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In organic chemistry, organocatalysis is a form of catalysis in which the rate of a chemical reaction is increased by an organic catalyst. This "organocatalyst" consists of carbon , hydrogen , sulfur and other nonmetal elements found in organic compounds.
Schreiner's thiourea, N,N'-bis3,5-bis(trifluormethyl)phenyl thiourea, combines all structural features for double H-bonding mediated organocatalysis: electron-poor; rigid structure; non-coordinating, electron withdrawing substituents in 3,4, and/or 5 position of a phenyl ring; the 3,5-bis(trifluoromethyl)phenyl-group is the preferred substituent
Proline organocatalysis is the use of proline as an organocatalyst in organic chemistry. This theme is often considered the starting point for the area of organocatalysis, even though early discoveries went unappreciated. [1] Modifications, such as MacMillan’s catalyst and Jorgensen's catalysts, proceed with excellent stereocontrol. [2]: 5574 [3]
One of the most common angiograms performed is to visualize the coronary arteries. A long, thin, flexible tube called a catheter is used to administer the X-ray contrast agent at the desired area to be visualized. The catheter is threaded into an artery in the forearm, and the tip is advanced through the arterial system into the major coronary ...
Intravenous digital subtraction angiography (IV-DSA) is a form of angiography which was first developed in the late 1970s.. IV-DSA is a computer technique that compares an X-ray image of a region of the body before and after radiopaque iodine based dye has been injected intravenously into the body.
Aqueous biphasic systems (ABS) or aqueous two-phase systems (ATPS) are clean alternatives for traditional organic-water solvent extraction systems.. ABS are formed when either two polymers, one polymer and one kosmotropic salt, or two salts (one chaotropic salt and the other a kosmotropic salt) are mixed at appropriate concentrations or at a particular temperature.
Former Buffalo Bills star wide receiver Eric Moulds has been accused of knowingly spreading a sexual transmitted disease and failing to disclose it to a sexual partner.
In the context of organocatalysis, both concepts of on-water reactions and in-the-presence-of-water reactions were criticized in 2007 as not so environmentally friendly by Donna Blackmond. According to Blackmond, separation of reaction product from the water phase usually requires organic solvent anyway, and in reported aqueous systems the ...