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The polysaccharide laminarin (β-1,3-glucan) is used as a long-term carbon storage compound in brown algae. This chemical storage form of carbon enables perennial brown algae in seasonally fluctuating ecosystems to uncouple growth from photosynthesis, i.e., most of these plants grow as seasonal anticipators in winter based on remobilization of laminarin, while in summer, growth typically ceased to fill up the storage pool. Because of this high ecological relevance, a reliable and precise method for determination and quantification of laminarin is needed. Therefore, a simple, efficient, cold water extraction method coupled to a new quantitative liquid chromatography-mass spectrometrical method (LC-MS) was developed. Laminarin was determined in 9 out of 12 brown algal species, and its expected typical molar mass distribution of 2000–7000 Da was confirmed. Furthermore, laminarin consisted of a complex mixture of different chemical forms, since 15 chemical laminarin species with distinct molecular weights were measured in 9 species of brown algae. Differences in chain length and number of laminarin species seem to be species specific and hence may indicate some chemotaxonomic value. Laminarin concentrations in the algal tissues ranged from 0.03 to 0.86 % dry weight (DW). The direct chemical characterization and quantification of laminarin by LC-MS represents a powerful method to verify the biochemical and ecological importance of laminarin for brown algae.

Drug-coated balloon catheters are a novel clinical treatment alternative for coronary and peripheral artery diseases. Calcium alginate, poly(vinylethylimidazolium bromide) and polyacrylamide hydrogels were used as vessel models in this in vitro study. In comparison to a simple silicone tube their properties can be easily modified simulating different types of tissue. Local drug delivery after balloon dilation in the first crucial minute was determined in a vessel-simulating flow-through cell by a simulated blood stream. Balloon catheters were coated with paclitaxel using the ionic liquid cetylpyridinium salicylate as a novel carrier. Drug transfer from coated balloon catheters to different simulated vessel walls was evaluated and compared to a silicone tube. The highest paclitaxel delivery upon dilation was achieved with calcium alginate as the vessel model (60%) compared to polyacrylamide with 20% drug transfer. The silicone tube showed the least amount of wash-off (

Application of light as a trigger for remote control of enzyme activation offers high temporal and spatial resolution. A known enzymatic system based on an acid phosphatase and 6-chloro-8-fluoro-4-methylumbelliferone phosphate as substrate is employed to study different strategies for improving the time resolution of enzyme activation by a light-induced pH jump. Hence, a single laser pulse excitation with a pulse duration of 6 ns resulted in a 4-fold enzyme activation by instantaneous proton release through the rearrangement of 2-nitrobenzaldehyde. The time resolution of the activation experiment is now limited only by the detection system, no longer by the excitation step. In addition, halogenated 2-nitrobenzaldehydes are tested for their suitability as phototriggers and a detailed study of the pH-dependent kinetics of the enzymatic reaction is performed, which reveals that the substrate can probably only bind to the enzyme in its monoanionic form.

Recovery of carbohydrates from aqueous solution represents a problem due to their large, multivalent and flexible structure and their high hydrophilicity. Organic solvents as well as alternative solvents such as ionic liquids are able to extract carbohydrates from aqueous media by the aid of primary amines. The mechanism of the extraction process has been explored by using galactose and its corresponding O -methyl galactoside. The results indicate that the mechanism is based on formation of an adduct between the aldo -structure of the monosaccharide and the primary amine to provide a hemiaminal, which is extracted into the organic phase. The extraction rate can be influenced by variation of temperature, time, and the amount of amine and depends on the structure of the carbohydrate. The selectivity can also be tuned using different types of ionic liquids. This procedure opens the possibility to recover a carbohydrate selectively from a mixture of different carbohydrates.

Enzymes on carriers can be easily recycled or used in fixed bed reactors. The immobilization often results in an improved stability. Depending on the support used and the method of coupling, this is a time-consuming process. While the wide applicability of microwaves (MWs) within organic synthesis is known since the 1980s, proteins (including enzymes) are generally considered as too sensitive toward MW irradiation. In this article, MW methods were investigated to improve the processing speed of covalent enzyme immobilization on inorganic supports. Herein two laccases from Trametes versicolor and Myceliophthora thermophilia (Novozyme 51003®) and the glucose oxidase from Aspergillus niger were immobilized onto samples of ceramic honeycomb and porous glass (TRISOPERL® 1000 AMINO). The enzymes showed different sensitivity to MW irradiation, but all were suitable for MW-assisted immobilization. Subsequent stability tests were conducted to compare conventional immobilization methods with those with MW irradiation. The glucose oxidase provided the best results. For all cases, a successful MW irradiation assisted covalent enzyme immobilization on solid support was obtained with a total 20-fold reduction of the time necessary.

A recombinant isoenzyme of pig liver esterase was used for the highly enantioselective desymmetrization of dimethyl cyclohex-4-ene-cis-1,2-dicarboxylate. The selected recombinant esterase showed a significant advantage in enantioselectivity over the commonly used esterase from the mammalian source. The process was scaled up to yield 265 g of product with a simplified pH control, and the target molecule was obtained with an enantiopurity of >99.5% ee.

