Nitration of salicylic acid using 2-propyl nitrate/sulfuric acid/tetrabutylammonium hydrogensulfate/dichloromethane/water yielded a mixture of 3-nitro and 5-nitrosalicylic acids in the ratio 56:44. Pure potassium 3-nitrosalicylate was crystallized and converted to 3-nitrosalicylic acid in 30% overall yield.
Nitration of salicylic acid using 2-propyl nitrate/sulfuric acid/tetrabutylammonium hydrogensulfate/dichloromethane/water yielded a mixture of 3-nitro and 5-nitrosalicylic acids in the ratio 56:44. Pure potassium 3-nitrosalicylate was crystallized and converted to 3-nitrosalicylic acid in 30% overall yield.