Cyclization Of Pseudoionone Research Articles

Molybdenum oxide modified montmorillonite K10 clay as novel solid acid for flow synthesis of ionone isomers

Molybdenum oxide modified montmorillonite K10 clay (Mt-K10) was developed to synthesize ionone isomers via cyclization of pseudoionone. A fixed bed flow reactor was used to convert the current homogenous batch process into a heterogeneous flow process. To increase the acidity, molybdenum oxide was loaded on Mt-K10. Since molybdenum oxide contains both Lewis and Bronsted acidity, the loading resulted in a higher acidity of 1% (w/w) MoO3/Mt-K10 catalyst compared to Mt-K10 alone. 1% (w/w) MoO3/Mt-K10 is new, green, and economical catalyst derived from ammonium heptamolybdate tetrahydrate as molybdenum precursor and using Mt-K10 as support. The support and catalyst were analyzed by various characterization techniques, including XRD, FTIR, NH3-TPD, BET, SEM, TEM, and XPS analysis. Thus, 100 % conversion of pseudoionone and 75 % selectivity of ionone isomers were obtained. 1% (w/w) MoO3/Mt-K10 catalyst could be easily prepared on a large scale and it is effective in the synthesis of isomers of ionone with higher selectivity in comparison with other solid acids.

Cyclization of Pseudoionone Catalyzed by Sulfuric Acid in a Microreactor

AbstractA microreactor system was developed to investigate the cyclization of pseudoionone (PI) catalyzed by sulfuric acid. The conversion of PI and selectivities of α‐ionone and β‐ionone were explored under various conditions. The effects of residence time, molar ratio of acid/PI (M‐ratio), reaction temperature, and sulfuric acid concentration on the reaction were evaluated. Sulfuric acid concentration was found to play a vital role in the reaction system, which could greatly influence the conversion and selectivities. A high yield of β‐ionone and total yield of α‐ionone and β‐ionone were achieved under optimized conditions. The formation of by‐products was determined in detail and the side reactions could be restrained by optimizing the reaction parameters.

Intensification of highly exothermic fast reaction by multi-injection microstructured reactor

Microstructured reactors (MSR) with characteristic dimensions below 100μm are warranted to maintain close to isothermal conditions when carrying out quasi-instantaneous highly exothermic reactions. Unfortunately, such small dimensions increase the risk of clogging, create high pressure drop and are costly to number-up. The multi-injection (MI) MSR, where one of the reactants is added stepwise along the reactor length, allows working with larger dimensions (diameter >500μm) while maintaining good temperature control. Herein presented MI-MSR is made of low temperature co-fired ceramics (LTCC) with herringbone mixing structure inside the reactor channels and is shown to mix efficiently in a large range of Reynolds numbers Re=20–130. The cyclization of pseudoionone is studied as a model of a highly exothermic fast reaction. The temperature profiles are characterized by a quantitative infrared thermography. The developed LTCC MI-MSR allows ∼ 8-fold reduction of hot spot temperature as compared to the adiabatic temperature rise. Moreover, ∼500-fold intensification is achieved as compared to the conventional semi-batch process with reduced solvent mass by a factor of 2 while attaining a yield of target product above 98%.

Heterogeneous Acid Catalysis Using a Perfluorosulfonic Acid Monolayer-Functionalized Microreactor

The inner walls of a glass microreactor were functionalized in a one-step procedure with a single layer of a strong perfluoroalkylsulfonic acid. The applicability of the catalytic device was demonstrated in the successful hydrolysis of benzaldehyde dimethyl acetal in acetonitrile, achieving quantitative conversion within a residence time of only 60 s. Furthermore, the catalytic system showed high conversion for the Friedlander quinoline synthesis between 2-aminobenzophenone and ethyl acetoacetate. The cyclization of pseudoionone in methylcyclohexane proved the wide applicability of the acid-functionalized microreactor also for reactions carried out in apolar media. The platform showed activity for 6 h to 2 days, depending on the solvent, and was reactivated by simple treatment with the catalyst precursor.

