- Isoprene synthesis from formaldehyde and isobutene over Keggin-type heteropolyacids supported on silica
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Gas phase Prins condensation of isobutene with formaldehyde has been studied over different Keggin-type heteropolyacids supported on amorphous silica. The catalysts were characterized by elemental analysis, X-ray diffraction, low temperature nitrogen adsorption, TPD of ammonia, FTIR of adsorbed pyridine and NMR spectroscopy. The activity of the supported heteropoly compounds was found to increase in the following order: H4SiMo12O40 3PMo12O40 4SiW12O40 ≈ H3PW12O40. The lower activity of the supported molybdenum heteropolyacids was attributed to their low thermal stability and partial decomposition during catalyst activation, which resulted in lower acidity. The variation of HPA content from 5 to 33 wt% was also shown to increase catalyst activity. Based on the relationship between the content of weak Br?nsted sites, the amount and type of carbonaceous deposits and the catalytic activity, it was concluded that the generation of working active sites over HPA catalysts involves the formation of unsaturated branched surface species over weak Br?nsted sites. These active carbonaceous species are responsible for selective isoprene synthesis. The best catalyst performance is observed over the catalyst with 20 wt% of H3PW12O40, which shows an isoprene yield of 48% with a selectivity of 63%.
- Sushkevich,Ordomsky,Ivanova
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- Synthesis of isoprene from formaldehyde and isobutene over phosphate catalysts
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Vapor phase Prins condensation of isobutene with formaldehyde has been studied over boron (BP), aluminum (AlP), titanium (TiP), zirconium (ZrP) and niobium (NbP) phosphates. The catalysts were characterized by elemental analysis, X-ray diffraction, low-te
- Sushkevich,Ordomsky,Ivanova
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- PYRAZOLO [4,3-c] CINNOLIN-3-ONE M1 RECEPTOR POSITIVE ALLOSTERIC MODULATORS
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The present invention is directed to pyrazolo [4,3-c] cinnolin-3-one compounds of formula (I) which are M1 receptor positive allosteric modulators and that are useful in the treatment of diseases in which the M1 receptor is involved, such as Alzheimer's disease, schizophrenia, pain or sleep disorders. The invention is also directed to pharmaceutical compositions comprising the compounds, and to the use of the compounds and compositions in the treatment of diseases mediated by the M1 receptor.
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Page/Page column 72
(2010/09/17)
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- Acid-catalyzed hydration of 4-methylenetetrahydropyran and 4-methyl-5,6-dihydro-2H-pyran
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Kinetics of hydration of 4-methylenetetrahydropyran and 4-methyl-5,6-dihydro-2H-pyran in aqueous sulfuric acid were studied at various temperatures.
- Ryvkina,Sinitsyn
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p. 1479 - 1481
(2007/10/03)
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- Regiochemical Control of the Ring Opening of 1,2-Epoxides by Means of Chelating Processes. 6. Opening Reactions of 3,4-Epoxytetrahydropyran
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The regiochemical control of the ring opening of epoxides bearing polar remote functionalities, through chelation processes assisted by metal ions, was verified in the title compound (4).The use of metal assisted procedures in several ring opening reactions of 4 leads to a modification of the regiochemical outcome, and the attack of the nucleophile on the C-4 oxirane carbon is highly favored.
- Chini, Marco,Crotti, Paolo,Gardelli, Cristina,Macchia, Franco
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p. 1261 - 1274
(2007/10/02)
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- REACTION OF 4-METHYL-3,4-EPOXYTETRAHYDROPYRAN WITH NUCLEOPHILES
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Reaction of 4-methyl-3,4-epoxytetrahydropyran with phenols, thiols, thiocyanic acid and benzoic acid, thiourea, and with sodium sulfite and thiosulfate occurs with opening of the epoxide ring.Using IR spectroscopy it was shown that the products occur via trans-diaxial opening of the oxide ring at the least-substituted carbon atom.
- Ibatullin, U. G.,Vasil'eva, S. A.,Karimova, Z. Kh.,Safarov, M. G.
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p. 1218 - 1221
(2007/10/02)
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- EXPERIMENTAL STUDIES OF THE ANOMERIC EFFECT. PART I. 2-SUBSTITUTED TETRAHYDROPYRANS.
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Variable temperature (1)H and (13)C n.m.r. studies in CFCl3/CDCl3 of equilibria in 2-substituted- and 2-substituted-4-methyl-tetrahydropyranes have given conformational enthalpy differences and conformational entropy differences for chloro, methoxy, hydroxy and methylamino substituents.For ΔHoa->e, the values obtained, in kcal /mol, were 1.67 (Cl), 0.03 (OCH3), -0.63 (OH) and -1.75 (NHCH3); for ΔSoa->e the values obtained, in cal K-1mol-1 were -1.69 (Cl), -2.52 (OCH3), -2.50 (OH) and -0.60 (NHCH3).The trend in ΔHo values confirms the importance of antiperiplanar n-?* stabilisation as a contributor to the explanation of the anomeric effect, and supports a suggestion that endo- and exo-anomeric effects which occur in the same conformation are competitive.A variable temperature (13)C n.m.r. study of (Me-(13)C)-4-methyl-tetrahydropyran in CD2Cl2 has given a conformational enthalpy difference (ΔHoa->e) of -1.86 kcal/mol and a conformational entropy difference (ΔSoa->e) of -0.07 cal K-1mol-1 for a methyl substituent at the 4-position of a tetrahydropyran.
- Booth, Harold,Kheidhair, Kheidhair A.,Readshaw, Simon A.
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p. 4699 - 4724
(2007/10/02)
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- CONDENSATION OF ISOBUTENE WITH FORMALDEHYDE IN NITROMETHANE.
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It is shown that condensation of isobutene with formaldehyde in nitromethane proceeds at a high rate and selectivity. The qualitative and quantitative compositions of the products formed in water and in nitromethane indicate that the reaction mechanisms in the two media are different.
- Zakoshanskii,Idlis
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p. 1769 - 1771
(2007/10/02)
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- REACTIONS INVOLVING SHIFTING OF THE DOUBLE BOND IN CYCLIC ETHERS
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4-Methylenetetrahydropyran undergoes isomerization to 4-methyl-5,6-dihydropyran in the presence of sodium on aluminum oxide.Both pyrans are converted to a vinyl ether, viz., 4-methyl-2,3-dihydropyran, under the influence of iron pentacarbonyl.
- Ibatullin, U. G.,Petrushina, T. F.,Akhmadeeva, A. A.,Safarov, M. G.
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p. 262 - 264
(2007/10/02)
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- SYNTHESIS OF SUBSTITUTED 5,6- AND 3,6-DIHYDRO-2H-PYRANS BY ACID CONDENSATION OF ISOBUTYLENE AND α-METHYLSTYRENE WITH ALIPHATIC ALDEHYDES
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2,4-Disubstituted dihydropyrans, isomeric with respect to the position of the double bond, were obtained by the reaction of isobutylene and α-methylstyrene with formaldehyde and aliphatic aldehydes.
- Romanov, N. A.,Kantor, E. A.,Karakhanov, R. A.,Rakhmankulov, D. L.
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p. 351 - 354
(2007/10/02)
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