Acylation Of 2-methoxynaphthalene Research Articles

Hierarchical ZSM-5 zeolite with uniform mesopores and improved catalytic properties

Uniform mesopores are generated in hierarchical ZSM-5 by a mesopore narrowing treatment, showing enhanced activity in the acylation of 2-methoxynaphthalene.

Alkylation of phenols and acylation 2-methoxynaphthalene over SSZ-33, SSZ-35 and SSZ-42 zeolites

Zeolites with different framework topology (SSZ-33, SSZ-35 and SSZ-42) were investigated in alkylation of phenol, m-cresol and p-cresol, and acylation of 2-methoxynaphthalene. Their catalytic behavior was compared with commercial zeolites BEA, USY, MOR and ZSM-5. Borosilicates SSZ-33 and SSZ-42 were isomorphously substituted into aluminum form by low temperature hydrothermal treatment. The phenol conversions decreased in the order: BEA 91.9% ∼ SSZ-33 90.5% > MOR 58.0% > SSZ-35 38.0% > SSZ-42 22.6%. The selectivity to C-alkylated product 2-cyclohexylphenol prevailed over selectivity to 4-cyclohexylphenol and phenyl cyclohexyl ether almost for all tested catalysts. The selectivities to 2-cylcohexylphenol were as follows: SSZ-35 85% > BEA 67% > SSZ-33 42% > SSZ-42 35% (at conversion of cyclohexene = 20%). Zeolite SSZ-33 was quite effective catalyst in acylation of 2-methoxynaphthalene. The conversions of 2-methoxynaphthalene achieved over SSZ-33 zeolite were similar to that obtained over zeolite BEA. The selectivities to 2-acetyl-6-methoxynaphthalene achieved over zeolites BEA and SSZ-33 were in the range 48–63 % for both tested acylating agents.

Synthesis of SFH-type aluminosilicate zeolite with 14-membered ring and its applications as solid acidic catalyst

The direct-synthesis method for preparing the SFH-type aluminosilicate zeolites, designated as [Al,B]-SFH-D, was successfully improved by adding the calcined SFH-type borosilicate zeolite as seeds into the mother gel in the presence of N,N,N-trimethyl-phenylcyclohexylmethylammonium hydroxide as organic-structure-directing agent. As a control, by the conventional post-synthesis method, the SFH-type aluminosilicate zeolites, designated as [Al,B]-SFH-P, were prepared. Thus prepared SFH-type aluminosilicate zeolites were characterized in details. The high-resolution 27Al MAS NMR results implied that there are marked differences in the distribution of Al atoms in the framework between the zeolites obtained by the direct- and post-synthesis methods. [Al,B]-SFH-D exhibited a higher catalytic performance in the acylation of 2-methoxynaphthalene with acetic anhydride than [Al,B]-SFH-P.

Single-Step Delamination of a MWW Borosilicate Layered Zeolite Precursor under Mild Conditions without Surfactant and Sonication

Layered borosilicate zeolite precursor ERB-1P (Si/B = 11) is delaminated via isomorphous substitution of Al for B using a simple aqueous Al(NO3)3 treatment. Characterization by PXRD shows loss of long-range order, and TEM demonstrates transformation of rectilinear layers in the precursor to single and curved layers in the delaminated material. N2 physisorption and base titration confirm the expected decrease of micropore volume and increase in external surface area for delaminated materials relative to their calcined 3D zeolite counterpart, whereas FTIR and multinuclear NMR spectroscopies demonstrate synthesis of Brønsted acid sites upon delamination. Comparative synthetic studies demonstrate that this new delamination method requires (i) a borosilicate layered zeolite precursor, in which boron atoms can be isomorphously substituted by aluminum, (ii) neutral amine pore fillers instead of rigid and large quaternary amine SDAs, and (iii) careful temperature control, with the preferred temperature window being around 135 °C for ERB-1P delamination. Acylation of 2-methoxynaphthalene was used as a model reaction to investigate the catalytic benefits of delamination. A partially dealuminated delaminated material displays a 2.3-fold enhancement in its initial rate of catalysis relative to the 3D calcined material, which is nearly equal to its 2.5-fold measured increase in external surface area. This simple, surfactant- and sonication-free, mild delamination method is expected to find broad implementation for the synthesis of delaminated zeolite catalysts.

Acilação de Friedel-Crafts do 2-metoxinaftaleno usando o ácido dodecafosfotúngstico suportado em sílica (HPW/SiO2) como catalisador e acetonitrila como solvente

The synthesis of fine chemicals intermediates using Friedel-Crafts acylation is one of the most important methods in chemical technology. In this work, the acylation of 2-methoxynaphthalene with acetic anhydride using a silica-supported dodecatungstophosphoric acid catalyst (HPW/SiO2) and acetonitrila as solvent was studied, showing that this reaction is a feasible alternative to produce intermediaries to replace the current methods of production. The reactions using acetonitrile solvent showed yields greater than or equal to the reactions using traditional solvents such as nitrobenzene and dichloroethane. Finally, the modified Eley-Rideal mechanism was proposed to elucidate the experimental data obtained.

