Nucleophilic Aromatic Substitution Reactions in Dipolar Aprotic Solvents: The Remarkable Effect of Trifluoromethyl Group on the Reactivity of Nitrophenyl Ethers with Nucleophiles.
| dc.contributor.author | Isanbor, C. | |
| dc.contributor.author | Babatunde, A.I. | |
| dc.date.accessioned | 2019-09-23T15:35:56Z | |
| dc.date.available | 2019-09-23T15:35:56Z | |
| dc.date.issued | 2019-01-17 | |
| dc.description.abstract | Rate constants are reported for the reactions of 4-phenoxy-3-nitrobenzotrifluoride 3c, 2-phenoxy-5- nitrobenzotrifluoride 4c and 1-phenoxy-2,4-dinitrobenzene 5c activated by trifluoromethyl (CF3) or nitro (NO2) groups with n-butylamine, pyrrolidine and piperidine in DMSO. The results are compared with results reported previously for same reactants and with the more strongly ring-activated compounds 4-phenoxy-3,5-dinitrobenzotrifluoride 1c and 2-phenoxy-3,5-dinitrobenzotrifluoride 2c in acetonitrile. A change in reaction medium from acetonitrile to DMSO leads to a reduction in values of kAm/k-1 as the proton-transfer from zwitterionic intermediates to catalysing amine becomes less thermodynamically favourable. Overall, the reactivity order is 5c > 3c> 4c and decreasing ringactivation in the 1-phenoxy compounds 1c - 5c leads to lower values of kAm/k–1 resulting in greater susceptibility to base catalysis. Specific steric effects leading to rate-retardation, is noted for the orthoCF3 group. The higher reactivity of para-CF3 group in compounds 3c compared to 4c has been attributed partly to the more effective polar hyperconjugative activation by the CF3 group in 3c and to a possible participation of unfavourable electrostatic repulsion for the ortho-CF3 group between the electronegative fluorine atoms in 4c and the incoming nucleophiles. | en_US |
| dc.identifier.citation | Isanbor, C., & Babatunde, A. I. (2019). Nucleophilic Aromatic Substitution Reactions in Dipolar Aprotic Solvents: The Remarkable Effect of Trifluoromethyl Group on the Reactivity of Nitrophenyl Ethers with Nucleophiles. Journal of Chemical Society of Nigeria, 44(1). | en_US |
| dc.identifier.uri | https://ir.unilag.edu.ng/handle/123456789/6056 | |
| dc.language.iso | en | en_US |
| dc.publisher | journals.chemsociety.org.ng | en_US |
| dc.subject | Research Subject Categories::NATURAL SCIENCES::Chemistry::Physical chemistry::Kinetics | en_US |
| dc.subject | Trifluoromethyl group | en_US |
| dc.subject | Proton transfer mechanism | en_US |
| dc.subject | Stereoelectronic effects | en_US |
| dc.subject | Nucleophilic aromatic substitution | en_US |
| dc.title | Nucleophilic Aromatic Substitution Reactions in Dipolar Aprotic Solvents: The Remarkable Effect of Trifluoromethyl Group on the Reactivity of Nitrophenyl Ethers with Nucleophiles. | en_US |
| dc.type | Article | en_US |