Flash C-H Chlorination of Ethylene Carbonate Using a New Photoflow Setup

We report flash C-H chlorination of ethylene carbonate, which gives chloroethylene carbonate, a precursor to ethylene carbonate. A novel photoflow setup designed for a gas-liquid biphasic reaction turned out to be useful for the direct use of chlorine gas in flow. The setup employed sloped channels so as to make the liquid phase thinner, ensuring high surface to volume ratio. When ethylene carbonate was introduced to the reactor, the residence time was measured to be 15 or 30 sec, depending on the slope of the reactor to be 15 or 5 °C, respectively. Such short time exposition sufficed the photo C-H chlorination. The partial irradiation of the flow channels sufficed for the C-H chlorination, which is consistent with the requirement of photoirradiation for the purpose of radical initiation. We also found that the contaminated water negatively influenced the performance of C-H chlorination. The 100% selectivity for single chlorination required the low conversion of ethylene carbonate such as 9%, which was controlled by limited introduction of chlorine gas. At a higher conversion of ethylene carbonate such as 63%, the selectivity for mono-chlorinated ethylene carbonate over di-chlorinated ethylene carbonate was 86%. We found that the contaminated water negatively influenced the performance of the C-H chlorination.

Chain length of bioinspired polyamines affects size and condensation of monodisperse silica particles

Polyamines play a major role in biosilicification reactions in diatoms and sponges. While the effects of polyamines on silicic acid oligomerization and precipitation are well known, the impact of polyamines chain length on silica particle growth is unclear. We studied the effects of polyamine chain length on silica particle growth and condensation in a known, simple, and salt-free biphasic reaction system; with tetraethyl orthosilicate as organic phase and polyamine dissolved in the aqueous phase. The particles at various growth stages were characterized by Cryo- Transmission Electron Microscopy, Scanning Electron Microscopy, Thermogravimetric Analysis, Zeta Potential, and solid-state NMR analysis. Polyamines were found co-localized within silica particles and the particle diameter increased with an increase in polyamine chain length, whereas silica condensation showed the opposite trend. Particle growth is proposed to progress via a coacervate intermediate while the final particles have a core shell structure with an amine-rich core and silica-rich shell. The results presented in this paper would of interest for researchers working in the field of bioinspired materials.

Assisted by Hydrogen-Bond Donors Cinchona Quaternary Salts as Privileged Chiral Catalysts for Phase-Transfer Reactions

This review is devoted to the asymmetric phase-transfer reactions with the use of hybrid ammonium <i>Cinchona</i> catalysts supported by hydrogen-bond donor groups. Herein, we present a recent advancement of this type of catalysts in the field of biphasic reaction systems. The main emphasis was put on the advantages of additional functional groups present in the structure of the catalysts, such as: hydroxyl, amide, (thio)urea or squareamide.

Development of a continuous-flow tubular reactor for synthesis of 5-hydroxymethylfurfural from fructose using heterogeneous solid acid catalysts in biphasic reaction medium

5-Hydroxymethylfurfural (5-HMF) is an important biomass-derived platform chemical used to produce polymers, biofuels and other valuable industrial chemicals. In this work, 5-HMF is synthesized from biomass-derived fructose through a continuous...

Pediatric Anaphylaxis: Etiology and Predictive Factors in an Emergency Setting

Anaphylaxis is a serious allergic life-threatening condition that needs immediate treatment to prevent unfavorable outcomes. The present study revealed that the prevalence of anaphylaxis in children increased with age and the adolescent group has the most frequent anaphylaxis events. Food-induced anaphylaxis was the most common cause of anaphylaxis in pediatric population. This etiology revealed a significant correlation with a known history of food allergy in the study population, P = .029. Anaphylaxis from insect stings associated with cardiovascular symptoms, P < .001 and inclined to be severe. Univariate analysis showed predicted probability of severe anaphylaxis increased with age with an odds ratio of 1.1. This finding strengthens and supports the view that physicians should be aware of severe anaphylaxis reactions in older age group when there is a documented history of insect sting. The overall pediatric anaphylaxis patients in the study population had favorable outcomes. The authors recommended at least 24 hours hospital observation in order to observe biphasic reaction in pediatric anaphylaxis especially in adolescent age group.