Reaction Of Anisole Research Articles

IMPROVED ACIDITY OF MESOPOROUS ZrO2-WO3 THROUGH NH3-AIR SUBSECTION-CALCINATION TREATMENT

ZrO2-WO3 mixed metal oxides are important solid acid catalysts, and typically, ammonia gas calcination reduces their acidity. However, in this study, we introduce an updated NH3 calcination technique that can increase the acidity of mesoporous ZrO2-WO3 solid acids. Their structures and acid properties were thoroughly characterized through X-ray diffraction (XRD), N2 adsorption measurement, pyridine-adsorbed infrared spectroscopy (Py-IR), temperature-programmed desorption of ammonia (NH3-TPD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis-DRS) analysis. The resulting materials exhibit remarkable activity in the Friedel-Crafts (F-C) reaction of anisole and benzyl alcohol. Our investigations showed that the subnanometer WOx clusters act as the most active sites for the F-C reaction, and NH3-air calcination is essential for the formation of WOx clusters. This treatment not only enhances acidity but also provides a novel method of obtaining acidic ZrO2-WO3 mixed metal oxides. Most importantly, it presents a fresh approach for regulating the formation of WO3 clusters and catalytic activity.

Bimetallic Niobium-Based Catalysts Supported on SBA-15 for Hydrodeoxygenation of Anisole

The effect of adding iron, cobalt or nickel to a prepared niobium-supported catalyst using mesoporous silica SBA-15 as a support was evaluated in the hydrodeoxygenation (HDO) reaction of anisole, chosen as a model compound in lignocellulosic biomass derived bio-oil. HDO activity as well as selectivity toward O-free products were highly dependent on the catalyst formulation: Ni incorporation showed the highest anisole conversion and selectivity to deoxygenated products, followed by Co and Fe counterparts. The activity was explained in terms of acidity, metal surface exposure and reducibility as a function of the interaction between the phases present. Regarding the characterization results, the better performance of NiNb/SBA-15 was associated with its lower acidity, higher Nb/Si surface exposure, NbO2/Nb2O5 ratio and better interaction between Ni and Nb species.

Mechanistic study of the hydrodeoxygenation of lignin-derived oxygenates on a CoPt bimetallic catalyst: reaction of anisole on Co-modified Pt(111)

Temperature programmed desorption and high-resolution electron energy loss spectroscopy were used to characterize the adsorption and reaction of anisole (C6H5–OCH3) on Pt(111) and Co-decorated Pt(111) surfaces. On both surfaces anisole was found to undergo O–CH3 bond cleavage to form an oxocyclohexadienyl-structured intermediate (C6H6O) which bonds to the surface in a η5-π configuration. Interaction of the O atom in this intermediate with Co adatoms was found to facilitate selective cleavage of the C–O bond to produce adsorbed benzene or phenyl groups. In parallel with this pathway, unselective decomposition of adsorbed anisole was also found to occur. The results obtained in this study along with those previously reported for the reaction of anisole on Zn-decorated Pt(111) surfaces provide further insight into how the addition of a second more oxyphilic metal to Pt affects surface reaction pathways and the hydrodeoxygenation selectivity of lignin-derived aromatic oxygenates.

Catalytic activity of niobium phosphate in the benzylation of anisole with styrene, benzyl alcohol and benzyl chloride

The catalytic activity of niobium phosphate was evaluated in the benzylation of anisole with three alkylating agents. Niobium phosphate was characterized by N2 adsorption, X-ray diffraction (XRD), solid state 31P NMR, NH3-TPD, structural FTIR and FTIR after adsorption of pyridine in order to determine its physico-chemical properties. The influence of catalyst calcination in the benzylation conversion was studied. A comparison between the benzylation with benzyl alcohol, benzyl chloride and styrene was done. The results indicated that the conversion of the benzyl alcohol and styrene on niobium phosphate was extremely dependent on the pre-treatment temperature. The catalyst calcined at 773 K showed high activity and selectivity to benzylated products in the benzylation with all alkylating agents and the conversion order was benzyl chloride > styrene > benzyl alcohol. Competitive reactions were also performed with two alkylating agents simultaneously. In the reaction of anisole with both benzyl alcohol and benzyl chloride, the alcohol was consumed faster than the chloride. The behavior indicates a phenomenon related to preferential adsorption, in which the alkylating agents compete for the sites, mainly Lewis sites, on the niobium phosphate. In the reaction of anisole with both styrene and benzyl alcohol, there was also an inversion of the relative reactivity, the alcohol was consumed faster, and in the reaction of anisole with styrene and benzyl chloride, both of them have presented similar conversions probably because HCl formed in the reaction with benzyl chloride catalysis the reaction of styrene.

