In spite of the tremendous importance of sulfuric and nitric acids, their uses are increasingly limited, due to concerns about worker safety. There is a fundamental need to find safer alternatives to these acids. One of these alternatives is the use of solid acids. Over the last two decades, applications of solid acids have become popular. Their many benefits include easy handling, enhanced worker safety, fewer reactor corrosion problems and the minimization of waste and by-products. The solid acids have proved to be helpful in chemistry due to the useful activation of starting materials, reduction in reaction times, substrate selectivity, and easy work-up. In previous studies on the application of solid acids, we had found that melamine easily reacts with neat sulfuric acid and concentrated nitric acid to produce melamine-(H2SO4)3 (I) and melamine-(HNO3)3 (II), respectively, in fast and clean reactions (Scheme 1). The present paper shows that a mixture of these solid acids can be used as an oxidizing system for the oxidation of urazoles and alcohols and can also be used for the nitration of active aromatic rings under solvent-free conditions. Initially, oxidation of 4-phenylurazole was run with melamine-(HNO3)3 in the absence of melamine-(H2SO4)3. It was found that the reaction did not occur using a ten-fold excess of melamine-(HNO3)3 even after a long reaction time. However, after the simple addition of the melamine-(H2SO4)3, the reaction was complete within 5minutes. This result prompted us to carry out the oxidation of a range of urazoles in the presence of melamine-(H2SO4)3 [(I), 0.5mmol] and melamine-(HNO3)3 [(II), 0.5mmol] at room temperature in the absence of organic solvents. These conditions were also successfully applied to the nitration of active aromatic rings. Since our melamine-(H2SO4)3/melamine-(HNO3)3 system could not oxidize alcohols alone (Table 1,

中文翻译：

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三聚氰胺-(H2SO4)3/三聚氰胺-(HNO3)3 代替 H2SO4/HNO3：用于原位 NO2+ 氧化/硝化反应的良性系统

尽管硫酸和硝酸非常重要，但由于对工人安全的担忧，它们的使用越来越受到限制。寻找这些酸的更安全替代品是一个基本需求。这些替代方案之一是使用固体酸。在过去的二十年中，固体酸的应用变得流行起来。它们的许多优点包括易于操作、提高工人安全性、减少反应器腐蚀问题以及最大限度地减少废物和副产品。由于起始材料的有用活化、反应时间的减少、底物选择性和容易的后处理，固体酸已被证明在化学中是有帮助的。在以往关于固体酸应用的研究中，我们发现三聚氰胺很容易与纯硫酸和浓硝酸反应，在快速和清洁的反应中分别生成三聚氰胺-(H2SO4)3 (I) 和三聚氰胺-(HNO3)3 (II)（方案 1）。本论文表明，这些固体酸的混合物可用作氧化尿唑类和醇类的氧化体系，也可用于无溶剂条件下活性芳环的硝化。最初，在没有三聚氰胺-(H2SO4)3 的情况下，使用三聚氰胺-(HNO3)3 进行 4-苯基脲唑的氧化。发现即使在很长的反应时间之后，使用十倍过量的三聚氰胺-(HNO 3 ) 3 也不会发生反应。然而，在简单地加入三聚氰胺-(H2SO4)3后，反应在5分钟内完成。这一结果促使我们在三聚氰胺-(H2SO4)3 [(I), 0.5mmol] 和三聚氰胺-(HNO3)3 [(II), 0.5mmol] 的存在下，在室温下进行一系列尿唑的氧化在没有有机溶剂的情况下。这些条件也成功地应用于活性芳环的硝化。由于我们的三聚氰胺-(H2SO4)3/三聚氰胺-(HNO3)3 系统不能单独氧化醇（表 1，