Pt-Sn脱氢催化剂浸渍状态的Sn-119和Pt-195的多核NMR研究

测定了Ｐｔ－Ｓｎ型催化剂浸渍状态下的Ｓｎ－１１９、Ｐｔ－１９５的多核核磁共振。当ＳｎＣｌ２／ＤＣｌ溶液体系中加入Ｈ２ＰｔＣｌ６以后，出现了Ｓｎ（Ⅳ）和另外一种Ｓｎ（Ⅱ）的构型，Ｓｎ－１１９峰向高场位移，说明部分Ｓｎ（Ⅱ）被氧化成Ｓｎ（Ⅳ），Ｈ２ＰｔＣｌ６的量对这种氧化性影响较小。而Ｈ２ＰｔＣｌ６／Ｄ２Ｏ溶液体系中加入ＳｎＣｌ２以后部分Ｐｔ（Ⅳ）被还原成Ｐｔ（Ⅱ），随着ＳｎＣｌ２量的增加，Ｐｔ（Ⅱ）     

Pt－Sn脱氢催化剂浸渍状态的Sn－119和Pt－195的多核NMR研究

测定了Ｐｔ－Ｓｎ型催化剂浸渍状态下的Ｓｎ－１１９、Ｐｔ－１９５的多核核磁共振。当ＳｎＣｌ２／ＤＣｌ溶液体系中加入Ｈ２ＰｔＣｌ６以后，出现了Ｓｎ（Ⅳ）和另外一种Ｓｎ（Ⅱ）的构型，Ｓｎ－１１９峰向高场位移，说明部分Ｓｎ（Ⅱ）被氧化成Ｓｎ（Ⅳ），Ｈ２ＰｔＣｌ６的量对这种氧化性影响较小。而Ｈ２ＰｔＣｌ６／Ｄ２Ｏ溶液体系中加入ＳｎＣｌ２以后部分Ｐｔ（Ⅳ）被还原成Ｐｔ（Ⅱ），随着ＳｎＣｌ２量的增加，Ｐｔ（Ⅱ）－１９５峰的强度逐渐增加而Ｐｔ（Ⅳ）－１９５峰逐渐减小。Ｐｔ（Ⅳ）－１９５较Ｐｔ（Ⅱ）－１９５峰向高场位移。在溶液状态下未发现Ｐｔ－Ｓｎ间的偶合分裂     

载铂铝交联蒙脱土的烷烃芳构化特性──Ⅰ．载铂铝交联蒙脱土对烷烃的择形芳构化作用

对比考察了Ｐｔ／ＫＬ沸石，Ｐｔ／Ａｌ２Ｏ３和载铂铝交联蒙脱土（Ｐｔ／Ａｌ－ＣＬＭ）催化剂对不同碳原子数烷烃的芳构化特性．脉冲微反的评价结果表明：Ｐｔ／Ａｌ－ＣＬＭ比Ｐｔ／Ａｌ２Ｏ３和Ｐｔ／ＫＬ具有较高的转化ｎ－Ｃ８，ｎ－Ｃ９为其对应芳烃的选择性，在转化ｎ－Ｃ８时，产物中的间、对位二甲苯收率很高，而转化ｎ－Ｃ９时有高的正丙苯收率．采用１２９Ｘｅ－ＮＭＲ、ＸＲＤ和孔分布测定考察了Ｐｔ／Ａｌ－ＣＬＭ和Ｐｔ／ＫＬ、Ｐｔ／Ａｌ２Ｏ３之间孔结构的差异．结果表明：由于ｎ－Ｃ８，ｎ－Ｃ９在反应过程中其过渡态的极限尺寸与Ｐｔ／Ａｌ－ＣＬＭ０．９ｎｍ左右的层间域相匹配，因而它对ｎ－Ｃ８，ｎ－Ｃ９具有择形芳构化作用．     

CO吸附微量量热法研究γ-Al2O3负载贵金属催化剂

用ＣＯ吸附微量量热法系统地研究了γ－Ａｌ２Ｏ３负载的Ｐｔ，Ｐｄ，Ｒｈ及Ｐｔ－Ｓｎ，Ｐｔ－Ｆｅ等贵金属催化剂，结果表明，Ｐｔ／γ－Ａｌ２Ｏ３，Ｐｄ／γ－Ａｌ２Ｏ３，Ｒｈ／γ－Ａｌ２Ｏ３贵金属催化剂上ＣＯ的微分吸附热能覆盖度的函数非常相似，其初始微分吸附热均约为１２０ｋＪ／ｍｏｌ，随着ＣＯ覆盖度的增加，ＣＯ的微分吸附热逐渐降低，Ｐｔ／γ－Ａｌ２Ｏ３催化剂上ＣＯ吸附位数目对ＣＯ微分吸附热不同区间的分布非     

