Catalytic oxidation of cyclohexene over metalloporphyrin supported on mesoporous molecular sieves of FSM-16 type—Steric effects induced by nanospace constraints

Microporosity in Mesoporous SBA-15 Supports: A Factor Influencing the Catalytic Performance of Immobilized Metalloporphyrin

“…On all AlSBA-15 supported catalysts the epoxide is the dominant product. This is at variance with the previously examined directly aluminated mesoporous silicas of HMS, MCM-41 and FSM-16 types, characterized by narrower pore dimensions, on which allylic oxidation is an important, and, in some cases, favoured reaction pathway [3][4][5]8]. The result proves that, indeed, the use of wide pore supports succeeds in removing steric obstacles prohibiting the formation of epoxide.…”

“…Another factor potentially influencing the product distribution is the manner of Al incorporation. In the case of mesoporous silicas with narrower pore sizes it has been found that the post synthesis alumination promoted epoxidation pathway, as it produced more exchange sites on the external support surface, rather than on the internal pore walls, thus increasing the abundance of metalloporphyrin species free of steric hindrance and capable of catalyzing epoxidation [4,8]. However, the present study provides that the pattern of product distribution might be related to the differences in supports morphologies has to be discarded as well.…”

Microporosity in Mesoporous SBA-15 Supports: A Factor Influencing the Catalytic Performance of Immobilized Metalloporphyrin

“…On all AlSBA-15 supported catalysts the epoxide is the dominant product. This is at variance with the previously examined directly aluminated mesoporous silicas of HMS, MCM-41 and FSM-16 types, characterized by narrower pore dimensions, on which allylic oxidation is an important, and, in some cases, favoured reaction pathway [3][4][5]8]. The result proves that, indeed, the use of wide pore supports succeeds in removing steric obstacles prohibiting the formation of epoxide.…”

“…Another factor potentially influencing the product distribution is the manner of Al incorporation. In the case of mesoporous silicas with narrower pore sizes it has been found that the post synthesis alumination promoted epoxidation pathway, as it produced more exchange sites on the external support surface, rather than on the internal pore walls, thus increasing the abundance of metalloporphyrin species free of steric hindrance and capable of catalyzing epoxidation [4,8]. However, the present study provides that the pattern of product distribution might be related to the differences in supports morphologies has to be discarded as well.…”

Porphyrins and Phthalocyanines on Solid-State Mesoporous Matrices as Catalysts in Oxidation Reactions

“…It was also observed that despite the slight differences in activity, all metalloporphyrin complexes showed selectivity towards the allylic oxidation products over the epoxide derivatives. According to Zimowska’s concept, this may be due to the location place of porphyrins on the support [ 60 ]. Porphyrins anchored inside the pores of MCM-41 gave cyclohexanone and cyclohexanol as products of oxidation, while those deposited on the external surface were more selective towards the epoxide ( Figure 4 ).…”

“… Direction of the oxidation reactions depending on the porphyrin location: inside the pores of support ( A ) and deposited on the external surface ( B ) [ 60 ]. …”

Highly Efficient Aerobic Oxidation of Cyclohexene Catalyzed by Iron(III) Porphyrins in Supercritical Carbon Dioxide

“…13 Such bimometic catalytic systems have been proved to be efficient in cyclohexene oxidation, but a large number of organic solvents were used in the process. 14 Except for the risk of toxicity and flammability of organic solvents, it is significantly difficult to separate products and catalyst after reaction. Supercritical carbon dioxide (scCO 2 ) is a particularly attractive medium as it is environmentally and economically convenient, nonflammable, non-toxic.…”

Microporosity in Mesoporous SBA-15 Supports: A Factor Influencing the Catalytic Performance of Immobilized Metalloporphyrin

“…On all AlSBA-15 supported catalysts the epoxide is the dominant product. This is at variance with the previously examined directly aluminated mesoporous silicas of HMS, MCM-41 and FSM-16 types, characterized by narrower pore dimensions, on which allylic oxidation is an important, and, in some cases, favoured reaction pathway [3][4][5]8]. The result proves that, indeed, the use of wide pore supports succeeds in removing steric obstacles prohibiting the formation of epoxide.…”

