The kinetics and mechanism of alkaline hydrolysis of N-substituted phthalimides

✍ Scribed by M. Niyaz Khan

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 513 KB
• Volume: 19
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550190206

✦ Synopsis

The aqueous cleavage of N-(2-bromoethyl)phthalimide (NBEPH), N-(3-bromopropyl)phth&mide (NBPPH), and N-carbethoxyphthalimide (NCPH) have been studied

within the [OH] range of 5 x 10 M to 2 x 10.' M, pH range of 8.82 to 10.62 and 8.06 to 8.66, respective1y:The observed pseudo-first-order rate constants, h,,,,, reveal a linear relationship with [OH] with essentially zero intercept. The alkaline bdrolysis of N-(hydroxymethyl)phthalimid~ (NHMPH) has been studied within the [OH] range of 5.64 x 10 M to 2.0 M. The [QHI-rate profile reveals that both ionized and nonionized NEMPH are reactive toward OH. The second-order rate constant, k,,,,, for the reaction of OH with non-ionized NHMPH is ca. lo4 times larger than that with ionized NHMPH. The values of kOH obtained for NBEPH, NBPPH, NCPH, and nonionized NHMPH show a reasonable linear relationship with Taft substituent constants, and the slope ( p " ) of the plot is 1.01 5 0.10. The low value of {I* of 1.01 is attributed to nucleophilic attack as the rate-limiting. The k,,, value for ionized NHMPH reveals nearly 10"-fold negative deviation from the linear Taft plot.