2270-61-3Relevant articles and documents
Isoprene synthesis from formaldehyde and isobutene over Keggin-type heteropolyacids supported on silica
Sushkevich,Ordomsky,Ivanova
, p. 6354 - 6364 (2016/08/18)
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%.
Synthesis of isoprene from formaldehyde and isobutene over phosphate catalysts
Sushkevich,Ordomsky,Ivanova
, p. 21 - 29 (2012/11/07)
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
Regioselective Ni(II)-assisted alkylation of 2-methoxy-5,6- dihydro-2H-pyran: A new route to 2-n.alkyl-5,6-dihydro-2H-pyrans
Guagnano, Vito,Lardicci, Luciano,Malanga, Corrado,Menicagli, Rita
, p. 2025 - 2026 (2007/10/03)
In the presence of a catalytic amount of NidppeCl2, 2-methoxy- 5,6-dihydro-2H-pyran reacts with primary Grignard reagents to give the corresponding 2-n.alkyl-5,6-dihydro-2H-pyrans in satisfactory yields.