Gas phase hydrodeoxygenation of anisole and guaiacol to aromatics with a high selectivity over Ni-Mo/SiO2

A very active Ni-Mo bimetallic catalyst supported on SiO2 was prepared for the hydrodeoxygenation (HDO) reaction of anisole and guaiacol under a H2 partial pressure of 83kPa. Generally, transition metal and their oxides were thought to have less HDO activity than others, such as sulfides, carbides, phosphides. However, this work achieved a novel deoxygenation result, where a high conversion (98.7%) at 673–693°C and atmospheric pressure for the model compounds and high selectivity (>96%) to aromatic hydrocarbons (BTX) were obtained. Furthermore, the methyl transfer reaction is greatly promoted by abundant acid sites of the catalyst, leading to a low carbon-loss. The present work provides a promising way and new insight for an economic and efficient HDO process for the lignin-derived thermal degradation products.

Cationic Scandium Anisyl Species in Styrene Polymerization Using Anisole and N,N-Dimethyl-o-toluidine as Chain-Transfer Agents

This work aimed to clarify the involvement of a cationic scandium anisyl species in the scandium-catalyzed chain-transfer polymerization of styrene using anisole as a chain-transfer agent (CTA) as well as its behavior in the presence of N,N-dimethyl-o-toluidine. The reaction of anisole with the catalyst precursor [(C5Me4SiMe3)Sc(CH2C6H4NMe2-o)][B(C6F5)4] (2) generated by the reaction of (C5Me4SiMe3)Sc(CH2C6H4NMe2-o)2 (1) with [Ph3C][B(C6F5)4] gave the structurally characterizable anisole-coordinated ion-pair complex [(C5Me4SiMe3)Sc(CH2C6H4NMe2-o)(C6H5OMe)][B(C6F5)4] (3). The aminobenzyl unit in 3 remained intact even in the presence of an excess amount of anisole. The formation of an anisyl species from 3 was not observed by 1H NMR. However, the polymerization of styrene by 3 at either room temperature or 70 °C yielded the anisyl-end-functionalized syndiotactic polystyrene (sPS) as a major product in addition to the dimethylaminobenzyl-end-capped sPS. These results suggest that an equilibrium between the ...

The use of bimetallics to control the selectivity for the upgrading of lignin-derived oxygenates: Reaction of anisole on Pt and PtZn catalysts

The adsorption and reaction of anisole on Pt and PtZn catalysts were investigated using both model single crystal and high surface area supported metal catalysts. Temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS) studies of the interaction of anisole with Pt(111) demonstrated that there is a strong interaction between the phenyl ring of anisole and the surface, resulting in CO and CH bond scission at relatively low temperatures. In contrast, anisole was observed to bond to a Zn-modified Pt(111) surface primarily via the oxygen at Zn sites or possibly adjacent Pt sites, with the phenyl ring tilted away from the surface. Such bonding configuration facilitated selective CO bond cleavage producing phenyl groups and methoxide groups with the latter being bonded to the Zn sites. These results suggested that PtZn may be an effective catalyst for hydrodeoxygenation (HDO) of lignin-derived aromatic oxygenates with low activity for ring hydrogenation. This hypothesis was then tested and verified by investigating the reaction of anisole and H2 over high surface area carbon-supported Pt and PtZn catalysts.

Formation of Subnanometer Zr-WOx Clusters within Mesoporous W–Zr Mixed Oxides as Strong Solid Acid Catalysts for Friedel–Crafts Alkylation

WO3-ZrO2 mixed metal oxides is an important class of acid solid. Here, we successfully synthesized a variety of mesoporous WO3-ZrO2 mixed metal oxides by a well-controlled sol-gel process (AcHE) using Zr(OBu)(4) and WCl6 as the inorganic precursors in the presence of poly block copolymer F127. Their structures and acid properties have been well characterized by XRD, Raman, N-2 adsorption measurement, and HRTEM analyses. In addition, new insights from TG-DSC and P-31 NMR characterization also provide useful information on the formation of strong acidity of this important solid acid. Moreover, their structure-to-properties relationship has been studied in the Friedel-Crafts (F-C) reaction of anisole and benzyl alcohol. We identified that the subnanometer WOx clusters act as the most active sites for the F-C reaction. Most importantly, we show that the formation of these subnanometer WOx clusters can be rationally controlled. It is shown that a minimum W concentration (0.07 at the calcination temperature of 800 degrees C) and a minimum calcination temperature (650 degrees C at a given W concentration of 0.1) are required during the preparation of these acid catalysts for the development of highly active subnano WOx clusters.

