Reaction of 1,2-naphthoquinone-4-sulfonate with aliphatic amines: Structure of the colored products and kinetics.
作者:YUTAKA ASAHI、MASAMI TANAKA、KAZUO SHINOZAKI
DOI:10.1248/cpb.32.3093
日期:——
Substitution of the 4-sulfonate in sodium 1, 2-naphthoquinone-4-sulfonate (I) with many kinds of aliphatic amines (II) yields colored 4-substituted 1, 2-naphthoquinones (Q) : 4-morpholino-Q (IIIa), 4-piperidino-Q (IIIb), 4-pyrrolidino-Q (IIIc), 4-(1, 2, 4-triazol-1-yl)-Q (IIId), 4-(2-pyrrolyl)-Q (IIIe), 4-dimethylamino-Q (IIIf), 4-diethylamino-Q (IIIg), 4-isopropylamino-Q (IIIh), and 4-(4-amino-2-methyl-5-pyrimidylmethylamino)-Q (IIIi). The eliminated sulfite adds rapidly to the 4-position in I to form a colorless by-product, disodium 2-hydroxy-1-oxo-1, 4-dihydro-4, 4-naphthalenedisulfonate (IV). The rates of reactions were measured by polarography. The formations of IIIa and IV are successive second-order reactions. The pH profile of the rate constant, with a rounded peak at pH 10, suggests nucleophilic substitution of the free base (II) at the 4-carbon in the o-quinone form (I). The hydrolysis of IIIa to 2-hydroxy-1, 4-naphthoquinone (V) is an acid-base-catalyzed pseudo-first-order reaction. The best conditions for photometric determination of morpholine (IIa) were found to be reaction of IIa with excess I at pH 8 and 25°C for 30 min.
将钠1,2-萘醌-4-磺酸盐(I)中的4-磺酸基替换成多种脂肪胺(II),得到有色的4-取代的1,2-萘醌(Q):4-吗啉代-Q(IIIa)、4-哌啶代-Q(IIIb)、4-吡咯烷代-Q(IIIc)、4-(1,2,4-三唑-1-基)-Q(IIId)、4-(2-吡咯基)-Q(IIIe)、4-二甲氨基-Q(IIIf)、4-二乙氨基-Q(IIIg)、4-异丙氨基-Q(IIIh)及4-(4-氨基-2-甲基-5-嘧啶基甲氨基)-Q(IIIi)。被取代的亚硫酸盐迅速加到I的4位上,形成一种无色的副产物,即二钠2-羟基-1-氧-1,4-二氢-4,4-萘二磺酸盐(IV)。反应速率是通过极谱法测量的。IIIa和IV的生成是连续的二级反应。速率常数的pH曲线在pH10处有一个圆顶峰,这说明自由基(II)在邻醌形式(I)的4-碳位上发生了亲核取代反应。IIIa水解成2-羟基-1,4-萘醌(V)是一个酸碱催化的假一级反应。通过研究找到了用光度法测定吗啉(IIa)的最优条件,即IIa与过量的I在pH8和25摄氏度下反应30分钟。