Residual Aromatic Extract

Laboratory studies with petroleum and petroleum fractions. The first report of microbial oxidation of sulfur heterocycles was published by Walker et al. (28). Using computerized mass spectrometry (MS) to analyze the residual oil extracted from aerobically-grown mixed cultures, they observed losses of 40% of the dibenzothiophenes and 50% of the naphthobenzothiophenes. They concluded that the sulfur-containing aromatics were approximately twice as resistant to microbial degradation as their hydrocarbon analogues. 

The 40,000 kg/h of catalytic reformate fed to stage 7 (counting from the top according to the convention in the EXTRACT block) is modeled as 50/50 n-heptane/toluene on a mass basis, and the residual aromatic content of the recovered sulfolane fed to the top of the extractor is 0.4 vol % toluene as given... 

Essential oils and aromatic extracts - Determination of residual benzene content... 

Paraffinic and naphthenic (cycloparaffinic) stocks may be used for the formulation of lubricating oils, each with favorable characteristics for particular uses. Paraffinic stocks are generally preferred for their superior lubricating power and oxidation resistance. Naphthenic stocks, on the other hand, have naturally lower pour points, i.e, they maintain flow characteristics at lower pour-points than paraffinics (Table 18.8) and are better solvents, features which are more important for applications such as heat transfer, metal working, and fire-resistant hydraulic fluids [33]. Any residual aromatics in the lubricating base stock will have been removed before formulation by solvent extraction, using N-methylpyrrolidone, furfural, or less frequently today, phenol (Eq. 18.39). 

To hydrolyse an ester of a phenol (e.g., phenyl acetate), proceed as above but cool the alkaline reaction mixture and treat it with carbon dioxide until saturated (sohd carbon dioxide may also be used). Whether a solid phenol separates or not, remove it by extraction with ether. Acidify the aqueous bicarbonate solution with dilute sulphuric acid and isolate the acid as detailed for the ester of an alcohol. An alternative method, which is not so time-consuming, may be employed. Cool the alkaline reaction mixture in ice water, and add dilute sulphuric acid with stirring until the solution is acidic to Congo red paper and the acid, if aromatic or otherwise insoluble in the medium, commences to separate as a faint but permanent precipitate. Now add 5 per cent, sodium carbonate solution with vigorous stirring until the solution is alkaline to litmus paper and the precipitate redissolves completely. Remove the phenol by extraction with ether. Acidify the residual aqueous solution and investigate the organic acid as above. 

After completion of the reaction, the mixture is diluted with water, extracted with ether and the residue from the ether phase purified by chromatography and/or recrystallization. If the substrate contains aromatic protons, the reduction procedure is repeated in protic medium to back exchange deuteriums incorporated into the aromatic ring. 

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