Extrusion – back to the future: Using an established technique to reform automated chemical synthesis

• Deborah E. Crawford

Beilstein J. Org. Chem. 2017, 13, 65–75, doi:10.3762/bjoc.13.9

• scale twin screw extruder (right). PTFE screw employed in single screw extrusion, with increasing root diameter (RD) from 45 mm to 95 mm and a final kneading section. Modulated stainless steel intermeshing co-rotating screws employed typically in twin screw extrusion, comprised of conveying and kneading

The digital code driven autonomous synthesis of ibuprofen automated in a 3D-printer-based robot

• Philip J. Kitson,
• Stefan Glatzel and
• Leroy Cronin

Beilstein J. Org. Chem. 2016, 12, 2776–2783, doi:10.3762/bjoc.12.276

• print (for the reaction vessel) and dispense liquids, so the 3D-printing carriage was modified to incorporate both a heated extruder for 3D printing as well as a holder for the polytetrafluoroethylene (PTFE)-lined dispensing needles required for the liquid handling part (see Supporting Information File

•  1 for further details). These needles were connected by PTFE tubing (internal diameter 0.8 mm) to a number of automatable syringe pumps which have been developed by our group. These pumps were controlled individually by dedicated Arduino control boards and were coordinated via the process-control

• situ during the synthesis of ibuprofen, showing the insertion of the PTFE-lined dispensing needle into the vessel. Synthetic route chosen for automated synthesis robot. The digitisation of the synthesis of ibuprofen. This flow diagram shows the individual steps of the process control software written

Continuous-flow synthesis of primary amines: Metal-free reduction of aliphatic and aromatic nitro derivatives with trichlorosilane

• Riccardo Porta,
• Alessandra Puglisi,
• Giacomo Colombo,
• Sergio Rossi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2016, 12, 2614–2619, doi:10.3762/bjoc.12.257

• solvent (typically CH2Cl2, although CH3CN affords comparable results). The continuous-flow reduction of 4-nitrobenzophenone (1a) was chosen as model reaction. A syringe pump equipped with two gas-tight 2.5 mL syringes was used to feed the reagents into a 0.5 mL PTFE reactor (i.d. = 0.58 mm, l = 189 cm

• the reaction (the first few hours). Having demonstrated that the flow transformation is very fast we next explored reaction scale-up employing a bigger flow reactor (5 mL PTFE reactor, i.d. = 2.54 mm, l = 100 cm), in order to increase the productivity of the process. Using the same reaction set-up

• molecules of pharmaceutical interest. The reduction of nitro compound 3 afforded 2-(4'-chlorophenyl)aniline (4), the direct precursor of the fungicide boscalid (Scheme 4). Under the best reaction conditions in a 5 mL PTFE reactor (flow rate 0.1 mL/min, 50 min residence time), the desired amine 4 was

Tunable microwave-assisted method for the solvent-free and catalyst-free peracetylation of natural products

• Manuela Oliverio,
• Paola Costanzo,
• Monica Nardi,
• Carla Calandruccio,
• Raffaele Salerno and
• Antonio Procopio

Beilstein J. Org. Chem. 2016, 12, 2222–2233, doi:10.3762/bjoc.12.214

• temperature-controlled program the instrument is able to tune the power magnetron in order to reach and to maintain the fixed temperature throughout the experiment. For each run 16 positions of the rotor was occupied by 0.3–3 mL glass vials sealed with a dedicated PEEK screw-cup together with a reliable PTFE

The in situ generation and reactive quench of diazonium compounds in the synthesis of azo compounds in microreactors

• Faith M. Akwi and
• Paul Watts

Beilstein J. Org. Chem. 2016, 12, 1987–2004, doi:10.3762/bjoc.12.186

• % was achieved in approximately 2.4 minutes and a small library of azo compounds was thus generated under these reaction conditions from couplers with aminated or hydroxylated aromatic systems. The scaled up synthesis of these compounds in PTFE tubing (i.d. 1.5 mm) was also investigated, where good

• reaction. In addition, industry always questions why reactions are done in micro structured reactors rather than simple tubular reactors. As such, we extended this investigation to study the optimized conditions obtained within the LTF microreactors within PTFE tubing (i.d. 1.5 mm) in order to scale up the

• reagents used for the reaction, amount of solvent added to facilitate quick dissolution of particulates as they are formed as well as the output of the reaction, i.e., conversion, yield and or even selectivity. The scaled-up synthesis of these compounds in PTFE tubing of 1.5 mm internal diameter is herein

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

• Forrest S. Etheridge,
• Roshan J. Fernando,
• Sandra Pejić,
• Matthias Zeller and
• Geneviève Sauvé

