Synthetic Diversity from a Versatile and Radical Nitrating Reagent

We leverage the slow liberation of nitrogen dioxide from a newly discovered, inexpensive succinimide-derived reagent to allow for the C−H diversification of alkenes and alkynes. Beyond furnishing a library of aryl β-nitroalkenes, this reagent provides unparalleled access to β-nitrohydrins and β-nitroethers. Detailed mechanistic studies strongly suggest that a mesolytic N−N bond fragmentation liberates a nitryl radical. Using in situ photo-sensitized, electron paramagnetic resonance spectroscopy, we observed direct evidence of a nitryl radical in solution by nitrone spin-trapping. To further exhibit versatility of N-nitrosuccinimide under photoredox conditions, the late-stage diversification of an extensive number of C−H partners to prepare isoxazolines and isoxazoles is presented. This approach allows for the formation of an in situ nitrile oxide from a ketone partner, the presence of which is detected by the formation of the corresponding furoxan when conducted in the absence of a dipolarophile. This 1,3-dipolar cycloaddition with nitrile oxides and alkenes or alkynes proceeds in a single-operational step using a mild, regioselective, and general protocol with broad chemoselectivity.     

Mechanochemical Pretreatment for Efficient Solvent-Free Synthesis of SSZ-13 Zeolite

The economical and environmentally benign synthesis of SSZ-13 zeolite was possible due to the mechanochemical activation of dry reagents by planetary mill. Contrary to manual grinding in a mortar, the proposed automatized approach is scalable and reproducible. This solvent-free process provided a huge gain in product/gel ratios, significantly minimized reaction space and organic structure-directing agent use, and allowed for the elimination of agitation. Obtained materials were comparable to the product of “classical” syntheses. The use of different silica sources resulted in SSZ-13 zeolites with various characteristics: different Si/Al ratio and crystal size.     

Argon,krypton and xenon adsorption coefficients on various activated carbons under dynamic conditions

Journal of Radioanalytical and Nuclear Chemistry - Currently, a method based on the radioactive isotopes retention of argon, krypton and xenon on an adsorption column with activated carbon is...     

Utilisation of beetroot powder for bakery applications

The suitability of beetroot powder as a potential source of dietary fibre for baked rolls was investigated in this study. Beetroot powder was characterised by high total dietary fibre (65.71%) and showed good hydration properties. The influence of beetroot powder addition (substitution levels 2–10 mass%) on the farinographic properties of wheat dough, physical characteristics, and sensory attributes of baked rolls was also studied. It was found that increasing level of beetroot powder in dough increased water absorption, delayed dough development time, and prolonged dough stability, while mixing tolerance index decreased. Physical properties of baked rolls (volume and specific volume) were significantly reduced with the increasing level of beetroot powder in products. Increased beetroot powder addition also reduced lightness, while redness of products increased. Results also indicated that baked rolls containing 2 mass% of beetroot powder were the most acceptable for assessors, higher levels of powder adversely affected sensory attributes, and overall acceptance of products (unpleasant earth-like odour and taste).     

Steric hindrance in the synthesis and properties of the dimer of 1-(2,4,6-Tri-tert-butylphenyl)phosphole 1-oxide

Steric hindrance was observed during the oxidation of 2,4,6-tri-tert-butylphenylphosphole to the P oxide and in the dimerization of this latter species to the corresponding phosphanorbornene derivative. Single-crystal X-ray analysis of the dimer revealed considerable steric crowding around the P atoms. Deoxygenation of the dimer of the phosphole oxide by Cl₃SiH–C₆H₅N could only be accomplished under forcing conditions at 110°C. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8 : 527–531, 1997     

Bacillus cereus Toxin Repertoire: Diversity of (Iso)cereulide(s)

The emetic Bacillus cereus toxin cereulide (1) poses a significant safety risk in the food industry, causing emesis and nausea after consumption of contaminated foods. Analogously to cereulide, the structures of various isocereulides, namely, isocereulides A–G, have been recently reported and could also be identified in B. cereus-contaminated food samples. The HPLC fractionation of B. cereus extracts allows us to isolate additional isocereulides. By applying MSⁿ sequencing, post-hydrolytic dipeptide, amino acid and α-hydroxy acid analyses using UPLC-ESI-TOF-MS to purify the analytes, seven new isocereulides H–N (2–8) could be elucidated in their chemical structures. The structure elucidation was supported by one-dimensional and two-dimensional NMR spectra of the isocereulides H (2), K (5), L and N (6 + 8) and M (7). The toxicity of 2–8 was investigated in a HEp-2 cell assay to determine their respective 50% effective concentration (EC₅₀). Thus, 2–8 exhibited EC₅₀ values ranging from a 0.4- to 1.4-fold value compared to cereulide (1). Missing structure-activity correlations indicate the necessity to determine the toxic potential of all naturally present isocereulides as single compounds to be able to perform a thorough toxicity evaluation of B. cereus-contaminated foods in the future.