甲烷直接芳构化反应的研究Ⅰ．负载Mo基催化剂在无氧条件下的催化性能

研究了催化剂制备方法、Ｍｏ含量、预处理条件和反应条件对在无氧条件下ＨＺＳＭ－５负载的Ｍｏ基催化剂上甲烷直接芳构化反应的影响，及积炭和烧炭再生对催化剂性能的影响．发现Ｍｏ含量为３．５～４％时催化剂活性最高，生成苯的速率高达１．２×１０－３ｍｏｌ·ｇ－１·ｓ－１．降低空速和提高反应温度均有利于甲烷的直接芳构化．随着反应的进行，乙烯的选择性不断提高，苯的选择性则不断降低．ＸＰＳ结果表明，反应后催化剂表面积炭，且研磨法制备的催化剂中Ｍｏ６＋被还原成不具活性的金属态Ｍｏ０．卡宾中间体（Ｍｏ＝ＣＨ２）可能是甲烷芳构化反应的起始物．     

甲烷在含镓沸石（MFI）上无氧活化性能的研究

采用水热法合成了不同Ｓｉ／Ａｌ、Ｓｉ／Ｇａ比的含镍分子筛，催化反应活性表征结果表明，地丙烷芳构化反应具有良好催化活性的含镍分子。没有显示出任何催化甲烷芳构化反应的特性；ＭｏＯ３作为添加组分显著地改变了催化剂的反应性能，３％ＭｏＯ３负载的含Ｇａ分子筛，在９７３Ｋ温度给出了约６％甲烷转化率和大于８０％的芳烃选择性，与ＺＳＭ－５相比，城相同的ＭｏＯ３担载条件下，含Ｇａ分子筛催化剂甲烷芳构化活性较低，但是     

沸石载体结构对甲烷无氧芳构化性能的影响

考察了担载ＭｏＯ３的沸石催化剂上甲烷的无氧芳构化性能，并与沸石结构相关联。结果表明，孔径与苯分子动态直径相当的ＺＳＭ－５、ＺＳＭ－８、ＺＳＭ－１１和β沸石等是甲烷无氧芳构化催化剂的良好载体，其中３％ＭｏＯ３／ＨＺＳＭ－１１具有最高的甲烷芳构化活性和稳定性，９７３Ｋ下的转化ＨＭＣＭ－４１和ＨＳＡＰＯ－３４为载体时芳构化活化很低，以ＨＭＯＲ、ＨＸ和ＨＹ为载体时仅有少量乙烯生成，而以ＨＳＡＰＯ－５和ＨＳ     

甲烷直接芳构化反应的研究Ⅰ.负载Mo基催化剂在无氧条件下催化性能

研究了催化剂制备方法，Ｍｏ含量，预处理条件和反应条件对无氧条件下ＨＺＳＭ－５负载的Ｍｏ基催化剂上甲烷直接芳构化反应的影响，及积炭和烧炭再生对催化剂性能的影响，发现Ｍｏ含量为３．５～４％时催化剂活性最高，生成苯的速率高达１．２×１０＾－３ｍｏｌ．ｇ＾－１．ｓ＾－１，降低空速和提高反应温度均有利于甲烷的直接芳构化，随着反应的进行，乙烯的选择性不断提高，苯的选择性则不断降低，ＸＰＳ结果表明，反应后催化剂     

甲烷在MoO_3／HZSM－5分子筛催化剂上的非氧催化转化

研究了反应温度、空速、Ｍｏ担载量和焙烧温度对ＭｏＯ３／ＨＺＳＭ－５催化剂上甲烷的芳构化反应的影响．ＨＺＳＭ－５分子筛的Ｂｒｏｎｓｔｅｄ酸性、孔道结构和Ｍｏ在分子筛中的分布是影响催化性能的重要因素．ＨＺＳＭ－５上Ｍｏ担载量为２～３％时活性最佳，在１０１３Ｋ反应温度下甲烷转化率可达９％，芳烃选择性大于９０％．空速影响的实验表明乙烯是反应的初始产物．在此基础上提出了＂甲烷酸助异裂活化＂的新概念、＂金属钼类碳烯中间物＂的新观点和甲烷芳构化的可能机理．     

水蒸气存在时Mo／HZSM—5催化剂上的甲烷芳构化反应性能

研究了水蒸气存在条件下Ｍｏ／ＨＺＳＭ－５沸石分了筛催化剂上的甲烷芳构化反应行为,发现水蒸气的引入可以明显地降低甲烷芳构化反应的起始温度,从而在较为温和的条件下实现甲烷的活化。适量水蒸气的加入可以在一定程度上改善Ｍｏ／ＨＺＳＭ－５催化剂的稳定性,过量水蒸气的引入则会抑制甲烷芳构化反应,在反应温度为９７３Ｋ时,引入适量的水蒸气对芳构化反应产物的分布没有明显影响。在低温条件下的甲烷芳构化反应过程中检测到     

甲烷在铕改性Mo/HZSM-5催化剂上的直接芳构化反应Ⅰ.制备条件及反应性能的考察

研究了稀土元素Ｅｕ对Ｍｏ／ＨＺＳＭ－５催化剂催化甲烷芳构化反应的影响，发现适量的稀土元素Ｅｕ可提高催化剂的甲烷转化率及苯选择性，在１０２３Ｋ反应时，甲烷的转化率达１９．３％，苯的选择性达９７．５％，且铕的促进作用随硅铝比的增加而加强．失活催化剂经氢气吹扫后，其活性较初活性略有提高．积炭分析表明，铕加速了催化剂的积炭，且适量积炭对芳构化反应也具有促进作用．     

