由烯烴的甲?；铣扇?/span>
烯烴經(jīng) Vilsmeier 反應(yīng)，可直接甲?；?。反應(yīng)操作簡(jiǎn)單，只需在 POCl3 存在下與 DMF作用即可。此反應(yīng)僅限于有給電子基的烯烴。 烯烴經(jīng)加成氧化反應(yīng)合成酮 末端烯烴可通過(guò)使用二價(jià)鈀的 Wacker 法氧化成甲基酮。催化劑有 PdCl 2 、Pd（CH 3 CO 2 ） 2 、Na 2 PdCl 4 等的鈀鹽。再氧化劑為 CuCl 2 ，CuCl， Cu（NO 3 ） 2 ，酞花菁鐵。氧化劑除了用氧氣外，還可用 H 2 O 2 ，t-BuOOH，苯醌電解氧化。 1，2-二取代烯或環(huán)狀烯可用 KMnO4 氧化，在中性~pH9 時(shí)生成 2-羥基酮，在醋酐中則生成 1，2-而酮。 烯烴經(jīng)加成- 氧化反應(yīng)合成酮示例 1 ：
A. 2-exo-Norbornyl formate. Approximately 800 g. (17.4 4 moles) of 98–100% formic acid is added to 400 g. (4.25 moles) of nobornene in a 2-l. round-bottomed flask equipped with a condenser, and the mixture is boiled under reflux for 4 hours. The dark solution is cooled and the flask arranged for distillation using a 30-cm. Vigreux column. The excess formic acid is removed under reduced pressure (b.p. 26–30°/21–30 mm.). Distillation of the residue then gives a forerun of about 100 ml. of a mixture of formic acid and ester followed by about 485 g. of 2-exo-norbornyl formate, a colorless oil, b.p. 65–67°/14–16 mm. n D 25 1.4594–1.4597. Another 55–65 g. of ester is obtained by adding water to the forerun, extracting with 30–60° petroleum ether, washing the extracts with dilute sodium carbonate solution, drying over sodium sulfate, and distilling. The total yield is 540–550 g.(90.5–92.5%).
B. 2-Norbornanone. A solution of 510 g. (3.64 moles) of 2-exo-norbornyl formate in 1.5 l.of reagent grade acetone is contained in a 5-l. three-necked flask equipped with a thermometer, stirrer, and dropping funnel containing 8N chromic acid solution. The flask is cooled with an ice bath and the oxidant is added at a rate such that the reaction temperature is maintained at 20–30°. Approximately 1870 ml. of oxidant solution is required, completion of the reaction being shown by the persistence of the brownish orange color. A slight excess of oxidant is added, and the solution is stirred overnight at room temperature. Solid sodium bisulfite is added in portions to reduce the excess oxidant.
The reaction mixture is poured into a large separatory funnel. The dark green chromic sulfate sludge, which has formed during the course of the reaction, is separated either by decantation and washing or by drawing it off from the bottom of the funnel. The acetone solution is washed three times with 200–250 ml. portions of an aqueous saturated potassium carbonate solution and finally is dried over anhydrous potassium carbonate. The acetone is removed by distillation through a 30-cm. Vigreux column at atmospheric pressure; benzene may be added near the end to assist in the removal of water by azeotropic distillation. When it is observed that the distillation of solvent is complete and the considerably hotter vapors of product begin to ascend the column, the condenser is removed from the top and replaced by an adapter and collection flask immersed in ice water. The adapter is heated and maintained above 100° by a free flame until the product begins to distil. 2-Norbornanone, 335–350 g. (83–87%), distils at 170–173° and crystallizes immediately in the collection flask. The crystals melt at 90–91°and are sufficiently pure for most preparative purpose.
烯烴經(jīng)加成- 氧化反應(yīng)合成酮示例 2 ：
In a 2-l. three-necked flask fitted with stirrer, dropping funnel, and thermometer are placed 700 ml. of formic acid (88%) and 140 ml. of hydrogen peroxide (30%, 1.37 moles). While the temperature is kept at 35–40°, 116.2 g. (117.3 ml., 1.00 mole) of indene (98%) is added dropwise, with stirring, over a period of 2 hours. An additional 100 ml. of formic acid is used to rinse the last of the indene from the dropping funnel into the reaction flask. The reaction solution is stirred at room temperature for 7 hours to ensure complete reaction. The solution is transferred to a 2- or 3-l. Claisen flask, and the formic acid is removed under aspirator pressure (b.p. 35–40°/20–30 mm.), care being taken to maintain the boiler temperature below 60°. The residue, after being cooled to room temperature, is a yellowish brown crystalline solid, the color being due to contamination by a small amount of brownish oil.
In a 5-l. flask fitted with a long condenser (about 40 cm.) connected to an ice-cooled receiver is placed 2 l. of 7% (by volume) sulfuric acid. The solution is heated to boiling, and the crude monoformate of 1,2-indanediol is added. Steam is introduced and the mixture is steam distilled, while external heat is applied with a flame in order to maintain the boiler contents at a constant volume of 2 l. The steam distillation is carried out at the rate of about 1 l. per hour until 5–6 l. of distillate have been collected and the 2-indanone has stopped distilling. The dark-brown oily residue becomes semisolid at room temperature.
The cold distillate is filtered with suction, and the white crystalline solid is sucked thoroughly dry on the filter. The crystals are dried further in a vacuum desiccator (at about 1mm.) at room temperature or below for about 12 hours. The melting point of the 2-indanone is 57–58°. The yield is 90–107 g. (69–81%).
除了以上方法，由烯烴合成酮的方法還有加成-還原、加成-水解、加成異構(gòu)化、插羰等