Many oxidation processes require the presence of molecular oxygen in the reaction media. Reactors are needed that provide favorable conditions for the mass transfer between the gas and the liquid phase. In this study, two recent key technologies, microreactor technology and biotechnology, were combined to present an interesting alternative to conventional methods and open up excellent possibilities to intensify chemical processes in the field of fine chemicals. An enzyme-catalyzed gas/liquid phase reaction in a falling-film microreactor (FFMR) was examined for the first time. The test reaction was the oxidation of v-D-glucose to gluconic acid catalyzed by glucose oxidase (GOx). Various factors influencing the biotransformation, such as oxygen supply, temperature, enzyme concentration, and reaction time were investigated and compared to those in conventional batch systems. The most critical factor, the volumetric mass-transfer coefficient for the efficient use of oxygen-dependent enzymes, was determined by using the integrated online detection of dissolved oxygen in all systems. The extremely large surface-to-volume ratio of the FFMR facilitated the contact between the enzyme solution and the gaseous substrate. Hence, in a continuous bubble-free FFMR system with a residence time of 25 seconds, a final conversion of up to 50 % in enzymatic oxidation was reached, whereas conversion in a conventional bubble column resulted in only 27 %. Finally, an option for scale-up was shown through an enlarged version of the FFMR.

The laccase-mediated heterocoupling of 3-methylcatechol and n -hexylamine was investigated at the milligram to gram scale, and an early eco-efficiency analysis and evaluation revealed bottlenecks in enzymatic synthesis. Eco-efficiency analysis was used as an optimisation tool to create more sustainable solutions and improve subsequent reactions, enabling the scaled-up biocatalytic process to become more economical and competitive compared with the chemocatalysed procedure using sodium iodate. When working with higher substrate concentrations (up to 100 mM), the following key aspects must also be considered: (1) the low solubility of n -hexylamine and the reaction products in aqueous solution, and (2) the poor stability of enzymes in unconventional solvents. The present study includes activity and stability experiments using laccases in methanol, a suitable solvent for the hydrophobic compound n -hexylamine. Contrary to previously published reports, excellent activities were obtained using Novozym 51003 at high methanol contents and substrate concentrations up to 100 mM. In addition, the use of this volatile organic solvent drastically simplified downstream processing.

An easy and efficient route to synthesize gel materials based on polymeric ionic liquids (PILs) is presented. The radical polymerization of imidazolium (Im)-based ionic liquids (ILs) bearing a vinyl group ([VEIm][Br], [VEIm][Ac], [VBIm][Br], [VBIm][Cl]) with crosslinker (CL) N,N′-methylenebisacrylamide (Bis) in water results in polyionic liquid hydrogels. Thermal and mechanical properties (tensile and compression tests) are investigated and compared with two different types of hydrogels. One is a polyacrylamide (PAAm) hydrogel having covalent-type crosslinking. The other is an alginate-based hydrogel having ionic-type crosslinking. Prepared IL-hydrogel materials provide favorable flexibility, adjustable by varying the CL ratio and water content. The higher the CL ratio is, the higher the fragility of the gel matrix. The gelation time of the hydrogels depends on the alkyl chain length, as well as the size of the anion.

The potential of the hydroxynitrile lyase from Manihot esculenta towards ketone substrates was investigated. It was observed that the length of the aliphatic chain is a key parameter for the conversion of aliphatic, non-branched ketones. Smaller substrates are readily converted with high enantioselectivites, but the elongation of the chain length causes a significant loss in enzyme activity. For a number of halogenated, herein especially fluorinated, acetophenone derivatives the corresponding cyanohydrins have been synthesized with good to moderate enantioselectivities.

The optical, chemical, and catalytic properties of metallic nanoparticles (NPs) depend strongly on their particle size and shape. Therefore, the preparation of monodisperse metallic NPs is very important for fundamental studies and practical applications. However, the isolation of the different structures by separation from a polydisperse sample, especially in the size range below 10 nm, is not well applied so far. Here, the asymmetric flow field flow fractionation (AF4) is adapted for the preparative separation of the Pd NPs regarding their size and shape in the sub-10-nm size range. To prove the efficiency of the applied method, small-angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (TEM) were utilized to determine the particle size distribution at different stages of the separation process. A major benefit of this method compared to most of the other separation techniques, the removal of impurities during the separation process, was proven by proton nuclear magnetic resonance (NMR). The obtained results demonstrate that the AF4 is well suited for the rapid preparation of the purified uniform precious metal NPs at the applied size range. Single fractions of the different-sized and -shaped Pd NPs were deposited on titania (TiO2) and tested in the catalytic hydrogenation of 2,5 hydroxymethylfurfural (HMF) in aqueous solution under mild conditions. While the spherical-shaped particles show a high activity, the separated agglomerated particles show a higher selectivity to the desired products.

Ionic liquids were found to be useful media for quenching of aluminum and steel alloys. In mixtures containing up to 10% w/w water or ethanol they prevent film boiling (Leidenfrost effect) and result in very high and constant cooling rates. The ionic liquids [EMIm][NTf2], [EMIm][EtSO4] and Ammoeng®110 exhibit remarkable stability when metals at temperatures well above the ionic liquid decomposition temperature were quenched.

