1、胺的氧化

      胺甲基化合物与六次甲基四胺在弱酸性溶液中加热可得醛（Sommelt 反应），收率在 60-70%左右。

      苄胺在 DMSO 溶液中与亚硝酸钠及三氟醋酸 100℃加热可得苯甲醛。

胺的氧化合成醛反应示例：

      A solution of 272 g. (261 ml., 2.00 moles) of α,α'-diamino-m-xylene, 1.00 kg. (7.1 moles) of hexamethylenetetramine, 480 ml. of concentrated hydrochloric acid, and 3.2 l. of 50% aqueous acetic acid in a 12-l. flask is stirred and heated at the reflux temperature for 2.5 hours. The hot amber reaction mixture is then poured into a large battery jar in a well-ventilated hood, and a solution prepared from 298 g. of sodium hydroxide and 3.85 l. of water is added slowly with stirring. The mixture is covered and allowed to stand overnight at about 5°. The product, which separates as long needles, is collected, washed on a Buchner funnel with 100ml. of cold water, and then dried to constant weight under vacuum (Note 3) over calcium chloride. There is obtained 158–166 g. (59–62%) of almost colorless needles of

isophthalaldehyde, m.p. 88–90°

2、由胺经由西佛碱的方法

      将胺与 4-吡啶甲醛反应成西佛碱后在强碱作用下使不饱和键异构化，再予水解，即可得醛。

由胺经由西佛碱的方法示例：

   1.77 g (12 mmol) of 4-chlorobenzylamine and 2.78 g (26 mmol) of isonicotinaldehyde were dissolved in 24 ml of DMF. 1.83 g (12 mmol) of DBU was added. The mixture was stirred overnight and acidified by 5% HCl, extracted with ehter. Organic phase was wahed with water, dried over Na 2 SO 4 and concentrated to give 1.40 g of 4-chlorobenzaldehyde.Yield: 83%. mp 42~46℃.