Acylation of 2-methoxynaphthalene with acetic anhydride over silica-embedded triflate catalysts

Silica sol–gel immobilized triflate compounds like La(OTf) 3, tert-butyldimethylsilyl trifluoromethanesulfonate (BDMST) and triflic acid (HOTf) were tested in the acylation of 2-methoxynaphthalene with acetic anhydride, leading to 1-acetyl-2-methoxynaphthalene as the major product. The reaction only proceeded with good yields on BDMST and HOTf catalysts, while La(OTf) 3 presented a low activity. For BDMST in solvent-free conditions, the resulting TOF was superior to that reported in literature for other heterogeneous catalysts and even for homogeneous triflates. The rates of reactions in various solvents strongly depend on the donor number of these solvents.

Friedel-crafts acylation of 2-methoxynaphthalene over h-beta catalysts: effect of Si/Al ratio

The acylation of 2-methoxynaphthalene with acetic anhydride was carried out over zeolite beta catalysts having various Si/Al ratios. It was found that the reaction performance is strongly dependent on the Si/Al ratio of the catalyst. The catalytic reaction features were elucidated in terms of the acidic properties of the catalysts.

Acylation of 2-Methoxynaphthalene and Isobutylbenzene over Zeolite Beta

The acylation of 2-methoxynaphthalene (2MN) with acetic anhydride is carried out in the liquid phase in the presence of zeolite beta. Two main products, 1-acetyl-2-methoxynaphthalene (1,2-AMN) and the desired 2-acetyl-6-methoxynaphthalene (2,6-AMN) are obtained. Variations of reaction temperature, the concentration of the acylating agent, and the weight of the catalyst are investigated to find reaction conditions sufficient to provide for good conversion of 2MN and limited deactivation. Surface-poisoning experiments show that the formation of 1,2-AMN occurs on the external surface of the zeolite. When the external surface of zeolite beta is passivated by coating with amorphous silica, a significant increase in the selectivity of 2,6-AMN is observed and this result is a clear example of shape-selective acylation with zeolite catalysts. The acylation of isobutylbenzene with acetic anhydride is investigated also. At conversions of around 10%, the selectivity to 4-isobutylacetophenone is excellent (>97%). For the acylation of isobutylbenzene, the external surface of the zeolite contributes significantly to the formation of 4-isobutylacetophenone, so the shape-selective properties of the zeolite are not utilized.

Solid acid catalysed acylation of 2-methoxy-naphthalene: role of intraparticle diffusional resistance

Synthesis of fine chemicals and intermediates by using Friedel–Crafts acylations is important in organic chemical technology. In most of the cases very good yields and selectivity can be obtained with aluminium chloride as catalyst in conjunction with nitrobenzene as solvent. However, with the current environmental restrictions, replacement of aluminium chloride–nitrobenzene pair with solid acid catalysts has great industrial relevance. Acylation of 2-methoxynaphthalene (2-MON), also known as yarayara, with acetic anhydride, was carried out using different solid acid catalysts such as zeolites, acid activated clays, ion exchange resins and sulphated zirconia. The products of the reaction are precursors for many organic and pharmaceutical products. The reaction products were isolated and confirmed by their melting points, 1H-NMR, gas chromatography, etc. A mathematical model is built to describe the kinetics of the reaction. At high molar ratios of acetic anhydride to 2-MON, the reaction is limited by intraparticle diffusion of the substrate 2-MON. However, this barrier is overcome for equimolar qualities. The reaction proceeds through the Eley–Rideal type of mechanism, wherein the chemisorbed acetic anhydride generates a carbocation and acetic acid, and the carbocation reacts with 2-MON from the liquid phase within the pore space to form 1-acetyl-2-methoxy-naphthalene.

Acylation of 2-Methoxynaphthalene in the Presence of Modified Zeolite HBEA

The influence of postsynthesis treatment such as calcination and acid treatment of zeolite HBEA has been studied in the acylation of 2-methoxynaphthalene with acetic anhydride. The contribution of the inner and outer surface of zeolite HBEA is examined by conversion and product selectivity to a bulky product, which can be formed only on the outer surface of HBEA, and to a linear product, which can be formed on the inner and outer surfaces. Calcination under high heating rate enhances the catalytic activity of the inner surface due to the formation of extraframework alumina species in the micropores. FTIR-adsorption experiments of the bulky probe molecule 2,4,6-tri-tert-butylpyridine, which does not fit into the micropores, revealed that these alumina species are located preferentially in the micropores of HBEA. Acid treatment increases the catalytic activity of the outer surface due to the extraction of catalytically active extraframework alumina species out of the micropores and due to the formation of silanol groups, respectively.

Acylation of 2-methoxynaphthalene with acyl chlorides in the presence of a catalytic amount of Lewis acids

The regiochemistry of the reaction of 2-methoxynaphthalene 1 with benzoyl chloride 2a using a catalytic amount of a Lewis acid is strongly influenced by the identity of the acid catalyst employed as well as by the reaction temperature. By using InCl3, FeCl3, SnCl4 or ZnCl2 and heating at 160 °C, 2-benzoyl-6-methoxynaphthalene 4a is selectively produced along with 1-benzoyl-7-methoxynaphthalene 5a, while in the case of AlCl3, SbCl5 or TiCl4, 1-benzoyl-2-methoxynaphthalene 3a is the major product. 2-Acyl-6-methoxynaphthalenes 4b–e can be selectively obtained using InCl3 and the corresponding acyl chlorides 2b–e in place of 2a. In the presence of a stoichiometric amount of InCl3, the reaction of 1 with 2a also gives 4a as the predominant product along with 5a even at 50 °C. This reaction appears to involve isomerisation of 3a to 4a and 5a.