Highly active polymer-alumina dually supported palladium catalysts for the carbonylation of allyl halides under atmospheric pressure

Polymer-alumina dually supported palladium catalysts (PVP-Pd/Al₂O₃, PVP = poly(N-vinyl-2-pyrrolidone); PPPO-Pd/ Al₂O₃, PPPO = phosphinated poly(phenylene oxide)) were used to catalyze the carbonylation of allyl halides to form butenoic acid under the mild conditions of 40C and 0.1 MPa. These catalysts exhibit high activity and stability towards the carbonylation of allyl halides. The maximum turnovers (mol CO/mol Pd) of PPPO-Pd/Al₂O₃ are up to 8.2×10⁵ and 4.6×10⁵ for the carbonylation of allyl bromide and allyl chloride respectively in an aqueous NaOH/benzene medium.     

Vapor phase carbonylation of ethanol with Ni-Zn/c catalyst

Vapor phase carbonylation of ethanol with Ni/C and Ni-Zn/C catalyst was investigatedunder atmospheric pressure.Ni-Zn/C was found to have a significantly higher activity andselectivity than Ni/C.Effects of Zn and Ni loading on ethanol conversion and productdistributions were also investigated,and the sequence of metal loading was compared.The cata-lyst was characterized by XRD(X-ray diffraction)and SEM-EDS.The spectra of XRDdemonstrated that the catalyst structure was changed from crystalline to non-crystalline in theprocess of carbonylation.Stable iodide compound was formed due to the interaction betweenC_2H_5I and active metals.The authors believe that the active phase of carbonylation might havebeen non-crystalline.     

超声辐射下钯系加氢催化剂的新型制备方法

提供了一种钯系加氢催化剂新型制备方法。采用经β-环糊精改性载体,以醋酸钯为活性组分前驱体在超声辐射下进行催化剂有机相制备;并以碳三液相加氢为探针反应,对利用4种不同方法制备的催化剂进行200 h对比评价。结果表明,该方法可有效提高活性组分分散度,使催化剂在保持较好加氢活性的同时具有较好的加氢选择性,为优化钯系加氢催化剂综合性能提供一条行之有效的途径。     

Highly efficient catalyst system for the synthesis of 2‐arylpropionic acids by carbonylation

Carbonylation of 1‐(4‐isobutylphenyl)ethanol has been studied using a homogeneous catalyst system consisting of PdCl₂(PPh₃)₂/ TsOH/ LiCl. Higher reaction rates with TOF up to 1200 h⁻¹ and ibuprofen selectivity >95% have been achieved at 388 K under a CO partial pressure of 5.4 MPa. The reaction proceeds through the formation of 4‐isobutylstyrene and 1‐(4‐isobutylphenyl)ethyl chloride as intermediates. The same catalyst system is shown to be effective for carbonylation of various α-arylethanols, vinyl aromatics and corresponding chloro derivatives. This revised version was published online in July 2006 with corrections to the Cover Date.     

过渡金属羰基络合催化剂在有机合成中的应用及催化机理

过渡金属羰基络合物作为一种绿色、高效催化剂,在羰基化反应过程中起到了很好的催化作用。综述了几种主要的过渡金属羰基络合催化剂在羰基化反应中的主要应用及其催化机理。羰基化反应主要包括不饱和烃、有机卤代物、醇、杂环化合物等有机物的羰基化反应。     

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by Pd complex with diimine ligands

Pd complexes with diimine ligands were investigated as novel Pd catalysts for direct synthesis of diphenyl carbonate by oxidative carbonylation of phenol using carbon monoxide and air. Best efficiency was obtained by using a PdCl₂(ArN=CH–)₂ or PdCl₂(ArN=CMe–)₂/Mn(TMHD)₃/(Ph₃P=)₂NBr system where TOF reached 8.08 and 8.00 mol-DPC/mol-Pd h, respectively. The efficiency was increased with increases in the CO pressure.     

Epoxidation of β-ionone using molecular oxygen over Pt/MCM-41 catalyst under mild conditions

The epoxidation of β-ionone over the Pt/MCM-41 catalyst using molecular oxygen in the liquid phase had been studied. The results indicated that the β-ionone was catalytically oxidized to 5,6-epoxy-β-ionone, 4-oxo-β-ionone, 4-hydroxy-β-ionone and dihydroactinidiolide using molecular oxygen as the sole oxidant. The effects of solvent, content of Pt, reaction temperature and time on the catalytic activity and product selectivity had also been investigated in detail.     

