The above reaction shows an epimeric steroid alcohol being converted by a catalyst of ruthenium and aluminum oxide to a racemic mixture of 17-estradiol 3-methyl ether and a ketone. The racemic mixture is formed by converting the beta version of the ether, where the hydroxyl group is on the top of the ring, to the alpha version of the ether, where the hydroxyl group is underneath the ring. The reaction is stopped when the amount of alpha ether is roughly equivalent to the amount of beta ether. In the notation used, the wavy line between the hydroxyl group and the ether shows that the hydroxyl group can be in either the front or the back of the molecule.
However, a ketone can be produced instead of the alpha ether when the alcohol is oxidized. Because the purpose of the reaction is to racemize the ether, this ketone is an unwanted side product. To prevent oxidation, toluene at 100 C is used as a solvent. The chemical properties of toluene slow the formation of the ketone so that at temperatures around 100 C, the yield of the racemic mixture is about 54%. Any ketone that does form can be separated from the ether by flash chromatography. This reaction is a good way to racemize the ether efficiently and inexpensively; it was traditionally synthesized at a much higher cost.
In the syntheses of aromatic esters and ethers, CsF-Celite has been found to be a very efficient, convenient and practical reagent. In fact, it is used for the coupling reactions of a number of aromatic and heteroaromatic phenols with alkyl, acyl or benzoyl halides.
Many other organic reactions have recently been catalyzed by CsF-Celite, such as the reactions to synthesize carboxylic esters, γ-lactones, N-alkylation of anilines, or carboxamides.
This is a potential pathway for the oxidation of toluene in Fe(III)-reducing microorganisms, which play important roles in sediments naturally composed of hydrocarbons. The oxidation of toluene, an aromatic hydrocarbon, in these microorganisms is coupled to Fe(III) reduction. GS-15 is the first microorganism discovered to link aromatic compound oxidation to the reduction of Fe(III). The oxidation of p-cresol and phenol in these organisms is also coupled to Fe(III) reduction. Under strict anaerobic conditions in these organisms, GS-15 can completely oxidize toluene to carbon dioxide by utilizing Fe(III) as the only electron acceptor in the reaction.
This mechanism can be used to clean up toxic oil spills or other toluene contaminations by introducing the microorganisms to the site.
D,L-1,2,4-butanetriol can be made in two different ways; the first way is commercial synthesis through reduction of esterified D,L-malic acid with sodium borohydride, NaBH4, while the second way involves microbes. The latter method was the focus of the journal article. Nitration of racemic D,L-1,2,4-butanetriol results in D,L-1,2,4-butanetriol trinitrate, a compound that is the energetic equivalent of nitroglycerin, but is less shock sensitive, more thermally stable, and less volatile. One of the final steps in the synthesis of D, L-1,2,4-butanetriol via microbes is the reduction of a racemic mixture of D,L-3,4-dihydroxybutanal (aldehyde), to the final alcohol product, as seen in the reaction below. The catalyst for the reaction is dehydrogenase from E. coli.
