Isomerization and dissociation of 2,3-dihydrofuran (2,3-DHF) induced by infrared free electron laser

• Infrared free electron laser at Tokyo University of Science was employed as a tunable light source inducing isomerization and dissociation reaction of 2,3-dihydrofuran in the gas phase.
• From the ratio of two photo isomerization products, the vibrational temperature of the hot 2,3-dihydrofuran generated through the infrared multiphoton excitation was estimated to be 1300–1500 K.
• The experimentally identified reaction pathways are well explainable by quantum chemical calculations.

We investigated infrared multiphoton dissociation and isomerization reactions of 2,3-dihydrofuran (2,3-DHF), cyclopropanecaboxaldehyde (CPCA) and crotonaldehyde (CA) with free electron laser at Tokyo University of Science (FEL-TUS). From 2,3-DHF as a starting material, CPCA and CA were the main isomerization products. From the measured [CPCA]/[CA] ratio, the equivalent temperature for the vibrationally hot 2,3-DHF was estimated to be 1300–1500 K. From CPCA, both 2,3-DHF and CA were detected as isomerization products. No isomerization reaction from trans-CA to CPCA and 2,3-DHF was recognized and the dissociation to propylene was the dominant process. The experimentally identified reaction pathways are well explainable by quantum chemical calculations at the MP2/cc-pVDZ level.