Electrodialysis (ED) is an advancing seawater sample processing tool that enables the separation of analytes from the often interfering salt matrix. In this study, we present the evaluation of a laboratory scale ED system for both dissolved organic matter (DOM) and target pollutant analysis of seawater. The developed sample processing protocol yields reproducible data and was found to be robust towards moderate changes in sample composition. At the final salinity of 0.1, the average recovery of DOM in the form of dissolved organic carbon, nitrogen and phosphorus (DOC, DON and DOP) was 44, 53 and 89%, respectively. DOM loss occurred mainly in the late stage of the ED process. When investigating specific ED processing parameters, it was discovered that the initial sample salinity does not influence DOM recovery. The final salinity, by contrast, is a dominant influence factor on DOM recovery. Furthermore, DOC and DOP recoveries could be improved by 8% by refining the electrical current in the ED cell. Surprisingly, adjustments of the sample pH did not lead to any improvements in DOM recovery. The experiments with target analytes showed that the recovery of individual molecules is determined by their n-octanol water partition coefficients logKow. High recoveries > 80% were achieved for compounds with medium logKow of −1 to 3. Hydrophobic compounds with logKow > 3 were lost through surface adsorption to the system walls and tubing. Small, polar and charged compounds with logKow

Highly porous and crystalline metal–organic framework MIL-101 has been synthesized and used for the preparation of rhodium supported catalyst. Acetylacetonato(1,5-cyclooctadiene)rhodium(I) has been used as catalyst precursor. The material has been characterized by XRD, XPS, SAXS, FTIR, SEM, TEM, AAS, and nitrogen adsorption. The catalytic properties of Rh@MIL-101 have been investigated in the hydroformylation of olefins with different structure and chain length to the corresponding aldehydes. High conversion and selectivity to n -aldehydes have been achieved in the hydroformylation of n -alk-1-enes. The obtained results show that the rhodium species are highly dispersed and preferentially located at internal and less accessible sites at the supertetrahedral units.

Seed extract and fractions of Cola lepidota (Sterculiaecae) were examined for antiproliferative and apoptotic activities using human breast adenocarcinoma (MCF-7) and osteocarcinoma (MG-63) cell line. The extracts were subjected to chromatographic analysis. Cytotoxicity-guided fractionation of seeds led to the LC-MS isolation of trimethylammoniumyl-acetate monohydrate, established by LC-MS, 2D NMR experiments and confirmed by X-ray crystallographic data.

Quenching as a part of heat treatment is an important process in the manufacturing chain of metallic components. One of the most common processes is immersion quenching in vaporising liquids. Unfortunately, this process is affected by the Leidenfrost-phenomenon. This effect can generate inhomogeneous quenching and thus asymmetrical residual stresses and avoidable distortion. In this work, ionic liquids have been investigated as new quenching media, which can be used as baths near room temperature. Aluminium cylinders have been quenched in baths of different ionic liquids with varying water contents and bath temperatures. The time-temperature curves have been recorded and the heat transfer coefficients were determined and compared to quenching in water. Addition of a few percents water to the ionic liquids increases the cooling rate significantly. Even at higher water contents, bubble boiling and convection are predominant and almost no Leidenfrost-effect occurs. This offers a huge potential to accelerate and homogenise immersion quenching.

Drug-coated balloons (DCB), which have emerged as therapeutic alternative to drug-eluting stents in percutaneous cardiovascular intervention, are well described with regard to clinical efficiency and safety within a number of clinical studies. In vitro studies elucidating the correlation of coating method and composition with DCB performance are however rare but considered important for the understanding of DCB requirements and the improvement of established DCB. In this context, we evaluated the applicability of a pipetting, dip-coating, and spray-coating process for the establishment of DCB based on paclitaxel (PTX) and the ionic liquid cetylpyridinium salicylate (Cetpyrsal) as novel innovative additive in three different compositions. Among tested methods and compositions, the pipetting process with 50 wt.% PTX resulted in most promising coatings as drug load was less controllable by the other processes and higher PTX contents led to considerable drug crystallization, as visualized by electron microscopy, accelerating PTX loss during short-term elution. Applying these conditions, homogeneous coatings could be applied on balloon catheter, whose simulated use in an in vitro vessel model revealed percental drug losses of 36 and 28% during transit and percental drug transfers of 12 and 40% under expansion for coatings applied in expanded and folded balloon condition, respectively. In comparison to literature values, these results support the high potential of Cetpyrsal as novel DCB matrix regarding low drug loss and efficient drug transfer.

Organic solvent nanofiltration (OSN) promises to be a versatile tool for mild and energy-saving downstream processing. In this case study, the use of modern solvent-resistant membranes to separate organocatalysts from reaction media was investigated. Commercially available membranes with molecular weight cut-offs (MWCOs) between 150 and 500 g mol–1 were used. They showed high rejections of up to 99% for native catalysts in THF. The enantioselective Henry reaction of ethyl pyruvate and nitromethane catalyzed by benzoyl cupreine was used to demonstrate the potential of this technique for preparative use.

