Triple-channel microreactor for biphasic gas–liquid reactions: Photosensitized oxygenations

• Ram Awatar Maurya,
• Chan Pil Park and
• Dong-Pyo Kim

Beilstein J. Org. Chem. 2011, 7, 1158–1163, doi:10.3762/bjoc.7.134

• -step synthesis [30][31], process safety [32][33][34], photo-reactions [35][36][37][38][39], gas-liquid reactions [40][41][42][43], etc. In a biphasic gas–liquid reaction, mass transfer from the gas phase to the liquid phase proceeds through the interfacial area. In traditional batch reactors, the

Hoveyda–Grubbs type metathesis catalyst immobilized on mesoporous molecular sieves MCM-41 and SBA-15

• Hynek Balcar,
• Tushar Shinde,
• Naděžda Žilková and
• Zdeněk Bastl

Beilstein J. Org. Chem. 2011, 7, 22–28, doi:10.3762/bjoc.7.4

• the RCM of 1,7-octadiene in cyclohexane. At 5 min after starting the reaction, about ½ of the volume of the liquid phase was separated by filtration and transferred into a new reactor, kept under identical reaction conditions. No increase in conversion was observed in this reactor. For the RCM of

• DEDAM in benzene, however, a considerable increase of substrate conversion in liquid phase after its separation from solid catalyst indicated that the Ru species released from the solid catalyst were capable of initiating catalytic reactions. Figure 5 shows the activity of 3/MCM-41 and 3/SBA-15 in the

• -octadiene with 3/SBA-15 (filled squares) and 3/MCM-41 (filled circles) in cyclohexane (T = 30 °C, molar ratio substrate/Ru = 600, c0substrate = 0.2 mol/L). Filtration experiments with 3/SBA-15. RCM of DEDAM in benzene (circles), 1,7-octadiene in cyclohexane (squares), liquid phase in contact with solid

From discovery to production: Scale- out of continuous flow meso reactors

• Peter Styring and
• Ana I. R. Parracho

Beilstein J. Org. Chem. 2009, 5, No. 29, doi:10.3762/bjoc.5.29

• critical issue is the possibility that some active metal migrates from the solid to the liquid phase and this leached metal would become responsible for a significant part of the catalytic activity which would then occur homogeneously. When the solid catalyst was removed from a batch reactor no reaction

Asymmetric reactions in continuous flow

• Xiao Yin Mak,
• Paola Laurino and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

• observed to be higher in the microreactor. A single-channel, falling film microreactor designed specifically for efficient gas-liquid phase contact was used to screen the asymmetric hydrogenation of (Z)-methyl acetamidocinnamate 4 and related substrates (Scheme 2) [13][14]. Seventeen chiral phosphines were

• materials as solid-supports for catalysts and reagents have been found to be particularly well-suited for flow chemistry [34][35][36]. These rigid structures have large surface areas, leading to improved mass-transfer between the supported catalyst with the liquid phase and do not suffer from large pressure

Synthesis of deep- cavity fluorous calix[4]arenes as molecular recognition scaffolds

• Maksim Osipov,
• Qianli Chu,
• Steven J. Geib,
• Dennis P. Curran and
• Stephen G. Weber

Beilstein J. Org. Chem. 2008, 4, No. 36, doi:10.3762/bjoc.4.36

• extraction of organic substrates into a fluorous liquid phase via hydrogen bonding [21]. Combining the selective nature of fluorous chemistry with the extensive molecular recognition capabilities of calixarenes should generate a scaffold for selective molecular receptors, yet few reports exist that detail

Microwave- assisted ring closure reactions: Synthesis of 8-substituted xanthine derivatives and related pyrimido- and diazepinopurinediones

• Joachim C. Burbiel,
• Jörg Hockemeyer and
• Christa E. Müller

Beilstein J. Org. Chem. 2006, 2, No. 20, doi:10.1186/1860-5397-2-20

• ammonia gas had ceased, the liquid phase was distilled off under reduced pressure. Compound 17 (0.16 g, 98%) was obtained as an off-white solid (purity as determined by NMR: >95%). (1H-NMR [see Supporting Information File 5] and 13C-NMR [see Supporting Information File 6] are added as additional files) 3

• irradiation was applied (200 W, 160°C) for 20 min. The resulting yellow solution was hydrolyzed with 4 ml of methanol while still warm (ca. 50°C). After the formation of ammonia gas had ceased, the liquid phase was distilled off under reduced pressure. The product was purified over a short silica gel column

Towards practical biocatalytic Baeyer- Villiger reactions: applying a thermostable enzyme in the gram- scale synthesis of optically- active lactones in a two-liquid- phase system

• Frank Schulz,
• François Leca,
• Frank Hollmann and
• Manfred T. Reetz

Beilstein J. Org. Chem. 2005, 1, No. 10, doi:10.1186/1860-5397-1-10

• well versed in the use of enzymes. Keywords: Baeyer-Villiger oxidation; monooxygenases; two-liquid-phase system; stereoselective catalysis; biocatalysis; Introduction First reported in 1899, the Baeyer-Villiger (BV) reaction of ketones with formation of esters or lactones has become a fundamental and

• [3.2.0]hept-2-en-6-one (1) and 2-phenylcyclohexanone (5) in a way that any synthetic organic chemist can perform. In particular we demonstrate that a BVMO can be stabilized in an aequeous-organic two-liquid phase medium under reaction conditions with high concentrations of several substrates. We chose

• case of CHMO-catalyzed oxidation of the same substrate.[31] In order to overcome this inhibition we tested the use of a second liquid phase in whole-cell catalysis using a water-immiscible organic phase to serve as substrate reservoir and product sink. Full conversion could be obtained using