Thermal reactions of bifunctional 1-chloro-2-propanol and 3-chloro-1-propanol on Cu(100) and oxygen-precovered Cu(100) are presented in this article. X-ray photoelectron spectroscopy, reflection-absorption infrared spectroscopy and temperature-programmed reaction/desorption have been employed to investigate the decomposition process of 1-chloro-2-propanol on Cu(100). The competitive dissociation of the functional C-Cl and CO-H at 265 K results in the formation of ClCH2CH(CH3)O- and CH2CH(CH3)O- surface intermediates at a 2:1 concentration ratio. This ratio decreases to ∼0.6:1 at 300 K. The CH2CH(CH3)O- oxametallacycle is theoretically predicted to be bonded on the Cu(100) surface, with both the O and CH2 at bridge sites. This surface intermediate decomposes mainly at 300 K producing CH3C(O)CH3 and CH3CH=CH2 in addition to H2 and CO. Preadsorbed oxygen atoms can stabilize the oxametallacycle and increases its reaction temperature to ∼350 K. Moreover, propene formation is promoted relative to acetone. In the reaction of 3-chloro-1-propanol on Cu(100), a low-temperature (159 K) formation channel of ClCH2CH=CH2 is observed. Other products presumably from CH2CH2CH2O- reaction, including CH2=CHCHO, CH3CH2CHO, C2H4, CO, and H2, evolve at a temperature higher than ∼300 K. No propene from C-O dissociation is formed. Preadsorption of oxygen causes the evolution of these products to be shifted to ∼400 K, with additional CH3CH2CH2OH and a small amount of CH3CH=CH2. The theoretical calculation indicates that CH2CH2CH2O- is bonded via the 3CH2 and O at atop and bridge sites, respectively, and has an energy slightly higher than that of CH2CH(CH3)O-, by 3.4 kcal·mol-1.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films