“…Another factor potentially influencing the product distribution is the manner of Al incorporation. In the case of mesoporous silicas with narrower pore sizes it has been found that the post synthesis alumination promoted epoxidation pathway, as it produced more exchange sites on the external support surface, rather than on the internal pore walls, thus increasing the abundance of metalloporphyrin species free of steric hindrance and capable of catalyzing epoxidation [4,8]. However, the present study provides that the pattern of product distribution might be related to the differences in supports morphologies has to be discarded as well.…”

Porphyrins and Phthalocyanines on Solid-State Mesoporous Matrices as Catalysts in Oxidation Reactions

“…It was also observed that despite the slight differences in activity, all metalloporphyrin complexes showed selectivity towards the allylic oxidation products over the epoxide derivatives. According to Zimowska’s concept, this may be due to the location place of porphyrins on the support [ 60 ]. Porphyrins anchored inside the pores of MCM-41 gave cyclohexanone and cyclohexanol as products of oxidation, while those deposited on the external surface were more selective towards the epoxide ( Figure 4 ).…”

“… Direction of the oxidation reactions depending on the porphyrin location: inside the pores of support ( A ) and deposited on the external surface ( B ) [ 60 ]. …”

Highly Efficient Aerobic Oxidation of Cyclohexene Catalyzed by Iron(III) Porphyrins in Supercritical Carbon Dioxide

“…13 Such bimometic catalytic systems have been proved to be efficient in cyclohexene oxidation, but a large number of organic solvents were used in the process. 14 Except for the risk of toxicity and flammability of organic solvents, it is significantly difficult to separate products and catalyst after reaction. Supercritical carbon dioxide (scCO 2 ) is a particularly attractive medium as it is environmentally and economically convenient, nonflammable, non-toxic.…”

Microporosity in Mesoporous SBA-15 Supports: A Factor Influencing the Catalytic Performance of Immobilized Metalloporphyrin

“…On all AlSBA-15 supported catalysts the epoxide is the dominant product. This is at variance with the previously examined directly aluminated mesoporous silicas of HMS, MCM-41 and FSM-16 types, characterized by narrower pore dimensions, on which allylic oxidation is an important, and, in some cases, favoured reaction pathway [3][4][5]8]. The result proves that, indeed, the use of wide pore supports succeeds in removing steric obstacles prohibiting the formation of epoxide.…”

“…Another factor potentially influencing the product distribution is the manner of Al incorporation. In the case of mesoporous silicas with narrower pore sizes it has been found that the post synthesis alumination promoted epoxidation pathway, as it produced more exchange sites on the external support surface, rather than on the internal pore walls, thus increasing the abundance of metalloporphyrin species free of steric hindrance and capable of catalyzing epoxidation [4,8]. However, the present study provides that the pattern of product distribution might be related to the differences in supports morphologies has to be discarded as well.…”

Porphyrins and Phthalocyanines on Solid-State Mesoporous Matrices as Catalysts in Oxidation Reactions

“…It was also observed that despite the slight differences in activity, all metalloporphyrin complexes showed selectivity towards the allylic oxidation products over the epoxide derivatives. According to Zimowska’s concept, this may be due to the location place of porphyrins on the support [ 60 ]. Porphyrins anchored inside the pores of MCM-41 gave cyclohexanone and cyclohexanol as products of oxidation, while those deposited on the external surface were more selective towards the epoxide ( Figure 4 ).…”

“… Direction of the oxidation reactions depending on the porphyrin location: inside the pores of support ( A ) and deposited on the external surface ( B ) [ 60 ]. …”

Highly Efficient Aerobic Oxidation of Cyclohexene Catalyzed by Iron(III) Porphyrins in Supercritical Carbon Dioxide

“…13 Such bimometic catalytic systems have been proved to be efficient in cyclohexene oxidation, but a large number of organic solvents were used in the process. 14 Except for the risk of toxicity and flammability of organic solvents, it is significantly difficult to separate products and catalyst after reaction. Supercritical carbon dioxide (scCO 2 ) is a particularly attractive medium as it is environmentally and economically convenient, nonflammable, non-toxic.…”