Synthesis and characterization of a novel carboxyl group containing (co)polyimide with sulfur in the polymer backbone

• Miroslav Mrsevic,
• David Düsselberg and
• Claudia Staudt

Beilstein J. Org. Chem. 2012, 8, 776–786, doi:10.3762/bjoc.8.88

• determine the relative moisture uptake. Maximum moisture uptake for all polyimides and (co)polyimides was found after the first day, which may be due to surface adsorption processes. Afterwards, no further moisture uptake was found. In Figure 6, the moisture uptake results of the 6FDA-3,3′-DDS/6FDA-DABA 4:1

Volatile organic compounds produced by the phytopathogenic bacterium Xanthomonas campestris pv. vesicatoria 85-10

• Teresa Weise,
• Marco Kai,
• Anja Gummesson,
• Armin Troeger,
• Stephan von Reuß,
• Silvia Piepenborn,
• Francine Kosterka,
• Martin Sklorz,
• Ralf Zimmermann,
• Wittko Francke and
• Birgit Piechulla

Beilstein J. Org. Chem. 2012, 8, 579–596, doi:10.3762/bjoc.8.65

• volatiles during incubation time, considering both qualitative and quantitative compositions of the profiles. In addition, gas-chromatographic analyses of highly volatile compounds, by using either direct headspace injection or solid-phase adsorption/thermodesorption separation on thick film capillaries

• through the hole, and the fiber was extended into the headspace. The time for the adsorption and accumulation of bacterial volatiles was set to 2 h. Volatile compounds were thermally desorbed and analyzed by using a GC/MS-QP5000 (Shimadzu; Kyoto, Japan, injection port set at 250 °C). The initial

Continuous preparation of carbon-nanotube-supported platinum catalysts in a flow reactor directly heated by electric current

• Alicja Schlange,
• Antonio Rodolfo dos Santos,
• Ulrich Kunz and
• Thomas Turek

Beilstein J. Org. Chem. 2011, 7, 1412–1420, doi:10.3762/bjoc.7.165

• adsorption of platinum colloid on the surface of the carbon support material followed by the chemical reduction step. The main advantage of the impregnation method is its simplicity in execution [22][23]. Nevertheless, catalysts prepared by impregnation show a broad cluster-size distribution and a large

Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

• M. Isabel Burguete,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2011, 7, 1347–1359, doi:10.3762/bjoc.7.159

• viscosity, can accelerate the adsorption and desorption steps of reactants and products in the catalytic sites. Thereby, a shift from adsorption- or desorption-controlled surface processes to surface-reaction-controlled processes can take place [23][35][36][37]. Besides, the solvent properties can be easily

• associated with the combination of the biocatalyst with the IL phase [99]. These authors studied in detail the influence of the support and the IL used, as well as the effect of the previous adsorption of the enzyme onto a modified silica surface [104]. A partly related approach is the immobilization of the

Scaling up of continuous-flow, microwave-assisted, organic reactions by varying the size of Pd-functionalized catalytic monoliths

• Ping He,
• Stephen J. Haswell,
• Paul D. I. Fletcher,
• Stephen M. Kelly and
• Andrew Mansfield

Beilstein J. Org. Chem. 2011, 7, 1150–1157, doi:10.3762/bjoc.7.133

• [24] the measurements obtained from N2 adsorption and desorption isotherms indicate a type H2 hysteresis, which is consistent with the disordered mesoporous structure seen in the micrograph shown in Figure 1 (also see Supporting Information File 1, Figure S2) Effect of Pd precursor on the activity of

• ) to demonstrate this methodology. The total pore volume accessible to the solution, determined by adsorption of water, was 0.20 mL for Pd-monolith-3.2 and 0.79 mL for Pd-monolith-6.4, which represents an almost 4-fold volume increase for the larger Pd-monolith-6.4. The activities of both monoliths for

• (thickness approximately 2 nm) by a SEMPREP 2 Sputter Coater (Nanotech Ltd.). Transmission electron microscopy (TEM) was carried out on a JEOL-2010 operating at 200 kV. The BET surface area and nm-scale pore-size distribution were obtained by measuring N2 adsorption and desorption isotherms at 77 K by means

Reductive amination with zinc powder in aqueous media

• Giovanni B. Giovenzana,
• Daniela Imperio,
• Andrea Penoni and
• Giovanni Palmisano

Beilstein J. Org. Chem. 2011, 7, 1095–1099, doi:10.3762/bjoc.7.125

• (<10 μm, 98+% Sigma-Aldrich) was effective while other forms of zinc (foil, wire, mossy or shots) gave only minute yields, showing the surface-related nature of the reduction step, likely dependent on the extent of the imine adsorption. This was additionally supported by the fact that 15 equiv of Zn

