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A novel biobased pickering emulsion (PE) material was prepared by the encapsulation of Cyanex 923 (Cy923) into chitosan (CS) to selectively recover rare earth elements (REEs) from the aqueous phase. The preparation of PE was optimized through sequentially applying a 23full factorial design, followed by a 33Box–Behnken design varying the Cy923 content, CS concentration, and pH of CS. The material was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), optical microscopy, rheological, compositional, and stability measurements. The resultant material was evaluated in the removal of yttrium by pH influence, nitrate concentration, kinetics, equilibrium isotherms, reusability, and a comparison with liquid–liquid (L–L) extraction and tested in a real scenario to extract Y from a fluorescent lamp powder waste. In addition, the selectivity of PE for REE was investigated with Y/Ca, Gd/Ca, and La/Ni systems. PE extracts REE at 1 ≤ pH ≤ 5 at nitrate concentrations up to 2 mol/L. The kinetics and equilibrium studies showed reaction times <5 min and a maximum sorption capacity of 89.98 mg/g. Compared with L–L extraction, PE consumed 48% less Cy923 without using organic diluents. PE showed a remarkable selectivity for REE in the systems evaluated, showing separation factors of 22.62, 9.35, and 504.64 for the blends Y/Ca, Gd/Ca/Mg, and La/Ni, respectively. PE showed excellent selectivity extracting Y from a real aqueous liquor from the fluorescent lamp powder. PE demonstrates to be an effective and sustainable alternative for REE recovering due to its excellent efficiency in harsh conditions, favorable green chemistry metrics, and use of a biopolymer material in its composition avoiding the use of organic solvents used in L–L extraction.

The heat capacities of NaPF6and KPF6were measured in a broad temperature range using differential scanning calorimetry. The suitability of applying a modified Neumann Kopp rule to calculate the heat capacity of “PF6” was evaluated in order to obtain a general method to predict the heat capacities of other hexafluorophosphates.

The optimization for an upscaled technical production of a lower rim-functionalized p-tert-butylcalix[4]arene, furnished with N4O4-donor ligands for superior solvent extraction separation between heavy and light lanthanides, is described. We demonstrate that reducing the polarity of the aprotic solvent in the (1,3)-distal esterification of p-tert-butylcalix[4]arene 1does not compromise the quality or yield of product 2. It was possible to use the technical quality educt 1, that is, without prior crystallization in toluene, in conjunction with reductions in reaction time and solvent volume. The raw diester product 2could be used, without prior recrystallization (which originally required 3 days) in the condensation reaction with hydrazine monohydrate to form hydrazide 3. Most importantly, the solvent volume required in the final condensation reaction of 3with 8-hydroxyquinoline-2-carboxaldehyde could be reduced by an order of magnitude by using chloroform. Not only was the final disubstituted product yield improved but also the purity of the final product could be ensured by preventing the precipitation of the intermediate monosubstituted product during reaction. The filtration characteristics of the final product, as well as its solvation properties during solvent extraction of lanthanides were significantly improved.

In view of the increasing demand for lithium and the unequal distribution of lithium deposits worldwide, local deposits such as the zinnwaldite deposit at Zinnwald/Cínovec are increasingly coming into focus. It could be shown that especially the direct carbonation process with supercritical CO2 represents a promising approach for a technical implementation due to the low chemical consumption as well as the high selectivity for lithium. Moreover, besides primary ore (zinnwaldite), the method is also suitable for recovering lithium carbonate from black mass, the lithium-containing fraction from lithium ion battery recycling.

This work describes the development and application of different lance-based monitoring systems coupled to an integrated multiparameter sensor probe for the spatial investigation of the liquid phase in biotechnological processes. Miniaturized electrochemical sensors are integrated into a housing, which is fixed at the head of a lance, both made of stainless steel. It can be moved inside a reactor in horizontal direction by the lance itself and in vertical direction by a flexible rope, which is connected to the sensor probe. Inserting the sensor unit directly into the liquid phase of a fermenter, e.g. in laminar processes like biogas and beer production, coupled with multiposition measurements allows to obtain space and time resolved data. The monitored parameters are the pH value, the redox potential, the temperature, and the concentration of dissolved carbon dioxide. Wireless data transfer is realized by means of radio technology with the virtual control center RAMOC (Radio Aided Monitoring) of the company innotas GmbH. Results of the real-timedetermination in the liquid phase in an industrial, continuously operated biogas plant during several weeks are presented as a case study.

