Synthesis of the Antibiotic Precursor Thiazolyl‐7‐Aminocephalosporanic Acid in a Microstructured Flow System

The synthesis of thiazolyl‐7‐aminocephalosporanic acid, a pharmaceutical precursor of the β‐lactam antibiotic drug cefodizime, could be successfully realized in a continuous microstructured flow system. This was accomplished by changing the process window from batch, having a reaction temperature of 60 °C with a reaction time of 1 h, to a flow system at temperatures > 100 °C and reaction times of several minutes. The space‐time yield could be increased by a factor of 130.     

N-Alkylation of amines by photocatalytic reaction in a microreaction system

A photocatalytic microreaction system was developed and photocatalytic N-alkylation process of benzylamine, aniline, and piperidine was examined. The reaction proceeded quite rapidly in the microreactors with immobilized Pt-free TiO₂ as well as Pt-loaded TiO₂, while it has been reported that the N-alkylation did not occur by the irradiation of Pt-free TiO₂ in conventional batch reactors. It was revealed that by using the unique features of the continuous-flow microreactor, for instance spatial illumination homogeneity and precise control of flow and irradiation conditions, one can control the selectivity of N-alkylation and N,N-dialkylation processes. These results suggest the possibilities of a photocatalytic microreaction system on organic synthetic reactions.     

A circular microreaction method to the safe and efficient synthesis of 3-methylpyridine-N-oxide

3-Methylpyridine-N-oxide is an essential intermediate in the preparation of 2-chloro-5-methylpyridine, which can be used to synthesize nicotine insecticides such as imidacloprid and acetamiprid. The traditional method of production of 3-methylpyridine-N-oxide is catalytic oxidation of 3-methylpyridine in semi-batch reactors.Due to strong exothermic reaction and explosive property of 3-methylpyridine, the reaction efficiency and safety is low using batch technology. Therefore, the development of a safer and efficient 3-methylpyridine-N-oxide production process is very necessary in industrial production. In this paper, microreaction systems were introduced into the preparation of 3-methylpyridine-N-oxide. The comparison of three different methods(traditional semibatch method, co-current microreaction method, and circular microreaction method) showed that the circular microreaction method was the most applicable, with relative higher product yield(～ 90%), less side reaction and better reaction control.     

微混合模块合成CdS量子点方法研究

以CdS量子点的合成为考察对象,分别使用梳型和级联两种混合模块搭建了连续操作的微反应系统,比较了两种模块的混合效果,通过优化前躯体流速和停留时间获得了理想的合成工艺,使得量子点的尺寸分布极窄。     

Modular Manufacturing Platform for Continuous Synthesis and Analysis of Versatile Nanomaterials

Nanoparticular materials have a great potential in various fields including technical and biomedical applications; to meet the specific requirements, a good control over the particle characteristics is mandatory. Addressing this, a modular system for the automated and continuous synthesis, workup, and analysis of a broad range of nanoparticles was developed. Application examples of inorganic (silica) and organic (polymersomes, niosomes) nanoparticles demonstrate the versatility of the production platform. Modules for downstream processing via a falling‐film microreactor or tangential flow filtration are presented. The hydrodynamic size as a key parameter is acquired in real time, with an inline dynamic light scattering device. All modules are controlled and operated by a process control system.     

Mixing and Reactions in Microchannels – an Educational Approach Using the Internet

In many fields, microprocess technology is gaining significance and is increasingly finding its way into use in industrial production. However, specialist knowledge regarding reactions of compounds, mixing and downstream processes in microchannels is required, as experience from the ”?macro world”? can only be applied in a limited way. The appropriate level of education required is still lacking. In this study, a number of educational experiments were set up focusing on mixing processes and emphasizing the significance of viscosity in mixing. Additionally liquid‐liquid extraction as an important downstream process was looked into as a student experiment. In order to make the training widely accessible, a web‐based education platform was established.     

Synthesis of Monodisperse Nanocrystals via Microreaction: Open-to-Air Synthesis with Oleylamine as a Coligand

Microreaction provides a controllable tool to synthesize CdSe nanocrystals (NCs) in an accelerated fashion. However, the surface traps created during the fast growth usually result in low photoluminescence (PL) efficiency for the formed products. Herein, the reproducible synthesis of highly luminescent CdSe NCs directly in open air was reported, with a microreactor as the controllable reaction tool. Spectra investigation elucidated that applying OLA both in Se and Cd stock solutions could advantageously promote the diffusion between the two precursors, resulting in narrow full-width-at-half maximum (FWHM) of PL (26 nm). Meanwhile, the addition of OLA in the source solution was demonstrated helpful to improve the reactivity of Cd monomer. In this case, the focus of size distribution was accomplished during the early reaction stage. Furthermore, if the volume percentage (vol.%) of OLA in the precursors exceeded a threshold of 37.5%, the resulted CdSe NCs demonstrated long-term fixing of size distribution up to 300 s. The observed phenomena facilitated the preparation of a size series of monodisperse CdSe NCs merely by the variation of residence time. With the volume percentage of OLA as 37.5% in the source solution, a 78 nm tuning of PL spectra (from 507 to 585) was obtained through the variation of residence time from 2 s to 160 s, while maintaining narrow FMWH of PL (26–31 nm) and high QY of PL (35–55%).     

Controllable preparation of thio-functionalized composite polysilsesquioxane microspheres in a microreaction system

Controllable preparation of monodispersed composite polysilsesquioxane microspheres (CPSQs) with scalability is required but difficult to realize in a conventional stirred batch reactor because of the reactors’ poor mixing performance and scaling-up effects. A new semi-continuous microreaction system integrating a microreactor with a stirred batch reactor was developed for the synthesis of monodispersed thio-functionalized CPSQs by employing a two-step sol–gel method. Methyltrimethoxysilane and (3-mercaptopropyl)trimethoxysilane were used as silicon sources. The effects of the synthesis variables were systematically studied. The particle size could be adjusted between several hundreds of nanometers and several micrometers with a narrow size distribution (the coefficient of variation was <10%), and the sulfhydryl group (SH) concentration reached 14.13 at.%. Compared with the batch reactor, the semi-continuous microreaction system showed higher synthesis reproducibility and higher potential for the large-scale production of CPSQs.     

Pressure Loss – Educational Experiments for Microreaction Technology using an Universal Experiment Platform

During the recent decade, microreaction technologies became an established technique for research and development purposes as well as industrial production. The superior advantages in terms of process intensification by enhanced heat and mass transfer as well as process control and safety issues lead to a growing need for scientists with microreaction technology experiences. The pressure loss and energy dissipation of fluids flowing in microdevices are the most important procedural basis. Pressure loss effects have to be taken into account for the layout of microsystems as well as the assembly of different microfluidic devices. Furthermore, the pressure loss is a quite sensitive parameter for changes in the hydrodynamic diameter of the used microdevices which may vary by production tolerances or fouling processes. Here, some educational experiments for experimental teaching of basic pressure loss principles in microdevices are presented.     

氢氯混合气体光化反应微型实验研究

对氢氯混合气体光化反应实验进行了微型化改进,并对微型反应的光照强度、气体纯度、混和气体的体积比、以及气体混合后进行强光照射的时间间隔等反应条件进行了研究。实验表明,采用微型实验比常规方法反应速度快、反应条件要求宽、实验成功率高,且节省时间和试剂。