Kinetic and equilibrium studies of σ-adduct formation and nucleophilic substitution in the reactions of morpholine with 1,3,5-trinitrobenzene and some phenyl aryl ethers in dimethyl sulphoxide

✍ Scribed by Rachel A. Chamberlin; Michael R. Crampton; Ian A. Robotham

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 429 KB
• Volume: 9
• Category: Article
• ISSN: 0894-3230
• DOI: 10.1002/(sici)1099-1395(199603)9:3<152::aid-poc769>3.0.co;2-4

✦ Synopsis

Reactions of morpholine in dimethyl sulphoxide at unsubstituted ring positions of 1,3,5-trinitrobenzene, and phenyl 2,4,64rinitrophenyl ether, yield anionic a-adducts via zwitterionic intermediates. Reactions at the 1- position of phenyl 2,4,64rinitrophenyl ether, phenyl 2,4-dinitronaphthyl ether, and phenyl 2,4-dinitrophenyl ether result in substitution of the phenoxy groups. In both these reaction types proton-transfer is rate-limiting. Comparison of kinetic and equilibrium data with those for corresponding reactions of piperidine shows that rate constants for proton transfer are similar for the two amines, but equilibrium constants for zwitterion formation have lower values for morpholine, the less basic amine. Implications for base catalysis are discussed.