脂肪体系中的亲核取代反应是最受有机化学家注意的单元反应之一，其中脂肪卤代烃或磺酸酯与金属氰化物的亲核取代合成腈得到了广泛的应用：

       在转化合成过程中最有用的是在直接取代机理方面有反应活性的底物。即伯类及未受阻碍的仲类脂肪卤代烷或磺酸酯。在叔烷基体系中发生消去反应的倾向是相当显著的，从而在涉及这些体系的转化合成方面限制了亲核取代{attr}2158{/attr}。有时侯，当非碘代的卤代烃反应活性不够时，需要在反应体系中加入 KI 或 NaI 增加卤代烃反应活性，或者假如氧离子络合剂，如18冠6等; 有不少文献报道用相转移催化方法完成这一取代。

       脂肪卤代烃可由相应醇经卤代反应制备，而磺酸酯可由相应醇经与甲烷磺酰氯或对甲苯磺酰氯反应得来。

1、烷基卤代物的氰基取代反应示例

    To a stirring solution of sodium cyanide (1.62 g, 33 mmol) and potassium iodide (66 mg,0.4 mmol) in dimethyl sulfoxide (20 ml) at 40 deg C., was slowly added 1-bromo-2-ethylbutane over 30 min. The reaction mixture was stirred at 80 deg C for 12 h, then at 110 deg C for 4 h. The reaction mixture was cooled and partitioned between Et 2 O

and water. The organic layer was washed with brine, dried over Na2SO4, filtered and concentrated in vacuo to yield 2.9 g (87percent yield) of 1-cyano-2-ethylbutane as an amber oil.

2、磺酸酯的氰基取代反应示例

  A mixture of 1-[(4-butylphenyl)methyl]-3-(4-chloro-2-methylphenyl)-1-[6-[(methylsulfonyl)oxyl]-hexyl]urea (2.0 g) in a few mL of DMF was added to a cooled stirring suspension of anhydrous sodium cyanide (0.50 g) in 3 mL of dry DMSO. The mixture was heated overnight at 80 ℃. Then it was poured into water (100 mL) and the product was extracted with dichloromethane. The combined extracts were washed water, dried (MgSO 4 )and concentrated to give 1-[(4-butylphenyl)methyl]-3-(4-chloro-2-methylphenyl)-1(6cyanohexyl)urea.