Ca对PtSn／MgAl2O4结构及丙烷脱氢性能的影响

比较研究了Ｃａ改性的ＰｔＳｎ／ＭｇＡｌ２Ｏ４在氮气及水蒸汽稀稀释下的丙烷脱氢性能，并利用ＴＰＲ、Ｈ２－ＴＰＤ、ＸＰＳ及脉冲氢吸附对催化剂进行了表征，结果表明，ＰｔＳｎ／ＭｇＡｌ２Ｏ４中加入０．５％的Ｃａ，增加了催化剂的丙烷脱氢活性，抑制了积炭失活，过量Ｃａ的加入则促进了催化剂中Ｓｎ组分的还原，生成了零价锡并可能与Ｐｔ形成合金，从而导致催化剂失活。在水汽中反应哩，水蒸汽一方面可调变催化剂结构，增加其     

水蒸汽对PtSn／Al2O3催化剂结构及反应性能的影响

比较研究了Ａｌ２Ｏ３负载的铂及ＰｔＳｎ催化剂在氮气及水蒸汽稀释条件下的丙烷脱氢性能,并利用ＸＰＳ及氢脉冲吸附对催化剂进行了表征。结果表明,水蒸汽可促使Ｐｔ／Ａｌ２Ｏ３催化剂的铂晶粒烧结。与在氮气氛中相比,在水蒸汽存在下反应显著提高了Ｐｔ／Ａｌ２Ｏ３的丙烷转化率,却降低了丙烯的选择性。另一方面,水蒸汽可调变ＰｔＳｎ／Ａｌ２Ｏ３催化剂的结构,破坏了ＰｔＳｎ／Ａｌ２Ｏ３中与锡相互作用的铂簇团结构。从而导     

水蒸汽对负载型催化剂丙烷脱氢性能的影响：Ⅰ.反应性能的研究

研究了ＭｇＡｌ２Ｏ４，ＺｎＡｌ２Ｏ４负载的Ｐｔ－Ｓｎ催化剂在氮气及水蒸汽中的丙烷脱氢性能。考察了还原温度，反应温度，催化剂载量对Ｐｔ－ＳＳｎ／ＭｇＡｌ２Ｏ４催化剂丙烷脱氢性能的影响。     

金属羰基络合物制备的Pt-Re/Al2O3催化剂的性能Ⅰ.不同方法制备的Pt-Re/Al2O3催化剂上正庚烷的转化

考察了由［Ｐｔ３（ＣＯ）６］５［ＮＥｔ４］２与Ｒｅ２（ＣＯ）１０共浸或分浸制备的一系列催化剂在接近工业运转的压力下的正庚烷转化反应。以羰基金属原子簇化合物作为前身物制备的Ｐｔ－Ｒｅ／Ａｌ２Ｏ３催化剂的活性、芳构化选择性和稳定性等明显地优于常规的以Ｈ２ＰｔＣｌ６与ＨＲｅＯ４溶液共浸制备的催化剂。常规Ｐｔ－Ｒｅ／Ａｌ２Ｏ３催化剂的活性和稳定性比Ｐｔ／Ａｌ２Ｏ３好，但芳构化选择性降低，若引入Ｒｅ２（ＣＯ     

甲烷部分氧化制合成气反应Pt/Al_2O_3和Pt/CeO2/Al_2O_3催化剂的研究(英文)

研究了Ｐｔ／Ａｌ２Ｏ３和Ｐｔ／ＣｅＯ２／Ａｌ２Ｏ３催化剂对甲烷部分氧化制合成气反应的催化活性，发现Ｐｔ／ＣｅＯ２／Ａｌ２Ｏ３显示了比Ｐｔ／Ａｌ２Ｏ３更高的甲烷转化率和合成气选择性。用Ｈ２ＴＰＲ，Ｈ２ＴＰＤ，ＳＥＭ和ＸＲＤ等手段和技术对催化剂进行了表征。ＣｅＯ２与Ｐｔ之间存在较强的相互作用（ＳＭＳＩ），这种作用促进了Ｐｔ在催化剂表面的分散，抑制了Ｐｔ在催化剂表面的迁移，大大降低了催化剂在反应中的完全燃烧活性，提高了催化剂的部分氧化活性和选择性，避免了因催化剂床层局部温度过高而导致催化剂活性下降或失活，提高了催化剂的稳定性。同时，在反应过程中，ＣｅＯ２通过促进水蒸气变换反应（ＷＧＳＲ）的进行使反应体系迅速达到平衡，提高了催化剂对Ｈ２的选择性。     

MICROCALORIMETRIC AND DEHYDROGENATION ACTIVITY STUDIES OF Pt/γ-Al_2O_3 AND Pt-Sn/γ-Al_2O_3 CATALYSTS

ＭＩＣＲＯＣＡＬＯＲＩＭＥＴＲＩＣＡＮＤＤＥＨＹＤＲＯＧＥＮＡＴＩＯＮＡＣＴＩＶＩＴＹＳＴＵＤＩＥＳＯＦＰｔ／γ┐Ａｌ２Ｏ３ＡＮＤＰｔ┐Ｓｎ／γ┐Ａｌ２Ｏ３ＣＡＴＡＬＹＳＴＳ＊ＪｉａＪｉｆｅｉ１，ＳｈｅｎＪｉａｎｙｉ２，ＸｕＺｈｕｓｈｅｎｇ１，ＧｅＸ...     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.