1、用氧銨鹽氧化
用氧銨鹽氧化醇即可得到相應(yīng)的醛酮。
用氧銨鹽氧化示例：
A 1-L, three-necked, round-bottomed flask is fitted with a mechanical stirrer, pressure-equalizing dropping funnel, and a thermometer. The flask is charged with 44.05 g (0.50 mol) of (S)-(?)-2-methyl-1-butanol, 0.78 g (5 mmol) of 2,2,6,6-tetramethylpiperidin-1-oxyl, 170 mL of dichloromethane, and a solution of 5.95 g (0.050 mol) of potassium bromide in 25 mL of water. The reaction mixture is vigorously stirred and cooled to ?10°C with a salt–ice bath, then 550 mL (0.55 mol) of 1 M aqueous sodium hypochlorite at pH 9.5 is added over 15–20 min, keeping the temperature of the reaction mixture between 10 and 15°C. The mixture is stirred for a further 3 min. The orange organic phase is separated and the aqueous phase is extracted with 50 mL of dichloromethane. The combined organic extracts are washed with 100 mL of 10% aqueous hydrochloric acid containing 1.6 g (0.010 mol) of potassium iodide, 60 mL of 10% aqueous sodium thiosulfate, and 60 mL of water. The organic phase is dried over anhydrous magnesium sulfate and then distilled at atmospheric pressure through a 20-cm Vigreux distilling column to give 35.3–36.3 g (82–84%) of (S)-(+)-2-methylbutanal as a colorless oil, bp 90–92°C (GC purity >99%),[α] D 22 +36.8° (acetone, c 2.5).
2、用高價(jià)碘試劑氧化
高價(jià)碘氧化劑可以在中性或接近中性的條件下，在室溫很溫和地可將伯醇和仲醇氧化為醛酮。一般用二氯甲烷作溶劑。
常用的高價(jià)碘氧化劑有三種，即 (Diacetoxyiodo)benzene (DIB)， o-iodoxybenzoic acid (IBX) 和 Dess-Martin periodinane (DMP)。
DMP 可由鄰碘苯甲酸通過兩步反應(yīng)制得。
DMP 氧化反應(yīng)示例：
To a solution of (Z)-hex-3-enol (9.55 g, 9.55 mmol) in CH 2 Cl 2 (100 mL) under argon was added at 0 °C the DMP (4.85 g, 11.46 mmol). After 5 min, the reaction mixture was allowed to warm to r.t. and stirred for 1 h. The mixture was cooled down to 0 °C and washed with a sat. soln (80 mL) of NaHCO 3 /Na 2 S 2 O 3 (1:1). After decantation the organic layer was washed once again (20 mL). The combined aqueous layers were extracted with CH2Cl2 (30 mL). After drying over MgSO 4 for 2 min, the organic phase was concentrated by slow distillation of CH2Cl2 at 760 mm Hg. Addition and distillation of anhyd benzene allowed obtaining an anhyd solution of hex-3-enal (Yield: 95%).
At 0 °C , to a stirred solution of the alcohol (46) (2.03 g, 1 equiv.) in CH2Cl2 (20 mL) was added a solution of Dess-Martin periodinane (7.47 g, 1.5 equiv.) in CH2Cl2 (80 mL). The mixture was stirred at rt for 1 h. The resulting suspension was filtered through a short silica plug and washed with CH2Cl2. The filtrate was washed with 1 N NaOH, H2O and brine, dried (MgSO4) and concentrated under reduced pressure to yield the desired ketone (60), as a white solid.
IBX 氧化反應(yīng)示例：
General procedure oxidation of alcohols with IBX: A sample of 11 mmol of recrystallised IBX and 10 mmol of general alcohols were added to (27.5mL) DMSO to form 0.4 M of solution and this mixture was stirred at room temperature for 4 h. Water (20mL) was then added to the reaction mixture to precipitate 2-iodobenzoicacid crystals, and these crystals were decanted. The mother liquid was extracted with ether (3x25mL), washed with NaHCO3 solution, and dried over MgSO4 to obtain aldehydes or ketones.
