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Aldehydes and Ketones. Acyl Addition Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
A hemiacetal has the structure R2COH(ORʹ). A hemiacetal is formed by the reaction of one equivalent of an aldehyde or ketone with an alcohol. However, a hemiacetal is not stable to the acidic reaction conditions and loses a molecule of water that allows reaction with a second equivalent of an alcohol to give an acetal.
Biodegradation of diisopropyl ether, ethyl tert-butyl ether, and other fuel oxygenates by Mycolicibacterium sp. strain CH28
Published in Bioremediation Journal, 2022
Ingrid Zsilinszky, Balázs Fehér, István Kiss, Attila Komóczi, Péter Gyula, Zsolt Szabó
Our comprehensive review of the literature failed to find any studies investigating the degradation pathway of DIPE. Biodegradation of MTBE, ETBE, dimethyl ether, diethyl ether, and aralkyl ethers was described to proceed through an O-dealkylation reaction (Bernhardt et al. 1988; Resnick and Gibson 1993; Chauvaux et al. 2001; Kim and Engesser 2005). In general, the monooxygenases being responsible for this reaction catalyze the incorporation of an oxygen atom to the alpha carbon atom of the ether bond. This process results in the formation of an unstable hemiacetal structure which spontaneously decomposes to an alcohol and a carbonyl compound (White, Russell, and Tidswell 1996). Accordingly, O-dealkylation of DIPE leads to the simultaneous formation of 2-propanol and acetone followed by the conversion of 2-propanol to acetone by a secondary alcohol dehydrogenase. This is in great agreement with our findings, since we have managed to detect 2-propanol and acetone as degradation intermediates. Considering our results and the literature discussed, we propose the upper pathway of DIPE degradation in strain CH28 yielding acetone as the major intermediate (Figure 7).