Dispersed colloidal Pt-nanoparticles with mean particle sizes between 1 and 4 nm were prepared continuously in microstructured devices using ethylene glycol as solvent and reducing agent and H 2 PtCl 6 as metal precursor. The Pt-nanoparticles were characterized directly in solution regarding the particle size and particle size distribution by small angle X-ray scattering (SAXS) and after deposition on a grid by TEM. Both methods gave comparable results. The particle size of the Pt-nanoparticles which are formed inside the microstructures can be controlled by the NaOH/Pt ratio. At a high NaOH/Pt-ratio, that means in alkaline medium, the Pt-nanoparticles have a mean particle size lower than 1.7 nm and a narrow size distribution indicating that nanoparticle formation is dominated by nucleation reaction under this condition. At a low NaOH/Pt-ratio, that means in acidic medium, the mean particle size increases to about 3.6 nm whereas also the particle size distribution increases which is mainly attributed to a larger influence of growth reactions on particle formation. Pt-nanoparticles with a similar mean particle size but a clearly narrower particle size distribution were obtained when a two-step process was used. In this process, Pt-seeds were formed in the microreactor in an alkaline medium. After mixing the alkaline Pt-seeds containing solution with a HCl/ethylene glycol solution in a micromixer the now acidic solution flows in a second microreactor where mainly particle growing takes place. The final particle size and its distribution can be influenced by both conditions for seed formation (temperature, flow rate) and particle growth (pH, temperature, flow rate).

Controlled initiation of biochemical events and in particular of protein activity is a powerful tool in biochemical research. Specifically, optical trigger signals are an attractive approach for remote control of enzyme activity. We present a method for generating optical control of enzyme activity applicable to a widespread range of enzymes. The approach is based on short laser pulses as optical "switches" introducing an instantaneous change of the pH-value for activation of protein function. The pH-jump is induced by proton release from 2-nitrobenzaldehyde. Reaction conditions were chosen to yield a pH-jump of almost 3 units on switching from inactive to active conditions for the enzyme. In this experimental setup, irradiation can be realized without any loss of enzyme activity. Following this change in pH-value, a controlled activation of hydrolytic activity of acid phosphatase is successfully demonstrated. This application provides a general method for photocontrol of enzymatic function for proteins having a significant pH-profile. The kinetic data for the substrate 6-chloro-8-fluoro-4-methylumbelliferone phosphate are determined.

Reaktion und Reaktor bilden eine Einheit und mussen aufeinander abgestimmt sein. Dies gilt besonders fur kinetische Racematspaltungen zur Gewinnung von enantiomerenreinen Bausteinen. Dabei ist die Art der Reaktion oder des Katalysators ohne Bedeutung, wenn auch fur die Mehrzahl der industriell wichtigen Prozesse Biokatalysatoren eingesetzt werden.

Persea americana Mill (Lauraceae) root bark is used in ethnomedicine for a variety of diseases including cancer.To isolate and characterize the chemical constituent in P. americana, and also to determine the anticancer property of a new alkene lactone from the root bark of P. americana.The MCF-7 cells were treated with different concentrations of the pure compound for 48 h. The percentage of cells in the various phases, online monitoring of metabolic changes and integrin receptor expression determined by flow cytometry.One novel alkene lactone (4-hydroxy-5-methylene-3-undecyclidenedihydrofuran-2 (3H)-one) (1) was isolated and characterized using 1D-NMR, 2D-NMR, infrared, UV and MS. At a concentration of 10 µg/mL, significant reduction of proliferation of MCF-7 was induced while MCF-12 A cell was significantly stimulated by 10 µg/mL. The IC50 value for MCF-7 cells is 20.48 µg/mL. Lower concentration of 1 harbor no significant effect on either MCF-7 or MCF-12A. The apoptotic rates of MCF-7 cells were increased significantly. At the final concentration 10 µg/mL, up to 80% of all breast cancer cells were dead. On the non-tumorigenic cell line MCF-12A, the same concentrations (1 and 10 µg/mL) of compound 1 caused significant enhanced apoptotic rates. A total of 1 µg/mL of 1 caused a decrease of α4-, α6-, β1- and β3-integrin expression.The compound caused a stimulatory effect on non-tumorigenic MCF-12A cells with respect to cell adhesion while tumorigenic MCF-7 cells detached continuously. This is the first report on the anticancer effects of this class of compound.

This themed collection reports on recent progress in the development of technologies, methods, materials and reactions for energy conversion with a particular focus on basic mechanisms.

Vapor pressure determination of extremely low volatile compounds, e.g., ionic liquids, is challenging and time-consuming using conventional techniques. Particularly, ionic liquids tend to decompose already at temperatures where the vapor pressure is still very low. Conventional methods for the determination of evaporation rates are thus limited to temperatures below the decomposition temperature where evaporation proceeds very slowly. A new method for the vapor pressure determination of low-volatile compounds, presented here, is able to overcome this limitation using differential fast scanning calorimetry on very short time scales in inert atmospheres. The method is based on the relatively fast evaporation of nanogram samples, exhibiting a significantly enhanced (up to a factor of 104) surface-to-volume ratio compared to conventional thermogravimetric samples. Due to extremely high heating rates, the sample is exposed to the thermal stress only for milliseconds. In these conditions the evaporation dominates in the mass loss even at temperatures above the possible onset of the decomposition process. In addition, since the method allows very high heating and cooling rates (up to 106 K s−1) evaporation of the samples on the way to and from the evaporation temperature is avoided and thus much higher temperatures can be reached in the measurement of the mass loss rate as compared to conventional methods. This method was tested using the diffusion pump oil Santovac® 5 and the ionic liquid [EMIm][NTf2] at temperatures up to 780 K and in atmospheres of different inert gases. The absolute vapor pressures of several aprotic ionic liquids: [EMIm][NTf2], [BMIm][Br], [BMIm][BF4], [BMIm][PF6], [EMIm][Cl], [BMIm][Cl], [EMIm][NO3], and [BMIm][NO3] were measured. The vapor pressures were fitted to the Clarke–Glew equation. The vaporization enthalpies and boiling temperatures of the ionic liquids were estimated. The advantages and limitations of this new method of absolute vapor pressure determination were discussed and the results are compared with the data available in the literature.

