Table 3.
Relative Abundances or Responses of Dimethylbenzene Isomers Associated with Various Formation and Modification Mechanisms
| Mechanism | Environment | Meta- | Para- | Ortho- | m+p/o |
|---|---|---|---|---|---|
| Space and laboratory processes | |||||
| High temperature (500°C) | Stellar atmosphere | 5 | 3 | 1 | 8 |
| High temperature (800°C) | Stellar atmosphere | 4 | 2 | 2 | 3 |
| Ion-molecule reaction | Molecular cloud | 6 | 2 | 2 | 4 |
| Radiation resistance | Grain mantle | High | Med | Low | High |
| Fischer–Tropsch | Solar nebula | 10.4 | 2.8 | 3.7 | |
| Degradation resistance | Parent body | Med | High | Low | Med |
| Catalytic cyclization | Earth laboratory | 27 | 7 | 33 | 1 |
| Terrestrial biosphere | |||||
| Blue Lias (type I kerogen) | Earth biosphere | 2 | 1 | 2 | |
| Low-volatile bituminous coal (type III kerogen) | Earth biosphere | 27 | 10 | 2.7 | |
| Charcoal (type IV kerogen) | Earth biosphere | 19 | 5 | 3.8 | |
Space and laboratory data from Sephton (2013) and references therein; biological data from samples used in this study.