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PALLADIUM-CATALYSED TRANSFER HYDROGENATION OF ALKENES IN THE PRESENCE OF ZINC POWDER AND VARIOUS ORGANIC ACIDS
I. B. Masesane1*, P. G. Steel2
Bulletin of the Chemical Society of Ethiopia , 2005,
Abstract: Catalytic transfer hydrogenation using palladium(II) chloride, zinc powder and various organic acids proved effective for the reduction of a variety of alkenes at ambient temperature and atmospheric pressure. The method was found to be convenient, economical and uses a stable nonpyrophoric catalyst. KEY WORDS: Catalytic transfer hydrogenation, Hydrogenation of alkenes, Palladium(II) chloride, Zinc powder, Organic acids, Nonpyrophoric catalyst Bull. Chem. Soc. Ethiop. 2005, 19(1), 149-152.
Palladium-catalysed transfer hydrogenation of alkenes in the presence of zinc powder and various organic acids  [cached]
I.B. Masesane,P.G. Steel
Bulletin of the Chemical Society of Ethiopia , 2005,
Abstract: Catalytic transfer hydrogenation using palladium(II) chloride, zinc powder and various organic acids proved effective for the reduction of a variety of alkenes at ambient temperature and atmospheric pressure. The method was found to be convenient, economical and uses a stable nonpyrophoric catalyst.
1,3-Dipolar Cycloadditions of N-Benzyl Furfuryl Nitrones with Electron-rich Alkenes  [PDF]
Pedro Merino,Sonia Anoro,Francisco L. Merchan,Tomas Tejero
Molecules , 2000, DOI: 10.3390/50200132
Abstract: The 1,3-dipolar cycloaddition reaction of N-benzyl-C-(2-furyl)nitrones with electron-rich alkenes gives preferentially trans-substituted 3,5-disubstituted isoxazolidines (endo approach). These experimental results are in good qualitative agreement with the predicted ones by semiempirical (AM1 and PM3) and ab initio (HF/3-21G) methods.
Effects of Supports and Promoter Ag on Pd Catalysts for Selective Hydrogenation of Acetylene
ZHU Shu-ying,HOU Rui-jun,WANG Tie-feng,
朱淑映
,侯瑞君,王铁峰