Beilstein J. Org. Chem. 2016, 12, 1925–1938, doi:10.3762/bjoc.12.182

• notably with polytetrafluoroethylene (PTFE) [16]. The small size and strong electron-withdrawing properties of fluorine make it ideally suited to tune the molecular orbital (MO) energy levels of polymer donors in OPVs without major influence on the structure [17][18][19][20][21][22]. In several cases, the

• grade chloroform. The solutions were filtered through a 0.45 μm PTFE filter, then spun-cast at 400 rpm for 60 s. Elemental analyses (C, H, and N) were performed under optimum combustion conditions by Robertson Microlit Laboratories. Thermal gravimetric analysis (TGA) was performed on a TA instrument

Experimental and theoretical investigations on the high-electron donor character of pyrido-annelated N-heterocyclic carbenes

• Michael Nonnenmacher,
• Dominik M. Buck and
• Doris Kunz

Beilstein J. Org. Chem. 2016, 12, 1884–1896, doi:10.3762/bjoc.12.178

• recorded using Bruker instruments (DRX-250, 300 or 500). 1H and 13C NMR spectra were referenced to TMS on the basis of the (residual) signal of the deuterated solvent. 77Se NMR shifts were calibrated towards Ph2Se2 (463 ppm) in CDCl3 as an external standard [80]. Medium-wall NMR tubes with a PTFE valve

Star-shaped and linear π-conjugated oligomers consisting of a tetrathienoanthracene core and multiple diketopyrrolopyrrole arms for organic solar cells

• Hideaki Komiyama,
• Chihaya Adachi and
• Takuma Yasuda

Beilstein J. Org. Chem. 2016, 12, 1459–1466, doi:10.3762/bjoc.12.142

• mL), followed by baking at 200 °C for 10 min under air. The photoactive layer was then prepared by spin-coating from a chloroform solution containing the donor material and PC71BM, after passing through a 0.45 μm PTFE membrane filter. Finally, a 6 nm thick MoO3 layer and a 100 nm-thick Ag layer were

Continuous formation of N-chloro-N,N-dialkylamine solutions in well-mixed meso-scale flow reactors

• A. John Blacker and
• Katherine E. Jolley

Beilstein J. Org. Chem. 2015, 11, 2408–2417, doi:10.3762/bjoc.11.262

• employed in this work, with increased surface area-to-volume ratio, allows effective heat dissipation under ambient conditions. Continuous reactor A nylon/PTFE tubular reactor was constructed that incorporates static mixers for enhanced mixing of the biphasic reaction solution, made of the acetal

• parallel reactors with HEL WinISO 2225 and HEL IQ 1.2.16 software. For the tube reactor, Harvard syringe pumps (model 981074) or JASCO PU-980 HPLC pumps were connected via a syringe and 1.5 inch, 21 guage disposable needle to PTFE tubing with 1/16 inch OD. The 1/16 inch stainless steel T-piece and

• stainless steel 1/16 inch to 1/4 inch increasing connector were obtained from Swagelok. The reactor tube comprises of PTFE tubing 1/4 inch OD and in-line plastic static mixers supplied by Nordson EFD (3/16 inch OD, mixer element diameter 1/8 inch, 3.5 inch length). For the CSTR, the same Harvard syringe

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• external cooling using dry ice/acetone. Pleasingly, a simple flow setup in which the two streams of neat reagents were mixed in a PTFE T-piece maintained at 25 °C was found effective in order to prepare the desired adduct 68 in high yield and quality showcasing the benefits of superior heat dissipation

• housed within a wider PTFE tube (3.2 mm o.d., 1.6 mm i.d.; Figure 3). Depending on the intended application the gas can be fed either into the inner or the outer tube and upon pressurisation penetrates into the reagent stream where the desired reaction occurs. It has also been shown that an applied

Properties of PTFE tape as a semipermeable membrane in fluorous reactions

• Brendon A. Parsons,
• Olivia Lin Smith,
• Myeong Chae and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2015, 11, 980–993, doi:10.3762/bjoc.11.110

• Brendon A. Parsons Olivia Lin Smith Myeong Chae Veljko Dragojlovic Wilkes Honors College of Florida Atlantic University, 5353 Parkside Drive, Jupiter, FL 33458, USA Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA 10.3762/bjoc.11.110 Abstract In a PTFE

• tape phase-vanishing reaction (PV-PTFE), a delivery tube sealed with PTFE tape is inserted into a vessel which contains the substrate. The reagent diffuses across the PTFE tape barrier into the reaction vessel. PTFE co-polymer films have been found to exhibit selective permeability towards organic

• compounds, which was affected by the presence of solvents. In this study, we attempted to establish general trends of permeability of PTFE tape to different compounds and to better describe the process of solvent transport in PV-PTFE bromination reactions. Though PTFE tape has been reported as impermeable

Photocatalytic nucleophilic addition of alcohols to styrenes in Markovnikov and anti-Markovnikov orientation