Using a commercially available solvent impregnated resin, Lewatit TP272, in an ion exchange process, it was possible to extract up to 90 % indium from a feed containing as little as 1 mg/L indium in the presence of high amounts of impurities, i.e. 1000 mg/L iron and zinc each. It was demonstrated that through gradient regeneration of obtained loaded ion-exchange resin, it is possible to yield a solution containing as much as 400 mg/L indium along with 400 mg/L iron, thereby upgrading its purity more than 600 times. Moreover, it was shown that this solution can be fed into an existing solvent extraction procedure which would yield an indium oxide with more than 99 % purity.

Enzyme catalysis in two-phase systems, particularly in the functionalization of siloxanes, is a new challenge for biocatalysis. On the basis of three different reaction systems, stirred tank reactor, enzyme membrane reactor and micro mixer, the influence of the phase boundary layer along the interface between an aqueous system and an organosiloxane on the synthesis of hydroxyalkylfunctionalized siloxanes is discussed and solutions presented. Micro mixers produce, through a large surface area to volume ratio, boundary layers within which through a formate dehydrogenasecatalyzed reaction the conversion of 1,3-bis-(3-formoxypropyl)tetramethyldisiloxane to 1,3-bis-(3- hydroxypropyl)tetramethyldisiloxane can be achieved. In contrast, in a stirred tank reactor even after 96 h only 45% of the formoxy siloxane has been converted.

ZusammenfassungEs werden Ergebnisse der Entwicklung und Erprobung eines komplexen Mikroreaktionssystems mit integrierter elektrochemischer Sensorik zur Überwachung und Optimierung biotechnologischer Prozesse vorgestellt. Zur Kontrolle der in einem röhrenförmigen Bioreaktor ablaufenden Reaktionen wurden unterschiedliche prozessrelevante Parameter bei einer Ganzzell-Biotransformation gemessen.

Importance of the field:Predicting drug metabolism after oral administration is highly complex, yet indispensable. Hitherto, drug metabolism mainly focuses on hepatic processes. In the intestine, drug molecules encounter the metabolic activity of microorganisms prior to absorption through the gut wall. Drug biotransformation through the gastrointestinal microflora has the potential to evoke serious problems because the metabolites formed may cause unexpected and undesired side effects in patients. Hence, in the course of drug development, the question has to be addressed if microbially formed metabolites are physiologically active, pharmaceutically active or even toxic. In order to provide answers to these questions and to keep the number of laboratory tests needed low, predictive tools – in vivoas well as in silico– are invaluable.Areas covered in this review:This review gives an outline of the current state of the art in the field of predicting the drug biotransformation through the gastrointestinal microflora on several levels of modelling.What the reader will gain:A comprehensive review of the literature with a thorough discussion on assets and drawbacks of the different modelling approaches.Take home message:The impact of the gastrointestinal drug biotransformation on patients’ health will grow with increasing complexity of drug entities. Predicting metabolic fates of drugs by combining in vitroand in silicomodels provides invaluable information which will be suitable to particularly reduce in vivostudies.

Formation of stable emulsions with the organic solvent is a general complication in the extractive workup of aqueous whole-cell biotransformations. This hold-up has been overcome by biocatalytic lysis of emulsifying agents present in the medium through addition of living microorganisms. Of these, Bacillus subtilisand Rhodococcus erythropolisexhibited the most powerful de-emulsifying activity. As exemplified by microbial treatment of cell-free biotransformation media of Saccharomyces cerevisiaeand Lactobacillus kefiri, phase separation time (tp) was drastically reduced from one week to 20 s without significantly affecting product integrity. This practicable ready-to-use method is appropriate to both fungal and bacterial biocatalysts. The highly efficient de-emulsification power and the considerably short phase separation time of this technique allow for cost-effective continuous extractions on a large-scale, for example with mixer-settler units.