过程工程学报 , 2012,
Abstract: SiO2,α-Al2O3,γ-Al2O3,ZrO2 and CeO2 were used as supports and Ag as promoter to study their effects on Pd catalysts for selective hydrogenation of acetylene.The catalysts were prepared by impregnated synthesis and characterized by XRD,BET and TEM.The catalytic reaction was carried out in a fixed-bed reactor.Overall,the low specific surface area supports were better to increase the ethylene selectivity at high conversion rate of acetylene.Among the four Pd catalysts on low specific surface area supports,the catalyst on low specific surface area SiO2(LSA-SiO2) retained a high ethylene selectivity even at complete conversion,while the other catalysts showed significant decrease in the selectivity at complete conversion.The performance of Pd/LSA-SiO2 was important to decrease the loss of ethylene in selective hydrogenation of trace acetylene in ethylene.Addition of Ag to Pd/LSA-SiO2 significantly decreased the formation of ethane,C4 alkenes and green oil,and improved the ethylene selectivity to 90% when Pd:Ag=1:1 and 1:3(ω).When the ratio of Pd to Ag was above 1,the activity of Pd-Ag bimetallic catalyst was similar to that of Pd monometallic catalyst,and the selectivity of ethylene increased with increasing of amount of Ag.When the ratio of Pd to Ag was below 1,the activity of bimetallic catalyst decreased with increasing of amount of Ag,while the selectivity of ethylene was kept unchanged.The optimum temperature was 200-230℃ for 0.02%(ω)Pd-0.02%(ω)Ag/LSA-SiO2 to give a high ethylene selectivity and low formation of green oil.
Mixtures of monodentate P-ligands as a means to control the diastereoselectivity in Rh-catalyzed hydrogenation of chiral alkenes
Reetz Manfred T,Guo Hongchao
Beilstein Journal of Organic Chemistry , 2005, DOI: 10.1186/1860-5397-1-3
Abstract: The previously reported concept of using mixtures of monodentate ligands in a combinatorial manner in order to influence enantio- or regioselectivity of transition metal catalyzed processes has been extended to include diastereoselectivity. Accordingly, 1,2- and 1,3-asymmetric induction in the Rh-catalyzed hydrogenation of a chiral allylic alcohol and a chiral homo-allylic alcohol has been studied by using mixtures of monodentate P-ligands. It was found that appropriate 1:1 mixtures of two different P-ligands enhance the degree of diastereoselectivity relative to the use of the respective pure ligands themselves. Here, as in the previous cases regarding enantio- or regioselectivity, this type of combinatorial catalysis leads to improved catalytic profiles without the need to prepare new ligands.
Removal of benzylidene acetal and benzyl ether in carbohydrate derivatives using triethylsilane and Pd/C
Abhishek Santra,Tamashree Ghosh,Anup Kumar Misra
Beilstein Journal of Organic Chemistry , 2013, DOI: 10.3762/bjoc.9.9
Abstract: Clean deprotection of carbohydrate derivatives containing benzylidene acetals and benzyl ethers was achieved under catalytic transfer hydrogenation conditions by using a combination of triethylsilane and 10% Pd/C in CH3OH at room temperature. A variety of carbohydrate diol derivatives were prepared from their benzylidene derivatives in excellent yield.
CATALYTIC HYDROGENATION OF THYMOL OVER Pd/MgO PREPARED BY SMAD METHOD
CáRDENAS T,GALO; OLIVA C,RICARDO; REYES N,PATRICIO;
Journal of the Chilean Chemical Society , 2006, DOI: 10.4067/S0717-97072006000400013
Abstract: in this work are summarized the results obtained in the thymol hydrogenation using pd/mgo catalyst. the catalyst was prepared from a colloidal dispersion of pd in 2-propanol using the smad ( solvent metal atom dispersion) methodology. the catalyst was characterized by means of transmission electron microscopy (tem) and by chemisorption of hydrogen (metallic area and dispersion). the particles show a bimodal distribution in the histogram of particle distribution with a range of particle size between 11 and 16.6 nm. the catalyst metallic area was 26m2/g with a 5.8 % dispersion. the products obtained from thymol hydrogenation were menthone and isomenthone. the catalyst was not able to hydrogenate the carbonyl group and did not produce the menthol and /or isomers. the different temperatures (80, 100, 125 and 150oc) only produce an effect in the catalyst activity, but not in the selectivity. the same results were obtained with increase in pressure (3, 5, 7 and 10 bars) and the charge catalyst (3, 7, 10 and 20%) was used. the studies were carried out with different thymol amounts over the same catalyst, and demonstrated no change in the activity. this reveals that the catalyst is poisoned most probably by unreacted thymol. the addition of a promotor (fe+3) to activate the carbonyl group, allows the obtention of a mixture of menthol isomers. the pd/mgo catalyst is more active than pd/c and pd/al2o3. this demonstrates that the support plays an important role, however, the pd is not able to hydrogenate the carbonyl group in menthone or isomenthone
CATALYTIC HYDROGENATION OF THYMOL OVER Pd/MgO PREPARED BY SMAD METHOD  [cached]
GALO CáRDENAS T,RICARDO OLIVA C,PATRICIO REYES N
Journal of the Chilean Chemical Society , 2006,
Abstract: In this work are summarized the results obtained in the thymol hydrogenation using Pd/MgO catalyst. The catalyst was prepared from a colloidal dispersion of Pd in 2-propanol using the SMAD ( Solvent Metal Atom Dispersion) methodology. The catalyst was characterized by means of Transmission Electron Microscopy (TEM) and by chemisorption of hydrogen (metallic area and dispersion). The particles show a bimodal distribution in the histogram of particle distribution with a range of particle size between 11 and 16.6 nm. The catalyst metallic area was 26m2/g with a 5.8 % dispersion. The products obtained from thymol hydrogenation were menthone and isomenthone. The catalyst was not able to hydrogenate the carbonyl group and did not produce the menthol and /or isomers. The different temperatures (80, 100, 125 and 150oC) only produce an effect in the catalyst activity, but not in the selectivity. The same results were obtained with increase in pressure (3, 5, 7 and 10 bars) and the charge catalyst (3, 7, 10 and 20%) was used. The studies were carried out with different thymol amounts over the same catalyst, and demonstrated no change in the activity. This reveals that the catalyst is poisoned most probably by unreacted thymol. The addition of a promotor (Fe+3) to activate the carbonyl group, allows the obtention of a mixture of menthol isomers. The Pd/MgO catalyst is more active than Pd/C and Pd/Al2O3. This demonstrates that the support plays an important role, however, the Pd is not able to hydrogenate the carbonyl group in menthone or isomenthone
Pd-Ag/C@TiO2核壳结构纳米棒阵列的制备及对NaBH4电氧化的催化性能  [PDF]
闫鹏,张栋铭,程魁,徐阳,李莹莹,叶克,曹殿学,王贵领
- , 2015,
Abstract: 摘要 通过热蒸发结合恒电位沉积法制备了具有核壳结构的Pd-Ag/C@TiO2催化剂. 利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等对所制备样品的形貌和结构进行了表征, 利用线性伏安扫描和计时电流技术研究了Pd-Ag/C@TiO2电极对NaBH4的电氧化性能. 结果表明, Pd-Ag/C@TiO2电极具有三维纳米核壳结构, 在电化学反应过程中有利于燃料与催化剂充分接触. 催化剂中Pd与Ag的原子比为0.37:0.17的Pd-Ag(2:1)/C@TiO2催化剂的效果最佳, 在3.0 mol/L NaOH+0.20 mol/L NaBH4溶液中电流密度达到672 mA/cm2, 在1200 s 测试时间内计时电流曲线衰减很小, 说明该Pd-Ag/C@TiO2电极对NaBH4电氧化具有很高的电化学活性和稳定性
Effect of Alkali Carbonate/Bicarbonate on Citral Hydrogenation over Pd/Carbon Molecular Sieves Catalysts in Aqueous Media  [PDF]
Racharla Krishna, Chowdam Ramakrishna, Keshav Soni, Thakkallapalli Gopi, Gujarathi Swetha, Bijendra Saini, S. Chandra Shekar
Modern Research in Catalysis (MRC) , 2016, DOI: 10.4236/mrc.2016.51001
Abstract:

The efficient citral hydrogenation was achieved in aqueous media using Pd/CMS and alkali additives like K2CO3. The alkali concentrations, reaction temperature and the Pd metal content were optimized to enhance the citral hydrogenation under aqueous media. In the absence of alkali, citral hydrogenation was low and addition of alkali promoted to ~92% hydrogenation without reduction in the selectivity to citronellal. The alkali addition appears to be altered the palladium sites. The pore size distribution reveals that the pore size of these catalysts is in the range of 0.96 to 0.7 nm. The palladium active sites are also quite uniform based on the TPR data. The catalytic parameters are correlated well with the activity data.

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