PREPARATION OF 1,2-DIKETONES - OXIDATION OF ALKYNES BY POTASSIUM-PERMANGANATE IN AQUEOUS ACETONE
PREPARATION OF 1,2-DIKETONES - OXIDATION OF ALKYNES BY POTASSIUM-PERMANGANATE IN AQUEOUS ACETONE
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DOI：
10.1021/jo01323a049
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发表时间：
1979-01-01
影响因子：
3.6
通讯作者：
LEE, DG
中科院分区：
文献类型：
--
作者：
SRINIVASAN, NS;LEE, DG
虽然高锰酸钾氧化烷基酮生成相应的1，2-二酮通常被认为是一种普遍的反应，但文献中只描述了两种实现这些转化的方法。其中一种仅限于硬脂酸等可溶于水的碱的炔烃，另一种则需要使用相转移剂。2在本笔记中，我们希望报告一种简单、通用的方法，用于在丙酮水溶液中将炔氧化成相应的1，2-二酮(表I)。为了获得好的产量，有必要保持一个大致中性的溶液。这可以通过添加一定量的碳酸氢钠和硫酸镁来实现。添加的盐用作缓冲剂(初始pH为7.0-7.5)，并中和高锰酸盐还原过程中产生的氢氧化物离子。4制备8，9-十六碳二酮。2-L Erlenmeyer烧瓶，浸泡在25℃的水浴中，充入试剂级丙酮(1.05 L)和8-十六烷(6 g，0.027摩尔)。在此基础上加入NaHCOA(1.36g，0.0162摩尔)和MgS04(13.6g，0.0552摩尔)的水溶液(600毫升)。用机械搅拌器搅拌混合物。在高锰酸钾中加入粉末高锰酸钾(16.6g，0.105摩尔)，搅拌4 h，少量加入少量NaNCl7 g和10%H 2SCL(70 M L)，将未反应的高锰酸盐和沉淀的MnOg还原为可溶的Mn2+离子。将溶液转移到2-L分离漏斗中，用氯化钠饱和，然后用己烷-乙醚混合物(1：1，3×200毫升)提取。使用旋转蒸发器去除有机溶剂。残留物溶解在乙醚(50毫升)中，用稀释的氢氧化钠溶液(5%，4×50毫升)提取，以去除存在的任何羧酸。乙醚层用饱和的氯化钠溶液洗涤，干燥(无水Na2S04)，在旋转蒸发器中除去溶剂。得到的粗品重6.75g(98%)。固体经甲醇重结晶后，得到8，9-十六烷二酮黄色平板(5.6g，81%)：熔点48.5-49.5℃(LIT)。6 49-50℃)；IR(熔体)2930,1705,1475厘米“1；核磁共振(CC14)h 0.9(t，6)，1.32(m，20 H)，2.67(t，4 H)。作者感谢加拿大国家研究委员会的财政支持。
Although the oxidation of alkynesto the corresponding 1, 2-diones by potassium permanganate is often considered to be a general reaction, the literature describes only two methods for effecting these transformations. One of them is restricted to alkynes such as stearolic acid, 1 which are soluble in aqueous base, and theother necessitates the use of phase-transfer agents. 2 In this note we wish to report a simple, general methodfor the oxidation of alkynes to the corresponding 1, 2-diones in aqueous acetone solutions (Table I). In orderto obtain good yields, it is necessary to maintain an approximately neutral solution. This can be achieved by addition of definite amounts3 of sodium bicarbonate and magnesium sulfate. The added salts serve as a buffer (pH 7.0-7.5 initially) and neutralize hydroxide ions which are produced during the reduction of permanganate. 4 Preparation of 8, 9-Hexadecanedione. A 2-L Erlenmeyer flask, immersed in a water bath at 25 C, was charged with reagent grade acetone (1.05 L) and 8-hexadecyne (6 g, 0.027 mol). To this was added a solution of NaHCOa (1.36 g, 0.0162 mol) and MgS04 (13.6 g, 0.0552 mol) in water (600 mL). The mixture was stirred with a mechanical stirrer. Powdered po-tassium permanganate5 (16.6 g, 0.105 mol) was added in one portion, and the mixture was stirred for 4 h. The unreacted permangante and the precipitated MnOg were reduced to soluble Mn2+ ions by adding a minimum quantity of NaNCL (7 g) and 10% H2SCL (70 mL) in small portions. The solution was transferred to a 2-L separating funnel, saturated with NaCl, and extracted with a hexane-ether mixture (1: 1, 3 X 200 mL). The organic solvents were removed using a rotary evaporator. The residue was dissolved in ether (50 mL) and extracted with a dilute NaOH solution (5%, 4 X 50 mL) to remove any carboxylic acids present. The ether layer was washed with a saturated solution of NaCl and dried (anhydrous Na2S04), and the solvent was removed in a rotary evaporator. The crude product obtained weighed 6.75 g (98%). The solid, when recrystallized from methanol, gave 8, 9-hexadecanedione as yellow plates (5.6 g, 81%): mp 48.5-49.5 C (lit. 6 49-50 C); IR (melt) 2930, 1705, 1475 cm” 1; NMR (CC14) h 0.9 (t, 6), 1.32 (m, 20 H), 2.67 (t, 4 H).Acknowledgment. The authors are grateful to the Na-tional Research Council of Canada for financial support.