Biological formations and reactions

Wallenfels, Kurt; Diekmann, H.

doi:10.1002/9780470771075.ch5

Cited by 7 publications

(3 citation statements)

References 207 publications

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“…The chemical properties of these ethers are typical of their structures, 179,180 and only brief mention is warranted here. The ether bond is relatively unreactive and stable to alkaline hydrolysis, e.g., compared to acyl glycerols.…”

Section: Propertiesmentioning

confidence: 99%

Glyceryl-ether monooxygenase [EC 1.14.16.5]. A microsomal enzyme of ether lipid metabolism

Taguchi¹,

Armarego²

1998

Med. Res. Rev.

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Section: Propertiesmentioning

confidence: 99%

Glyceryl-ether monooxygenase [EC 1.14.16.5]. A microsomal enzyme of ether lipid metabolism

Taguchi¹,

Armarego²

1998

Med. Res. Rev.

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“…Subsequent partitioning of TBF to atmospheric water may result in hydrolysis to TBA, as represented by pathway D. In the vadose zone, MTBE may also be transformed via TBF to TBA (Pathways B and D), if recent results obtained with soil fungi prove to have widespread relevance [24]. Alternatively, TBA may be formed directly in aerobic surface waters, soils, and groundwaters by microbially mediated hydrolysis [25], oxidation [26,27] (Pathway C), or both. Further oxidation of TBA may give organic acids and eventually CO 2 , and this process is significant when mediated by hydroxyl radicals in the atmosphere [21].…”

Section: Introductionmentioning

confidence: 99%

HYDROLYSIS OF tert-BUTYL FORMATE: KINETICS, PRODUCTS, AND IMPLICATIONS FOR THE ENVIRONMENTAL IMPACT OF METHYL tert-BUTYL ETHER

Church¹,

Pankow²,

Tratnyek³

1999

Environ Toxicol Chem

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Abstract-Assessing the environmental fate of methyl tert-butyl ether (MTBE) has become a subject of renewed interest because of the large quantities of this compound that are being used as an oxygenated additive in gasoline. Various studies on the fate of MTBE have shown that it can be degraded to tert-butyl formate (TBF), particularly in the atmosphere. Although it is generally recognized that TBF is subject to hydrolysis, the kinetics and products of this reaction under environmentally relevant conditions have not been described previously. In this study, we determined the kinetics of TBF hydrolysis as a function of pH and temperature. Over the pH range of 5 to 7, the neutral hydrolysis pathway predominates, with k N ϭ (1.0 Ϯ 0.2) ϫ 10 Ϫ6 /s. Outside this range, strong pH effects were observed because of acidic and basic hydrolyses, from which we determined that k A ϭ (2.7 Ϯ 0.5) ϫ 10 Ϫ3 / (M·s) and k B ϭ 1.7 Ϯ 0.3/(M·s). Buffered and unbuffered systems gave the same hydrolysis rates for a given pH, indicating that buffer catalysis was not significant under the conditions tested. The activation energies corresponding to k N , k A , and k B were determined to be 78 Ϯ 5, 59 Ϯ 4, and 88 Ϯ 11 kJ/mol, respectively. In all experiments, tert-butyl alcohol was found at concentrations corresponding to stoichiometric formation from TBF. Based on our kinetics data, the expected half-life for hydrolysis of TBF at pH ϭ 2 and 4ЊC (as per some standard preservation protocols for water sampling) is 6 h. At neutral pH and 22ЊC, the estimated half-life is 5 d, and at pH ϭ 11 and 22ЊC, the value is only 8 min.

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Section: Introductionmentioning

confidence: 99%

Hydrolysis of tert‐butyl formate: Kinetics, products, and implications for the environmental impact of methyl tert‐butyl ether

Church

Pankow

Tratnyek

1999

Enviro Toxic and Chemistry

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Asessing the environmental fate of methyl tert‐butyl ether (MTBE) has become a subject of renewed interest because of the large quantities of this compound that are being used as an oxygenated additive in gasoline. Various studies on the fate of MTBE have shown that it can be degraded to tert‐butyl formate (TBF), particularly in the atmosphere. Although it is generally recognized that TBF is subject to hydrolysis, the kinetics and products of this reaction under environmentally relevant conditions have not been described previously. In this study, we determined the kinetics of TBF hydrolysis as a function of pH and temperature. Over the pH range of 5 to 7, the neutral hydrolysis pathway predominates, with kN = (1.0 ± 0.2) × 10−6/s. Outside this range, strong pH effects were observed because of acidic and basic hydrolyses, from which we determined that kA = (2.7 ± 0.5) × 10−3/(M·s) and kB = 1.7 ± 0.3/(M·s). Buffered and unbuffered systems gave the same hydrolysis rates for a given pH, indicating that buffer catalysis was not significant under the conditions tested. The activation energies corresponding to kN, kA, and kB were determined to be 78 ± 5, 59 ± 4, and 88 ±11 kJ/mol, respectively. In all experiments, tert‐butyl alcohol was found at concentrations corresponding to stoichiometric formation from TBF. Based on our kinetics data, the expected half‐life for hydrolysis of TBF at pH = 2 and 4°C (as per some standard preservation protocols for water sampling) is 6 h. At neutral pH and 22°C, the estimated half‐life is 5 d, and at pH = 11 and 22°C, the value is only 8 min.

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Biological formations and reactions

Cited by 7 publications

References 207 publications

Glyceryl-ether monooxygenase [EC 1.14.16.5]. A microsomal enzyme of ether lipid metabolism

Glyceryl-ether monooxygenase [EC 1.14.16.5]. A microsomal enzyme of ether lipid metabolism

HYDROLYSIS OF tert-BUTYL FORMATE: KINETICS, PRODUCTS, AND IMPLICATIONS FOR THE ENVIRONMENTAL IMPACT OF METHYL tert-BUTYL ETHER

Hydrolysis of tert‐butyl formate: Kinetics, products, and implications for the environmental impact of methyl tert‐butyl ether

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