Thermolysis of N-aryl-N-nitrosoureas to afford aryl isocyanates and nitrosamines via O-nitrosoisourea intermediates.
作者:Masayuki TANNO、Shoko SUEYOSHI、Shozo KAMIYA
DOI:10.1248/cpb.38.2644
日期:——
Nitrosation of 3, 3-dialkyl-1-(4-tolyl)ureas (9) with sodium nitrite in formic acid under ice-cooling gave 3, 3-dialkyl-1-(4-tolyl)-1-nitrosoureas (10). In the nitrosation of the ureas with a benzyl group, small amounts of dealkylated nitrosourea, 3-benzyl-1-(4-tolyl)-3-nitrosourea, were formed as a by-product. Decomposition of 10 in CCl4 at 33°C under an argon atmosphere gave 4-tolyl isocyanate (11) and N-nitrosodialkylamines (12) besides ureas (9), 3, 3-dialkyl-1-(2-nitro-4-tolyl)ureas (13) and 3, 3-dialkyl-1-(4-tolyl)triazenes (14). Formation of 11 and 12 suggests the involvement of an O-nitrosoisourea intermediate (15) in the decomposition of 10. In the thermolysis of 10 involving radical decomposition, nitric oxide generated from 10 was trapped as an NO3 complex of N, N'-etylenebis-(salicylideneiminato)iron (Fe(III)-salen-NO3).
在冰冷却条件下,3,3-二烷基-1-(4-甲苯基)脲(9)与亚硝酸钠在甲酸中进行亚硝化反应,生成3,3-二烷基-1-(4-甲苯基)-1-亚硝基脲(10)。在含有苄基的脲的亚硝化反应中,作为副产物形成了少量的脱烷基化亚硝基脲,即3-苄基-1-(4-甲苯基)-3-亚硝基脲。在氩气氛下,10在四氯化碳中于33°C分解,除了生成脲(9)、3,3-二烷基-1-(2-硝基-4-甲苯基)脲(13)和3,3-二烷基-1-(4-甲苯基)三氮烯(14)外,还生成4-甲苯基异氰酸酯(11)和N-亚硝基二烷基胺(12)。11和12的形成表明,10的分解过程中涉及到了一个O-亚硝基异脲中间体(15)。在涉及自由基分解的10的热分解过程中,从10产生的氮氧化物被捕获为N,N'-亚乙基双(水杨醛亚胺)铁(Fe(III)-salen-NO3)的NO3复合物。