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Benzodioxinols, compounds with 6-membered heterocycles containing two oxygen atoms, exhibit promising analgesic activity. In the current study, synthesis of dioxinol via two-step approach including Prins cyclization of isopulegol with benzaldehyde to tetrahydropyran and its ring-rearrangement to dioxinol was investigated. Different acidic and basic catalysts were studied in the second step and the highest selectivity toward dioxinol was achieved using mesoporous Ce-composite material. [ABSTRACT FROM AUTHOR]

Woodextractives such as α-pinene oxide and β-pineneoxide are important renewable chemicals for the synthesis of finechemicals, pharmaceuticals, and value-added intermediates. In thiswork, catalytic transformations of biomass derived extractives, isomerizationof α,β-pinene oxides were studied over supported ionicliquid catalysts (SILCAs). SILCAs consist of catalytic species (e.g.,metal nanoparticles or metal complexes) in a thin layer of ionic liquidwhich is immobilized on a solid support material (e.g., active carboncloth). The reaction kinetics of the isomerization reactions oversupported ionic liquid catalysts were studied and modeled. Mechanistickinetic models describing the differences in selectivity and activityof the catalysts containing different ionic liquids were developed,and the models described the reaction rates and product distributionsvery well. [ABSTRACT FROM AUTHOR]

The isomerisation of α-pinene oxide to campholenic aldehyde, an expensive ingredient utilized by e.g. flavor industry, was studied over Supported Ionic Liquid Catalysts (SILCAs) consisting of catalytically active species residing in ionic liquid. The ionic liquid, in turn, was immobilized on a solid support material. SILCAs were demonstrated as efficient catalysts for the transformation of α-pinene oxide into campholenic aldehyde, with the product distribution and activity being dependent on the nature of the ionic liquid. [ABSTRACT FROM AUTHOR]

Ce-modified mesoporous silica materials MCM-41 and SBA-15, namely 32 wt % Ce-Si-MCM-41, 16 wt % Ce-H-MCM-41 and 20 wt % Ce-Si-SBA-15, were prepared, characterized and studied in the selective preparation of trans-carveol by α-pinene oxide isomerization. The characterizations of these catalysts were performed using scanning electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption and FTIR pyridine adsorption. Selective preparation of trans-carveol was carried out in the liquid phase in a batch reactor. The activity and the selectivity of catalyst were observed to be influenced by their acidity, basicity and morphology of the mesoporous materials. The formation of trans-carveol is moreover strongly influenced by the basicity of the used solvent and in order to achieve high yields of this desired alcohol it is necessary to use polar basic solvent. [ABSTRACT FROM AUTHOR]

Abstract: Four different Sn modified zeolites, namely three Beta zeolites with varying SiO2/Al2O3 ratio along with Sn-Y were synthesized, and characterized by XRD, TEM, SEM, pyridine adsorption desorption, nitrogen adsorption, XPS and EXAFS. Kinetics in β-pinene oxide isomerization into myrtanal was studied at 70°C in toluene as a solvent with different catalysts. The initial isomerization rate increases with increasing acidity. Complete conversion of β-pinene oxide was achieved with the three most acidic catalysts within 30min, whereas only 72% conversion in 1440min was obtained with the catalyst exhibiting the lowest acidity, Sn-Beta-300. The catalyst most selective to the formation of myrtanal was Sn-Beta-300 giving 64% selectivity at 72% conversion, which is related to low amounts of acid sites. [Copyright &y& Elsevier]

Synthesis of fine and specialty chemicals involving heterogeneous catalysts is discussed according to the type of reactions (e.g., hydrogenation, oxidation, isomerization, etc.) for various biomass derived feedstocks (carbohydrates, lignans, phenols, flavonoids, tannins, and stilbenes, tall oil, and fatty acids). [ABSTRACT FROM AUTHOR]

Hydroisomerization of long chain paraffins for the production of branched alkanes has recently been intensively studied due to a large availability of these compounds. The most interesting research topics have been the development of novel bifunctional catalysts to maximize the yield of isomers and to suppress the cracking reactions. Since both of these reactions are catalyzed by Brønsted acid sites, the optimum catalyst exhibits equal amounts of metal and acid sites, and it facilitates rapid mass transfer. Thus, several hierarchical and nano-shaped zeolites have been developed, in addition to composite catalysts containing both micro- and mesoporous phases. In addition to catalyst development, the effect of the reactant structure, optimal reaction conditions, catalyst stability and comparison of batch vs continuous operations have been made. [ABSTRACT FROM AUTHOR]

Few types of ZSM-5 based micro-mesoporous materials obtained via a dual template method, steam-assisted conversion and dual-functional templating were evaluated in α-pinene oxide isomerization. Complete conversion and the highest selectivity towards trans-carveol (ca. 40–43%) were achieved over X-ray amorphous micro-mesoporous aluminosilicates as well as mesoporous molecular sieves AlSi-SBA-15. In addition, X-ray amorphous samples containing the secondary building units of ZSM-5 zeolite demonstrated the highest rate of α-pinene oxide isomerization. The yield of the most desired product trans-carveol to a large extent depends on the accessibility of acid sites to the reagents molecules and acidity of the catalysts (strength and concentration of Brønsted and Lewis acid sites). [ABSTRACT FROM AUTHOR]

The isomerisation of β-pinene oxide was studied over supported ionic liquid catalysts (SILCAs) consisting of Lewis acids in immobilized ionic liquid. SILCAs were demonstrated as efficient catalysts for the transformation of β-pinene oxide to myrtanal with the product distribution and activity being dependent on the nature of the ionic liquid and Lewis acid strength of catalytic species. With the catalyst ZnCl 2 /[N(3-OH-Pr)Py][NTf 2 ]/ACC, the highest myrtanal molar yield obtained was 68%. [ABSTRACT FROM AUTHOR]

