Oxygenates, synthesis economics

Natural Gas Upgrading via Fischer-Tropsch. In the United States, as in other countries, scarcities from World War II revived interest in the synthesis of fuel substances. A study of the economics of Fischer synthesis led to the conclusion that the large-scale production of gasoline from natural gas offered hope for commercial utiHty. In the Hydrocol process (Hydrocarbon Research, Inc.) natural gas was treated with high purity oxygen to produce the synthesis gas which was converted in fluidized beds of kon catalysts (42). 

Fermentation. Much time and effort has been spent in undertaking to find fermentation processes for vitamin C (47). One such approach is now practiced on an industrial scale, primarily in China. It is not certain, however, whether these processes will ultimately supplant the optimized Reichstein synthesis. One important problem is the instabiUty of ascorbic acid in water in the presence of oxygen it is thus highly unlikely that direct fermentation to ascorbic acid will be economically viable. The successful approaches to date involve fermentative preparation of an intermediate, which is then converted chemically to ascorbic acid. 

The most widely used industrial synthesis of phenol is based on isopropylbenzene (cumene) as the star ting material and is shown in the third entry of Table 24.3. The economically attractive features of this process are its use of cheap reagents (oxygen and sulfuric acid) and the fact that it yields two high-volume industrial chemicals phenol and acetone. The mechanism of this novel synthesis forms the basis of Problem 24.29 at the end of this chapter. 

There are very few totally synthetic antibiotics presently on the market. One of these is the 1-oxacephem, moxalactam (96). One may speculate that the enhanced potency of moxa-1actam stems in part from the substitution of the smaller oxygen atom for the sulfur normally present in the six-membered ring of cephalosporins thereby enhancing the reactivity of the adjoining four-membered ring. It is also partly a measure of the present stage of development of chemical synthesis and of the relative economics of production of 7-aminocephalosporanic acid that such an involved synthesis apparently is economically competitive. 

Since NO is a precursor in NDMA formation and high combustion temperatures (usually from 1500 to 1800 0) yield high reaction rates between oxygen and nitrogen, a decrease in NDMA formation can also be achieved by lowering the flame temperature. Excess air seems to be the most economic way to reduce flame temperature and NO synthesis. In a new type of burner developed on this principle the resulting air had only 0.05 - 0.1 mg NO /m as compared with 14 mg/m in conventional burners. Accordingly, malt dried with such burners contains only 1 to 3 mg/kg NDMA, a 15-30 fold reduction of the NDMA concentration. 

Further development in the area of alternate value-added products for improving economics included other oxygenated sulfur compounds [246,247], This invention included alkylated 2-(2-hydroxyphenyl) benzenesulfinic acid and 2-(2-hydroxyphenyl)-benzenesulfonic acid compounds and compositions which consist essentially of 2-(2-hydroxyphenyl) benzenesulfinic acid, 2-(2-hydroxyphenyl)-benzenesulfonic acid and/or substituted derivatives. The compositions are useful as hydrotropes and are also of use as, or as starting materials for, surfactants, and as starting materials for the synthesis of other useful chemicals such as, polymers and resins, solvents, adhesives, and biocides. 

For the synthesis of chemicals from CO/H2 three considerations will influence the economics and process feasibility, namely the ratio of C0 H2, the loss of oxygen as by-product water or CO2, and the interrelation of chemicals/fuels. The two first points are exemplified in Table I. 

Also of great attractiveness is the direct synthesis of acetic acid from syngas, which would circumvent the two step process of Monsanto. Selectivities of up to 50 % are claimed. An economic analysis by Hoechst A.G. indicates (1/7) that this process is already economically feasible at a 80 % C2 Oxygenate selectivity. 

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