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Experiments were conducted to study the effects of reaction conditions on the hydrolysis of miscanthus dissolved in 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) catalyzed by H2SO4. It was determined that while there is a small co-inhibition effect associated with the simultaneous hydrolysis of the cellulosic and hemicellulosic portions of miscanthus, the largest rate decreases were observed for the hydrolysis of the hemicellulosic portion. This rate decrease was attributed to the chemical linkage between hemicellulose and lignin in miscanthus, which could be broken with chemical pretreatment. While chemical pretreatment increased the rate of the hydrolysis of the hemicellulosic component, delignification showed no further benefit. The rate of hydrolysis was determined to be first order in concentrations of β-1,4 glycosidic linkage and acid, and zero order in water concentration. The activation energy for the hydrolysis of the glycosidic linkages in the cellulosic and hemicellulosic components were determined to be 95 kJ mol−1and 114 kJ mol−1respectively. Progressive addition of water during the first hour of the reaction increased conversion and selectivity to saccharine products, while limiting dehydration of the sugars formed. The conversion of the cellulosic portion of miscanthus could be increased after the first hour of the reaction by increasing the reactor temperature. While miscanthus is only partially soluble in [Emim][Cl], it was found that the initial miscanthus loading could be increased to 9 wt% before significant yield decreases attributed to solubility limitations of the cellulosic component were observed. By proper adjustment of reaction conditions, it was possible to achieve yields of sugars approaching 84% from the cellulosic and hemicellulosic components of miscanthus, with minimal dehydration of the sugars to furans. [ABSTRACT FROM AUTHOR]

The immobilization of N-sulfonyl-(Ra)-binam-d-prolinamide using polystyrene as a support allows the recovery of an efficient catalytic system for the enantioselective direct aldol reaction between different ketones and aldehydes under solvent-free or aqueous conditions. The polystyrene-supported N-sulfonyl-(Ra)-binam-d-prolinamide catalyst in combination with benzoic acid showed similar results to those obtained with unsupported N-tosyl-binam-derived prolinamide under similar reaction conditions. The aldol products were obtained at room temperature and using only 2 equivalents of the ketone with high yields, regio-, diastereo- and enantioselectivities. The aldol reaction between aldehydes can also be performed under these reaction conditions with moderate results. The recovered catalyst can be reused up to six times without having a detrimental effect on the achieved results. [ABSTRACT FROM AUTHOR]

Covering: up to the end of 2009 [ABSTRACT FROM AUTHOR]

The biological synthesis of metal nanoparticles from ions has recently emerged as a novel technique for an environmentally benign recovery of heavy metals. Bacteria are known to recover palladium(0) in the form of nanoparticles that are catalytically active. However, the extent of the reactions that can be catalysed by bio-recovered palladium has not been investigated. This study demonstrates that the Suzuki–Miyaura and Mizoroki–Heck reactions can be catalysed by bio-generated palladium nanoparticles formed on the surface of Gram-negative bacteria. The results suggest that the range of applications of this catalyst can be extended to the realm of carbon–carbon bond formation in synthetic organic chemistry. [ABSTRACT FROM AUTHOR]

The palladium-catalysed carbonylation of vinyl aziridines can give either the trans- or cis-β-lactam preferentially or even the δ-lactam simply by adjusting the reaction parameters ([Pd], [CO], temperature). [ABSTRACT FROM AUTHOR]

The PERCA (PEroxy Radical Chemical Amplification) technique, which is based on the catalytic conversion of ambient peroxy radicals (HO2 and RO2, where R stands for any organic chain) to a larger amount of nitrogen dioxide (NO2) amplified by chain reactions by adding high concentrations of NO and CO in the flow reactor, has been widely used for total peroxy radical RO2* (RO2* = HO2 + ΣRO2) measurements. High-sensitivity and accurate measurement of the NO2 concentration plays a key role in accurate measurement of the RO2* concentration. In this paper, we report on the development of a dual-channel chemical amplification instrument, which combined the PERCA method with the incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS), for peroxy radical measurements. The IBBCEAS method is capable of simultaneously measuring multiple species with high spectral identification, and can directly measure NO2 concentrations with high sensitivity and high accuracy and without interference from other absorbers. The detection sensitivity of the developed PERCA–IBBCEAS instrument for HO2 radicals was estimated to be about 0.9 pptv (1σ, 60 s) at a relative humidity (RH) of 10%. Considering the error sources of NO2 detection, CL determination, and the radical partitioning in the air sample, the total uncertainty of RO2* measurements was about 16–20%. [ABSTRACT FROM AUTHOR]

We used relief and planographic printing methods to print the catalytic effect of an enzyme, but not the enzyme molecules, onto paper. Printing enzymatic reactions have applications in bioactive papers, low-cost diagnostics, anti-counterfeiting devices and advanced packaging materials. These methods can create novel printing effects on commodity surfaces for advanced applications. [ABSTRACT FROM AUTHOR]

In this paper, we present a micromachined Y-cut quartz resonator based thermal sensor array which is configured with a reaction chamber that is physically separated but located in close proximity to the resonator for sensitive calorimetric biosensing applications. The coupling of heat from the reaction chamber to the quartz resonator is achieved viaradiation and conduction through ambient gas. The sensor was packaged onto a 300 μm thick stainless plate with an opening in the middle. The sensor array was aligned to the opening and mounted from the underside of the plate. A reaction chamber designed for performing (bio)chemical reactions was used in the measurements. This configuration of the sensor allows for a very robust sensing platform with no fouling of the sensor surface or degradation in its performance metrics. Impedance-based tracking of resonance frequency was used for chemical, enzymatic, and cellular activity measurements. The sensor described has an impedance sensitivity of 852 Ω °C−1or a frequency sensitivity of 7.32 kHz °C−1for the 91 MHz resonator used in this work. Results on exothermic reaction between hydrochloric acid and ammonium hydroxide, the hydrolysis reaction of urea by urease and the catalytic reaction of glucose with glucose dehydrogenase are reported. From the signal to noise ratio analysis of the glucose sensor, <10 μM glucose sensitivity could be obtained improving the detection limit by a factor of 250 in comparison to our previous work using thermopile sensors. Finally, calcium ionophore induced cellular activity was measured in pancreatic cancer cells using the sensor. [ABSTRACT FROM AUTHOR]

Described in this paper is a personal overview of the green chemistry aspects of fluorous technologies. The unique phase separation and broad combinatorial capabilities of fluorous technologies have led to the development of fluorous chromatography-free separations, chemical recycling techniques, atom economic reactions, energy-focused microwave reactions, metal-free organocatalysis, aqueous media reactions, and modified reagents. These green chemistry techniques have been demonstrated in discovery chemistry, medicinal chemistry, and academic research labs dealing with small-scale organic synthesis. Issues such as the environmental impact of fluorous chemicals are also discussed. [ABSTRACT FROM AUTHOR]