CAN INTERSTELLAR PROPENE (CH₃CHCH₂) BE FORMED VIA GAS-PHASE REACTIONS?

Methylacetylene (CH3CCH) and propene (C3H6) formation in cold dense clouds: A case of dust grain chemistry

“…Based on the recent calculations by Lin et al (2013) and the current review of gas-phase reactions, gas-phase reactions are unlikely to produce enough of these species. These results are in good agreement with the suggested scenario by Miettinen et al (2006) who found a gasphase methylacetylene abundance which increases with the temperature in star forming regions, suggesting its formation on ice surfaces followed by thermal desorption.…”

“…They performed theoretical calculations leading to a high rate constant for this reaction, in disagreement with (McEwan et al 1999). Lin et al (2013) also showed that the radiative association leading to protonated propene was slow, whichever C 3 H 5 + isomer was considered, so that this process in unimportant in the cold interstellar medium. In a similar manner to methylacetylene, the protonation acts as an overall loss of C 3 H 6 as the DR (Anicich 2003) which all involve small fluxes under dense cloud conditions by pure gas phase models, as C 2 H 6 and C 3 H 8 are not produced efficiently by gas phase reactions.…”

Chemical and radiative transfer modeling of propylene oxide

“…But recent study by Lin et al (2013) found that above two reactions contain some activation barrier (25.5 and 24.7 kJ/mol respectively). In the low-temperature regime, it is problematic to overcome such a high barrier in the gas phase and thus the formation of gas phase C 3 H + 7 is inadequate by these routes which suggest considering some alternative reaction pathways to enable the formation of C 3 H 6 rather than by the electron recombination reaction as proposed by Herbst et al (2010).…”

Astrochemistry of dust, ice and gas: introduction and overview

“…A prime example is photodissociation rates of small radicals and ions through calculation of the excited electronic states and their transion dipole moments [69][70][71] . Other examples include radiative association reactions 72 , rates and barriers for neutral-neutral reactions 73,74 , state-selective reactions 75 , and the structure 76 and infrared spectroscopy 77 of large molecules.…”