Catalysis Studies of Macroreticular Polystyrene Cation‐exchange Resin with Terminal Perfluoroalkanesulfonic Acids

AbstractMacroreticular p‐(ω‐sulfonic‐perfluoroalkylated) polystyrene (FPS) resin with the advantages of both sulfonic polystyrene (such as macroreticular Amberlyst‐15) and perfluoroalkanesulfonic resin (such as superacidic Nafion NR50) has exhibited excellent catalytic selectivity and activity in cyclization of pseudoionone and condensation of indole. In this paper, FPS was characterized by XPS, nitrogen sorption technique, FESEM and Hammett indicator method, and employed as the solid acid catalyst in the esterification, acylation and alkylation reactions. The FPS resin showed better activity than commercial solid acid catalysts (Amberlyst‐15 and Nafion NR50) owing to its high surface area and strong acidity close to superacidity.

A new kind of porous hybridized nanocomposite: ω-sulfonic-perfluoroalkylated polyalkoxysilane/silica

A new kind of ω-sulfonic-perfluoroalkylated polyalkoxysilane/silica porous nanocomposite SFPAOS/SiO2 has been synthesized at mild conditions by following polycondensation of diphenyldimethoxysilane, perfluoroalkylation with ω-fluorosulfonylperfluorodiacyl peroxides (SFAP), alkali hydrolysis, gelation with tetraethoxysilane (TEOS) and acidification with aqueous HCl. The porous hybridized nanocomposite SFPAOS/SiO2 with superacidic terminal perfluoroalkylsulfonic acid groups analogous to Nafion was characterized by FTIR, SEM, TEM, TGA, XPS, EDX, acidimetry and nitrogen adsorption technique, and their pore structure and acidic amount were easily adjusted by controlling the reaction conditions of both gelation and perfluoroalkylation. Due to higher exchange capacity than that of commercial Nafion resin and its composite with SiO2, and stronger acidity than that of widely used macroporous Amberlyst 15, SFPAOS/SiO2 behaved higher activity and selectivity than these solid acids in cyclization of pseudoionone into α-ionone.

ω-Sulfonic-perfluoroalkylated poly(styrene–maleic anhydride)/silica hybridized nanocomposite as a new kind of solid acid catalyst

A new kind of ω-sulfonic-perfluoroalkylated poly(styrene–maleic anhydride)/silica hybrid nanocomposite FSMA/SiO2 has been synthesized under mild conditions by perfluoroalkylation of styrene–maleic anhydride copolymer (SMA) with ω-fluorosulfonylperfluorodiacyl peroxides (SFAP), and followed in turn by aminolysis using (3-aminopropyl)triethoxysilane (APTES), alkali hydrolysis, gelation with tetraethoxysilane (TEOS) and finally acidification. The hybrid solid acid FSMA/SiO2 with terminal perfluoroalkylsulfonic and carboxyl groups was characterized by FTIR, SEM, TEM, TGA, XPS, EDX, acidimetry and nitrogen sorption technique. Its pore structure, acid strength and acid amount were easily modulated by controlling the gelation and perfluoroalkylation conditions. The catalytic activity and selectivity, as well as reusability of FSMA/SiO2 were tested in three important reactions, namely, cyclization of pseudoionone, condensation of indole and esterification of benzoic acid. Owing to the higher exchange capacity than that of Nafion/SiO2, and the stronger acidity than that of Amberlyst-15, the nanocomposite FSMA/SiO2 showed higher activity and selectivity than these commercial solid acids in the reactions.

Cyclization of Pseudoionone to β-Ionone: Reaction Mechanism and Kinetics

Cyclization of pseudoionone (PI) to β-ionone is an important reaction used in the synthesis of vitamin A and in perfumery. Though the reaction is used for commercial production, its mechanism and kinetics are not known, and the same holds for the optimal performance of the process. This paper deals with experimental investigations of reaction mechanism and kinetics. The inherent characteristics of the reaction such as heat of reaction, thermal stability, and reactants/products distribution in biphasic (sulfuric acid-toluene) system was investigated experimentally. To overcome the mass transfer limitations, the intrinsic kinetics was studied in a batch reactor using a solvent (1-nitropropane) miscible with the reactant and the homogeneous catalyst. It was revealed that the reaction consists of two steps with the first being rapid, while the second is relatively slower. Therefore, the kinetics of only the second step was investigated which was observed to be first order with an activation energy of 65 kJ/mol.