In many fields, microprocess technology is gaining significance and is increasingly finding its way into use in industrial production. However, specialist knowledge regarding reactions of compounds, mixing and downstream processes in microchannels is required, as experience from the ”macro world” can only be applied in a limited way. The appropriate level of education required is still lacking. In this study, a number of educational experiments were set up focusing on mixing processes and emphasizing the significance of viscosity in mixing. Additionally liquid-liquid extraction as an important downstream process was looked into as a student experiment. In order to make the training widely accessible, a web-based education platform was established.

A chimeric cyanophycin synthetase gene composed of the cph A Te coding region from the cyanobacterium Thermosynechococcus elongatus BP-1, the constitutive 35S promoter and the plastid targeting sequence of the integral photosystem II protein PsbY was transferred to the tobacco variety Petit Havanna SRI and the commercial potato starch production variety Albatros. The resulting constitutive expression of cyanophycin synthetase leads to polymer contents in potato leaf chloroplasts of up to 35 mg/g dry weight and in tuber amyloplasts of up to 9 mg/g dry weight. Both transgenic tobacco and potato were used for the development of isolation methods applicable for large-scale extraction of the polymer. Two different procedures were developed which yielded polymer samples of 80 and 90% purity, respectively

A series of ribofuranosyl- and 2-deoxyribofuranosyl homo- and spacered-C-nucleosides have been synthesized by reaction of fully protected 3-(1-deoxy-β-D-ribofuranosyl-1-yl)propanal (1), 3-(1,2-dideoxy-β-D-ribofuranos-1-yl)propanal (14), 1-(1-desoxy-β-D-ribofuranos-1-yl)pent-4-yn- 3-on (19), 1-(1-desoxy-β-D-ribofuranos-1-yl)-5-phenyl-pent-4-yn-3-on (20), 1-(1,2-didesoxy-β- D-ribofuranos-1-yl)pent-4-yn-3-on (29), and 1-(1,2-didesoxy-β-D-ribofuranos-1-yl)-5-phenyl- pent-4-yn-3-on (30) with different nucleophiles. The preparation of 1 and 14 proceeds by Knoevenagel reaction with malononitrile, cyanoacetamide and 2-cyano-N-(4-methoxy- phenyl)acetamide and subsequent cyclization with sulphur to thiophenes 5, 7, 8, 16 and then by cyclization with triethyl orthoformate to give thienopyrimidine 6 and thienopyrimidinone 9, 10, and 17. Treatment of acetylenic ketones 19, 20, 29, and 30 with acetamidinium chloride, benzamidinium chloride, and S-methylisothiouronium sulphate provided the corresponding pyrimidines 21-26, 31, 32. Finally, the use of 4H-1,2,4-triazol-3-amine and 2-aminobenz- imidazole as 1,3-N,N'-dinucleophiles afforded the triazolopyrimidines 35, 39 and the pyrimidobenzimidazoles 36, 37, and 40, respectively. Deprotection of a selected number of C- nucleosides was achieved by one or two steps procedure without serious problems. That makes these C-nucleosides promising candidates for the synthesis of monomers suitable for solid phase nucleic acid oligomerization.

In einem Eintopf-Verfahren werden aus Olefinen durch Hydroformylierung mit Synthesegas (CO/H2 = 1/1) und nachfolgende saurekatalysierte Umsetzung mit Glycerin langkettige Acetale in Ausbeuten > 95 % hergestellt. Die erhaltenen Gemische von 5- und 6-Ringverbindungen stellen neuartige potenzielle Kraftstoffadditive dar. Durch Optimierung der Reaktionsbedingungen und geeignete Katalysatorwahl ([Rh(COD)]acac/Xantphos) gelingt eine hochregioselektive Hydroformylierung zu den linearen Acetalen. Zur Herstellung von ausreichenden Mustermengen wurde Glycerin mit Alkenen im 2-L-Autoklav und mit Aldehyden im 60-L-Ruhrreaktor umgesetzt. Long chain olefins are converted into aldehydes by hydroformylation using synthesis gas CO/H2 and further converted in an acid-catalyzed conversion with glycerol in a one-pot procedure. Yields are up to 95 %. The obtained mixtures of 5- and 6-membered rings are potential fuel additives offering alternative use of glycerol from renewable resources. By optimization of reaction conditions such as catalyst precursor, ligand, pressure, temperature, solvent or catalyst/substrate ratio a highly selective hydroformylation towards linear acetals was achieved. For synthesis of larger amounts, glycerol was converted with alkenes on a 2-L-scale and with aldehydes on a 60-L-scale.

