Deuterium incorporation into cellulose: a mini-review of biological and chemical methods

Cellulose - Isotopic enrichment offers structural insights that are not easily accessible with natural abundance isotopic composition. Deuterated cellulose has attracted considerable attention in...     

乙醇制1,3-丁二烯MgO/SBA-15催化剂的制备及其催化性能

以介孔分子筛SBA-15为载体,采用浸渍法制备了新型负载型MgO/SBA-15催化剂,采用低温N₂吸附-脱附、X射线衍射(XRD)、透射电子显微镜(TEM)、²⁹Si核磁共振(²⁹Si NMR)、NH₃程序升温脱附(NH₃-TPD)、CO₂程序升温脱附(CO₂-TPD)等表征手段研究了不同MgO负载量(质量分数)对催化剂的结构、物化性能和催化乙醇合成丁二烯反应活性的影响。 研究结果表明,MgO负载量为20%时,所制备的催化剂的活性最好,此时MgO高度分散在载体SBA-15的有序孔道中,形成了Mg-O-Si结构,有利于提高目标产物丁二烯的选择性。 该催化剂在温度350 ℃、进料质量空速2.64 h^-1的反应条件下,可获得最佳催化效果,乙醇转化率最高可达55.8%,丁二烯选择性可达80.2%。 MgO/SBA-15催化剂在乙醇法生产丁二烯工艺中具有潜在的应用前景。     

Cooperative catalysis with chiral Brønsted acid-Rh2(OAc)4: highly enantioselective three-component reactions of diazo compounds with alcohols and imines

An asymmetric three-component reaction of diazo compounds and alcohols with imines catalyzed cooperatively by a rhodium complex and a chiral Br?nsted acid provides a general and efficient entry to beta-amino-alpha-hydroxyl acid derivatives in high yields with excellent stereoselectivities.     

CeO<Subscript>2</Subscript>–ZrO<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Ternary Oxides Synthesized via Supercritical Anti-Solvent and as a Support for Pd Catalyst for CO Oxidation

CeO₂–ZrO₂–Al₂O₃ ternary oxides as a support for CO oxidation was synthesized successfully via supercritical anti-solvent (SAS) precipitation using CO₂ as the anti-solvent and methanol as the solvent. It was found that the CeO₂–ZrO₂–Al₂O₃ fabricated by SAS precipitation (CZA1) had superior resistance to sintering compared to the traditional co-precipitation method (CZA2). Meanwhile, the oxygen storage/release rate of CAZ1 was almost 1.5 times higher than that of CZA2 and the total oxygen storage capacity (OSC) of CAZ1 was almost twice as high as CZA2. The interactions between the Pd and the CeO₂–ZrO₂–Al₂O₃ support were stronger for the support synthesized by SAS precipitation. The conversion of CO oxidation of Pd/CZA1 was even better than that of Pd/CZA2, especially at high GHSV.     

An efficient route for the construction of cyclopenta[b]quinoline derivatives via intramolecular cyclopropanation

A one-pot process to introduce diazoacetoacetate functionality into quinoline was identified with excellent yield and regioselectivity. An intramolecular cyclopropanation of the resulting adducts gave tetracyclic cyclopenta[b]quinoline derivatives in nearly quantitative yields. A synthetic utility of the tetracyclic derivatives was examined by a simple ring opening reaction to afford cyclopenta[b]quinoline in a good yield.     

The preparation and characterization of chemically deuterium incorporated cotton fibers

Cellulose - Preparation of deuterium incorporated cellulose is a vital tool to investigate cellulose internal structure and to expand the application fields of cellulose materials. In this study,...     

Structural Determinants of the Binding and Activation of Estrogen Receptor α by Phenolic Thieno[2,3-d]pyrimidines

Synthetic, structural, and computational approaches were used to solve the puzzle as to how a phenolic nonsteroidal estrogen 1 with only a single H-bond to its receptor was more potent than an isomer 2 which formed an intricate network of H-bonds. Synthesis of a series of substituted phenols revealed that pK_a was not a determinant of estrogenic activity. First-principles calculation also failed to explain the difference in activity of 1 and 2 . Molecular dynamics revealed that 1 formed a more stable receptor complex compared to 2 , which may explain its increased activity despite forming fewer apparent H-bonds with the protein.