Process telescoping

Synthesis gas is obtained either from methane reforming or from coal gasification (see Coal conversion processes). Telescoping the methanol carbonylation into an esterification scheme furnishes methyl acetate directly. Thermal decomposition of methyl acetate yields carbon and acetic anhydride,... 

Large-Scale Synthesis of Thienobenzazepine Derivatives Using Two Efficient Metal Catalyzed Processes Telescoped Nitro Reduction and Intramolecular Aminocarbonylation... 

All process development starts with chemistry. The selection criteria for the most suitable chemistry for a continuous process do not suffer from the same constraints as those for a large-scale batch process. For example, highly exothermic reactions are not only possible in a flow reactor, but are in fact preferred [47]. As operator exposure will be low and so will stock levels, different safety considerations come into play that may allow utilisation of otherwise intolerably toxic reagents. Process telescoping is a necessity to minimise the number of intermediate isolations. Examination of all these factors is facilitated by online analysis because of its speed and maintenance of experimental integrity (i.e. no requirement for sampling). 

The imposition of permanent surnames on colonial populations offers us a chance to observe a process, telescoped into a decade or less. 

Case Study m. An astronomy cataloguer wants to process telescope images, identify stellar objects of interest and place their descriptions into a database for future use. 

Keywords Continuous flow Heterocycles Microreactor Sustainable processes Telescoping... 

Ammoxidation illustrates several principles. First, it shows the benefit of telescoping two successive processes into one reactor. The Sohio inventor, James D. Idol, Jr., observed that catalysts for two successive stages in an earlier ammoxidation procedure were very similar. He then found that the same catalyst could be used for both, thus eliminating a complete plant stage, at great saving of capital and operating cost ... 

Telescope the Process by Combining Stages. This has been done successfully in the conversion of propylene to acrylonitrile by direct ammoxidation rather than oxidation to acrolein followed by reaction with ammonia in a separate stage, as was described in the earlier patent literature. The oxychlorination of ethylene and HC1 directly to vinyl chloride monomer is another good example of the telescoping of stages to yield an economic process. 

In summary, we have described a novel and efficient synthesis of thienobenzazepine derivatives in which the key transformation includes a telescoped process involving a selective intro reduction followed by palladium-mediated intramolecular amidation. The process developed is quite amenable for preparative scale (multi-gram) and presents significant advantage to those reported previously with respect to overall yield (e.g., 50% vs. 17% overall yield), total number of synthetic transformations (4 vs. 9), and reagents and/or conditions that are suitable for large-scale synthesis. 

In 1994, a unique incident occurred the impact of the Shoemaker-Levy comet on the Jovian atmosphere. Die strong gravitational field of Jupiter caused the comet to break up before it could enter the atmosphere, and the parts of the comet crashed separately into the atmosphere one after the other. This unique spectacle was observed by many observatories and also by the Galileo spacecraft and the Hubble telescope. It led to the discovery of yet another phenomenon the most intensive aurora effects in the solar system, observed at Jupiter s poles. Astronomers assume that the energy for these comes from the planet s rotation, possibly with a contribution from the solar wind. This process differs from that of the origin of the aurora on Earth, where the phenomenon is caused by interactions between the solar wind and the Earth s magnetic field. 

Studies carried out on Earth, for example, by the NASA infrared telescope on Mauna Kea (Hawaii), showed albedo variations which indicated the presence of holes in the Titanian cloud formations (Griffith, 1993). It is, however, still unclear as to whether these inhomogeneities result from differences in the surface composition. Lorenz et al. (1997) reported large variations in Titan s atmosphere due to photochemical processes. The methane contained in the dense nitrogen atmosphere is decomposed by solar and thermal radiation, and its content may be replenished from methane lakes or from clathrates. 

Recent observations of the HF (1-0) R9 line at 2.3 /tm with the Phoenix spectrograph on the Gemini-South telescope has opened a new window that sheds light on understanding the chemical evolution of fluorine and the nuclear processes that produce this element. Until recently, only a small number of observations of fluorine were available and the trend of fluorine abundances with metallicity had yet to be probed in the Galaxy. 

Orion Constellation This is a mosaic picture of 18 (6x3) frames. Additional four frames are added around the Barnard Loop region to increase S/N. Vignetting of the telescope is corrected by flat fielding, using proprietary software written in IDL. Distortion correction and initial colour match is done in Registar, with final colour correction and mosaic processed using Photoshop. (Reproduced by permission of Wei-Hao Wang, Institute for Astronomy at University of Hawaii)... 

At the end of the synthesis reactions, the product can be pumped to another vessel or container via transfer lines. If the chemical reactions proceed to completion with negligible trace quantities of impurities, the next stage of production may commence in the same reaction vessel with addition of fresh raw materials. This process is called telescoping. 

Process Improvements. Phase 1 Benzene was replaced with a safer solvent, toluene, which was also used for the [2 + 2] cycloaddition reaction, thus facilitating the telescoping of the two reactions. However, dichloromethane was added during the work-up to prevent product precipitation. The product was ciystallized from 2-propanol in 80% yield. The phase I of development eliminated the use of benzene and allowed for telescoping of the two chemical steps. However, a solvent exchange from toluene-dichloromethane to 2-propanol was still needed to crystallize the product. The color of the product after this modification was dark-brown. 

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