|关键词||烯烃 氢羧基化反应 氢酯基化反应 水油两相催化 多相催化体系|
Carboxylic acid and its ester are important intermediates in fine chemicals and pharmaceuticals. Carbonylation of olefins provide an atom-economical route for C=C double bond functionalization, and for this reason, the reactions attract more attention. Palladium-phosphine complexes, especially for the oil-soluble phosphine ligands are the conventional catalysts in these reactions for their high activities. However, the problem of difficulty in separation of catalyst from the reaction mixture was posed in utilization of these oil-soluble phosphine ligands. To solve this problem, aqueous-organic biphasic catalytic system and heterogeneous catalytic system are developed. Generally, the catalytic activities of these two systems are lower than the homogeneous catalytic system for the problem in mass-transfer resistance. In this paper, the main objective was focus on increasing the catalytic activities of aqueous organic biphasic and heterogeneous catalysts. The main works and conclusions are as follows: 1. Hydrocarboxylation of 1-octene catalyzed by Pd-TPPTS complexes Generally, Pd-TPPTS complexes catalyzed hydrocarboxylation of 1-octene in aqueous organic biphasic system with low activity for the low solubility of 1-octene. To improve the activity, surfactants are always used to enhance the mass-transfer. In this paper, different reaction conditions were studied in the reaction, and under the optimum conditions (H2O 16 mL, c(Pd) 2.0 mmol/L, c(TPPTS)/c(Pd) 25, c(p-TsOH) 33.8 mmol/L，c(CTAB) 79.4 mmol/L，5.5 h，4 MPa and 150 oC), the conversion of 1-octene was up to 90.8%, the selectivity of total acids was near to 80% and n/i molar ratio was about 4. Additional, the possible reaction mechanism was proposed. 2. The effect of alkali metal halides on the hydrocarboxylation of styrene catalyzed by Pd-TPPTS complexes. The former studies have found the addition of alkali metal halides could improve the catalytic activity of Pd-TPPTS complexes, but the main reason for this effect was not clear. So, to study this effect, different kinds and amounts of alkali metal halides were investigated, and the results were further confirmed by 1H NMR in hydrocarboxylation of water-soluble olefins in D2O. The changes of the phosphine ligand were monitored by 31P NMR and then the reaction mechanisms were proposed. It was found that the alkali metal halides could improve the total yield of acids and the selectivity of linear product, and the promote effect in selectivity of linear product agreed to the order of MCl < MBr < MI. From the results of 31P NMR and 1H NMR, it was also found that the alkali metal halide could stabilize the Pd(II) species and the C=C double bond could coordinate with Pd strongly even in the room temperature. 3. Hydroesterification of styrene and its derivatives catalyzed by a heterogeneous Pd-TPPTS-OTPPTS/LSI-600 catalyst Br?nsted acid is always needed in hydroesterification of olefins. The weak coordinated homogeneous acid such as p-TsOH is most commonly used in the reaction. However, corrosion problem is posed from the utilization of homogeneous acid. In this paper, some solid acidic resins supporting Pd-TPPTS complexes were prepared as heterogeneous catalysts for hydroesterification of olefins, and the OTPPTS was found to improve the catalytic activity and the selectivity of branched product for its weak coordination ability to Pd atom. In the following study, it was found the pore size had a great effect on the regioselectivity of branched ester. Pd(II) was acceleratively reduced to Pd(0) by adding OTPPTS, and the Pd(0) was found to be as activity species from the results of poisoning and hot filtration tests then the reaction mechanism was proposed. 4. Hydroesterification of styrene catalyzed by Nano-Pd(0)-TPPTS/SiO2 heterogeneous catalyst Pd(0) was found to be catalytic active species in the former studies. In this paper, Pd(II) was initially reduced to Pd NPs before uses. PVP was used as stabilizer in the preparation of Pd NPs, however, the PVP was found to decrease the catalytic activity in the reaction. So the PVP should be removed before the hydroesterification. PVP was extracted by ethanol in the ScCO2 system and then the Nano-Pd(0)-TPPTS/SiO2 catalyst was obtained. From the results of catalyst characterizations, it was found that most of the PVP was removed after the extraction. Additionally, the water-soluble phosphine ligands TPPTS with poorly soluble in organic liquids was used in the reaction, and the catalyst can be reused for at least 7 times without loss in activity. 5. Hydroesterification of styrene catalyzed by Pd-TPPTS/Polymer-BAILs Recently, the Br?nsted acid ionic liquids (BAILs) were found to be acid promoters in hydroesterification of olefins. Supported BAILs combines the advantages of both ionic liquids and heterogeneous catalyst. In this paper, BAILs supported on polymer was prepared and used as a carrier in the Pd-TPPTS/Polymer-BAILs catalyst for hydroesterification of olefins. It was found that the catalytic process was carried out in the ionic liquids film on the surface of polymer, which was similar to the SAPC catalyst system. High activity was found in hydroesterification of styrene catalyzed by this heterogeneous catalyst. Under the optimum conditions (3 MPa，100 oC，5 h and the molar ratio of P/Pd was 20), the conversion of styrene, selectivity of total esters and b/l molar ratio were up to 98.9%, 99.9% and 4.91, respectively.
|何珍红. 钯膦络合物催化烯烃氢羧基化及氢酯基化反应[D]. 北京. 中国科学院大学,2014.|
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