ChemInform Abstract: Retropinacol Rearrangement in the Synthesis of 3,3,4‐Trimethyl‐2‐azaspiro[4.5]deca‐1,6,9‐trien‐8‐one Derivatives.

AbstractWith the object to obtaining biologically active substances, the three‐component reaction of anisole (I), pivalaldehyde (II) and nitriles (III) is performed.

Activation of Anisole by Organoplatinum(II) Complexes: Evidence for Rate-Determining C–H Activation

A study of the basis of selectivity of C–H bond activation of anisole by electrophilic methylplatinum(II) complexes is reported. Anisole reacts with [PtXMe(NN)] in trifluoroethanol solvent to give methane and [PtXAr(NN)], Ar = 2-, 3-, and 4-anisyl, in 90:8:2 ratio when X = HOB(C6F5)3 and NN = (2-C5H4N)2CO (DPK) but not when NN = 2,2′-bipyridine. Similar results are obtained when X = triflate or when NN = (2-C5H4N)2NH. Competition between reaction of anisole and anisole-d8 with [PtXMe(NN)], X = HOB(C6F5)3 and NN = DPK, in trifluoroethanol gave an isotope effect kH/kD = 3.6. Several 4-anisyl complexes, [PtClAr(NN)], [PtAr2(NN)], and [PtMeAr(NN)], NN = DPK, DPA, or bipy, were prepared and reacted with HX [X = Cl, OTf, or HOB(C6F5)3]. Reaction of [PtMeAr(NN)], NN = DPK or bipy, with HX gave a detectable hydride [PtXHMeAr(NN)] when X = Cl, followed by loss of methane to give [PtClAr(NN)], but only [Pt(OTf)Ar(NN)] was detected when X = OTf. Reaction with more HOTf gave anisole and [PtX2(NN)], X = OTf, and no isomerization of the 4-anisyl group to the more favored 2-anisyl group was observed at any stage. The similar reaction of [PtMeAr(NN)] and HOTf in CD3OD/CD2Cl2 gave CHnD4–n (n = 0–4) and mostly 4-MeOC6H4D. It is argued that the anisole C–H bond cleavage step in anisole activation, or the anisyl–H bond forming step in protonolysis, is responsible for the observed selectivity in these reactions.

Retropinacol rearrangement in the synthesis of 3,3,4-trimethyl-2-azaspiro[4.5]deca-1,6,9-trien-8-one derivatives

In the recent years 2-azaspiro[4.5]deca-1,6,9-trien8-one derivatives have attracted researchers’ attention due to their biological activity [1, 2]. These compounds may be synthesized in different ways; for example, 7-methoxy-2-methyl-2-azaspiro[4.5]deca-6,9diene-3,8-dione was obtained by heating 2-[(3,4-dimethoxybenzyl)(methyl)amino]-2-oxoethyldiazonium salt for a short time [3]. The simplest procedure for the synthesis of 2-azaspiro[4.5]deca-1,6,9-trien-8-one derivatives is based on three-component condensation of substituted anisole with isobutyraldehyde and nitrile in concentrated sulfuric acid [4–7]. Generation of carbenium ion as key intermediate in the Ritter heterocyclization is also possible via retropinacol rearrangement of the corresponding alcohol [8]; in this way, 3,3,4-trimethyl-3,4-dihydroisoquinoline derivatives can be obtained. In fact, by reaction of anisole (I) or 1-methoxynaphthalene (II) with pivalaldehyde and nitriles (such as methyl thiocyanate and methyl and ethyl cyanoacetates) under the conditions described in [8] we obtained the corresponding 2-azaspiro[4.5]deca-1,6,9-trien-8-one derivatives III–VIII in 28–49% yield (Scheme 1). The reaction was accompanied by concurrent Danilov rearrangement [9], so that 2 equiv of pivalaldehyde was necessary.

Sulfonation of anisole, phenol, toluene and related alkyl and alkoxy derivatives with SO3. The influence of the solvent system on the reactivity and the sulfonic acid product distribution

The reactions of anisole (1), phenol (2), the alkoxy- and alkylphenyl ethers 3–11, toluene (12) and the o-dialkylbenzenes 13–15 with sulfur trioxide in dichloromethane or trichlorofluoromethane have been studied. Our results have been compared with those obtained with the same substrates upon reaction with SO3 in nitromethane and dioxane. We show that ortho substitution is enhanced for sterically unhindered phenyl ethers and phenols due to complex formation between SO3 and the C(sp2)-bonded oxygen when dichloromethane is used as solvent instead of nitromethane or dioxane. This is mainly as a result of intramolecular SO3, transfer from the oxygen to the ortho carbon and subsequent conversion of the resulting σ-complex into the ortho sulfonic acid.