• Martin Weiser,
• Sergej Hermann,
• Alexander Penner and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2015, 11, 568–575, doi:10.3762/bjoc.11.62

• LEDs (λ = 530 nm), a syringe pump, and temperature control to 30 °C. The second one was constructuted for exposure to sunlight and consisted of a PTFE tubing to demonstrate applicability of this photocatalysis without need for electricity. Mesoflow experiments were executed using either sunlight, to

Inclusion of trans-resveratrol in methylated cyclodextrins: synthesis and solid-state structures

• Lee Trollope,
• Dyanne L. Cruickshank,
• Terence Noonan,
• Susan A. Bourne,
• Milena Sorrenti,
• Laura Catenacci and
• Mino R. Caira

Beilstein J. Org. Chem. 2014, 10, 3136–3151, doi:10.3762/bjoc.10.331

• outcome of the experiment. We found that nylon filters remove RSV from the aqueous solution completely, allowing only some of the molecules which are protected by the CD to pass through the filter membrane. Of all the membranes tested the PTFE filters were found to give the most consistent results

• each CD solution and the solutions were allowed to stir at 25 ± 0.5 °C for 48 h. The solubility of RSV in the absence of CD (So) was determined by preparing solutions containing an excess of RSV in water, and stirring at 25 ± 0.5 °C for 48 h. Samples were subsequently filtered through 0.45 μm PTFE

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• vs. SCE. Furthermore, the use of PTFE-coated platinum as working electrode proved to be beneficial. Presumably, the reaction sequence proceeds within the hydrophobic electrode coating, where the highly reactive intermediate 53 is protected from side-reactions and the reaction with the hydrophobic

A study on the inhibitory mechanism for cholesterol absorption by α-cyclodextrin administration

• Takahiro Furune,
• Naoko Ikuta,
• Yoshiyuki Ishida,
• Hinako Okamoto,
• Daisuke Nakata,
• Keiji Terao and
• Norihiro Sakamoto

Beilstein J. Org. Chem. 2014, 10, 2827–2835, doi:10.3762/bjoc.10.300

• the FeSSIF (37 °C) and mixing for a few seconds, the mixture was shaken at 37 °C at an agitation rate of 100 rpm. The mixture was then filtered through a 0.2 μm PTFE filter and the filtrate was diluted 1/10 using MilliQ water. The α-CD and taurocholate concentrations in the test solution were analyzed

• was shaken at 37 °C for 30 minutes at 100 rpm. 30 mg of cholesterol was then added into the mixture, and the mixture was shaken again at 100 rpm and 37 °C. After centrifuging the mixture for 10 minutes at 10,000 rpm, the supernatant was filtered using a 0.2 μm PTFE filter. An equal amount of ethyl

• acetate was added to the filtrate and mixed for 30 seconds using a vortex mixer. After centrifuging for 15 min at 3,000 rpm, the ethyl acetate layer was filtered through a 0.2 μm PTFE filter and the filtrate was analyzed by HPLC. A control solution was prepared using the same procedure but without the

Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

• Francesco Trotta,
• Fabrizio Caldera,
• Roberta Cavalli,
• Andrea Mele,
• Carlo Punta,
• Lucio Melone,
• Franca Castiglione,
• Barbara Rossi,
• Monica Ferro,
• Vincenza Crupi,
• Domenico Majolino,
• Valentina Venuti and
• Dominique Scalarone

Beilstein J. Org. Chem. 2014, 10, 2586–2593, doi:10.3762/bjoc.10.271

• oven at 70 °C. DMF solutions of the samples (3 mg/mL) were filtered through 0.45 μm PTFE membrane filters. Calibration was obtained with PEG/PEO molecular weight standards. All Raman measurements were carried out on dried samples deposited on a glass slide in air and at room temperature. Spectra were

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• filter press type cell with flow distribution, which is commercially available. The electrodes are pressed together with a PTFE coated glass fibre net between them. This way, the inter-electrode gap remains constant during consumption of the anode. In a 2 L solution with 200 g of reactant, a product

Specific DNA duplex formation at an artificial lipid bilayer: fluorescence microscopy after Sybr Green I staining

• Emma Werz and
• Helmut Rosemeyer

Beilstein J. Org. Chem. 2014, 10, 2307–2321, doi:10.3762/bjoc.10.240

• design. The bilayer slide encloses two microfluidic channels (cis and trans) which are separated by a thin medical-grade PTFE (= polytetrafluoroethylene, Teflon) foil. This foil hosts a central 100 µm aperture which is located 120 µm above the cover slip and thus within the working distance of high NA

Pd/C-catalyzed aerobic oxidative esterification of alcohols and aldehydes: a highly efficient microwave-assisted green protocol

• Marina Caporaso,
• Giancarlo Cravotto,
• Spyros Georgakopoulos,
• George Heropoulos,
• Katia Martina and
• Silvia Tagliapietra

