Reactive intermediates, organic synthesis

Organic Synthesis Theory and Applications Progress in Heterocydic Chemistry Progress in Macrocydic Chemistry Progress in Physical Organic Chemistry Reactive Intermediates (Plenum)... 

NFPA Health 1, Flammability 3, Reactivity 0 Storage Store in tightly closed containers in cool, well-ventilated area separate from work place limit quantities in use Uses Solvent for natural and syn. resins, cellulose esters and ethers, paints, printing inks, waxes, veg. oils, pharmaceuticals organic synthesis chemical intermediate in polishes brake fluids degreasing solvent antiseptic antifoam, solvent in cosmetics synthetic flavoring agent in foods and pharmaceuticals in food-pkg. adhesives in cellophane for food pkg. 

Uses organic synthesis chemical intermediate with high solvency for halogenated materials reactive diluent of epoxy-resin systems forms chemical bonds with the resin during cure and accelerates the curing process A... 

Dichloroacetic acid [79-43-6] (CI2CHCOOH), mol wt 128.94, C2H2CI2O2, is a reactive intermediate in organic synthesis. Physical properties are mp 13.9°C, bp 194°C, density 1.5634 g/mL, and refractive index 1.4658, both at 20°C. The Hquid is totally miscible in water, ethyl alcohol, and ether. Dichloroacetic acid K = 5.14 X 10 ) is a stronger acid than chloroacetic acid. Most chemical reactions are similar to those of chloroacetic acid, although both chlorine... 

Because of their manifold reactivity, Mannich bases 4 are useful intermediates in organic synthesis. For example the elimination of amine leads to formation of an o ,/3-unsaturated carbonyl compound 8 ... 

Intermediates 18 and 19 are comparable in complexity and complementary in reactivity. Treatment of a solution of phosphonium iodide 19 in DMSO at 25 °C with several equivalents of sodium hydride produces a deep red phosphorous ylide which couples smoothly with aldehyde 18 to give cis alkene 17 accompanied by 20 % of the undesired trans olefin (see Scheme 6a). This reaction is an example of the familiar Wittig reaction,17 a most powerful carbon-carbon bond forming process in organic synthesis. 

C-C and C-E (E = heteroatom) bond formations are valuable reactions in organic synthesis, thus these reactions have been achieved to date by considerable efforts of a large number of chemists using a precious-metal catalysts (e.g., Ru, Rh, and Pd). Recently, the apphcation range of iron catalysts as an alternative for rare and expensive transition-metal catalysts has been rapidly expanded (for recent selected examples, see [12-20, 90-103]). In these reactions, a Fe-H species might act as a reactive key intermediate but also represent a deactivated species, which is prepared by p-H elimination. 

The direct reductive amination (DRA) is a useful method for the synthesis of amino derivatives from carbonyl compounds, amines, and H2. Precious-metal (Ru [130-132], Rh [133-137], Ir [138-142], Pd [143]) catalyzed reactions are well known to date. The first Fe-catalyzed DRA reaction was reported by Bhanage and coworkers in 2008 (Scheme 42) [144]. Although the reaction conditions are not mild (high temperature, moderate H2 pressure), the hydrogenation of imines and/or enam-ines, which are generated by reaction of organic carbonyl compounds with amines, produces various substituted aryl and/or alkyl amines. A dihydrogen or dihydride iron complex was proposed as a reactive intermediate within the catalytic cycle. 

Generally, trialkylboranes are useful intermediates in the field of organic synthesis with versatile reactivity. The polymers prepared by polyaddition between diene monomers and thexylborane are polymer homologues of trialkylboranes, which can be converted to poly(alcohol)s, poly(ketone)s, and other polymers having some functional groups (scheme 4).8-12... 

In recent years, the emphasis of research has been directed more and more toward utilizing nitro compounds as reactive intermediates in organic synthesis. The activating effect of the nitro group is exploited in carrying out many organic reactions, and its facile transformation into various functional groups has broadened the importance of nitro compounds in the synthesis of complex molecules. 

Beginning as chemical curiosities, carbenes are now solidly established as reactive intermediates with fascinating and productive research areas of their own. Six decades of divalent carbon chemistry have provided us with a vast repertoire of new, unusual, and surprising reactions. Some of those reactions, once classified as exotic, have become standard methods in organic synthesis. These highly reactive carbene species have been harnessed and put to work to achieve difficult synthetic tasks other reactive intermediates cannot easily perform. 

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