Catalytic synthesis of terpenoid-derived hexahydro-2H-chromenes with analgesic activity over halloysite nanotubes

Halloysite Nanotubes: Smart Nanomaterials in Catalysis

“…Most recently, the condensation of p-menta-1,8-diene-5,6-diol 1 with decanal on acidmodified HNTs, to obtain the hexahydro-2H-chromene-4,8-diol 2 which possesses a high analgesic activity, was also investigated (Figure 4) [57]. unexpected high yield (ca.…”

“…Most recently, the condensation of p-menta-1,8-diene-5,6-diol 1 with decanal on acidmodified HNTs, to obtain the hexahydro-2H-chromene-4,8-diol 2 which possesses a high analgesic activity, was also investigated (Figure 4) [57]. In comparison to other clays, the use of HNTs led to an increase in the total yield of the corresponding hexahydro-2H-chromene-4,8-diols 2 and higher 4S/4R isomers ratio.…”

Effect of the nickel impregnation method on clay supports in the hydroconversion reaction of n-decane

“…In this context and in order to evaluate the effect of the method of metal incorporation (Ni) in properties such as metallic dispersion and metal–support interaction, in this work three synthesis routes are proposed, i) auto-combustion, ii) microwave assisted auto-combustion and iii) wet impregnation, for the supported metallic phase, while the acid function is modulated based on the support using different clays: a bentonite and a vermiculite (clays type 2 : 1, two layers of silicon tetrahedra per one layer of aluminum octahedra), 40 whose fundamental difference is their interlaminar charge (bentonite has a lower charge compared to vermiculite) 41 and a halloysite (clay 1 : 1, has a layer of silicon tetrahedra for a layer of aluminum octahedra) which has the particularity of forming nanotubes with the silicon groups on the exterior surface and the aluminum groups on the interior surface of the nanotubes. 42…”

“…39 In this context and in order to evaluate the effect of the method of metal incorporation (Ni) in properties such as metallic dispersion and metal-support interaction, in this work three synthesis routes are proposed, i) auto-combustion, ii) microwave assisted auto-combustion and iii) wet impregnation, for the supported metallic phase, while the acid function is modulated based on the support using different clays: a bentonite and a vermiculite (clays type 2 : 1, two layers of silicon tetrahedra per one layer of aluminum octahedra), 40 whose fundamental difference is their interlaminar charge (bentonite has a lower charge compared to vermiculite) 41 and a halloysite (clay 1 : 1, has a layer of silicon tetrahedra for a layer of aluminum octahedra) which has the particularity of forming nanotubes with the silicon groups on the exterior surface and the aluminum groups on the interior surface of the nanotubes. 42 In this sense, to our knowledge, the study of the method of Ni incorporation via auto-combustion or microwaveassisted auto-combustion on natural clay minerals (bentonite, vermiculite and halloysite) has not yet been reported in the specialized literature and could open up new alternatives to traditional impregnation for controlling and adapting the properties of the bifunctional catalyst based on simple syntheses, with short times and with structural, textural, reductive and acid characteristics comparable or superior to those obtained by impregnation, and active in the hydroconversion reactions of alkanes.…”