二甲醚羰基化催化剂的烧炭再生

以水热合成的H-MOR分子筛催化剂,通过对二甲醚羰基化反应失活后催化剂进行再生,考察了不同再生气体、再生温度、O₂体积分数、烧炭升温速率等条件,烧炭后催化剂上二甲醚羰基化活性性能。TPO表征结果表明：反应后H-MOR分子筛上有两种不同性质的积炭。积炭催化剂在3%（体积） O₂/N₂气氛中,从室温以2℃·min^-1升温至320℃恒温一段时间,然后以相同速率升温至550℃进行烧炭,再生催化剂活性几乎完全恢复。NH₃-TPD和BET表征结果表明,再生催化剂活性得以恢复是因为优化了烧炭方案,分子筛表面积炭能够被烧除干净同时分子筛孔道不被破坏。     

Palladium nanoparticles as reusable catalyst for the synthesis of N-aryl sulfonamides under mild reaction conditions

An efficient palladium nanoparticles-catalyzed N-arylation of sulfonamides and sulfonyl azides is described. This procedure serves as an active protocol for intermolecular C–N bond formation using Pd(OAc)₂ in PEG-400 under air. Aryl bromides and triflates react at 35°C, while aryl chlorides require heating to 50°C and give the desired products only in low yields. This reaction proceeds smoothly in acceptable yields using low catalyst loading.     

Preparation of nickel-on-active carbon catalyst by CVD method for methanol carbonylation

The nickel on active carbon (Ni/A.C.) catalysts prepared by a simple chemical vapor deposition (CVD) method showed comparable catalytic activities for the vapor phase carbonylation of methanol to those of the catalysts prepared by impregnating A.C. with nickel nitrate and activating by hydrogen treatment. The CVD method was successfully applied to the in situ catalyst preparation.     

Selective Aryl α‐Diimine/Palladium‐Catalyzed Bis‐Alkoxy‐ carbonylation of Olefins for the Synthesis of Substituted Succinic Diesters

Aryl α‐diimine derivatives have been used, for the first time, as efficient new ligands for the palladium‐catalyzed oxidative bis‐alkoxycarbonylation reaction of olefins. The most active catalyst was formed in situ from bis(9‐anthryl)‐2,3‐dimethyl‐1,4‐diazabutadiene and palladium(II) trifluoroacetate [Pd(TFA)₂]. This catalytic system was able to selectively convert olefins into succinic diesters in good yields (up to 97%) and low catalyst loading (up to 0.5 mol%) under mild reaction conditions [4 bar of carbon monoxide (CO) at 20 °C in the presence of p‐toluenesulphonic acid as additive and p‐benzoquinone as oxidant]. The optimized conditions could be successfully applied to both aromatic and aliphatic olefins, by using methanol, benzyl alcohol or isopropyl alcohol as nucleophiles.

     

甲醇氧化羰基化合成碳酸二甲酯催化剂研究进展

碳酸二甲酯(DMC)是一种重要的绿色有机合成中间体。在合成DMC的方法中,甲醇氧化羰基化法对设备腐蚀小、原料易得、产物易分离,有着诱人的工业化前景。文中介绍了该反应中所使用的Co、Pd、Cu和Au这4类催化剂的结构特点和催化性能,比较了不同催化剂在氧化羰基化中的催化效果。为了进一步提高催化剂的活性、选择性、减少其腐蚀性,开发出性能更好的工业催化剂,可以通过研究催化反应机理,并通过添加助剂和载体来实现。其中无卤铜系催化剂是今后羰基化合成DMC的重要研究方向。     

芳胺化PVDC负载钯化合物在微波促进下催化Suzuki偶联反应

聚偏二氯乙烯(PVDC)被二苯胺(DPA)修饰后可以有效负载氯化钯,从而制得催化剂PVDC-DPA-Pd。利用TG,DTA,IR等测试手段对其表征。热分析表明,催化剂在室温至150℃有很好的热稳定性。该催化剂在微波促进条件下在较短时间内就可以有效地催化芳基溴化合物(甚至活化的芳基氯化物)与四苯硼钠间的Suzuki偶联反应,并且在较短的时间(10 min)或较少的催化剂用量(0.01%)下,仍有很好的产率。并且催化剂回收再利用3次后,产率仍能达到75%。     

Oxidative Alkoxycarbonylation of Alkynes by Means of Aryl α‐Diimine Palladium(II) Complexes as Catalysts

