Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Multi-phase Photochemical Reactions

Meyer et al. examined the formation of rose oxide by the oxidation ofdtronellol with singlet oxygen in a temperature-resistant glass (Borofloat) microreactor [9]. A 10 mL P-citronellol-ethanol solution with Ru(T py)3Cl2 is circulated through the microchannel reactor (hold-up volume 0.27 mL). Products are identified by H PLC analysis. After an irradiation time of 40 min, space-time yields of 0.8 mmol L min are obtained. In a comparable batch process, space-time yields are 10 times lower. [Pg.447]

Multi-phase photochemical reactions take place across phase boundaries. In most cases, substrate molecules are either dissolved in different liquid phases or one reactant is in the gas phase and interacts with the liquid phase. For this reaction category, phase transfer kinetics, in addition to the actual photochemical reaction, have to be taken into account, assuming microreactors to be ideal reaction engineering tools due to their low mass transfer limitations. [Pg.447]

L h for the falling film microreactor. The authors explain the increase in selectivity with the fact that in the micro reactor the concentration of chlorine radicals can be kept lower due to its large surface-to-volume ratio. In the microreactor, the entire fluid film can be penetrated by the inddent light, in contrast to the batch reactor, where only a thin film of the fluid is irradiated in the vicinity of the light [Pg.448]

With a similar microreactor, a photoinduced [4 + 2]-cycloaddition was carried out by Jahnisch [12]. 2-Cyclopentene-l,4-diol is formed through the reaction of [Pg.449]


Multi-phase Photochemical Reactions 449 1 -Chlon)melhyl-2,4 dii ocyanatobenzene (1 -CI-TDI)... [Pg.449]

Multiphase copolymers, Ziegler-Natta catalysts for, 26 535, 537-540 Multiphase laminar flow patterning, in microfluidics, 26 961 Multiphase reactions, in microbial transformations, 16 412-414 Multi-phase reactors, 21 333-335 Multiphoton effects, in photochemical technology, 19 109... [Pg.606]

Until recently organic photochemistry has only partially focused on stereoselective synthesis, one of the major challenges and research areas in modern organic synthesis. This situation has dramatically changed in the last decade and highly chemo-, regio-, diastereo- as well as enantioselective reactions have been developed. Chemists all over the world became aware of the fascinating synthetic opportunities of electronically excited molecules and definitely this will lead to a new period of prosperity. Photochemical reactions can be performed at low temperatures, in the solid or liquid state or under gas-phase conditions, with spin-selective direct excitation or sensitization, and even multi-photon processes start to enter the synthetic scenery. [Pg.624]

Flow systems also allow the use a two phase liquid-gas flow. This form of multi-phase flow increases the surface area between the gas and liquid phases, allowing for more effective mass transfer between the two phases and an increase in reaction efficiency. Such liquid-gas slug flows have been applied to a variety of photochemical transformations wherein the gas is a reagent for the reaction. " An excellent example by Kakiuchi and co-workers is a diastereoselective [2 -I- 2] cycloaddition of ethylene. ... [Pg.184]

Abstract Key features of tropospheric photochemistry are highlighted including both homogeneous gas-phase and heterogeneous reactions that are important in clouds and haze aerosol. Fundamental aspects of photochemical kinetics are reviewed and then extended to the major chromophores present in the multi-phasic, tropospheric atmosphere. Tables of up-to-date absorption cross sections and quantum yields as a function of wavelength range are presented. Primary emphasis is placed on reactions occurring within the troposphere and within clouds. [Pg.77]


See other pages where Multi-phase Photochemical Reactions is mentioned: [Pg.443]    [Pg.447]    [Pg.443]    [Pg.447]    [Pg.173]    [Pg.367]    [Pg.226]    [Pg.157]    [Pg.264]   


SEARCH



MULTI PHASE

Multi reactions

Photochemical multi-phase

Photochemical phase

Reactions multi-phase

© 2024 chempedia.info