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在中性或碱性溶液中，芳香族重氮盐用亚硝酸钠处理，即以较好产率生成芳香族硝基。本法适用于合成特殊取代位置的芳香族硝基化合物。例如．邻二硝基苯、对二硝基苯均不能由直接硝化法制得，但它们可由邻硝基苯胺、对硝基苯胺形成的重氮盐与亚硝酸钠制得。通常，铜盐或铜及其氧化物是反应有效的催化剂。为避免重氮盐中的阴，如氮离子，引起的竞争性副反应，一般用BF4－作为阴离子。

p-troaniline (32 g,0.25 mol) is dissolved in  fluoboric (110 mL) solution in a 400-cc.beaker. The beaker is placed in an ice bathand the solution stirred with an efficient stirrer.A cold solution of (17 g, 0.25 mol) of sodium nitrite in 34 mL of water is added dropwise. Whenthe is complete, the mixture is stirred for a few minutes and filteredby suction on a sintered glass filter. The soliddiazonium fluoborate is washed once with 25–30 mL of cold fluoboric acid, twice with 95 percent alcohol, and several times with ether. The product weighs 56–59 g (95–99per cent of the theoretical amount). Two hundred grams of sodium nitrite is dissolved in 400 mLof water in a 2-L. beaker, and 40 g of copper powder is added.The mixture is stirred with an efficient stirrer, and a suspension of the p-nitroenyldiazonium fluoborate in 200 mL ofwater is added slowly. Mu frothing occurs, and 4–5 mL ofether is added from time to time to breakthe fo The is complete when all the diazonium compound has beenadded. The product is filtered with suction, washed several times with water,twice with dilute sodium hydroxide solution, andagain with water. The solid is dried in an oven at 110°, powdered, andextracted with 300 mL., 200 mL., and 150 mL portions ofboiling benzene. The benzeneis evaporated on a water bath, and the residue iscrystallized from 120–150 mL of boiling glacial acetic acid. The resulting reddish yellow crystals,melting at 172–173°, weigh 28–34.5 g (67–82% yield). Recrystallization from alcohol yields pale yellow crystals melting at173°C.

【  Organic Syntheses, Coll.Vol. 2, p.225; Vol. 19, p.40.】

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