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Madhavan, D.; Murugalakshmi, M.; Lalitha, Appaswami; Pitchumani, Kasi

doi:10.1023/a:1009030413003

Cited by 15 publications

(8 citation statements)

References 7 publications

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“…The results of these experiments are presented in Table 1 (entries [6][7][8][9]. An analysis of the data obtained for α pinene oxidation in the presence of these catalysts shows similar behavior of Fe 2 O 3 , Fe 2 O 3 /Al 2 O 3 , Fe 2 O 3 /SiO 2 , and Fe PILC/MA.…”

Section: Resultsmentioning

confidence: 78%

Catalytic oxidation of α-pinene with tert-butyl hydroperoxide in the presence of Fe-pillared montmorillonite

2006

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The reaction of α pinene with tert butyl hydroperoxide can proceed via allylic oxidation or α pinene isomerization, depending on the structural features of the catalysts based on Fe pillared montmorillonite.In spite of diversity of available methods for allylic oxidation of olefins, only few oxidation systems give α,β unsaturated alcohols or carbonyl compounds in ap propriate yields. Oxidation systems based on the lead(IV), selenium(IV), and chromium(VI) compounds turned out to be good in laboratory practice. 1 The main disadvantage of these methods is the use of considerable excess of oxi dizing reagents and, as a consequence, a lot of hazardous Pb , Se , and Cr containing waste. This fact stimulated the development of catalytic methods for the allylic oxi dation of olefins, 2 among which a special role belongs to the methods of heterogeneous catalytic oxidation using aluminosilicates 3 or aluminophosphates 4 modified by transition metals as catalysts.Among a wide series of natural and synthetic alumi nosilicates, minerals of the smectite group, including montmorillonite, are of highest interest for researchers due to their accessibility, low cost, and a possibility of purposeful control of the chemical properties and porous structure of these minerals by the intercalation into the interlayer space of ions or polynuclear metal hydroxo complexes and other modifying agents.As a rule, the catalytic properties of aluminosilicates are based on the Lewis and Brönsted acidic sites. Natural Na montomorillonite is rarely used as a catalyst for trans formations of organic substrates because of its low ther mal stability and fairly low catalytic activity. The catalytic activity and sorption properties of montmorillonite can substantially be enhanced by its activation with mineral acids. Such a treatment removes octahedrally coordinated ions (Al, Fe) and isomorphously substituted tetrahedrally coordinated ions from the montmorillonite structure 5 and, as a consequence, increases the number of acidic sites. Another method for the modification of layered alumino silicates is the exchange of interlayer cations for cations of other metals, which increases the total number of acidic sites and also changes the ratio of the Lewis and Brönsted sites. Acid activated and M n+ modified montmorillonites have been used successfully as catalysts in olefin isomer ization 6 and dimerization, 7 addition of water, halogen chlorides, alcohols, and thiols at the double bond of ole fins, 8 acylation 9 and alkylation 10 of alcohols, hydrolysis of acetals and ketals, 11 rearrangements of alkylphenyl es ters, 12 Diels-Alder 13 and Friedel-Krafts 14 reactions, etc. As a rule, the conversion and selectivity of the processes are much lower in the presence of mineral or Lewis acids.One more method for the modification of layered alu minosilicates, in particular, montmorillonite, is the sub stitution of interlayer cations for metal polyhydroxo complexes. Intercalated polyhydroxocomplexes undergo complete or partial dehydroxylation upon the thermal trea...

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Section: Resultsmentioning

confidence: 78%

Catalytic oxidation of α-pinene with tert-butyl hydroperoxide in the presence of Fe-pillared montmorillonite

2006

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“…The solid acids (Table 2) consisted of sulfuric acid treated montmorillonite clay (MMT-K10), a cross-linked polystyrene-based hydrated cation exchange resin (Dowex HCR-W2), a macroreticular cation exchange resin (Amberlyst-15), sulfated zirconia, and Nafion (a perfluorinated sulfonic acid resin). MMT-K10 which has been utilized for the dimerization of activated olefins such as 1,1-diphenylethene, 15 and more recently, b-pinene and its ring-opened isomers, 16 was used without modification in a dimerization reaction. At room temperature, no reaction occurred, while at the reflux temperature (116 C) complete isomerization to a mixture of four isomers was observed (Scheme 4).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of renewable jet and diesel fuels from 2-ethyl-1-hexene

Harvey

Quintana

2010

Energy Environ. Sci.

121

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“…The MCM-41/ Nafion Ò composite was a good catalyst to produce MDP-1 in the dimerization reaction of a-methylstyrene at the reaction temperature of 60°C, while 91% yield of TPI could be selectively obtained at 100°C [7]. The dimerization reaction of a-methylstyrene to produce TPI has been developed in the presence of cation-exchanged montmorillonite, a 75% yield of TPI was achieved [8]. Recently, metallic catalysts such as RuCl 3 Á H 2 O, InBr 3 and Pd(OAc) 2 /PPh 3 /In(OTf) 3 , have been used in the dimerization reaction of a-methylstyrene, and moderate to good product selectivities were obtained [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Study on Selective Dimerization of α-Methylstyrenes Promoted by Ionic Liquids

Shen

et al. 2008

Catal Lett

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The catalytic systems composed of ionic liquids containing BF 4 -anion and HBF 4 showed high catalytic activity to produce 4-methyl-2,4-diphenyl-1-pentene (MDP-1) or 1,1,3-trimethyl-3-phenylindan (TPI) under different temperature conditions. Up to 90.8% selectivity to MDP-1 with a 98.7% conversion of a-methylstyrene was obtained at 60°C in the presence of [HexMIm]BF 4 -HBF 4 , while exclusive TPI was yielded when the reaction temperature increased to 120°C. Further studies showed that another ionic liquid, [BMIm]Cl Á 2AlCl 3 , could act as an excellent catalyst and solvent for the dimerization of a-methylstyrene to produce TPI. The dimerization of a-methylstyrene catalyzed by [HexMIm]BF 4 -HBF 4 and [BMIm]Cl Á 2AlCl 3 performed the same reaction mechanism and the proton was the active species.

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Cited by 15 publications

References 7 publications

Catalytic oxidation of α-pinene with tert-butyl hydroperoxide in the presence of Fe-pillared montmorillonite

Catalytic oxidation of α-pinene with tert-butyl hydroperoxide in the presence of Fe-pillared montmorillonite

Synthesis of renewable jet and diesel fuels from 2-ethyl-1-hexene

Study on Selective Dimerization of α-Methylstyrenes Promoted by Ionic Liquids

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