The reaction of 1-bromo-2-X-2-(Y-phenyl) ethane derivatives (1: X = Y = H; 2: X = Ph, Y = H; 3: X = H, Y = 4-Ac; 4: X = H, Y = 3-NO2; 5: X = H, Y = 4-NO2; 6: X = H, Y = 3-Me; 7: X = H, Y = 4-Me) in basic solution was studied, and in most cases, only the elimination product is formed. Only (2-bromo-1-phenylethyl)benzene, 2, yielded significant substitution product, and this yield decreased with the concentration of HO-. Addition of cyclodextrin (β-CD) diminished (about half for 0.02 M cyclodextrin concentration) the reaction rate of all substrates but 4 and 5. In the latter two cases, the rate rises. The observed rate-constant value at 0.5 M NaOH is 6.78 × 10-4 s-1 (at 40°C) and 1.80 × 10-3 s-1 (at 25°C) for 4 and 5, respectively. Under the same reaction conditions but with 0.01 M β-CD, the corresponding rates were 7.70 × 10-4 s-1 and 5.20 × 10-3 s-1. The elimination yield for 2 increased from 64 to 98% when the β-CD changed from zero to 0.02 M at 0.5 M NaHO. Also, there was an increase in the relative elimination products of 20-40% for compounds 6 and 7. The Hammet ρ values were 1.3 and 2.3 for the reaction in pure solvent and in the presence of β-cyclodextrin, indicating an increase in the negative character of the transition state for the reactions in the latter conditions. The results are interpreted in terms of the formation of an inclusion complex whose structure depends on the substrate.Key words: cyclodextrin, elimination reactions, inhibition, catalysis.
1-溴-2-X-2-(Y-苯基)乙烷衍生物(1:X = Y = H;2:X = Ph,Y = H;3:X = H,Y = 4-Ac;4:X = H,Y = 3-NO2;5:X = H,Y = 4-NO2;6:X = H,Y = 3-Me;7:X = H,Y = 4-Me)在碱性溶液中的反应进行了研究,在大多数情况下,只形成消除产物。只有(2-溴-1-苯基乙基)苯,2,产生了显著的取代产物,这种产量随着HO-浓度的减少而减少。环糊精(β-CD)的添加减少了所有底物的反应速率(对于0.02 M环糊精浓度减少了约一半),但对于4和5而言,速率却上升了。在后两种情况下,速率增加。在0.5 M NaOH下观察到的速率常数值分别为6.78 × 10-4 s-1(在40°C下)和1.80 × 10-3 s-1(在25°C下)对于4和5。在相同的反应条件下,但使用0.01 M β-CD,相应的速率分别为7.70 × 10-4 s-1和5.20 × 10-3 s-1。当β-CD从零变为0.02 M时,2的消除产量从64%增加到98%。此外,化合物6和7的相对消除产物增加了20-40%。在纯溶剂和β-环糊精存在的情况下,Hammet ρ值分别为1.3和2.3,表明在后一种条件下反应的过渡态的负性特征增加。结果根据形成取决于底物的包含复合物的结构进行解释。关键词:环糊精,消除反应,抑制,催化。