Intraannular photoreactions in pseudo-geminally substituted [2.2]paracyclophanes

• Henning Hopf,
• Vitaly Raev and
• Peter G. Jones

Beilstein J. Org. Chem. 2011, 7, 658–667, doi:10.3762/bjoc.7.78

• utilize zeolites as supramolecular hosts for photoreactions [12][13][14]. Internal complexation, or intracrystalline adsorption, occurs by diffusion of the guest into the channels and cavities of the zeolite crystal and is size- and shape-selective. Complexation of organic compounds may reversibly depend

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

• Bernhard Gutmann,
• Toma N. Glasnov,
• Tahseen Razzaq,
• Walter Goessler,
• Dominique M. Roberge and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2011, 7, 503–517, doi:10.3762/bjoc.7.59

• pre-catalyst in continuous flow Mizoroki–Heck chemistry [59]. Catalysis essentially proceeds via dissolution/re-adsorption of Pd from the support (here from the steel coil). The mechanism is quasi-homogeneous with small Pd0 species (colloids/nanoparticles) in solution acting as the catalytically

A new fluorescent chemosensor for fluoride anion based on a pyrrole–isoxazole derivative

• Zhipei Yang,
• Kai Zhang,
• Fangbin Gong,
• Shayu Li,
• Jun Chen,
• Jin Shi Ma,
• Lyubov N. Sobenina,
• Albina I. Mikhaleva,
• Guoqiang Yang and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2011, 7, 46–52, doi:10.3762/bjoc.7.8

• significantly and a new adsorption peak appeared at 375 nm with a sharp isosbestic point formation at 352 nm, which indicated that only two species are present in the equilibrium throughout the titration process [14]. The absorption peak at 375 nm in CH3CN was partially returned to 340 nm when a protic solvent

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

• in accord with the amount of Ru removed from the support by leaching as determined from elemental analysis. The results obtained suggest that the Ru species in 3/SBA-15 were attached to the sieves by a non-covalent interaction (probably via physical adsorption). The small residual Ru content, which

• that 3 was attached to the sieve surface by non-covalent interactions. Approximately 76% of the Ru content could be recovered from the sieve as 3 (as shown by NMR) by washing with THF at room temperature (indicating physical adsorption of 3 on the sieve). The residual Ru species on the sieve exhibited

• adsorption isotherms: surface area SBET = 972 and 934 m²/g, average pore diameter d = 3.8 and 6.9 nm and volume of pores V = 1.14 and 0.96 cm³/g. The particle size (by SEM) ranged from 1 to 3 μm for all supports used. Techniques UV–vis spectra of catalysts were recorded with a Perkin-Elmer Lambda 950

Stereoselectivity of supported alkene metathesis catalysts: a goal and a tool to characterize active sites

• Christophe Copéret

Beilstein J. Org. Chem. 2011, 7, 13–21, doi:10.3762/bjoc.7.3

• adsorption) [37][38], and therefore reacts faster than propene (Scheme 4). In other words, isomerisation is faster than productive metathesis, so that the thermodynamic ratio of 2-butenes is almost reached even at relatively low conversions. This equation also indicates that modification of adsorption

• was also obtained for Re2O7/Al2O3 [40][41], which infers similar structural features for the active sites [42]. Finally, this shows that modifying the surface adsorption properties can favour the formation of primary products by slowing down secondary processes such as isomerisation, but that

• of catalysts supported on alumina, the support plays a major role because it controls the rate of adsorption/desorption of reactants and products. This precludes high selectivity being reached as secondary isomerisation processes via metathesis are favoured. Overall, the current data show that

ROMP-Derived cyclooctene-based monolithic polymeric materials reinforced with inorganic nanoparticles for applications in tissue engineering

• Franziska Weichelt,
• Solvig Lenz,
• Stefanie Tiede,
• Ingrid Reinhardt,
• Bernhard Frerich and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2010, 6, 1199–1205, doi:10.3762/bjoc.6.137

• compound was less homogeneous, supporting the explanation of polar interactions between organic components and HAp in the polymerization mixture. Nitrogen adsorption measurements of the monolithic powders confirmed their highly porous structure, showing specific surface areas of between 2 m2/g (unfilled

Syntheses and properties of thienyl-substituted dithienophenazines

• Annemarie Meyer,
• Eva Sigmund,
• Friedhelm Luppertz,
• Gregor Schnakenburg,
• Immanuel Gadaczek,
• Thomas Bredow,
• Stefan-S. Jester and
• Sigurd Höger

Beilstein J. Org. Chem. 2010, 6, 1180–1187, doi:10.3762/bjoc.6.135

• functional theory at the B3LYP/TZVP level and verify the experimental data. Adsorption of the dithienophenazines on highly ordered pyrolytic graphite (HOPG) was investigated by scanning tunneling microscopy, showing that one of the compounds forms highly organized self-assembled monolayers. Keywords

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• physical adsorption of poly(2-aminoethyl methacrylate) or polyethylene imine polycations. As expected, the uptake of the capsules modified by the polycation was found to be higher than for non-modified capsules. Rosenbauer et al. used the same route but in the presence of a surfactant which crosslinked the

