由3-甲基-4-羟基辛酸生成顺式和反式橡木内酯的速率。
Rates of formation of cis- and trans-oak lactone from 3-methyl-4-hydroxyoctanoic acid.
作者信息
Wilkinson Kerry L, Elsey Gordon M, Prager Rolf H, Pollnitz Alan P, Sefton Mark A
机构信息
School of Chemistry, Physics and Earth Sciences, Flinders University of South Australia, PO Box 2100, Adelaide, South Australia 5001, Australia.
出版信息
J Agric Food Chem. 2004 Jun 30;52(13):4213-8. doi: 10.1021/jf0496550.
The rates of formation of both cis- and trans-oak lactone from the corresponding isomers of 3-methyl-4-hydroxyoctanoic acid have been measured in model wine at room temperature for a range of pH values. The half-life for formation of the trans-isomer at pH 2.9 was calculated to be 3.1 h, whereas that for the cis-isomer, at the same pH, was calculated to be 40.5 h. The k(trans)/k(cis) ratio in model wine was found to 12.86 +/- 1.34 over the range of pH values employed. A reason for the more facile formation of the trans-isomer, based on conformational reasons, has been proposed. In acidic aqueous media the equilibrium between the oak lactones and their corresponding ring-opened analogues was found to favor the former entirely, with no evidence for the latter being found. Implications of the present study for the future analysis of oak samples, as well as for the interpretation of existing data, are discussed.
在室温下，针对一系列pH值，已在模拟葡萄酒中测定了由3-甲基-4-羟基辛酸的相应异构体生成顺式和反式橡木内酯的速率。计算得出，在pH 2.9时反式异构体形成的半衰期为3.1小时，而在相同pH值下顺式异构体的半衰期经计算为40.5小时。在所采用的pH值范围内，模拟葡萄酒中k（反式）/k（顺式）的比率为12.86±1.34。基于构象原因，已提出了反式异构体更容易形成的原因。在酸性水性介质中，发现橡木内酯与其相应的开环类似物之间的平衡完全有利于前者，未发现后者存在的证据。讨论了本研究对未来橡木样品分析以及对现有数据解释的影响。
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