The activity and selectivity of platinum-modified zeolites (Beta, Y, Mordenite) were investigated in the ring opening of decalin at 473–543 K in the presence of hydrogen. In the course of decalin transformation, skeletal isomerization, stereoisomerization, ring opening, and cracking took place. The presence of platinum resulted in an enhancement of isomerization and ring-opening rates, as compared to the proton-form zeolites. The isomerization and ring-opening rates increased 3 and 5 times, respectively. Hydrogen pressure was found to suppress the secondary reactions and to prevent the catalyst deactivation. The isomerization and ring-opening reactions were not affected by hydrogen presence. Variations in catalyst deactivation were observed and attributed to different locations of organic deposits. Interactions between platinum and Brønsted acid sites suggested that the platinum crystallites were located partially in the channels of the studied zeolites. As a result of these interactions, the strength of Brønsted acid sites was reduced and consequently less cracking products were formed, at comparable conversions, over platinum-modified zeolites than over the corresponding parent zeolites. [Copyright &y& Elsevier]

The activity of H-Beta-25, H-Beta-75, H-Y-12, H-Mordenite-20, and H-MCM-41 was investigated in the ring opening of decalin at 498–573 K in the presence of hydrogen. The catalysts activity and deactivation were correlated to their acidity determined by FTIR pyridine adsorption, pore structure, and surface area changes. Skeletal isomerization, stereoisomerization, ring opening, and cracking were the prevailing reactions taking place. Skeletal isomerization included several parallel and consecutive reactions resulting in a wide variety of products, which underwent ring opening, and subsequently cracking. Virtually no direct ring opening of decalin was observed; i.e., decalin must first be isomerized to alkyl-substituted bicyclononanes and bicyclooctanes to make possible its ring opening. The main products were grouped according to their structural features to evaluate the product distribution, which was influenced by catalyst acidity and pore structure. The initial activity of the catalysts increased with increasing acidity and reaction temperature, respectively. The deactivation of the investigated catalysts depended on their pore structure; H-Y was deactivated faster than Beta zeolites as it allowed the formation of large hydrocarbon intermediates inside the cavities. [Copyright &y& Elsevier]

Heterogeneous supported metal catalysts were applied for the isomerization reaction of linoleic acid (cis-9,cis-12-octadecadienoic acid) to conjugated linoleic acid (CLA) between 80 and 120 °C in a diluted system. Ru, Ni, Pd, Pt, Rh, Ir, Os, and bimetallic Pt-Rh supported by activated carbon, Al2O3, SiO2Al2O3, MCM-22, H-MCM-41, H-Y, and H-β were screened. Catalyst characterization was done by XRD, X-ray fluorescence, XPS, H2-TPD, DCP-AES, and nitrogen adsorption techniques. The isomerization reaction was conducted batchwise in both 1-octanol and n-decane as solvents. Reactions taking place were the isomerization of linoleic acid to CLA, hydrogenation of linoleic acid and CLA to monounsaturated octadecenoic acids (oleic acid, elaidic acid, cis-vaccenic acid, and trans-vaccenic acid), as well as the further hydrogenation of monounsaturated acids to stearic acid (n-octadecanoic acid) with isomerization and hydrogenation being two competing parallel reactions. The isomerization reaction was enhanced by catalyst preactivation under hydrogen. The presence of chemisorbed hydrogen increased the conversion but reduced the isomerization selectivity. Ru and Ni showed the best isomerization properties whereas Pd favored the double bond hydrogenation reaction. [Copyright &y& Elsevier]

Highlights: [•] Transformation of α-pinene oxide to campholenic aldehyde in toluene. [•] Synthesis of Fe Beta-75; ZSM-5, MCM-41 by impregnation and solid-state ion exchange. [•] Extensive characterization of catalysts. [•] Strong influence of acidity on activity and selectivity. [•] The highest selectivity of 66% with Fe-MCM-41. [Copyright &y& Elsevier]

Abstract: Gold catalyst supported on mesoporous carbon and silica were synthesized, characterized by TEM, XRD, XPS and tested in linoleic acid isomerization. Nature of the support affects the selectivity towards isomerization in relation to unwanted hydrogenation. In particular carbon support allowed much higher selectivity in double bond migration compared to silica. Effect of carbon surface oxidative pre-treatment on selectivity of catalyst was investigated. [Copyright &y& Elsevier]

The isomerization reaction of linoleic acid (cis-9,cis-12-octadecadienoic acid) to conjugated linoleic acids (CLA) was studied. A new heterogeneously catalytic pathway was developed for synthesis of CLA at mild reaction conditions (80–120°C) over Ru/C and Ni/H–MCM-41 catalysts in a diluted system. The isomerization reaction was tested in 1-octanol and n-decane. Solvents with low polarity were selected to afford good reactant adsorption on the catalyst surface and a high solvent-to-reactant ratio was used to prevent potential side reactions. Catalyst characterization was done by X-ray powder diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy, hydrogen temperature-programmed desorption, direct current plasma atomic emission spectrometry, and BET techniques. The reactions taking place were isomerization of linoleic acid C18:2, hydrogenation of C18:2 acids to C18:1 monounsaturated octadecenoic acids (oleic acid, elaidic acid, cis-vaccenic acid and trans-vaccenic acid), and further hydrogenation of C18:1 acids to C18:0 stearic acid (n-octadecanoic acid) where isomerization and hydrogenation were two competing parallel reactions. The isomerization reaction was enhanced by preactivation of the catalysts under hydrogen, but such a treatment also increased the side reaction double-bond hydrogenation. [Copyright &y& Elsevier]