The lipase-catalyzed polycondensation of sebacic aid and 1,4-butanediol can be performed in a biphasic reaction system composed of an aqueous reaction phase and an organic extraction phase. The shift of the equilibrium to higher product yields can be realized by the integrated product removal (IPR). In this biphasic reaction system the product yield, molecular weight and polydispersity is depending on the partitioning of the substrates and the product between the phases. By the biphasic approach substrate inhibition as well as molecular weight and polydispersity can be controlled by medium engineering. The polyester concentration can be increased up to 98% by optimising the reaction conditions. The molecular weight is limited in the biphasic system due to its removal while the polydispersity is independent of the reaction conditions but connected to the biphasic approach. Additional to the conversion the partition coefficients have been investigated either experimentally and via calculation by the quantum...

The production of biodegradable polymers that can be used to substitute petrochemical compounds in commercial products in transgenic plants is an important challenge for plant biotechnology. Nevertheless, it is often accompanied by reduced plant fitness. To decrease the phenotypic abnormalities of the sprout and to increase polymer production, we restricted cyanophycin accumulation to the potato tubers by using the cyanophycin synthetase gene (cphA(Te)) from Thermosynechococcus elongatus BP-1, which is under the control of the tuber-specific class 1 promoter (B33). Tuber-specific cytosolic (pB33-cphA(Te)) as well as tuber-specific plastidic (pB33-PsbY-cphA(Te)) expression resulted in significant polymer accumulation solely in the tubers. In plants transformed with pB33-cphA(Te), both cyanophycin synthetase and cyanophycin were detected in the cytoplasm leading to an increase up to 2.3% cyanophycin of dry weight and resulting in small and deformed tubers. In B33-PsbY-cphA(Te) tubers, cyanophycin synthetase and cyanophycin were exclusively found in amyloplasts leading to a cyanophycin accumulation up to 7.5% of dry weight. These tubers were normal in size, some clones showed reduced tuber yield and sometimes exhibited brown sunken staining starting at tubers navel. During a storage period over of 32 weeks of one selected clone, the cyanophycin content was stable in B33-PsbY-cphA(Te) tubers but the stress symptoms increased. However, all tubers were able to germinate. Nitrogen fertilization in the greenhouse led not to an increased cyanophycin yield, slightly reduced protein content, decreased starch content, and changes in the amounts of bound and free arginine and aspartate, as compared with control tubers were observed.

Extraction of catalytically active biomolecules using ionic liquid-based aqueous two-phase systems (IL-based ATPS) composed of the IL Ammoeng™ 110 and K2HPO4/KH2PO4 represents a powerful tool for the integration of several process steps into one unit operation within downstream processing. The technique can be used in order to combine the purification of active enzymes with the performance of enzyme-catalysed reactions. However, a fundamental understanding of the driving forces which are involved in the partitioning of proteins between the two phases is still lacking. By investigating the distribution of four model proteins at varying system characteristics of the IL-based ATPS, we found a combination of different interactions between the proteins and the ionic liquid to be responsible for the enrichment within the IL-containing upper phase. Among these, the proteins’ charge as well as the molecular weight is of major importance. Therefore, we propose the electrostatic interaction between the charged amino acid residues at a protein's surface and the positively charged IL-cation to be the main driving force of the extraction process. Based on these findings, a model for describing protein partitioning in IL-based ATPS was established and employed for predicting the partition coefficient of two further model proteins, pepsin and hemoglobin.

This work has been undertaken to obtain new thermochemical data for ethanediol and propanetriol acetates and to improve the group contribution methodology for the prediction of the thermodynamic properties of compounds relevant to biodiesel. Standard molar enthalpies of formation in the gaseous state of a series of 1,2-ethanediol monoacetate, 1,2-ethanediol diacetate, and 1,2,3-propanetriol triacetate have been obtained from combustion calorimetry and results from the temperature dependence of the vapor pressure measured by the transpiration method. To verify the experimental data, ab initio calculations of all compounds have been performed. Enthalpies of formation derived from the Gaussian 03 second-order Moller−Plesset (G3MP2) method are in good agreement with the experimental results. The strength of the hydrogen bond in 1,2-ethanediol monoacetate and in 1,2-ethanediol have been obtained using ab initio calculations and the group additivity method.

Acetonitrile as a solvent used in liquid chromatography/mass spectrometry (LC/MS) of peptides and proteins is a relatively toxic solvent (LD50 oral; rat; 2,460 mg/kg) compared to alternatives like methanol (LD50 oral; rat; 5,628 mg/kg) and acetone (LD50 oral; rat; 5,800 mg/kg). Strategies to minimize its consumption in LC are either to reduce the inner diameter of the column or replace acetonitrile with a suitable alternative. Methanol is often recommended to replace acetonitrile in peptide analysis. In this study however, the main focus lies on another alternative solvent for LC/MS of peptides; acetone. A number of model proteins were tryptically digested and the peptide solutions were analyzed on a linear trap quadrupole (LTQ) mass spectrometer. The performances of acetonitrile, methanol and acetone were compared according to the quality of the chromatograms obtained and identification of the peptides using the BioWorks software developed by Thermo Scientific. In accordance to the elutropic series, acetone was found to significantly reduce the retention times of peptides separated by C18 column material with regard to acetonitrile while methanol led to increased retention times. Acetone was the superior solvent to methanol for most of the tested model proteins reaching similar sequence coverage and numbers of identified peptides as acetonitrile. We therefore propose acetone as an alternative to acetonitrile in LC/MS of peptides.