HZSM-5结晶度和晶粒度对甲烷无氧芳构化催化剂性能的影响

使用高能球磨机通过研磨法制备了Ｍｏ／ＨＺＳＭ－５催化剂，对不同球磨时间下的催化剂结构进行了表征，并考察了其催化甲烷芳构化性能。结果表明，球磨使ＨＺＳＭ－５分子筛的粒度变小，且使Ｍｏ与骨架发生了同晶置换，导致ＺＳＭ－５骨架破坏；球磨时间越长，结晶度越低，其催化甲烷芳构化活性和苯选择性越差。因此，较高的结晶度和较大的晶粒度对甲烷的无氧芳构化反应更有利。     

Ni改性Mo／HZSM－5催化剂上甲烷芳构化性能研究

Ｎｉ改性Ｍｏ／ＨＺＳＭ－５催化剂上甲烷芳构化性能研究王冬杰，张一平，费金华，郑小明（杭州大学催化研究所，杭州，３１００２８）关键词甲烷，Ｍｏ－Ｎｉ／ＨＺＳＭ－５催化剂，芳构化，芳烃由于甲烷氧化偶联和部分氧化遇到了转化率和选择性不易兼顾及甲烷深度氧化难...     

担载型钼催化剂上的丙烷芳构化

与新鲜Ｍｏ／ＨＺＳＭ－５（Ｆ）催化剂相比,于９７３Ｋ以甲烷活化后的Ｍｏ／ＨＺＳＭ－５（Ａ）对丙烷芳构化的活性和芳烃选择性都得到显著提高,芳烃的收率从３．３５％提高到１３．８２％,根据催化剂（Ｆ）用于甲烷芳构化时存在活性诱导期,结合本实验的丙烷芳构化结果及ＸＲＤ结果,提出担载于分子筛表面的ＭｏＯ３经甲烷活化后转化为α－Ｍｏ２Ｃ后才对烷烃芳构化有较高活性。碳化钼是活性相,它的作用不在于活化烷烃,而是为     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Regiospecific synthesis of quercetin O-β-d-glucosylated and O-β-d-glucuronidated isomers

Quercetin, the polyphenolic compound, which has the highest daily intake, is well known for its protective effects against aging diseases and has received a lot of attention for this reason. Both quercetin 3-O-β-d-glucuronide and quercetin 3′-O-β-d-glucuronide are human metabolites, which, together with their regioisomers, are required for biological as well as physical chemistry studies. We present here a novel synthetic route based on the sequential and selective protections of the hydroxyl functions of quercetin allowing selective glycosylation, followed by TEMPO-mediated oxidation to the glucuronide. This methodology enabled us to synthesize the five O-β-d-glucosides and four O-β-d-glucuronides of quercetin, including the major human metabolite, quercetin 3-O-β-d-glucuronide.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Deuterodehalogenation—a mild method for synthesising deuterated heterocycles

We report a mild and efficient method for introducing deuterium into a range of heterocycles by reacting readily available halide analogues in a deuterodehalogenation reaction using D₈-IPA or Et₃SiD under palladium-catalysed conditions.     

The conversion of 2-cyano cyanothioformanilides into 3-aminoindole-2-carbonitriles using triphenylphosphine

2-Cyano cyanothioformanilide 3a reacts with triphenylphosphine in the presence of water to give 2-(cyanomethyleneamino)benzonitrile 4a, 2-(cyanomethylamino)benzonitrile 5, 3-aminoindole-2-carbonitrile 2a and (2-cyanoindol-3-yl)iminotriphenylphosphorane 6a. In the presence of p-toluenesulfonic acid in MeOH the reaction between 2-cyano cyanothioformanilide 3a and triphenylphosphine (2 equiv) gives 3-aminoindole-2-carbonitrile 2a in 90% yield. Under the same conditions 2-(cyanomethyleneamino)benzonitrile 4a gives anthranilonitrile 8a, 3-aminoindole-2-carbonitrile 2a and N-(2-cyanophenyl)formamide 9. In addition, substituted 2-cyano cyanothioformanilides 3b-f react with triphenylphosphine and p-toluenesulfonic acid in MeOH to give 3-aminoindole-2-carbonitriles 2b-f in 63-75% yields. Under analogous conditions 2-cyano-4,5-dimethoxyphenyl cyanothioformanilide 2g gives only 4,5-dimethoxyanthranilonitrile 8g and 4,6,7-trimethoxyquinazoline-2-carbonitrile 14g, but in refluxing dry PhMe in the absence of p-toluenesulfonic acid 2-cyano-4,5-dimethoxyphenyl cyanothioformanilide 3g, (2-cyano-5,6-dimethoxyindol-3-yl)iminotriphenylphosphorane 6g and 2-(cyanomethyleneamino)-4,5-dimethoxybenzonitrile 4g are obtained. The structure of 2-(cyanomethyleneamino)-4,5-dimethoxybenzonitrile 4g is supported unambiguously via independent synthesis and comparison to the isomeric 6,7-dimethoxyquinazoline-2-carbonitrile 15. All new compounds are fully characterised and a tentative mechanism for the transformation of 2-cyano cyanothioformanilides to indoles is proposed.     

Sulfur-mediated C(sp2)–H imidation and 1,2-imidofluorination of vinyl sulfides

A new strategy for the C(sp²)–H imidation and 1,2-imidofluorination of vinylsulfides has been established through simple treatment with N-fluorobis(benzenesulfonyl)imide, which acts as both oxidant and nitrogen source. For alkyl and electron-rich aryl vinylsulfides, alkyl/arylthioenamines are produced in up to 92% total yields. However, for steric and electron-deficient aryl vinylsulfides, 1,2-imidofluorination products are prepared in up to 73% yields. The chemoselectivity is controlled by the steric and electronic effects of aryl substituents. Thionium ions are proposed as key intermediates in the two reactions.