Thermal Reactions of Cyclic Ethers at High Temperatures. 5. Pyrolysis of 2,3-Dihydrofuran behind Reflected Shocks

Article abstract of DOI:10.1021/j100340a024

The thermal decomposition of 2,3-dihydrofuran was studied behind reflected shocks in a single-pulse shock tube over the temperature range 900-1300 K and overall densities of cca. 2.5 x 1E-5 mol/cm³.Under these conditions the following reaction products were found in the postshock analyses: c-C3H5CHO, CH3CH=CHCHO, C3H6, CO, C2H4, C2H2, CH2=CO, CH2=CHCH2CH3, CH4, C2H6, CH2=CHCHO, butadiene, and small quantities of CH2=C=CH2, CH3-C<*>CH, and C4H4.The major reaction of 2,3-dihydrofuran is a unimolecular isomerisation to cyclopropanecarboxaldehyde (c-C3H5CHO) with the following rate parameters: 2,3-dihydrofuran -> c-C3H5CHO, k₁ = 1.95 x 1E13 exp(-49.38 x 10³/RT) s^-1, where R is expressed in units of cal/(K mol).The major fragmentation reaction of 2,3-dihydrofuran is the dissociation to ethylene and ketene with the following rate parameters: 2,3-dihydrofuran -> C2H4 + CH2=CO, k₂ = 5.75 x 1E15 exp(-69.28 x 10³/RT) s^-1.Propylene and carbon monoxide are the pyrolytic products of the highest concentration but are formed from the pyrolysis of cyclopropanecarboxaldehyde and not of 2,3-dihydrofuran.Rate parameters for the formation of the various reaction products are deduced, and the general reaction mechanism is discussed.