Isomerization of 2-Methyl-4,5-dihydrofuran. Studies with a Single-Pulse Shock Tube

Article abstract of DOI:10.1021/j100060a023

The isomerization of 2-methyl-4,5-dihydrofuran was studied behind reflected shock waves in a pressurized driver single-pulse shock tube over the temperature range 805-1030 K and densities of approximately ca 3*10^-5 mol/cm³.Two isomerization products, acetylcyclopropane and 3-penten-2-one, are obtained in the isomerization.Acetylcyclopropane is formed in an irreversible process from 2-methyl-4,5-dihydrofuran.It further isomerizes, at higher temperatures, to cis- and trans-3-penten-2-one.At high temperatures where the conversion of 2-methyl-4,5-dihydrofuran is high, the main source for 3-penten-2-one is acetylcyclopropane.At lower temperatures 3-penten-2-one is formed mainly by a direct isomerization of 2-methyl-4,5-dihydrofuran.A small concentration of decomposition products, mainly methane and ethane, are also found in shock mixtures of 2-methyl-4,5-dihydrofuran, particularly at high temperatures.The Arrhenius relations for the tree aforementioned processes are as follows: 2-methyl-4,5-dihydrofuran -> acetylcyclopropane, k₁=10^15.4 exp(-56.8*10³/RT) s^-1; 2-methyl-4,5-dihydrofuran -> 3-penten 2-one, k₂=10^15.7 exp(-63.6*10³/RT) s^-1; acetylcyclopropane -> 3-penten-2-one, k₃=10^14.4 exp(-58.3*10³/RT) s^-1, where R is expressed in units of cal/(K mol).