کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
68612 48518 2006 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Alumina as heterogeneous catalyst for the regioselective epoxidation of terpenic diolefins with hydrogen peroxide
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Alumina as heterogeneous catalyst for the regioselective epoxidation of terpenic diolefins with hydrogen peroxide
چکیده انگلیسی

The epoxidation of several terpenic diolefins (carvone, limonene, terpinolene, α-terpinene and γ-terpinene) in anhydrous conditions using alumina as a heterogeneous catalyst and hydrogen peroxide as the oxidant agent is studied in this work. Several kinds of chromatographic aluminas have been employed (acidic, basic and neutral), in order to study the effect of the surface acidity on the reaction. The reusability of the catalyst has also been addressed. Basic alumina was the catalyst that gave better activity and selectivity. The reactivity of the substrate increases with the nucleophilic character of its double bonds, and the regioselectivity to some monoepoxides is also related to this nucleophilic character. The epoxidation rate of carvone, limonene and terpinolene increased with the alumina/terpene molar ratio. The selectivity to epoxides increased for carvone, and it passed through a maximum for limonene and terpinolene with this variable. From the comparison between experiments performed removing the catalyst, without removing it, and without catalyst, it was deduced that alumina is responsible for the high activity and selectivity obtained when it is added to the reaction medium, and that a heterogeneous epoxidation occurs on alumina surface. The study of the reusability of alumina in the epoxidation of limonene and terpinolene shows negligible changes on selectivity after several cycles, whereas the decrease of activity in successive cycles is significant for the long reaction times used in limonene epoxidation.

The epoxidation of several terpenic diolefins (carvone, limonene, terpinolene, α-terpinene and γ-terpinene) in anhydrous conditions using alumina as a heterogeneous catalyst and hydrogen peroxide as oxidant agent is studied in this work. Several kinds of chromatographic aluminas have been employed (acidic, basic and neutral). The reusability of the catalyst has also been addressed. Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Catalysis A: Chemical - Volume 256, Issues 1–2, 18 August 2006, Pages 208–215
نویسندگان
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