass films (and other metal-coated glass capillaries) can be used for a variety of synthetically important flow chemistry applications in an elevated temperature regime [ 63 – 64 ], including Mizoroki–Heck chemistry [ 62 ]. It should be emphasized that our interest in this steel-based immobilized catalytic Pd system was mainly to demonstrate reactor contamination/fouling and not of a preparative nature.…”

Section: Resultsmentioning

confidence: 99%

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Unusual behavior in the reactivity of 5-substituted-1H-tetrazoles in a resistively heated microreactor

Gutmann¹,

Glasnov²,

Razzaq³

et al. 2011

Beilstein J. Org. Chem.

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SummaryThe decomposition of 5-benzhydryl-1H-tetrazole in an N-methyl-2-pyrrolidone/acetic acid/water mixture was investigated under a variety of high-temperature reaction conditions. Employing a sealed Pyrex glass vial and batch microwave conditions at 240 °C, the tetrazole is comparatively stable and complete decomposition to diphenylmethane requires more than 8 h. Similar kinetic data were obtained in conductively heated flow devices with either stainless steel or Hastelloy coils in the same temperature region. In contrast, in a flow instrument that utilizes direct electric resistance heating of the reactor coil, tetrazole decomposition was dramatically accelerated with rate constants increased by two orders of magnitude. When 5-benzhydryl-1H-tetrazole was exposed to 220 °C in this type of flow reactor, decomposition to diphenylmethane was complete within 10 min. The mechanism and kinetic parameters of tetrazole decomposition under a variety of reaction conditions were investigated. A number of possible explanations for these highly unusual rate accelerations are presented. In addition, general aspects of reactor degradation, corrosion and contamination effects of importance to continuous flow chemistry are discussed.

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Section: Resultsmentioning

confidence: 99%