Hybrid biofunctional nanostructures as stimuli-responsive catalytic systems

• Gernot U. Marten,
• Thorsten Gelbrich and
• Annette M. Schmidt

Beilstein J. Org. Chem. 2010, 6, 922–931, doi:10.3762/bjoc.6.98

• unspecific adsorption [25][35]. The ability of magnetic nanoparticles to show considerable heat dissipation due to relaxation processes is recently employed in the combination with thermoresponsive polymers [34][36][37][38][39]. In ac magnetic fields in the kHz range, the nanoparticles transform magnetic

• trypsin leaching from the carriers, we continued the data collection for a couple of minutes after magnetic separation of the magnetic nanoparticles from the BAPNA solution. No further increase in adsorption was detected. By linearly plotting the reaction rates vs the BAPNA concentration cBAPNA (Cornish

Chromo- and fluorophoric water-soluble polymers and silica particles by nucleophilic substitution reaction of poly(vinyl amine)

• Katja Hofmann,
• Ingolf Kahle,
• Frank Simon and
• Stefan Spange

Beilstein J. Org. Chem. 2010, 6, No. 79, doi:10.3762/bjoc.6.79

• -dimethylcyclodextrin or by pre-adsorption onto silica particles. Furthermore, 1 was converted with isopropylamine into the model compound 1-M. All new compounds were characterized by NMR, FTIR, UV–vis and fluorescence spectroscopy. The solvent-dependent UV–vis absorption and fluorescence emission band positions of the

• consecutive adsorption of PVAm and 1 onto silica particles. The adsorbed substances were reacted directly on the silica particle surface. The reaction products (yield on the surface of silica particles) were analyzed using high-resolution X-ray photoelectron spectroscopy (XPS). The XPS method is very surface

• to remove unreacted 1. 1-Si was obtained as intensively colored purple solid. The 13C-{1H}-CP-MAS NMR spectrum of 1-Si shows the characteristic signals of the fluorophore as well as those of the aliphatic carbons of the polymer backbone. The FTIR spectrum of 1-Si confirms the adsorption of the

Synthesis, electronic properties and self-assembly on Au{111} of thiolated (oligo)phenothiazines

• Adam W. Franz,
• Svetlana Stoycheva,
• Michael Himmelhaus and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2010, 6, No. 72, doi:10.3762/bjoc.6.72

• thiols on Au{111}. The ability of the molecules to form SAMs was investigated by solution adsorption of different systems onto gold films of 100 nm thickness thermally evaporated onto Si wafers using 10 nm of Ti as adhesion promoter. This procedure is known to yield polycrystalline gold films with

• relative coverage θ obtained experimentally is calculated from θ = dexp/dth as given in Table 2. From these values it is clear that of 2, only 2a and 2d show good SAM formation, suggesting an odd–even effect on film growth, which might be related to steric hindrance during adsorption when an even number of

• the impact of steric effects on the adsorption kinetics and thus may lead to a more densely packed film. As a consequence, thiolated mono- and terphenothiazines 2 (n = 1, 3) and the dithiolated derivative 4 can be easily self-assembled to give stable monolayers on gold surfaces. This feature makes

New amphiphilic glycopolymers by click functionalization of random copolymers – application to the colloidal stabilisation of polymer nanoparticles and their interaction with concanavalin A lectin

• Otman Otman,
• Paul Boullanger,
• Eric Drockenmuller and
• Thierry Hamaide

Beilstein J. Org. Chem. 2010, 6, No. 58, doi:10.3762/bjoc.6.58

• stability and the biological points of view. In such block copolymers, the hydrophobic part is enhanced in comparison to molecular surfactants, which allows a better adsorption (by reducing the exchange dynamics) and increases the long term stability. This stronger adsorption also reduces the residual

• copolymer and their related syntheses were based on the following criteria: 1 - the monosaccharide must be anchored onto the polymer backbone by the use of a hydrophilic spacer in order to allow more freedom inside the aqueous phase after adsorption onto the polymer particles; 2 - syntheses must be simple

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

• of whether or not a pre-wash is used. The induction is therefore most likely to be limited by adsorption of the aryl bromide onto the catalyst surface once catalyst activation is achieved. This is consistent with the Langmuir–Hinshelwood mechanism [17] for surface kinetics which depends on adsorption

• become deposited on the catalyst beads on standing between studies and that the initial linear increase in yield was a consequence of the salts being washed off in the continuous flow and adsorption of the organobromide on to the newly freed reactive sites. It is seen from Figure 6 hat the production of

• concentration is necessarily high. If the rate limiting step in the reaction is the adsorption of the organobromide onto the surface of the catalyst, as we have proposed according to the Langmuir–Hinchelwood mechanism [17], then increasing the flow rate does not give sufficient time for adsorption of the aryl

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

• unmodified silica lowered the activity of the catalyst system, presumably via adsorption of some of the Ru(II) catalyst. Under optimal flow conditions, the transfer hydrogenation of acetophenone in isopropanol (using a flow-reactor consisting of a column packed with a slurry of the immobilized catalyst