A convenient procedure for the racemization of α-amino acid esters in the presence of catalytic amounts of salicylaldehydes is described. The combination of this racemization protocol with lipase-catalyzed ester hydrolysis allows successful dynamic kinetic resolution of various α-amino acid esters. The corresponding α-amino acids are obtained in high yield and optical purity.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A new method for the purification of N-acetylneuraminic acid (Neu5Ac) is presented. A mixture of phenylboronic acid (PBA) and trioctylmethylammonium chloride (TOMAC) efficiently extracts the compound, which usually needs to be purified by elaborate chromatographic procedures or precipitation with glacial acetic acid. The presented extraction method is suitable to enrich Neu5Ac referring to pyruvate and the other compounds and facilitate further purification via classical crystallisation or chromatography, thus facilitating the established production process which utilises a large excess of pyruvate. The extraction system was characterised in detail by equilibrium studies for various solvents, pH values and carrier and substrate concentrations. The equilibrium constants determined for the two reaction steps (reaction with phenylboronic acid and reactive extraction) show that the equilibrium of extraction is more important than the extent of reaction with phenylboronic acid. The results obtained for pure compounds could be assigned to mixtures and reaction solutions without difficulty. Furthermore an efficient recovery of the carbohydrates from the organic phase is presented. The treatment of reactions mixtures showed that this system is not only feasible at lab scale and concentrations typical for scientific studies, but also for high substrate concentrations as used in industrial processes. The extraction step was shown to be the limiting factor in the extraction/recovery process.

Pervaporation proved to be one of the best methods to remove solvents out of a solvent producing Clostridium acetobutylicum culture. By using an ionic liquid (IL)-polydimethylsiloxane (PDMS) ultrafiltration membrane (pore size 60 nm), we could guarantee high stability and selectivity during all measurements carried out at 37 degrees C. Overall solvent productivity of fermentation connected with continuous product removal by pervaporation was 2.34 g l(-1) h(-1). The supported ionic liquid membrane (SILM) was impregnated with 15 wt% of a novel ionic liquid (tetrapropylammonium tetracyano-borate) and 85 wt% of polydimethylsiloxane. Pervaporation, accomplished with the optimized SILM, led to stable and efficient removal of the solvents butan-1-ol and acetone out of a C. acetobutylicum culture. By pervaporation through SILM, we removed more butan-1-ol than C. acetobutylicum was able to produce. Therefore, we added an extra dose of butan-1-ol to run fermentation on limiting values where the bacteria would still be able to survive its lethal concentration (15.82 g/l). After pervaporation was switched off, the bacteria died from high concentration of butan-1-ol, which they produced.

A fundamental concern in the Quantitative Structure-Activity Relationship approach to toxicity evaluation is the generalization of the model over a wide range of compounds. The data driven modelling of toxicity, due to the complex and ill-defined nature of eco-toxicological systems, is an uncertain process. The development of a toxicity predicting model without considering uncertainties may produce a model with a low generalization performance. This study presents a novel approach to toxicity modelling that handles the involved uncertainties using a fuzzy filter, and thus improves the generalization capability of the model. The method is illustrated by considering a data set dealing with the fathead minnow (Pimephales promelas) toxicity of 568 organic compounds.

The overcoming of thermodynamic limitations in the synthesis of optically active ketone cyanohydrins by using organic solvent-free systems has been investigated. Therefore, substrates with known unfavorable results within hydroxynitrile lyase-catalyzed reactions were selected for the determination of limitations and bottlenecks in ketone cyanohydrin synthesis. The highly (S)-selective hydroxynitrile lyase from Manihot esculenta (MeHNL) has been chosen for the conversion of acetophenone and the corresponding derivatives, which are substrates that exhibit only low grades of conversion also with several other hydroxynitrile lyases. With organic solvent-free systems under optimized reaction conditions conversions up to 78 % with>99.0 ee (S) were obtained. Finally, 5 mL of (S)-acetophenone cyanohydrin with an enantiomeric excess of 98.5 % ee (S) were synthesized.

Oligomeric and polymeric polyether polyols, especially poly(propylene oxide), are used for the production of detergents, nonionic surfactants, washing agents, and cleaners, but they are predominantly used in polyurethane production processes. Tin phosphate coordination polymers show good activity in the selective polymerization of epoxides. The catalyst can be easily synthesized by the condensation of tributyl phosphate and butyl tin trichloride. Investigations of this achiral organotin phosphate condensate in the stereoregular polymerization of propylene oxide, including the properties controlling the molecular weight of the resulting poly(propylene oxide) and structural and mechanistic studies, are presented. Additionally, the polymerization of propylene oxide occurs with high activity, no allyl end groups, just a small number of irregularities, and a high percentage of isotacticity (88%) in the polymer.

Switchable-hydrophilicity solvents (SHSs) are solvents that can switch reversibly between a water-miscible state to a state that forms a biphasic mixture with water. In this case study, SHSs have been studied for easy product/catalyst separation as well as catalyst recycling. A series of tertiary amine SHSs have been identified for the extraction of the hydrophilic product from the postreaction mixture. Here, we determined high extraction efficiencies for the product (84%) and low extraction rates for the catalyst (0.1%). With the catalyst recycling experiments, we isolated the product in high purity (98%) without further purification steps. At the same time, the catalyst was reused without any loss of activity (91% enantiomeric excess,99% yield) four times. Furthermore, we optimized the extraction efficiency by working with a microextractor. In addition, with the use of a falling-film microreactor, we obtained the product with high enantioselectivity by working at ambient conditions.