Cyclization of Pseudoionone into α-Ionone Over Heteropolyacid Supported on Mesoporous Silica SBA-15

Cyclization of pseudoionone into α-ionone was performed over the series heteropolyacid supported on SBA-15 in liquid-phase at 363 and 373 K using a batch reactor. It has been demonstrated that the liquid-phase synthesis of α-ionone by pseudoionone cyclization can be efficiently achieved on heteropolyacid/SBA-15 materials. The high catalytic performance of PW12/SBA-15 materials is due to their strong Bronsted acidity, high dispersion of active phase and also to absence of steric constraints for pseudoionone cyclization. PW12/SBA-15 catalysts are specially active and selective for this reaction giving predominantly α-ionone, as the main product, with high yield (about 60% at 373 K after 2 h) close to that obtained via the homogeneous synthesis. This catalytic system is more active and efficient in comparison with heteropolyacid supported on commercial silica. In order to achieve comparable amount of α-ionone, as is got for PW12/SBA-15, belongs to apply five times more of the catalyst based on classical SiO2. Cyclization of pseudoionone was performed over the series heteropolyacid supported on SBA-15 in liquid phase at 363 and 373 K using a batch reactor. PW12/SBA-15 hybrid catalysts are specially active and selective for this reaction giving predominantly α-ionone, as the main product, with high yield (about 60% at 373 K) for the reaction carried out over catalyst with loading higher than 30 wt%. This value is comparable to that obtained via the homogeneous synthesis.

Ionone synthesis by cyclization of pseudoionone on silica-supported heteropolyacid catalysts

The liquid-phase cyclization of pseudoionone to ionones (α, β and γ isomers) was studied on silica-supported heteropolyacid (HPA) catalysts containing between 18.8 and 58.5% HPA. The HPA used was tungstophosphoric acid (H 3PW 12O 40). The catalyst surface and structural properties were thoroughly characterized by several techniques. The density, chemical nature and strength distribution of the surface acid sites were determined by adsorbing and monitoring by temperature-programmed desorption and infrared spectroscopy probe molecules such as NH 3 and pyridine. The pseudoionone conversion to ionones increased linearly with the Brønsted acid site density until the HPA loading approached to the monolayer saturation coverage. For higher HPA contents, the pseudoionone adsorption and conversion were hampered because of spatial constraints that diminished the reactant accessibility to the proton active sites. The highest ionone yield, 79%, was obtained on a 58.5 wt% HPA/SiO 2 catalyst at 383 K and is comparable to the best values reported in literature for the homogeneously catalyzed reaction using sulfuric acid. The ionone isomer distribution was modified by varying both the temperature and the reaction time. A reaction mechanism was postulated in which ionone isomers (α, β and γ) are primary products, but γ-ionone is isomerized to α-ionone while β-ionone is not converted in the other isomers.

Synthesis of Ionones by Cyclization of Pseudoionone on Solid Acid Catalysts

Ionone synthesis (α, β and γ isomers) by pseudoionone cyclization was studied on zeolite HBEA, Amberlyst 35W, SiO2–Al2O3, and unsupported and silica-supported heteropolyacids (HPA/SiO2). Ionone formation was preferentially promoted on strong Bronsted acid sites. A 79% ionone yield was obtained on 58.5 wt.% HPA/SiO2 after 1.5 h of reaction at 383 K and 250 kPa. This value is similar to the best yields reported for the homogeneously-catalyzed reaction using sulfuric acid.

Preparation and characterization of SO4 2−/TiO2 and S2O8 2−/TiO2 catalysts

Nanosized solid superacids SO4 2−/TiO2 and S2O8 2−/TiO2, as well as MCM-41-supported SO4 2−/ZrO2, were prepared. Their structures, acidities, and catalytic activities were investigated and compared using XRD, N2 adsorption-desorption, and in situ FTIR-pyridine adsorption, as well as an evaluation reaction with pseudoionone cyclization. The results showed that SO4 2−/TiO2 and S2O8 2−/TiO2 possess not only nanosized particles with diameters < 7.0 nm, a BET surface greater than 140 cm2/g and relatively regular mesostructures with pores around 4.0 nm, but also a pure anatase phase and strong acidity. Different from the Lewis acid nature of SO4 2−/ZrO2/MCM-41, SO4 2−/TiO2 and S2O8 2−/TiO2 exhibit mainly Bronsted acidities. The strongest Bronsted acid sites were produced on SO4 2−/TiO2 promoted with H2SO4, while Lewis acid sites on S2O8 2−/TiO2 even stronger than those on SO4 2−/ZrO2/MCM-41 were generated when persulfate solution was used as sulfating agent. Because of their distinct acid natures, SO4 2−/TiO2 and S2O8 2−/TiO2 exhibited catalytic activities for the cyclization of pseudoionone that were much higher than that of SO4 2−/ZrO2/MCM-41. It can be concluded that the existence of more Brønsted acid sites was favorable for proton participation in the cyclization reaction.

