碳正離子加成到腈基的氮原子上生成的腈鹽加水分解得到相應(yīng)的酰胺加水可以分解為酰胺。一般能產(chǎn)生碳正離子化合物都可以發(fā)生這類反應(yīng)。由于醇或烯烴在濃硫酸或其他強酸加熱條件下反應(yīng)，一般在次條件下穩(wěn)定的腈都可用于該類反應(yīng)。
這類反應(yīng)通過腈和酸在溶劑中反應(yīng)，但對于乙腈來說，直接用乙腈中應(yīng)即可，對于其他較為復(fù)雜，沸點較高的底物，一般用冰醋酸稀釋。
一般鹵代物用于這一反應(yīng)比烯烴和醇要差，但用亞硝基四氟硼酸鹽（NOBF 4 ）和亞硝基六氟磷酸鹽(NOPF 6 )可以室溫以下反應(yīng) [5] 。這兩個試劑也可直接拔除三取代碳上的氫生成碳正離子。
當使用醇作反應(yīng)物時，則可以得到相應(yīng)的 N-烴基酰胺
而通過鹵素或有機硒等對烯烴加成，得到的碳正性的中間體也可用于對乙腈的加成。如果所用的是環(huán)狀烯烴，則為反式加成。
Ritter 反應(yīng)示例一
A solution of 5.3 g (0.1 mol ) of acrylonitrile, 50 ml of acetic acid and 7.4 g of t butylalcohol in an ice-bath was treated with conc. sulfuric acid (10.1 g, 0.1 mol) with stirring so as to keep the temperature below 40 ℃ during the addition and subsequent reaction (an hour), the reaction mixture was poured onto 200 g of ice, the product filtered and air dried, yield 10 g (yield 80 %). The product could be recrystallized from benzene.
Ritter 反應(yīng)示例二
To a mixture of alcohol (10 mmol) and trimethylsilyl cyanide (20 mmnol), cooled to - 15°C in an ice-salt bath, under nitrogen, is added concentrated sulfuric acid (30 mmol) dropwise with vigorous stirring (caution: highly exothermic). After the addition, the cold bath is removed and the mixture is stiffed at ambient temperature for 18 hrs. Tile mixture is then poured onto ice, and neutralized with 50% NaOH solution to pH = 7. The aqueous is extracted with t-BuOMe or CHCl 3 , and the combined organic extracts are washed with brine, and dried over MgSO 4 . The crude product is purified by recrystallization (solid) or flash chromatography (oil).
