Influence of the calcination treatment on the catalytic properties of hierarchical ZSM-5

The effect of the calcination conditions on the properties and catalytic performance of hierarchical ZSM-5 zeolite has been investigated using different reactions as catalytic tests: acylation of aromatic substrates and rearrangement of linear and cyclic epoxides. The hierarchical h-ZSM-5 material was prepared by crystallization of silanized protozeolitic units. The removal of the organics present in the as-synthesized ZSM-5 samples has been carried out using two different calcination procedures: (i) directly under air atmosphere; (ii) following a two-step (nitrogen-air) treatment.Clear differences are noticed related to the textural properties of the ZSM-5 samples, since the h-ZSM-5 presents higher BET and external surface area than standard ZSM-5 zeolite. Whereas the calcination method does not affect the properties of the reference ZSM-5 sample, noticeable changes were observed over the hierarchical zeolite. The concentration of Brønsted acid sites decreases by half for one-step air calcination, but only a quarter when using a two-step nitrogen/air calcination, showing that the aluminium present in hierarchical ZSM-5 is very sensitive to the calcination conditions as it may undergo framework extraction and dehydroxylation phenomena. For all the studied reactions, the hierarchical sample, calcined by a two-step treatment, presents higher activity than when using direct air calcination.     

Nano-sulfated titania (TiO ) as a new solid acid catalyst for Friedel–Crafts acylation and Beckman rearrangement in solvent-free conditions

A novel protocol for the highly selective N-monoalkylation of the sulfamate ester moiety has been developed. This reaction proceeded efficiently using alkyl halides, benzyl halides and α-halo ketones as the electrophile in the presence of KF-Al₂O₃ as a cost-effective and robust catalyst. This approach provides new access to N-monoalkylated Topiramate (anticonvulsant drug) derivatives which are potentially of great importance in medicinal chemistry.     

分子筛Hβ担载磷钨杂多酸催化甲苯与乙酸酐的酰化反应研究

 分别以SiO₂、HZSM-5分子筛、Hβ分子筛为载体，采用浸渍法制备了几种担载型12-磷钨杂多酸（PW-12）催化剂，采用BET、XRD、Py-IR等手段对催化剂的结构和酸性进行了表征，考察了制备的催化剂在甲苯与乙酸酐（AA）常压Friedel-Crafts酰基化反应中的作用规律。结果表明，Hβ分子筛经脱铝处理后骨架结构未发生变化，担载量为20%（质量分数）的PW-12制得的催化剂20%PW/Hβ的比表面积高、活性中心分散度良好、总酸量大并拥有较多的B酸位; 该催化剂对常压、100 ℃条件下的甲苯与乙酸酐（AA）酰基化反应具有良好的催化活性，甲基苯乙酮（MAP）收率为14.06%，产物中对甲基苯乙酮（p-MAP）的质量分数为97.65%。     

弱酸艳红3B合成工艺的研究

将4-氯-2氨基苯苄醚重氮化,在碱性介质中与对甲苯磺酰基H酸在进行偶合等工艺,综合加工制得染料成品;并讨论了原料配比,反应温度的影响。     

Selectivity of C- versus O-acylation of diphenols by clay catalysts. I. Acylation of resorcinol with phenylacetyl chloride

Resorcinol was acylated by phenylacetyl chloride with a set of catalysts consisting of the montmorillonite-based K-series and their cation-exchanged forms. The selectivity of C-acylation over O-acylation could be significantly increased by an appropriate ion exchange and by a solvent-free reaction mode, resulting in a 60% preparative yield of 1-(2,4-dihydroxyphenyl)-2-phenyl-ethanone. This revised version was published online in June 2006 with corrections to the Cover Date.     

Catalytic Friedel–Crafts Acylation of Heteroaromatics

Catalytic Friedel–Crafts acylation of heteroaromatics has been achieved using metal triflates as catalysts. While conventional Friedel–Crafts acylation often requires the use of more than stoichiometric amounts of aluminum chloride, metal triflates such as tin(II) triflate, scandium triflate, and gallium triflate, etc. have enabled efficient acylation reactions by catalytic use.     

Palladium‐Catalyzed Regioselective ortho‐Acylation of Azoxybenzenes with Aldehyde Derivatives

An efficient strategy for the regioselective ortho‐acylation of azoxybenzenes with various aldehydes in the presence of palladium catalysts has been developed and furnishes good to excellent yields. The reaction proceeds smoothly and can tolerate a variety of functional groups.

     

纤维素长链脂肪酸酯的合成进展

纤维素是地球上储量最大的天然高分子材料,随化石资源的稀缺性日益凸显,纤维素的开发与应用愈来愈受到重视。作为纤维素重要衍生物之一,纤维素长链脂肪酸酯具有良好的生物降解性、有机溶剂可溶性、可熔融加工性等优点,可应用于诸多领域,其研究开发具有重要意义。综述了近年来纤维素长链脂肪酸酯的合成方法,涵盖了在DMF、甲苯、吡啶等惰性溶剂中的非均相衍生化和诸如在DMAc/LiCl体系、DMSO/TBAF体系、离子液体等中的均相酰化。     

几种碳纤维表面酰氯化处理及XPS表征

通过先酸氧化、后酰氯化处理，研究了T300、T800和某国产型号碳纤维3种碳纤维的表面活性。利用X射线光电子能谱（XPS）对酸氧化及酰氯化处理后的样品进行了表面化学性质分析。结果表明，酸处理后T300表面-COOH含量最高，为14，50％，酰氯化处理后表面Cl元素含量也最高，为3．88％，Cl元素与T300样品表面以酰氯共价键形式（COCI）结合。     

Acylation of a substituted benzofuran over an HY zeolite and its subsequent deacylation and reacylation

The acylation reaction of 2-butylbenzofuran withp-anisoyl chloride andp-anisic acid in the presence of faujasite type zeolites, in the liquid phase, is reported. A good initial selectivity to the 3-acylated derivative is obtained, but the selectivity decreases with time. This result is explained by the involvement of a deacylation-reacylation process.