Catalytic Performance of Sulfated Silica MCM-41 for the Cyclization of Pseudoionone to Ionones

Abstract A series of sulfated silica MCM-41 samples denoted as SM and ASM were prepared by calcination at different temperatures using H2SO4 and (NH4)2SO4 solution as the promoter, respectively. The mesostructure, sulfation process, and surface acidity of the two samples were investigated by N2 adsorption-desorption, temperature-programmed desorption of adsorbed NH3 (NH3-TPD), thermogravimetric analysis (TG-DTG), elemental analysis, and Fourier transform infrared (FT-IR) spectroscopy. The activity of the samples for the traditional liquid acid-catalyzed cyclization reaction of pseudoionone to ionones was investigated. For the SM and ASM samples calcined at 450°C (denoted as SM-450 and ASM-450, respectively), SO42- was successfully chelated onto the silica surface in bidentate complex forms, and no free H2SO4 molecules existed as the original promoter or intermediate of thermal decomposition inside the mesopores. The in situ pyridine adsorption FT-IR and NH3-TPD measurements revealed that ASM-450 contained both Bronsted and Lewis acid sites of weak strength. The catalytic performance of SM-450 and ASM-450 was comparable with that of the commercial acid resin Amberlyst-15, and the chelating structure of SO42-/SiO2, which was generally considered to be inactive, was responsible for the high activity. ASM-450 showed better catalytic performance compared with Amberlyst-15 at relatively low temperature, and it could be reused 5 times with good activity.

A new type of hybridized macroreticular catalyst: Polystyrene with both perfluoroalkanesulfonic and sulfonic functional groups

A new type of solid acid catalyst (FPSS) with two different acid functional groups, aromatic sulfonic similar to that of Amberlyst and perfluoroalkanesulfonic similar to that of Nafion, was synthesized by the following aromatic ω-fluorosulfonylperfluoroalkylation with perfluorodiacyl peroxide (SFAP), chlorosulfonation, hydrolysis and acidification. By changing synthetic conditions, the loading of two acid functional groups can be modulated. The FPSS resins showed high activity and good α-ionone selectivity in cyclization of pseudoionone.

Sulfated and Persulfated TiO2/MCM-41 Prepared by Grafting Method and their Acid-catalytic Activities for Cyclization of Pseudoionone

Solid acid catalysts of SO 4 2− /TiO2/MCM-41 and S2O 8 2− /TiO2/MCM-41 were prepared via grafting method and sulfate/persulfate promotion. The catalysts exhibited desirable activity and better selectivity for cyclization reaction of pseudoionone compared to traditional SO 4 2− /TiO2. A combination of XRD, N2 adsorption–desorption and FTIR spectroscopy indicated that the catalysts possess well-ordered mesostructure, and the grafted TiO2 are in highly dispersed amorphous form rather than crystalline phase. For S2O 8 2− /TiO2/MCM-41 higher S content and more Bronsted acid sites can be achieved by persulfation, which is favorable for the protons participated cyclization reaction. The similar Si–O–Ti–O–S=O structure of all acid sites on pore surface of the catalysts is attributed to the improvement of selectivity in comparison with SO 4 2− /TiO2.

Macroreticular p-(ω-sulfonic-perfluoroalkylated) polystyrene ion-exchange resins: a new type of selective solid acid catalyst

Macroreticular p-(omega-sulfonic-perfluoroalkylated) polystyrene (FPS) cation-exchange resins have been synthesized by sequential p-perfluoroalkylation of macroreticular polystyrene (PS) with omega-fluorosulfonylperfluorodiacyl peroxide 2, hydrolysis and acidification; the fluorinated mesoporous resins exhibited higher activity and selectivity than commercial Amberlyst 36 and Nafion NR50 in the cyclization of pseudoionone.

Cyclization of Pseudoionone by Acidic Reagents.

Cyclization of Pseudoionone by Acidic Reagents.