Secodecahedradiene 2a, featuring very proximate, perfectly syn-periplanar and significantly pyramidalized C=C bonds, was synthesized as testing object for in-plane(σ)-homoconjugational electron delocalization, starting from the available pagodane 15b. The response of 2a (and in part its diester 2b) – in π,π-distance (average 3.08 Å), olefinic pyramidalization (average 26.9°), and π,π-split (PE, 1.15 eV) intermediate between disecododecahedradiene 1a and 1,16-dodecahedradiene 3a – to selected 4π-reagents, electrophiles, and radicals was explored experimentally and by calculations. Intriguing multistep reaction sequences attest to the ease of competing stabilization pathways for the 3C/2e in-plane homoconjugated cationic intermediates. PE, CV, and ESR measurements and calculations (DFT) characterize the radical cation generated from 2a as in-plane homoconjugated 4C/3e-species 2a^.+, persistent in a Freon matrix, but only very shortly existent in solution (CIDNP). Consequently, NMR control of the two-electron oxidation in SbF5/SO2ClF did not disclose the σ-bis-homoaromatic dication 4C/2e (see 2a²⁺), but a bis-allylic dication 75 as persistent species. In support of 2a²⁺ as intermediate, evidence is presented for very limited kinetic protection offered by the secododecahedral framework to through H-cage σ-homoconjugated cations.

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By taking advantage of the novel SN2 pagodane → dodecahedrane routes a preparatively potent access to the parent pentagonal dodecahedrane (2) was explored. The one-pot catalytic procedure (Pd/C/H2) starting from an eightfold functionalized secopagodane (14, C20H12Br6(CO2CH3)2) excells in shortness but, rather erratic (33–53%), falls out of the competition. The longer route via 1,6-dicarboxyl/dibromo dodecahedranes (35, 22) turned out as first choice with a total yield of 74–76% based on the common pagodane precursor (13). © 1997 Elsevier Science Ltd.

For two- to six-fold functionalised dodecahedranes (7–10) the chances for selective variation of their substitution have been explored, as part of a program directed at homododecahedranes and at highly unsaturated dodecahedranes, ultimately C20 fullerene. With 1,6-dimethyl ester 7 several side chain transformations next to the very bulky dodecahedral cage were effected (1,6-bismethylene derivatives 25–31). In changing environments, Barton-type halogenative/hydrogenative decarboxylations (15–17, 38, 49, 59, 60, 77) as well as various nucleophilic substitutions (18, 20, 23, 39, 61–64) were achieved, mostly with good to high efficiency and retention of the substitution patterns. For the cage olefins 8/9 and the diepoxide 10, front-side cis-1,2-addition faced only slight competition in the reactions with HBr and CF3CO2H, but was only a minor pathway in the reaction with Br2. In the latter case, by a sequence of Br+ addition/HBr elimination steps, up to nine vicinally placed bromine substituents were implanted upon the C20 skeleton. The fate of variously functionalised dodecahedranes upon electron impact was studied—the competition between external (C–X/Y) and internal (C–C) bond cleavage was found to be typically dependent on the nature and relative orientation of the functionalities (X,Y) involved. There is good evidence that ions between m/z 242 (C20H2) and 256 (C20H16) resulting from the elimination of the respective Br, CO2CH3, CO2NH2, OCOCF3 substituents represent unsaturated dodecahedranes with up to nine C&z.dbd6;C double bonds.

In the course of investigating microbial syntheses for chiral pharmaceutical intermediates, ethyl 4,4,4-trifluoro acetoacetate (1) was submitted to baker's yeast reduction. With the purpose of obtaining the d-carbinol in high enantiopurity, several additives were tested for l-reductase inhibitor activity. Allyl alcohol proved to be not only a suitable additive, but also an inducer for effective defluorination of the substrate.

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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.