Degradation Ether bond

Aliphatic and benzylic ethers are degraded by hydroxylation of the a-methylene group followed by scission of the ether bond with the formation of an aldehyde and an alkanol (White et al. 1996 Kim and Engesser 2004). In contrast, the degradation of 2-chloroethylvinyl ether by Ancylobacter... 

White GF, NJ Russell, EC Tidswell (1996) Bacterial scission of ether bonds. Microbiol Rev 60 216-232. Yoch D (2002) Dimethylsulfoniopropionate its sources, role in the marine food web, and biological degradation to dimethylsulfide. Appl Environ Microbiol 68 5804-5815. 

Alcohol ether sulfates. Ready aerobic biodegradation of AESs has been described [113], with co/(3-oxidation and cleavage of the sulfate and ether bonds attributed to the process [10]. However, molecular oxygen is not necessary for the two latter steps, and primary and ultimate degradation has been described under both aerobic and anaerobic conditions [114]. 

Figure 1. 3-0-4 lignin substructure model compounds and products of their degradation by ligninolytic cultures of Phanerochaete chrysosporium and by lignin peroxidase. D H, and 0 of 3-ether bond and of H2 0, respectively. B and C show results of stable isotope experiments. 

Kraft pulping involves the cooking of wood chips at 340-350°F and 100-135 psi in liquor that contains sodium hydroxide, sodium sulfide, and sodium carbonate. This process promotes cleavage of the various ether bonds in lignin and the degradative products so formed dissolve in alkaline pulping liquor. The Kraft process normally incorporates several steps to recover chemicals from the spent black liquor [3]. 

Figure 1. /3-0-4 lignin substructure model dimers 1-4 and their degradation by white-rot fungi, Phanerochaete chrysosporium, Coriolus versicolor, and Coriolus hirsutus. The ether bond between the C/ and the B-aromatic nucleus is referred to as /3-0-4 bond in lignin chemistry. 

The introduction of an ethoxy group to the alkyl chain weakened the molecule, as shown by Tachimori s study with HDHoEP (di(hexyloxyethyl)phos-phoric acid). Under the same conditions, the yields of monoester were 6.6 for HDHOEP and 2.1 for HDEHP. Furthermore, the presence of an oxygen atom in the alkyl chain led to the formation of a supplementary degradation product (a diacidic compound, probably formed by the scission of the ether bond), compared to HDEHP or HDiDP (32). 

Cleavage of the ether bond to yield an ethyl alcohol derivative. Both metabolites are susceptible to further degradation... 

Lundquist K, Lundgren R (1972) Acid degradation of lignin VII The cleavage of ether bonds Acta Chem Scand 26 2005-2023... 

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