The lipase-catalysed kinetic resolution of rac-4-phenyl-2-azetidinone was investigated in supercritical carbon dioxide (scCO2). Water (0.5mol equivalent) was used as nucleophilic donor. The effects of pressure and temperature were studied in a batch reactor (internal volume: 30mL). The optimum pressure and temperature of the β-lactam ring-opening reaction proved to be 14MPa and 70°C. Under optimum conditions, full conversion was achieved in 120h. The resulting (R)-β-phenylalanine (ee≥98%) and (S)-4-phenyl-2-azetidinone (ee≥99%) could be easily separated by scCO2 extraction of the (S)-β-lactam and subsequent washing of the enzyme with hot water to recover the amino acid.

The asymmetric hydrogenation of isophorone in the presence of ( S )-proline was reinvestigated in the light of recent papers of Torok et al. and Lambert et al. Beside kinetic resolution of trimethyl cyclohexanone with ( S )-proline, the chemo- and diastereoselective hydrogenation of isophorone is the source of optically active trimethyl cyclohexanone, which was proved by reaction rate, GC, GC–MS measurements and preparative experiments.

Pure 4-(4-fluoro-[2,3,5,6-2H4]benzyl)piperidine was prepared via the Grignard reaction of 4-fluoro-[2,3,5,6-2H4]bromobenzene and pyridine-4-aldehyde followed by consecutive deoxygenation and heteroatomic ring saturation in the presence of palladium on carbon catalyst. An improved method for the catalytic H/D exchange in benzylic positions of 4-(4-fluorobenzyl)piperidine and its d4 derivative has also been described. Copyright © 2005 John Wiley & Sons, Ltd.

A short, scalable and environmentally benign synthesis of 2- and 4-substituted benzylpiperidines has been developed. The method is based on the temperature-programmed consecutive deoxygenation and heteroaromatic ring saturation of aryl(pyridin-2-yl)- and aryl(pyridin-4-yl)methanols and aryl(pyridin-4-yl)methanones in the presence of Pd/C catalyst. The crucial roles of the temperature, the acidity and the substrate structure in the change of selectivity have been demonstrated by isolation of several substituted aryl(piperidine)methanols. The carbinols and ketones were prepared from commercially available pyridinecarbaldehydes or 4-cyanopyridine and substituted bromobenzenes via organometallic intermediates. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).

A Pt-Sn/γ-Al2O3 catalyst was modified by gold, iridium and palladium using metal adsorption technique. The parent and the modified catalysts were tested in n-octane reforming under conditions close to industrial applications. The added gold and iridium slightly increased the activity of the parent catalyst and decreased the temperature dependence of the liquid yield. Less isoparaffin and more aromatic hydrocarbon was found in the liquid product of the modified catalysts than in the product of the reference catalyst, while the octane numbers were similar to the reference ones. The gold-modified catalyst produced almost identical Cn distribution at both temperatures. On the palladium-modified catalyst the conversion, the liquid yield and the octane number is somewhat poorer than on the reference one. The product distribution is, however, favorable: the aromatic content decreased while the isoparaffin content increased.

The authors' hypothesis is that the members of the tricarboxylic acid cycle (TCA cycle) such as citrate decrease in association with increased ketone body formation. To prove this hypothesis the connection between ketone bodies and citrate formation of milk was studied. A fluorimetric method was used to determine citrate and a headspace sampling gas chromatographic (GC) method was developed for determination of ketone bodies. Under real conditions of milk sampling, transport and storage, preserved milk samples of 119 clinically healthy dairy cows obtained in the 48 hours after milking were investigated. A low level of acetoacetate (ACAC) was found in all samples. This fact can be explained by the spontaneous decarboxylation of acetoacetate during sample storage (previously decarboxylised acetoacetate = pdACAC) and, consequently, the majority of the amount of acetoacetate in the samples (AC + pdACAC) appeared in the measured acetone concentrations. Based on the measured acetone concentration of milk samples two groups were formed retrospectively: HA (high-acetone) group (n = 41) with an AC + pdACAC concentration of > 0.4 mmol/l and a LA (low-acetone) group (n = 78) with an AC + pdACAC level of < or = 0.4 mmol/l. In the milk of cows of Group HA a positive correlation (r = +0.623) and linear connection between acetone (AC + pdACAC) and beta-hydroxybutyrate (BOHB) levels was found [BOHB = 2.491 + 0.586 x (pdAC + ACAC)]. Furthermore, in this group a negative correlation between citrate and BOHB and AC + pdACAC was also established (r = -0.579). Focusing on the results of this group the authors found a significant drop of AC + pdACAC and citrate during the metabolically critical first 1-4 weeks of lactation. For this reason they suggest that simple, easy, automated methods (i.e. flow injection analysis, Fourier transformation infrared analysis) should be introduced for the simultaneous determination of acetone and citrate concentration in milk to make the evaluation of the energy status of high-producing dairy cows easier and more certain.

An automatic flow injection (FIA) and two possible reference gas chromatographic (liquid and headspace sampling GC) methods including appropriate sample preparation were developed and validated for determination of acetone in milk. The methods were tested by preserved raw milk samples.The FIA results were compared with data obtained by GC determinations. It was found that FIA procedure is suitable for rapid automated measurement of acetone in the range of 0-5 mmol l(-1) in milk, therefore it is a promising analytical method for ketosis monitoring in dairy farms.

α-Amylases of different origins were investigated with a Synchropak propyl column and a linearly descending salt gradient in order to isolate the active fraction from among the inactive proteins present. Fractions collected by several injections were assayed for enzymatic activity by the modified Wohlgemut method. An experimental hydroxypropyl packing was tested for the separation of α-amylases under isocratic conditions, using a dilute buffer or plain water as eluent. The chromatograms obtained can serve as fingerprints for the quality control of some industrial proteins.

Phenylamino-propanediols were analysed by capillary gas chromatography as various derivatives. Trimethylsilyl and methylboronic acid derivatives were detected with a FID. The trifluoroacetyl derivatives were analysed using an ECD. The structure of the derivatives was confirmed by GC-MS.