Isomerization of Small Aliphatic Epoxides

In 1968 Venuto and Landis reported on the use of sodium- and rare-earth metal-doped zeolite X in the rearrangement of ethylene oxide and propylene oxide to the corresponding aldehydes [17]. In addition to the desired propanal, acetone was formed with these catalysts because of the hydride shift induced by the intermediate carbocation consecutive reactions were also observed. Such catalysts also suffer from rapid deactivation. 

2-Methyl-2,3-epoxybutene can be eonverted to methylisopropylketone (51 %), pivalic aldehyde (40 %) and isoprene (7 %) by use of aluminum-containing zeolite MFI (Si/Al =37,6) at 150 °C and a WHSV of ea 2 h [8,16]. The pivalic aldehyde is formed via a pinacol-type rearrangement. If the temperature is increased to 300 °C isoprene is the main product [19]. 

Similarly, butyraldehyde can be prepared from butene-1-oxide with Zn, Cd, and Ag ion-exchanged zeolite A with selectivities between 55 % and 72 % [20]. 

The bulkier 1,2-epoxyoctane can be rearranged over zeolites HY (Si/Al = 15) and H-OFF (Si/Al 3.6) at 160 °C in an autoclave, with toluene as solvent this results in 45 % and 46 %, respectively, seleetivity to octanal 17 %/25 % to allylic alcohols, and 18%/14% to aldolization products, e. g. 2-/z-hexyldec-2-en-l-al [21], A kinetic study of this reaction over different acidic heterogeneous catalysts, e. g. phosphoric acid, ZnCU immobilized on various supports, sulfated zirconia, zeolites, and dodecatungstenophosphoric acid, was reported by Yadav and Satoskar [22], 

---