Liquid phase rearrangement of long straight-chain epoxides over amorphous, mesostructured and zeolitic catalysts

Selective isomerization of epoxides using magnetically recyclable ZSM-5 zeolite catalyst

“…This indicated that the zeolite catalyst would favour the formation of aldehyde products. 4,9,19 The highest conversions of reaction were obtained at catalyst loading of 5%, for which the conversion was $100% and 99.1% aer 4 h for 2-methyl-2,3epoxybutane and styrene oxide, respectively. At the amount of catalyst lower than 5% could still give good conversion of 2methyl-2,3-epoxybutane and styrene oxide, but the reactions were slower and longer reaction times were required in order for them to go to completion.…”

“…4,25 Moreover, the low selectivity towards aldehyde obtained might be related with the basic character of the methanol which could accelerate the formation of alcohol byproduct. 9,25,26 The conversion yield was high aer just 1 h in solvents of acetone and dichloromethane. It's observed that the higher solvent polarity the lower conversion of epoxide.…”

“…[4][5][6][7][8] Acidcatalyzed epoxide rearrangement reaction usually leads to ketones and aldehydes, whereas the base-catalyzed reaction forms allylic alcohols as main products. 9 Using of homogeneous catalysis presents numerous drawbacks such as loss of the catalyst, corrosivity, toxicity and generation of contaminated streams in most cases. Thus many efforts have been conducted to nd out heterogeneous catalysts to solve these problems.…”

“…[10][11][12][13][14] Nevertheless, the competitive aldol condensation or polymerization of aldehydes and rapid deactivation of catalysts by aggregation or coke formation are still difficult problems at the industrial scale. 3,9,15 The use of conventional catalysts oen results in the formation of aldol condensation products and mixtures of ketones and aldehydes as by-products. The numerous molecules formed by aldol condensation are the rst step in the formation of coke thus limiting the lifetime of catalysts.…”

“…16,18 Moreover, the well dened pore system of zeolites may suppress the side reactions mentioned above. 9,19 Hence, high selectivities to aldehydes could be achieved in the isomerization of styrene oxide and derivatives over various acid zeolites. Besides, the practical application of catalysts in liquid phase reactions is hindered by both high costs and difficulties in catalyst separation and recycling.…”