2-Chloro-5-methylnitrobenzene

Rondevstedt, C. S., Chem. Eng. News, 1977, 55(27), 38 Synthesis, 1977, 851-852 In an attempt to reduce 2-chloro-5-methylnitrobenzene to the aniline by treatment with excess hydrazine and Pd/C catalyst, the hydroxylamine was unexpectedly produced as major product. During isolation of the product, after removal of solvent it was heated to 120°C under vacuum and exploded fairly violently. Many aryl-hydroxylamines decompose violently when heated above 90-100°C, especially in presence of acids. GLC is not suitable as an analytical diagnostic for arylhydroxyl-amines because of this thermal decomposition. 

Table 4.3 presents the relative rate constants of the chlorine-to-methoxy substitution in the nitrobenzene series (Epiotis 1973). The methoxide ion replaces chlorine in 4-chloro-3-methyl-nitrobenzene more rapidly than in 6-chloro-3-methylnitrobenzene (Table 4.3, entries 1 and 2). This... 

Table 4-3 presents the relative rate constants of chlorine-to-methoxy substitution in the nitrobenzene series (Epiotis 1973). The methoxide ion replaces chlorine in 4-chloro-3-methylnitrobenzene more rapidly than in 6-chloro-3-methylnitrobenzene (Table 4-3, nos. 1 and 2). This agrees with the fact that the anion radical of 3-methylnitrobenzene has a greater spin density in position 4 than in position 6. The aforementioned HFC constants of the 3-nitrochlorobenzene anion radical and the relative rate constants (kre ) for the substitution of methoxyl for chlorine at the / th carbons (Table 4-3, nos. 3 and 4) correlate in the same way. 

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