Beilstein J. Org. Chem. 2014, 10, 1454–1461, doi:10.3762/bjoc.10.149

• substrate) were added to this mixture. The reaction was carried out under magnetic stirring in a MW reactor SynthWave. The 1 L pressure-resistant PTFE cavity (up to 200 bar) equipped with a 15 position vial rack was loaded with O2 (2.5 bar) followed by the addition of N2 up to 20 bar total pressure. The

Continuous flow nitration in miniaturized devices

• Amol A. Kulkarni

Beilstein J. Org. Chem. 2014, 10, 405–424, doi:10.3762/bjoc.10.38

• consisted of two syringe pumps, which pump the reactants – a nitrating mixture and benzaldehyde – through 20 mL glass syringes connected to SS316 tubes by a glass-to-metal PTFE connector. After the micromixer a hastelloy tube (1.38 mm i.d. and 6 m long) acted as a residence time unit immersed in a

• step to isolate the product. However, since the large-scale synthesis of nitropyrazoles is not a safe reaction under batch conditions, the continuous flow synthesis is the process of choice. Henke and Winterbauer [46] reported a corrosion resistant microreactor built up of PTFE and tantalum for the

• simulation of different nitration reactions. The microreactor proposed for this adiabatic nitration included components made in tantalum and PTFE connected in series. In the reactor, the dimensions of the components vary along the length and thus they induce mixing, initially of sulfuric acid with nitric

Studies on the photodegradation of red, green and blue phosphorescent OLED emitters

• Susanna Schmidbauer,
• Andreas Hohenleutner and
• Burkhard König

Beilstein J. Org. Chem. 2013, 9, 2088–2096, doi:10.3762/bjoc.9.245

• /PTFE septum. Two samples were prepared from each complex for the testing under atmospheric and inert conditions. In case of the photodegradation studies under inert conditions, the vials were degassed via three consecutive freeze-pump-thaw cycles under argon. All samples were irradiated in a custom

The application of a monolithic triphenylphosphine reagent for conducting Ramirez gem-dibromoolefination reactions in flow

• Kimberley A. Roper,
• Malcolm B. Berry and
• Steven V. Ley

Beilstein J. Org. Chem. 2013, 9, 1781–1790, doi:10.3762/bjoc.9.207

• , dibenzoyl peroxide (9) was then added and the temperature maintained at 50 °C until this had completely dissolved. The mixture was then transferred to a glass column, the ends sealed with custom-made PTFE end pieces and heated to 92 °C for 48 hours using a Vapourtec R4 heating unit. This protocol can be

Polymeric redox-responsive delivery systems bearing ammonium salts cross-linked via disulfides

• Christian Dollendorf,
• Martin Hetzer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 1652–1662, doi:10.3762/bjoc.9.189

• methylene blue was oxidized again. Synthesis of cross-linked polymer discs in bulk To investigate the physical properties of polycationic hydrogels, polymer discs were synthesized in bulk polymerizations using a polytetrafluoroethylene (PTFE) plate containing several cavities (refer to Supporting

Stability of SG1 nitroxide towards unprotected sugar and lithium salts: a preamble to cellulose modification by nitroxide-mediated graft polymerization

• Guillaume Moreira,
• Laurence Charles,
• Mohamed Major,
• Florence Vacandio,
• Yohann Guillaneuf,
• Catherine Lefay and
• Didier Gigmes

Beilstein J. Org. Chem. 2013, 9, 1589–1600, doi:10.3762/bjoc.9.181

• . The size-exclusion chromatography analyses were performed by using an EcoSEC system from TOSOH equipped with a differential refractometer detector. THF was used as an eluent with 0.25 vol % toluene as a flow marker at a flow rate of 0.3 mL·min−1 after filtration on Alltech PTFE membranes with a

Hypervalent iodine/TEMPO-mediated oxidation in flow systems: a fast and efficient protocol for alcohol oxidation

• Nida Ambreen,
• Ravi Kumar and
• Thomas Wirth

Beilstein J. Org. Chem. 2013, 9, 1437–1442, doi:10.3762/bjoc.9.162

• of two syringes driven by a syringe pump, a T-connector and a tubing reactor (PTFE tubing, length: 4 m, internal diameter: 0.75 mm) was used for the oxidation of benzyl alcohol to benzaldehyde. The tubing reactor was inserted in a water bath at constant temperature as shown in Figure 1. In all flow

• . Both syringes were placed in a syringe pump (Fusion 100) and connected via a T-piece to a tubing reactor (PTFE, length: 4 m, internal diameter: 0.75 mm). The tubing reactor was immersed in a thermocontrolled water bath at 35 °C. The total flow rate was adjusted to 0.4 mL min–1 resulting in a residence