2027-17-0Relevant academic research and scientific papers
Isopropylation of naphthalene by isopropyl alcohol over USY catalyst: An investigation in the high-pressure fixed-bed flow reactor
Wang, Jun,Park, Jung-Nam,Park, Yong-Ki,Lee, Chul Wee
, p. 265 - 272 (2003)
Catalytic performances of USY, H-mordenite, dealuminated H-mordenite, and H-MCM-22 zeolite catalysts in the isopropylation of naphthalene by isopropyl alcohol with decalin or cyclohexane as a solvent were compared in a high-pressure fixed-bed flow reactor. For the USY catalyst, reaction conditions, such as reaction temperature and pressure, reactant ratio and space velocity, and solvent concentration and type, were controlled to investigate in detail the effect of reaction conditions on the catalytic activity. Over H-mordenite, it was found that 2,6-diisopropylnaphthalene (2,6-DIPN) could be selectively synthesized with a 2,6-/2,7-DIPN ratio of 2.46, and dealumination could enhance not only the selectivity of 2,6-DIPN, with a 2,6-/2,7-DIPN ratio of 2.67, but also the conversion of naphthalene, which was 27.4%, three times as high as that over the unmodified one at 6 h of reaction time on stream. However, neither the H-mordenite or the dealuminated one were catalytically stable and the selectivity of DIPN was at a very low level of less than 12%. In contrast, over the USY catalyst, a high and stable conversion of about 90%, a high selectivity of DIPN of more than 40%, and a considerable 2,6-/2,7-DIPN ratio of 1.46 could be achieved by adjusting the reaction conditions, although no shape selectivity was observed on USY. On the other hand, only a low 2,6-/2,7-DIPN ratio of 0.47 with a low conversion of about 30% was revealed over H-MCM-22, which indicates that the reaction takes place on the external surface of this zeolite. An attempt has been made to explain the catalytic activity, selectivity, and stability in relation to the zeolite structures, product properties, and reaction conditions.
Shape-selective synthesis of 2,6-diisopropylnaphthalene on H-mordenite catalysts
Brzozowski, Robert,Buijs, Wim
, p. 181 - 187 (2012)
To finally dispel any doubts on the shape-selective formation of 2,6-diisopropylnaphthalene (2,6-DIPN) over H-MOR zeolites, naphthalene alkylation was carried out over high-silica H-MOR catalysts with propylene or isopropanol as an alkylating agent and with or without cyclohexane as a solvent. Isomeric composition of DIPN's, determined by one-dimensional GC analysis, was additionally confirmed with advanced two-dimensional GC × GC. Our results proved beyond any doubt shape-selective formation of 2,6-DIPN over these H-MOR catalysts from naphthalene and propylene and without cyclohexane as a solvent. The DIPN mixture contained 60-64% 2,6-DIPN, and the ratio of 2,6-DIPN/2,7-DIPN was in the range 2.5-2.8. We also showed that shape-selective formation of 2,6-DIPN over H-MOR catalyst was depressed by using isopropanol instead of propylene and in the presence of cyclohexane.
Dialkylation of naphthalene with isopropanol over H3PO 4/MCM-41 Catalysts for the environmentally friendly synthesis of 2,6-dialkylnaphthalene
Ghiaci,Aghabarari,Rives,Vicente,Sobrados,Sanz
, p. 141 - 149 (2010)
AlMCM-41 materials with SiO2/Al2O3 molar ratios 20, 70, 110, 150, 200, and Si-MCM-41 were synthesized following standard procedures, and loaded with different amounts of H3PO4. The catalysts were well
Bidentate Lewis acid catalyzed inverse-electron-demand Diels-Alder reaction for the selective functionalization of aldehydes
Schweighauser, Luca,Bodoky, Ina,Kessler, Simon N.,Haeussinger, Daniel,Wegner, Hermann A.
, p. 2195 - 2199 (2012)
The inverse-electron-demand Diels-Alder (IEDDA) reaction catalyzed by a bidentate Lewis acid was applied to enamines generated in situ from aldehydes. In general, a high functional group tolerance has been observed. Side reactions during the enamine forming step can limit the yield of the desired naphthalene. For citronellal as substrate, the initial intermediate after the catalyzed IEDDA reaction was trapped by an intramolecular Diels-Alder reaction to furnish a tricyclic compound. This scaffold represents the framework of natural products such as valerianoids A-C or the patchouli alcohol. Georg Thieme Verlag Stuttgart New York.
Mechanistic Study of Domino Processes Involving the Bidentate Lewis Acid Catalyzed Inverse Electron-Demand Diels?Alder Reaction
Strauss, Marcel A.,Kohrs, Daniel,Ruhl, Julia,Wegner, Hermann A.
, p. 3866 - 3873 (2021)
The detailed understanding of mechanisms is the basis to design new reactions. Herein, we studied the domino bidentate Lewis acid catalyzed inverse electron-demand Diels?Alder (IEDDA) reaction developed in our laboratory computationally as well as by synthetic experiments, to characterize different pathways. A quinodimethane intermediate was identified as key structure, which is the basis for all subsequent transformations: Elimination to an aromatic naphthalene, rearrangement to a dihydroaminonaphthalene and a photo-induced ring opening. These insights allow to optimize the reaction conditions, such as catalytic utilization of amine, as well as to advance new reactions in the future.
Shape-selective diisopropylation of naphthalene in H-Mordenite: Myth or reality?
Bouvier, Christophe,Buijs, Wim,Gascon, Jorge,Kapteijn, Freek,Gagea, Bogdan C.,Jacobs, Pierre A.,Martens, Johan A.