3、亞硝酸鈉和醋酐氧化
一個(gè)較實(shí)用的合成醛的方法，反應(yīng)一般在室溫下進(jìn)行，反應(yīng)時(shí)間較短，可氧化大部分伯醇、烯丙醇和芐醇，而且產(chǎn)率較高，副反應(yīng)較少。
亞硝酸鈉和醋酐氧化反應(yīng)示例：
A typical procedure for oxidation of 4-nitrobenzyl alcohol: a mixture of NaNO 2 (1035 mg, 15 mmol) and 4-nitrobenzyl alcohol (5 mmol) in acetic anhydride (2 mmol) was stirred. A spontaneous exothermic reaction took place. The mixture was cooled in ice bath. After completion of the reaction (TLC), the product was extracted with ether (2 × 10 ml). Removal of the solvent under reduced pressure give crude product which was purified by column chromatography (petroleum ether–ethyl acetate, 9 : 1).
其它的氧化方法還有 TPAP Perruthenate-ley 氧化，Oppenauer 氧化，碳酸銀和氧化銀氧化，過渡金屬氧化劑氧化等。TPAP ([n-Pr 4 N][RuO 4 ])是比較溫和的將醇氧化為醛酮的方法(Reviews: Ley, Synthesis,1994, 639)，反應(yīng)為均相，收率較高，常用于對復(fù)雜分子的氧化。
General procedure:
N-Methylmorpholine oxide (NMO, 1.5 eq) was added to a solution of alcohol (1 eq) in anhydrous CH 3 CN at room temperature. To this mixture was added tetrapropylammonium perruthenate (TPAP, 0.05 eq) as a solution in CH 3 CN (2 ml) and MS4A (2 eq (wt)). The solution was stirred for 5 h. The solvent was evaporated in vacuo and the residue passed through a short column of silica gel (2 cm) and eluted with EtOAc to afford aldehyde (Yield:70~80%).
4、1,2-二醇的氧化
氧化 1,2-二醇的氧化劑一般為過碘酸及四醋酸鉛。用過碘酸氧化的反應(yīng)雖然選擇性好且有意義，但因氧化劑不溶于有機(jī)溶，應(yīng)用受到了限制。為了彌補(bǔ)這個(gè)缺點(diǎn)，可用相轉(zhuǎn)移催化劑的雙相體系氧化的改良法或使用硅膠的非均相反應(yīng)，二者都很有效。乙酸鈷，硝酸鉈也可氧化 1,2-二醇類化合物。
1,2-二醇的氧化示例
A large, magnetic stir bar is added to the flask that contains the crude solid diacetonide and 700–800 mL of dichloromethane (10 mL/g of diacetonide) is added. The flask is equipped with a condenser and heating mantle, and the slurry is stirred vigorously and heated to reflux until the solids are digested to an even consistency. The mantle is removed, the slurry is allowed to cool below reflux, and Celite (10 g) is added with stirring. The contents are further cooled to room temperature and vacuum-filtered through a pad of Celite on a glass frit filter into a three-necked, 2-L vessel. The flask is rinsed with 50 mL of dichloromethane and the rinse is filtered through the funnel. The 2-L vessel is then equipped with an overhead stirrer, thermometer, and water bath, and stirring is begun at 300–350 rpm. A solution of 30–40 mL of saturated aqueous sodium bicarbonate (0.4 mL/g of diacetonide) is added with stirring, followed by 130–140 g of sodium metaperiodate (2.0 mol equiv), added portionwise over 2–3 min. The resulting mixture is stirred while the internal temperature is maintained below 35°C with water bath cooling. After the solution is stirred for 2 hr, 35–50 g of magnesium sulfate (0.5 g/g of diacetonide) is added and stirring is continued for 20 min. The slurry is vacuum-filtered through a glass frit filter into a 2-L, one-necked, round-bottomed flask. The filter cake is removed, transferred back into the three-necked vessel, 200 mL of dichloromethane is added, and the resulting slurry is stirred for 10 min. The slurry is vacuum-filtered and the filtrate is added to the one-necked flask.
The filtrate-containing flask is equipped with a 12"-Vigreux column, distillation head, receiver, and heating mantle, and dichloromethane is removed by distillation (head temperature to 40°C). The residual oil is cooled and transferred to a 250-mL, round-bottomed flask and the flask is equipped with a simple distillation head, cow receiver, and heating mantle. After a brief forerun (2–3 g), product is collected by distillation at 30 mm (65–120°C) into a chilled receiver (5°C) to afford 54–68 g (75–85%) of crude 2,3-O-isopropylidene-D-glyceraldehyde. The crude product is transferred to a 100-mL, round-bottomed flask equipped with a 6"-Vigreux column, cow receiver, and heating mantle, and redistilled at 30 mm, collecting the fraction distilling at 67–73°C into a chilled receiver to afford 50–64 g of product (70–80%, 34–45% overall)。
1,2-二醇可以通過甲磺?；缓髩A消除合成酮。
