醛和酮还原转变成醇的方法一直是分别制备伯醇和仲醇的一个较为常用的方法。还 原醛和酮到醇主要方法可以分为两类：化学还原法和催化氢化法。 

1、醛和酮的加氢还原 

      醛和酮的羰基也可通过加氢还原为相应的伯醇和仲醇。催化剂一般为负载在载体上的镍、铬、铜或铜铬等。若加氢原料含有硫化物，则采用镍、钴或钨的氧化物或硫化物 型抗硫催化剂。 

      醛和酮的氢化活性通常大于芳环而小于不饱和键。醛比酮更易氢化，所以醛加氢条 件比较温和，一般温度为 50～150℃（采用镍或铬催化剂）或 200～250℃（采用硫化物 催化剂）；而酮加氢的条件在采用上述相同的催化剂时则相应地温度为 150～250℃及 300～350℃。为了加速反应，及提高平衡反应的转移，这类化合物加氢时也在压力下进 行。用镍催化剂时，压力为 1～2Mpa，铬催化剂时为 5～20Mpa，而用硫化物催化剂时 则为 30Mpa。           脂肪族醛，酮的氢化活性较之芳香族醛，酮为低，通常用 Raney 镍和铂为催化剂，而钯催化剂的效果较差。一般需在较高温度和压力下还原。例如，由葡萄糖氢化得山梨 醇（sorbitol）。

      芳香醛酮的氢化还原，如用钯为催化剂，在加氢剧烈时生成的醇会进一步氢解为烃特别对于芳环上有强推电子基团存在或二芳基酮（。但如选用适当活 性的 Raney 镍为催化剂，在温和的条件下，可得到醇。如天麻素（gastrodine）中间体的 制备。 

       催化剂钌，铑，铱等金属的三苯膦等配合物，在强碱条件下，可成功地还原脂肪酮 和芳香酮为相应的醇 

醛和酮的加氢还原示例

     In a 2-l. three-necked flask equipped with a stirrer and thermometer are placed 336 g. (2.62 moles) of 3,4-dihydro-2-methoxy-4-methyl-2H-pyran, 630 ml. of water, and 24 ml. of concentrated hydrochloric acid. The mixture is stirred for 2 hours, during which the temperature may reach 50℃ but should not be permitted to rise higher. Solid sodium bicarbonate is then added until the solution is neutral to pH indicator paper. The entire reaction mixture weighing about 1 kg. together with 39 g. of Raney nickel2 is introduced into a 3-l. stainless-steel rocking hydrogenation autoclave. A hydrogen pressure of at least 1625 p.s.i. is applied, and the autoclave is heated to 125℃ and held there with shaking for 4 hours. The mixture is allowed to cool overnight, and the catalyst is separated either by suction filtration through Filter-Cel or by centrifugation. The solution is distilled through a 12-in. Vigreux column. After the methanol and water are separated, the 3-methyl-1,5-pentanediol distils at 139–146℃/17 mm., 149–150℃/25 mm. The yield is 251–256 g. (81–83%), n25D 1.4512–1.4521.