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首页> 外文期刊>Chemistry: A European journal >Phosphotungstic acid as a versatile catalyst for the synthesis of fragrance compounds by alpha-pinene oxide isomerization: Solvent-induced chemoselectivity
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Phosphotungstic acid as a versatile catalyst for the synthesis of fragrance compounds by alpha-pinene oxide isomerization: Solvent-induced chemoselectivity

机译：磷钨酸作为通过α-pine烯氧化物异构化合成香料化合物的通用催化剂：溶剂诱导的化学选择性

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摘要

The remarkable effect of the solvent on the catalytic performance of H3PW12O40, the strongest heteropoly acid in the Keggin series, allows direction of the transformations of alpha-pinene oxide (1) to either campholenic aldehyde (2), trans-carveol (3), trans-sobrerol (4a), or pinol (5). Each of these expensive fragrance compounds was obtained in good to excellent yields by using an appropriate solvent. Solvent polarity and basicity strongly affect the reaction pathways: nonpolar nonbasic solvents favor the formation of aldehyde 2; polar basic solvents favor the formation of alcohol 3; whereas in polar weakly basic solvents, the major products are compounds 4a and 5. On the other hand, in 1,4-dioxane, which is a nonpolar basic solvent, both aldehyde 2 and alcohol 3 are formed in comparable amounts. The use of very low catalyst loading (0.005-1 mol%) and the possibility of catalyst recovery and recycling without neutralization are significant advantages of this simple, environmentally benign, and low-cost method. This method represents the first example of the synthesis of isomers from cc-pinene oxide, other than campholenic aldehyde, with a selectivity that is sufficient for practical usage.
机译：溶剂对H3PW12O40（Keggin系列中最强的杂多酸）的催化性能产生了显着影响，使α-pine烯氧化物（1）转变为樟脑醛（2），反式香芹酚（3），反式Sobrerol（4a）或Pinol（5）。这些昂贵的香料化合物中的每一种均通过使用适当的溶剂以良好至优异的收率获得。溶剂的极性和碱性强烈影响反应路径：非极性非碱性溶剂有利于醛2的形成;极性碱性溶剂有利于醇3的形成;在极性弱碱性溶剂中，主要产物是化合物4a和5。另一方面，在非极性碱性溶剂1,4-二恶烷中，醛2和醇3的生成量相当。这种简单，对环境无害且成本低廉的方法的显着优点是，使用极低的催化剂负载量（0.005-1 mol％）以及无需中和就可以回收和回收催化剂的显着优势。该方法代表了从c-pine烯氧化物合成除樟脑醛以外的异构体的第一个实例，其选择性足以满足实际应用。

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