The Substituent Constant of the 3,4-Benzo Group

Abstract

SUBSTITUENT CONSTANT OF THE 3,4-BENZO GROUP 155Stirring was continued at reflux for 5 hr. and the bromide was then recovered in the usual way. The recovered bromide showed a slight increase in the amount of trans isomer, as evidenced by the diagnostic infrared bands of the latter, but was still very predominantly cis.(c) The above experiment was repeated, expect that pure as-bromide was used and the bromide was added to the silver acetate suspension one minute before bromine addition commenced. In this way, the cis-bromide was exposed to both bromine and silver bromide under the reaction conditions, rather than to silver bromide only. After 1 hr. boiling at reflux with stirring, the mixture was worked up as previously described. The product showed a marked ester band in the infrared at 5.77µ and very weak bands ascrib-able to the irons isomer, the one at 11.4µ being the most prominent (about six scale divisions). However, the recovered material was still very largely as-bromide.

A linear Br�nsted-type behavior in the aminolysis of substituted naphthyl acetates

“…However, the reactivity of 1 is higher compared to 2 toward these amines (Table III), which is reflected in a smaller ␤ value for 1, which is consistent with the earlier reported works wherein smaller ␤ values were obtained for more reactive esters [2,3,18]. Present observation conforms with the earlier reports, which suggest that the reactivity of 6-substituted naphthalene system is largely decided by the 3,4-benzo substituent (with larger values) rather than by the actual substituent present [60,61]. Thus, for 2 the electron-withdrawing effect of the acetyl group is less pronounced to reach the reaction center, which makes the naphthoxide ion act as a poor nucleofuge.…”