Efficient isomerization of safrole by amino-grafted MCM-41 materials as basic catalysts

[Display omitted] ► We show isomerization of safrole to isosafrole over recyclable amino-grafted MCM-41 materials, being the maximum conversion of around 85% with a cis/trans ratio of 1/9 at 433 K in DMF. ► Isomerization is strongly dependent on the nature of the support and changed in the following...

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Bibliographic Details
Published in:	Catalysis today 2012, Vol.179 (1), p.159-163
Main Authors:	Sobczak, Izabela, Ziolek, Maria, Pérez-Mayoral, Elena, Blasco-Jiménez, Davinia, López-Peinado, Antonio J., Martín-Aranda, Rosa M.
Format:	Article
Language:	eng
Subjects:	acidity AlMCM-41 Aminopropyl trimethoxysilanes Basicity Catalysis catalysts catalytic activity Chemistry Colloidal state and disperse state Exact sciences and technology General and physical chemistry Isomerization Isosafrole MCM-41 Mesoporous materials NbMCM-41 perfumes Porous materials Safrole silica Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
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Summary:	[Display omitted] ► We show isomerization of safrole to isosafrole over recyclable amino-grafted MCM-41 materials, being the maximum conversion of around 85% with a cis/trans ratio of 1/9 at 433 K in DMF. ► Isomerization is strongly dependent on the nature of the support and changed in the following order: APMS/AlMCM-41 > APMS/NbMCM-41 ≫ APMS/MCM-41. ► The nature of the amine chain is also responsible of the activity. The order of activity is APMS/AlMCM-41 > 2APMS/AlMCM-41 > 3APMS/AlMCM-41. Design of base catalyst featuring large mesoporous surfaces allows performing base-catalysed reactions in the fields of production of perfumes. Post-synthesis grafting of organotrialkoxysilanes has effectively been applied to incorporate active organic functional groups onto the mesoporous silica surfaces. The novelty of our study is the use of mesoporous materials with different chemical compositions: silicate (MCM-41), aluminosilicate (AlMCM-41; Si/Al = 64) and niobosilicate (NbMCM-41; Si/Nb = 64) and consequently, different acidity, as supports for three aminopropylalkoxysilanes (APMS), [3-(2-aminoethylamino) propyl]trimethoxysilane (2APMS) and 3-[2-(2-aminoethylamino) ethylamino]propyltrimethoxysilane (3APMS). Isomerization of safrole to the corresponding thermodynamically stable isosafrole has been carried out on these amino-grafted MCM-41 materials. Maximum conversion of around 85% with a cis/trans ratio of 1/9 at 433 K in DMF as solvent was obtained. Isomerization is strongly dependent on the nature of the support and changed in the following order: APMS/AlMCM-41 > APMS/NbMCM-41 ≫ APMS/MCM-41. The nature of the amine chain is also responsible of the activity. The order of activity is APMS/AlMCM-41 > 2APMS/AlMCM-41 > 3APMS/AlMCM-41.
ISSN:	0920-5861 1873-4308