EFFECT OF THIOCYANATE ON NITROSATION OF AMINES
EFFECT OF THIOCYANATE ON NITROSATION OF AMINES
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DOI：
10.1038/248601a0
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发表时间：
1974-01-01
期刊：
影响因子：
64.8
通讯作者：
WALKER, SA
中科院分区：
文献类型：
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作者：
BOYLAND, E;WALKER, SA
致癌亚硝胺是由亚硝酸与啮齿动物胃中的仲胺和某些叔胺之间的化学反应形成的1 -3。亚硝胺在人体胃中也能形成，因此对人体有致癌危险。亚硝化反应可由某些阴离子催化4，特别是硫氰酸盐5，6。硫氰酸盐在唾液中分泌，在非吸烟者中通常含有约50 mg l-1（约1 mM），但在吸烟者中含有3至4倍于此浓度。在没有催化剂的情况下，N-甲基苯胺和其他一些仲胺的亚硝化反应在pH 3时最大，但在硫氰酸盐存在下，反应在酸性条件下进行得更快，例如在pH 1和2之间的胃液中（图1）。在pH1.5时，1.0mM硫氰酸盐使反应速率提高约550倍.在低于pH 2的酸性条件下，亚硝化反应速率与（1）亚硝酸盐;（2）硫氰酸盐;和（3）胺的浓度成正比8。在pH3.5和更高的硫氰酸盐具有较小的催化作用，并且主导反应与亚硝酸盐浓度的平方成比例，但很慢。
CARCINOGENIC nitrosamines are formed by chemical reaction between nitrous acid and secondary and some tertiary amines in the stomachs of rodents1–3. Nitrosamines could be formed similarly in the human stomach and so present a carcinogenic hazard to man. The nitrosation reaction is catalysed by some anions4particularly thiocyanate5,6. Thiocyanate is secreted in saliva which in non-smokers normally contains about 50 mg l−1(approximately 1 mM) but in smokers contains three to four times this concentration7. In the absence of catalyst the nitrosation of N-methylaniline and some other secondary amines is maximal atpH 3, but in the presence of thiocyanate the reaction proceeds much more rapidly in acid conditions, such as in gastric juice, betweenpH 1 and 2 (Fig. 1). AtpH 1.5, 1.0 mM thiocyanate increases the rate of reaction about 550 times. Under these acid conditions belowpH 2 the nitrosation reaction rate is proportional to the concentrations of (1), nitrite; (2), thiocyanate; and (3), amine8. AtpH 3.5 and greater thiocyanate has less catalytic action and the predominant reaction is proportional to the square of the nitrite concentration, but is slow.