For the prediction and optimisation of the equilibrium conversion in biphasic catalysed reactions, the equilibrium constant of the desired reaction and the partition coefficients of all reactants have to be known. Within this contribution we have examined the alcohol dehydrogenase-catalysed reduction of several linear and aromatic ketones in biphasic reaction media with respect to equilibrium conversion. In this example, the equilibrium constant can be expressed in terms of differences in oxidation-reduction potentials ΔE0. However, for a large variety of organic compounds, these data are quite rare in the literature. To overcome this lack of data, we have utilised methods of computational chemistry to calculate data for the Gibbs free energy ΔGR leading to the equilibrium constants of a homologous series of linear ketones. To obtain comparable data for the reduction of substituted acetophenone derivatives, the Hammett relation leads to the necessary equilibrium constants. Furthermore, we compare the equilibrium conversions of a set of cofactor regeneration methods for the alcohol dehydrogenase-catalysed reductions. These results lead to a time-saving experimental design for the enantioselective reduction of 2-octanone to (R)-2-octanol on a preparative scale utilising biphasic reaction conditions.

Using the organic solvents acetonitrile and 1,4-dioxane as water-miscible additives for the alcohol dehydrogenase (ADH)-catalyzed reduction of butan-2-one, we investigated the influence of the solvents on enzyme reaction behavior and enantioselectivity. The NADP(+)-dependent (R)-selective ADH from Lactobacillus brevis (ADH-LB) was chosen as biocatalyst. For cofactor regeneration, the substrate-coupled approach using propan-2-ol as co-substrate was applied. Acetonitrile and 1,4-dioxane were tested from mole fraction 0.015 up to 0.1. Initial rate experiments revealed a complex kinetic behavior with enzyme activation caused by the substrate butan-2-one, and increasing K(M) values with increasing solvent concentration. Furthermore, these experiments showed an enhancement of the enantioselectivity for (R)-butan-2-ol from 37% enantiomeric excess (ee) in pure phosphate buffer up to 43% ee in the presence of 0.1 mol fraction acetonitrile. Finally, the influence of the co-solvents on water activity of the reaction mixture and on enzyme stability was investigated.

Theoretically, dynamic kinetic resolution gives stereochemically pure compounds in 100% yield. Practically, this target is seldom reached. In this work, we identified limiting factors for a given r...

Understanding the behavior of ionic liquids on the molecular level is essential for explaining solubilizing or reaction processes, including catalytic reactions in ionic liquids or with ionic liquids as co-solvent. Using mass spectrometry techniques it is possible to characterize their aggregate formation behavior, which depends on the used solvent. With increasing polarity of the solvent and decreasing ionic liquid concentration, the size of the formed aggregates decreases. From conductivity measurement curves “critical aggregate concentrations” were calculated, which confirm the results of mass spectrometry measurements. Addition of ionic liquids increases the solubility of acetophenone in water. This effect can be explained by the aggregate formation ability of ionic liquids. The findings can be used to explain the outstanding solubility and solvation properties of ionic liquids.

In this paper, we describe the hydroformylation of terminal and internal olefins to terminal aldehydes using a catalyst system of rhodium and BIPHEPHOS. According to industrial processes, the catalyst concentration lies in a range from 0.01 to 0.001 mol%. The conversions are, depending of the substrate, up to 99% and yields up to 86% of the aldehydes can be found. The ratio of linear to branched products is up to 99:1.

Ionic liquids (IL) offer new possibilities for solvent engineering for biocatalytic reactions. The deracemization of (±)-mandelic acid using a lipase-mandelate racemase two-enzyme system was used to investigate the scopes and limitations of ionic liquids as new reaction media for a dynamic resolution approach. Mandelate racemase [EC 5.1.2.2] from Pseudomonas putida ATCC 12633 was observed to be active in ionic liquids such as 1,3-dimethylimidazolium methylsulfate ([MMIM][MeSO 4 ]) or 1-butyl-3-methylimidazolium octylsulfate ([BMIM][OctSO 4 ]) at water activities a w >0.74. Mandelate racemase activity could also be obtained in a biphasic system consisting of water and 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM][PF 6 ]) in a ratio of 1:10.

This review discusses recent achievements in the field of cofactor regeneration for the nicotinamide cofactors NADH and NADPH. The examples discussed include alcohol dehydrogenases, formate dehydrogenase, glucose dehydrogenase and a hydrogenase. For the reaction either one-phase systems or two-phase systems in combination with an organic solvent are discussed. For the enantioselective reduction of 2-octanone to (R)-2-octanol it could be shown that enzyme coupled NADPH regeneration with glucose dehydrogenase and glucose results in shorter reaction times and higher yields when compared to the substrate coupled regeneration with 2-propanol.ADH: alcohol dehydrogenase; LDH: Lactose dehydrogenase; GDH: Glucose dehydrogenase; FDH: Formate dehydrogenase; LB-ADH: alcohol dehydrogenase from Lactobacillus brevis; HL-ADH: alcohol dehydrogenase from horse liver; TB-ADH: alcohol dehydrogenase from Thermoanaerobicum brockii; PS-GDH: Glucose dehydrogenase from Pseudomonas species; [BMIM][PF6]: Butyl-methyl-imidazoliumhex...