Sequential catalytic condensation-hydrogenation of ketones
Sequential catalytic condensation-hydrogenation of ketones
复制标题
酮的连续催化缩合-氢化
DOI：
10.1021/jo01313a007
复制
发表时间：
1980
影响因子：
3.6
通讯作者：
Yeon
中科院分区：
文献类型：
--
作者：
C. Pittman;Yeon
采用固定化酸催化剂（Nafion-H或Amberlite IR-120）和Pd/C在氢气下同时进行羟醛缩合和缩合产物的氢化。在60-140 ℃和20-300 psi氢气下，在一锅多步法中将丙酮转化为4-甲基-2-戊酮。4-甲基-2-戊酮的产率高于在不存在氢化催化剂的情况下获得的异亚丙基丙酮的平衡限制产率，表明异亚丙基丙酮的平衡通过异亚丙基丙酮氢化而移动为4-甲基-2-戊酮。2-丙酮加氢与缩合反应是竞争性反应，丙酮加氢的主要副产物是丙醇。高沸点的产品，发现在羟醛缩合，没有形成在缩合加氢过程。使用RhCl（PPh 3）3或其聚合物结合的类似物作为氢化催化剂减少了丙酮氢化的量，但减缓了缩合-氢化反应。苯甲醛和丙酮在NaFion-H和Pd/C催化下交叉羟醛缩合-加氢制得4-苯基-2-丁酮。主要的副反应是苯甲醛竞争加氢生成甲苯。2，5-己二酮的分子内缩合反应主要生成2，5-二甲基呋喃，而酮的缩合-加氢一锅法反应主要生成2，5-二甲基四氢呋喃，酮的羟醛缩合反应是乙醛经缩合、脱水、加氢合成正丁醇等工业过程的基础。1由丙酮合成甲基异丁基酮和4-甲基-2-戊醇是另一个例子（等式1）。丙酮的羟醛缩合反应，然后是三羟甲基氨基甲烷-
Aldol condensation and hydrogenation of the condensation product have been carried out simultaneously by using an immobilized acid catalyst (Nafion-H or Amberlite IR-120) and Pd/C under hydrogen. Acetone was converted to 4-methyl-2-pentanone in a one-pot multistep process at 60-140 C and 20-300 psi of hydrogen. The yields of 4-methyl-2-pentanone were higher than the equilibrium-limited yields of mesityl oxide obtained in the absence of the hydrogenation catalyst, demonstrating that the equilibrium to mesityl oxide was shifted by mesityl oxide hydrogenation to 4-methyl-2-pentanone. 2-Propanol was the major byproduct because acetone hydrogenation was competitive with condensation. High-boiling products, found in aldol condensations, were not formed in the condensation-hydrogenation process. Use of RhCl (PPh3) 3 or its polymer-bound analogue as the hydrogenation catalyst reduced the amount of acetone hydrogenation but slowed the condensation-hydrogenation reactions. The crossed aldol condensation-hydrogenation of benzaldehyde and acetone gave 4-phenyl-2-butanone with Nafion-H and Pd/C. The major side reaction was the competitive hydrogenation of benzaldehyde to toluene. The intramolecular condensation of 2, 5-hexanedione gave mainly 2, 5-dimethylfuran while the one-pot condensation-hydrogenation reaction gave 2, 5-dimethyltetrahydrofuran.The aldol condensation of ketones is the basis for several industrial processes such as the synthesis of 1-butanol from acetaldehyde via condensation, dehydration, and hydro-genation. 1 The synthesis of methyl isobutyl ketoneand 4-methyl-2-pentanol from acetone is another example (eq 1). Aldol condensation of acetone, followed by dehydra-