Synthesis of isoprene from 1,3-dioxolane and isobutylene

Liquid-Phase Synthesis of Isoprene from Methyl tert-Butyl Ether and Formalin Using Keggin-Type Heteropolyacids

“…In addition, there seems to be no limit of the range of the MTBE/formaldehyde ratio (or isobutene source/formaldehyde source ratio) for increasing isoprene yield or selectivity. Our results were consistent with the previous studies for isoprene synthesis from MTBE and formalin using acidic aqueous solutions as catalysts, isobutene and 1,3-dioxolane using para-toluenesulfonic acid catalyst, and TBA and 1,3,5-trioxane using Granion D001 resin as catalyst . The increase in selectivity with increasing MTBE/formaldehyde ratio was due to the high MTBE being able to yield higher excess amount of isobutene.…”

“…For the temperature range of 130–140 °C, isoprene yield was low (2.2–7.5%); the yield then sharply increased (16.9%) at 150 °C, approaching a maximum (19.6%) at 160 °C. At a high temperature of 170 °C, the isoprene yield decreased (10.0%), which was due to a high loss of isoprene to its consecutive reaction products similar to the results from previous work on isoprene synthesis from isobutene and 1,3-dioxolane using Amberlyst 36 Dry resin catalyst . Compared with the above effects, the MTBE/formaldehyde ratio had a negligible effect on isoprene yield (Figure d).…”

“…Further attempts to reduce energy consumption and the amount of wastewater from the reaction utilize isobutene, anhydrous formaldehyde precursors, and/or solid acids. For the synthesis from isobutene and 1,3-dioxolane using Amberlyst 36 dry resin catalyst, isoprene yield strongly depended on the 1,3-dioxolane/isobutene ratio, and the intermediate, 5,5-dimethyl-1,4-dioxepine, was proposed as a precursor of isoprene . Recently, Burkin and Akhmedyanova reported on the synthesis from TBA and 1,3,5-trioxane reaction using Granion D001 resin catalyst; they reported that a high isoprene yield could also be achieved at low temperature (120 °C) and preferentially high TBA/trioxane ratio.…”