The straightforward in situ synthesized bis(2,6‐diisopropyl)acenaphthenequinonediimine palladium triflate catalyst was generally employed for both the mono‐alkoxycarbonylation of terminal alkynes, and the bis‐alkoxycarbonylation of 1,2‐disubstituted alkynes by using mild reaction conditions [carbon monoxide pressure (P_CO)=4 bar, temperature=20 °C]. Utilizing low catalyst loading (down to 0.5 mol%), a variety of propiolic esters were synthesized with good to excellent isolated yields. Most importantly the system was very efficient not only with methanol but also with a range of different alcohols, starting from the less hindered benzyl alcohol to the most hindered ones, such as isopropyl alcohol and tert‐butyl alcohol. In addition, aromatic and aliphatic 1,2‐disubstituted alkynes were converted into maleic acid derivatives, together with an acid‐catalyzed isomerization reaction, showing modest to good selectivity and excellent combined yields. In particular 3‐hexyne showed a satisfactory degree of selectivity for the maleic diesters of methanol and benzyl alcohol, obtaining the corresponding products with good isolated yields.

     

Silica sulfuric acid as a mild and chemoselective catalyst for dithioacetalization under solvent-free conditions

Various carbonyl compounds have been protected as dithioacetals in very good yields using silica sulfuric acid as a mild, chemoselective catalyst under solvent-free conditions.     

A novel and direct synthesis of thiolesters using cyanuric chloride under mild conditions

A direct synthesis of thiolester from carboxylic acids and thiols under mild conditions using cyanuric chloride as an inexpensive and readily available reagent is described.     

交联腐植酸负载钯催化剂对Heck反应催化性能研究

通过简单的方法制得了环氧氯丙烷交联腐植酸负载钯配合物催化剂,并通过IR、TG进行表征。该催化剂能够成功地催化芳基卤和不同取代芳基卤与丙烯酸、苯乙烯和丙烯酰胺的Heck反应。进一步研究显示:环氧氯丙烷交联腐植酸负载钯催化剂还能够催化溴苯与丙烯酸、苯乙烯和丙烯酰胺的反应,产率都达到95%以上;在62℃及催化剂钯含量为0.038%的条件下也能很好地催化碘苯与丙烯酸的反应。催化剂经过简单的分离处理重复使用7次仍然可以得到75.6%的产率。     

Promoting effect of CeO2 addition to Ni/AC catalyst for vapor phase carbonylation of ethanol to propionic acid

Ni/AC catalysts promoted with or without CeO₂ for vapor phase carbonylation of ethanol to propionic acid were tested and investigated by CO chemisorption, XRD and H₂-TPR techniques. The catalytic test results showed that the proper amount of CeO₂ addition could remarkably enhance the activity and stability of Ni/AC catalyst. The characterization results indicated that CeO₂ added can improve the dispersion and metal area of Ni on the catalyst, suppress the sintering of Ni crystallite and benefit the reduction of Ni, which are closely related to high performance of the Ni/AC catalyst promoted with CeO₂.     

Pd/polyaniline as the catalysts for 2‐ethylanthraquinone hydrogenation. The effect of palladium dispersion

By doping of polyaniline (PANI) in PdCl₂ aqueous and ethanol solutions the catalysts containing crystalline and colloidal Pd particles of different sizes were prepared. The size of palladium particles present in Pd/PANI catalysts (characterised by SEM and XRD methods) influenced the course of 2‐ethylanthraquinone (eAQ) hydrogenation, a key step in the industrial production of H₂O₂. The presence of large palladium particles promotes reactions leading to the formation of the so‐termed “degradation products” not capable of hydrogen peroxide formation. This revised version was published online in July 2006 with corrections to the Cover Date.     

FTIR study of hydration of dodecatungstosilicic acid

The isomerization of 2‐methyl‐2‐pentene has been studied on boron phosphate (BP) catalysts with P/B ratios from 0.8 to 1.6 and at various reaction temperatures and contact times. Double‐bond shift occurs on the compositions with P/B of 1.0 and less, while methyl shifts occur on samples with P/B of 1.2–1.6, demonstrating the presence of strong acidity on the latter solids. Ammonia chemisorption and proton MAS NMR is employed to provide supplementary evidence of the variation in acidity with composition. Although BP of P/B < 1 contains predominantly Lewis acid sites, 2‐methyl‐2‐pentene isomerizes through carbocations, which are formed on the strong Brønsted acid sites on BP with P/B > 1.