Oxygen compounds synthesis

Fischer-Tropsch Process. The Hterature on the hydrogenation of carbon monoxide dates back to 1902 when the synthesis of methane from synthesis gas over a nickel catalyst was reported (17). In 1923, F. Fischer and H. Tropsch reported the formation of a mixture of organic compounds they called synthol by reaction of synthesis gas over alkalized iron turnings at 10—15 MPa (99—150 atm) and 400—450°C (18). This mixture contained mostly oxygenated compounds, but also contained a small amount of alkanes and alkenes. Further study of the reaction at 0.7 MPa (6.9 atm) revealed that low pressure favored olefinic and paraffinic hydrocarbons and minimized oxygenates, but at this pressure the reaction rate was very low. Because of their pioneering work on catalytic hydrocarbon synthesis, this class of reactions became known as the Fischer-Tropsch (FT) synthesis. 

Shortly after their first report of all-oxygen bridged cryptands, Dietrich, Lehn and Sauvage reported incorporation of sulfur in the strands. The experimental methods used were essentially similar to those applied in the syntheses of the parent cryptands. As in previous cases, a diacyl chloride was condensed with a diamine under high dilution conditions. In this case, however, the diamine contained sulfur atoms rather than oxygen. The synthesis of compound 5 was accomplished in two stages as illustrated below in Eq. (8.3). The first cyclization step affords the macrocyclic amine in 55% yield. The macrobicyclic product (5) is formed in 25% yield from the monocyclic diamine and the acid chloride. 

Functionalization of various substrates to produce oxygenated compounds with high selectivity is a permanent challenge in metal-catalyzed organic synthesis. Most of these products present interesting biological properties. For instance polyether antibiotics contain often a furan or a pyran ring [1]. Simi-... 

Oxidation is the first step for producing molecules with a very wide range of functional groups because oxygenated compounds are precursors to many other products. For example, alcohols may be converted to ethers, esters, alkenes, and, via nucleophilic substitution, to halogenated or amine products. Ketones and aldehydes may be used in condensation reactions to form new C-C double bonds, epoxides may be ring opened to form diols and polymers, and, finally, carboxylic acids are routinely converted to esters, amides, acid chlorides and acid anhydrides. Oxidation reactions are some of the largest scale industrial processes in synthetic chemistry, and the production of alcohols, ketones, aldehydes, epoxides and carboxylic acids is performed on a mammoth scale. For example, world production of ethylene oxide is estimated at 58 million tonnes, 2 million tonnes of adipic acid are made, mainly as a precursor in the synthesis of nylons, and 8 million tonnes of terephthalic acid are produced each year, mainly for the production of polyethylene terephthalate) [1]. 

For production of liquid hydrocarbons and oxygenated compounds other than methanol, shifting is usually carried to C0 H2 ratios in the range 1.8-2.4 and use is made of variants of Fischer-Tropsch synthesis ). 

A number of 5-nitro-2-furaldehyde derivatives, called nitrofurans, are used in the treatment and/or prophylaxis of microbial infections, primarily in the urinary tract. Recent evidence suggests that the reduction of the 5-nitro group to the nitro anion results in bacterial toxicity. Intermediate metabolites modify various bacterial macromolecules that affect a variety of biochemical processes (e.g., DNA and RNA synthesis, protein synthesis) this observation may explain the lack of resistance development to these drugs. Evidence also indicates that the nitro anion undergoes recycling with the production of superoxide and other toxic oxygen compounds. It is presumed that the nitrofurans are selectively toxic to microbial cells because in humans, the slower reduction by mammalian cells prevents high serum concentrations. 

Functionalized organomagnesium compounds Synthesis and reactivity 569 2. Addition to oarbon-oxygen bonds... 

Application of fluidized catalyst techniques to the Fischer-Tropsch synthesis (30) has yielded a process that produces chiefly (about 70%) motor gasoline, with minor amounts (about 30%) of fuel oil and oxygenated compounds. The fluidized iron catalyst process is outstanding because of its very high space-time yield and because it may be competitive with existing petroleum production and refining processes, if natural gas at 10 cents or less per 1000 cubic feet is available as the raw material for synthesis gas production. 

Replacement of the carbonyl oxygen atom by sulfur may be effected by heating with phosphorus pentasulfide (49JCS2142), boron sulfide or silicon disulfide which gives high yields under mild conditions, as, for example, in the synthesis of 7-methoxy-2-methylchromene-4-thione (438) (69JCS(C)2192). Such compounds are more easily converted into their oximes or hydrazones than the oxygen compounds. 

Using air, the oxidation of hydrocarbons generally results in a mixture of oxygenated compounds and is not a useful synthesis of alcohols except under special circumstances. Cyclohexanol may be prepared by air oxidatron of cydohexane inasmuch as only one isomer can result. 

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