, p. 60 - 66 (2010)
Selective diisopropylation of naphthalene to 2,6-diisopropylnaphthalene is a challenging goal in sustainable catalysis. Ultrastable Y and H-Mordenite zeolites are the best catalysts reported in the literature with respect to 2,6-diisopropylnaphthalene selectivity. It is generally accepted that in the case of H-Mordenite, shape-selectivity is responsible for the observed 2,6-diisopropylnaphthalene selectivity, while on Ultrastable Y-zeolite, the observed selectivity reflects the internal thermodynamic equilibrium of positional isomers. Revisiting both the experimental and the computational work in this field now leads to the conclusion that shape-selectivity of whatever kind can be ruled out in the case of H-Mordenite. H-Mordenite catalysts produce usually a kinetically controlled mixture of diisopropylnaphthalene isomers which can shift to the direction of a thermodynamical distribution at high reaction temperatures or over more active catalysts.
Isopropylation of naphthalene by isopropanol over conventional and Zn- and Fe-modified USY zeolites
Banu, Marimuthu,Lee, Young Hye,Magesh, Ganesan,Lee, Jae Sung
, p. 120 - 128 (2014)
Catalytic performances of USY, MOR, and BEA zeolites were compared for the isopropylation of naphthalene by isopropyl alcohol in a high-pressure, fixed-bed reactor. The USY catalyst showed a high conversion of 86% and good stability but a low 2,6-/2,7-DIPN shape selectivity ratio of 0.94. In contrast, over the MOR catalyst, 2,6-DIPN was selectively synthesized with a high 2,6-/2,7-DIPN ratio of 1.75, but low naphthalene conversions and fast deactivation of the catalyst were observed. The USY catalyst was modified by Zn and Fe using the wet impregnation method to enhance the selectivity for 2,6-DIPN. The highest conversion (~95%) and selectivity for 2,6-DIPN (~20%) were achieved with 4% Zn/USY catalyst. It appeared that small metal oxide islands formed in the USY pores to decrease the effective pore size and thus render it mildly shape-selective. Zn loading also decreased the number of strong acid sites responsible for coke formation and increased the number of weak acid sites. The high conversion and stability of Zn-modified catalysts were ascribed to the presence of a suitable admixture of weak and strong acid sites with less coke deposition. The Fe-modified USY catalysts were less effective because the modification increased the number of the strong acid sites.
An Amine Group Transfer Reaction Driven by Aromaticity
Ahles, Sebastian,G?tz, Silas,Schweighauser, Luca,Brodsky, Mirko,Kessler, Simon N.,Heindl, Andreas H.,Wegner, Hermann A.
, p. 7034 - 7038 (2018)
A stereoselective domino inverse electron-demand Diels-Alder/amine group transfer reaction catalyzed by a bidentate Lewis acid provides 1-amino-1,2-dihydronaphthalenes, a core structure in many bioactive compounds. A concerted mechanism is proposed based on experimental studies as well as DFT computations demonstrating a new general reactivity scheme. The broad scope of the reaction was evaluated by variation of all three starting compounds, phthalazines, aldehydes, and amines. Scalability was demonstrated by a gram scale reaction without diminished yield.
Disproportionation of isopropylnaphthalene on zeolite catalysts
Brzozowski, Robert,Skupinski, Wincenty
, p. 13 - 22 (2003)
Disproportionation of isopropylnaphthalene (IPN) was tested over H-mordenite, HY, H-beta zeolites and over amorphous aluminosilicate in the range of 150-300°C. High β,β-selectivity in diisopropylnaphthalene (DIPN) product obtained over zeolites was observed. However, the 2,6-DIPN/2,7-DIPN mole ratio was dependent on the pore structure of the applied zeolite and on the temperature. Over H-mordenites 2,6-DIPN was the most preferred isomer, whereas 2,7-DIPN was favored over HY and H-beta zeolites. Such disproportion in isomer predominating in the DIPN product can be explained by a bimolecular mechanism of disproportionation. Due to the zeolite pore architecture the bent transition-state complex, leading to 2,7-DIPN (HY and H-beta) or more linear, leading to 2,6-DIPN (H-mordenite), was preferred. At high temperatures the monomolecular disproportionation mechanism (dealkylation realkylation) dominated and concealed (simultaneously with side reactions) the shape-selectivity effect. As a result the 2,6-DIPN/2,7-DIPN mole ratio in the product approached equilibrium value.
Zeolite pore entrance effect on shape selectivity in naphthalene isopropylation
Brzozowski,Skupinski
, p. 313 - 318 (2002)
Naphthalene alkylation with propylene was studied over various large-pore zeolites and also over amorphous aluminosilicate catalysts. Isomeric distribution of isopropylnaphthalenes (IPN) and diisopropylnaphthalenes (DIPN) were compared at different temperatures. The shape-selectivity effect that occurred in the entrances to the pores could be responsible for high α-selectivity in monoisopropylation and 1NR-selectivity in diisopropylation observed in the naphthalene alkylation over wide pore zeolites. The product was then relatively rich in 1-IPN, 1,3-DIPN, and 1,4-DIPN. This type of shape selectivity suppressed other shape-selectivity effects, e.g., high β-selectivity of reactions occurring inside channels or cavities of the zeolite. High concentration of TIPN in alkylation products could be explained superbly with the help of catalysis in pore entrances. The explanation of such results was proposed to be a specific shape-selectivity effect of alkylation reaction occurring in the entrances to the pores of zeolite.
