Calcium Stearate as an Acid Scavenger for Synthesizing High Concentrations of Bromobutyl Rubber in a Microreactor System

The preparation of bromobutyl rubber (BIIR) faces two challenges, the high viscosity of the reaction system and the accumulation of generated HBr during the reaction, which result in lower productivity, higher energy consumption, and lower selectivity for BIIR-1. In this work, we developed an efficiently intensified technology using calcium stearate as the acid scavenger and a microreactor as the reaction platform. We successfully realized both high productivity and high selectivity for synthesizing high concentrations of bromobutyl rubber. The optimized results indicate that using predispersed calcium stearate in a butyl rubber (IIR) solution (<i>x</i>_Ca of about 0.8 wt %) as the acid scavenger could guarantee sufficiently high selectivity for BIIR-1 (<i>w</i> of almost 95%). A T-junction microreactor with slitlike microchannels is suitable for mixing a high-viscosity IIR solution and a Br₂ solution. As the concentration of IIR increases from 10 wt % to 15 wt %, the conversion of IIR could increase by 13%, and the residence time could be shortened to less than 1 min. The utility of the reactants and the reaction efficiency have both been largely improved

In Situ Removal of HBr via Microdroplets for High Selectivity Bromobutyl Rubber Synthesis in a Microreaction System

To obtain a high quality bromobutyl rubber product, a higher selectivity of brominated secondary allylic structure is necessary, but it is difficult to realize in traditional reaction devices. We developed a microreaction system and used microwater droplets as an extractant to in situ remove HBr, the catalyst of the isomerization side reaction, from the organic reacting solution to prevent converting brominated secondary allyl to brominated primary allyl and degradation of the polymer chain. The microreaction system contains two micromixers, including a membrane dispersion micromixer for dispersing microwater droplets in the butyl rubber solution and a cross-junction micromixer for blending butyl rubber and Br₂ solutions. A volume adjustable delayed loop after the micromixers is used to carry out the reaction. The results show that 1 wt % water in the organic phase is satisfied to remove HBr, and 97% selectivity of brominated secondary allyl is successfully obtained under optimized operating conditions

Kinetic Study of Reactions of Aniline and Benzoyl Chloride Using NH₃ as Acid Absorbent in a Microstructured Chemical System

NH₃ was used as acid absorbent to intensify the reactions between aniline and benzoyl chloride in a microstructured chemical system in this work. By suppressing the side reaction, the addition of NH₃ could reduce the reaction time needed for 99% reactants conversation to less than 1/10 of the condition without NH₃. Furthermore, a complete kinetic model containing two rapid main reactions and two reversible consecutive side reactions was established, and six reaction rate constants and their corresponding activation energies and pre-exponential factors as well as confidence intervals were determined precisely. The accuracy of the obtained parameters was verified by comparing the calculated data with experimental data at extensional temperature. The kinetic model was used to optimize the intensification operating conditions, and effects of reactants concentration, temperature, NH₃ addition amount, and NH₃ feed methods were discussed based on the simulation results. This work proves that the microstructured chemical system not only provides an effective intensification ability but also develops a reliable platform for kinetic studies

Pheophytin analogues from the medicinal lichen <i>Usnea diffracta</i>

<p>A new pheophytin, (13²<i>S</i>, 17<i>S</i>, 18<i>S</i>)-13²-hydroxy-20-chloro-ethylpheophorbide a (<b>3</b>), along with two known analogues (<b>1</b>–<b>2</b>) were isolated from the lichen <i>Usnea diffracta</i> Vainio (Parmeliaceae). Among them, compound <b>3</b> was a rare C-20-chloro type pheophytin obtained from lichens. Their structures were elucidated by extensive spectroscopic analysis, and all the compounds were obtained for the first time from <i>U. diffracta</i>. Compounds (<b>1</b>–<b>3</b>) were evaluated for their xanthine oxidase (XO) inhibitory activities <i>in vitro</i>, and the results showed that <b>1–3</b> possessed significant enzyme inhibitory actions with IC₅₀ values of 46.9 ± 3.8, 75.9 ± 7.4 and 42.1 ± 1.7 μg/mL, respectively.</p

Additional file 4: Table S3. of Genome-wide alteration of 5-hydroxymenthylcytosine in a mouse model of Alzheimer’s disease

Aged DTg unique_annotated genes. (XLSX 39 kb

Additional file 2: Table S1. of Genome-wide alteration of 5-hydroxymenthylcytosine in a mouse model of Alzheimer’s disease

Reads info. (XLSX 10 kb

Additional file 1: Figure S1. of Genome-wide alteration of 5-hydroxymenthylcytosine in a mouse model of Alzheimer’s disease

A representative image of methylene blue staining showing the equal spotting of DNA in the membrane. Figure S2 5hmC chromosome-wide densities showing the distribution profiling on chromosomes. A depletion is observed on chr-X relative to autosomes. Figure S3 Representative IGV images show the decrease of 5hmC in some genomic regions of genes identified in two AD EWAS datasets. (PPTX 2495 kb

Additional file 3: Table S2. of Genome-wide alteration of 5-hydroxymenthylcytosine in a mouse model of Alzheimer’s disease

DhMR_DTg unique_annotated genes. (XLSX 10 kb