Benzoylation of Anisole over Silicotungstic Acid Modified Mesoporous Alumina

Mesoporous alumina (MA) molecular sieves were synthesized by using aluminum sec-butoxide as Al precursor and lauric acid as the structure directing agent. The synthesized MA was functionalized with silicotungstic acid (STA) via wet impregnation method and characterized by various physico-chemical techniques. The XRD patterns of a series of HPA functionalized MA are showing the ordered structures. N2 sorption analysis shows type IV isotherm. NH3–TPD measurements revealed an increase in number of acid sites with an increase in loading of STA over MA. At the same time decrease in the acidity was observed with the increase in calcination temperature of the supported materials. Functionalization of STA were also carried out over different alumina supports such as catapol-B (CB) and alumina synthesized without surfactant (ASW) and their activities were evaluated by carrying out liquid phase Friedel–Craft acylation (FC) reaction of anisole with p-toluoyl chloride in a batch reactor at 120 °C. Recycling was performed in the FC reaction using 30 wt% STA–MA two times and no major deactivation of the catalyst was observed.

Highly efficient heterogeneous acylations of aromatic compounds with acid anhydrides and carboxylic acids by montmorillonite-enwrapped titanium as a solid acid catalyst

Montmorillonite-enwrapped titanium hydroxide species (Ti4+-mont) acted as a highly efficient heterogeneous acid catalyst for the acylation of aromatic compounds with acid anhydrides or carboxylic acids. The catalytic activity of the Ti4+-mont was higher than those of other acid catalysts such as zeolites, SO42−/ZrO2 and p-toluenesulfonic acid. For example, the reaction of anisole with dodecanoic acid in the presence of the Ti4+-mont catalyst gave 1-(4-methoxyphenyl)-1-dodecanone in 97% yield. Furthermore, the Ti4+-mont catalyst was easily separated from the reaction mixture and was recyclable.

An investigation into factors which influence the formation of p-cresol in the methanol alkylation of phenol over MCM-22 and ZSM-5

In the methanol alkylation of phenol, the primary products are anisole and cresol. Secondary reactions mainly result from further reactions of anisole. In the present study, it was observed that p-cresol formed preferentially, i.e. greater than the thermodynamically expected amount, over H-MCM-22, especially in the case of catalysts where the crystallite sizes were greater than approximately 1 μm. It is thus proposed that in the case of MCM-22 the 10MR pores in the layers allow easy diffusion of p-cresol and that the effect of this phenomenon is enhanced when the crystallite sizes are relatively large. Many similar observations have been made in the case of the methylation of toluene. Steaming of H-MCM-22 also produces the enhanced diffusional resistance due to the presence of the extra-framework Al species. Further investigations in which the internal acid sites were inertized supported the above observations.

Friedel–Crafts hydroxyalkylation: reaction of anisole with paraformaldehyde catalyzed by zeolites in supercritical CO 2

Supercritical CO 2 has been found to be a very convenient reaction medium for the Friedel–Crafts hydroxyalkylation of anisole with paraformaldehyde. The high diffusion coefficients of molecules in the supercritical state are a crucial factor contributing to the catalytic activity when the reaction is carried out with microporous zeolites. Thus, the activity of mordenite for the hydroxyalkylation in supercritical CO 2 at 60 °C is about threefold higher than that observed for the same zeolite in toluene at 110 °C.

Synthesis and Rearrangement of 1‐Substituted 3,3,7‐Trimethyl‐2‐azaspiro[4.5]deca‐1,6,9‐trien‐8‐ones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis and rearrangement of 1-substituted 3,3,7-trimethyl-2-azaspiro[4.5]deca-1,6,9-trien-8-ones

