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Ch.23
Types of reactions in organic chemistry
| Term | Definition |
|---|---|
| Initiation of a substitution reaction | Homolysis- The splitting up of a chlorine molecule (Cl2) into 2 chlorine free radical (2Cl*) by ultraviolet light. (uv) |
| Propagation of a substitution reaction p.1 | The Cl* attacks a methane molecule (CH4) to form hydrogen chloride (HCl)and a methyl free radical (CH3*) |
| Propagation for a substitution reaction p.2 | Reaction of the methyl free radical with a chlorine molecule to form monochloromethane (CH3Cl) and a chlorine free radical, a chain reaction occurs |
| Termination of a substitution reaction | The combination of free radicals to form a molecule. Cl* + Cl* -> Cl2 CH3* + CH3* -> C2H6 Cl* + CH3* -> CH3Cl |
| Experimental Evidence- UV | Promoted by UV at room temperature: The effect of the uv suggests a free radical mechanism, Photons split Cl2 for every photon absorbed many mechanism |
| Experimental Evidence- photons | For every photon absorbed many chloromethane molecules formed:evidence for chain reaction or propagation |
| Experimental Evidence-Free radicals | Add source of free radicals (tetra- methyl lead): only a free radical mechanism would be affected, increased rate, free radicals promote chain reaction |