We previously synthesized 3,3-dimethyl-1-methylthio-2-azaspiro[4.5]deca-1,6,9-trien-8-one by threecomponent condensation of anisole, 1,2-epoxy-2methylpropane, and nitriles in the presence of concentrated sulfuric acid [1]. An analogous result was obtained in the reaction of anisole with isobutyraldehyde and nitriles [2]. Taking into account that the product composition strongly depends on the nature and position of substituents in the aromatic ring [3], we thought it reasonable to examine the same transformation of anisole homologs, in particular of methyl o-tolyl ether. We have fount that introduction of a methyl group into the ortho-position of anisole does not change the reaction direction. Addition of an equimolar mixture of methyl o-tolyl ether, isobutyraldehyde, and methyl thiocyanate to concentrated sulfuric acid at 035oC, followed by dilution of the reaction mixture with cold water and neutralization of the aqueous phase with ammonium carbonate, leads to formation of 3,3,7-trimethyl-1-methylthio-2-azaspiro[4.5]deca1,6,9-trien-8-one (IIa) in 67% yield. The isolated product was a single enantiomer whose configuration was not determined. The presence of an asymmetric spiro-carbon atom in molecule IIa is confirmed by the H NMR spectrum, where splitting of signals from diastereotopic protons of the CH2 and 3-CH3 groups is observed. Spiro compounds IIb and IIc, formed in the reactions with ethyl cyanoacetate and cyanoacetamide, undergo dienone3phenol rearrangement during isolation. As a result, amides III and IV were obtained. The relatively ready hydrolysis of structurally related ____________ * This study was financially supported by the Russian Foundation for Basic Research (project no. 01-03-96 479). spiro compounds with carbonyl-containing groups (derived from anisole) was noted by us previously [4]. 3,3,7-Trimethyl-1-methylthio-2-azaspiro[4.5]deca-1,6,9-trien-8-one (IIa). A mixture of 12.2 g (0.1 mol) of methyl o-tolyl ether, 7.2 g (0.1 mol) of isobutyraldehyde, and 7.3 g (0.1 mol) of methyl thiocyanate was added dropwise over a period of 15320 min to 50 ml of 96% sulfuric acid stirred at 035oC. The mixture was stirred for 30 min, poured into 300 ml of water, and extracted with 50 ml of toluene. The aqueous phase was separated and neutralized with (NH4)2CO3 to pH 839. The precipitate was filtered off, washed with water, dried, and recrystallized twice from methanol. Yield 15.75 g (67%), mp 63364oC. IR spectrum, n, cm: 1660 (CIO), 1630 (CIC), 1605 (CIN), 1580. H NMR spectrum, d, ppm: 1.36 s and 1.39 s (6H, 3-CH3), 1.82 s (3H, 7-CH3), 2.18 s and 2.20 s (2H, 4-H),

Anisole Alkylation with N-Arenesulfonylimines of Dichloro(phenyl)acetaldehyde and Derivatives Thereof

N-[1-4-Methoxyphenyl-2-phenyl-2,2-dichloroethyl]arenesulfonamides are formed in reaction of N-(2-phenyl-2,2-dichloroethylidene)-4-chlorobenzenesulfonamide and N-(2-phenyl-2,2-dichloroethylidene)-4-methylbenzenesulfonamide with anisole catalyzed by boron trifluoride etherate, and in reaction of anisole with 1,1-di(arenesulfonamido)-2-phenyl-2,2,-dichloroethanes in the presence of concentrated sulfuric acid.

Zeolite Catalysts as Solid Solvents in Fine Chemicals Synthesis: 2. Competitive Adsorption of the Reactants and Products in the Friedel–Crafts Acetylations of Anisole and Toluene

The liquid-phase acetylations of anisole by acetic anhydride and isopropenyl acetate and that of toluene by acetic anhydride, using zeolites HBEA, HMFI, and HFAU as catalysts, were carried out under batch conditions using various molar ratios of the reactants without added solvent. Evidence has been obtained for competitive adsorption effects of the reactants resulting from differences in their adsorption equilibrium constants (AEC). Estimated values of the AEC show that preferential adsorption is in the order toluene<acetic anhydride (AA)<anisole<isopropenyl acetate (IPA). In all cases, the acetylation products are adsorbed more strongly than the reactants, but the competitive adsorption of acetic acid and acetone appear to be negligible when AA and IPA are used as acetylating agents, respectively. The effect of dealumination was investigated for the acetylation of toluene by acetic anhydride, using HBEA as catalyst. Both the initial and the quasi-stationary-state reaction rates are proportional to Al content, i.e., the number of Brønsted sites at low Al content. The rates decrease at high aluminium content, indicating that competitive adsorption effects are enhanced due to the increased zeolite polarity and polarisability. Initial rate constants for the acetylation of anisole, derived by assuming a Langmuir–Hinshelwood model, show that the rate-determining step is most likely to be the reaction of anisole with an acyl cation equivalent formed by reaction of either acetic anhydride or isopropenyl acetate with the zeolite (HBEA). A possible mechanism is proposed in which the formation of an acyl cation–zeolite complex is the initial step. This proposal is based in part on the colour change of the zeolite when it is contacted with the reactant mixture and during reaction, the colour being attributed to the formation of the zeolite–acyl cation complex. The present work confirms that competitive adsorption effects, involving both reactants and products, need to be controlled in order to achieve maximum catalytic performance when zeolites are used as catalysts in the liquid phase.