Article
Chemistry, Multidisciplinary
Christoph Wallach, Felix S. Geitner, Thomas F. Fassler
Summary: Despite being known for two decades, homoatomic nine-atom germanium clusters have been rarely investigated for their chemical properties. This study shows that Zintl ion main group-element clusters have a reactive lone pair of electrons, and introduces a new pathway for binding ligands to the [Ge-9] cluster core through Ge-C bond formation. The reactivity of [Ge-9{Si(TMS)(3)}(2)](2-) towards a series of Lewis acidic bromo-boranes is explored, leading to the formation of different products depending on reaction conditions. Overall, the study highlights the unique substitution patterns and reactivity of these germanium clusters in interaction with borane compounds.
Article
Chemistry, Applied
Saeideh-Sadat Mortazavi, Majid Masteri-Farahani, Alireza Abbasi
Summary: By entrapping a multi-SO3H functionalized ionic liquid inside the pores of a porous solid support, the advantages of both homogeneous and heterogeneous catalytic systems were combined. The prepared catalyst exhibited high catalytic efficiency and stability in the ring-opening reaction of epoxides. Various physicochemical methods were employed to fully elucidate the properties of the catalyst.
APPLIED ORGANOMETALLIC CHEMISTRY
(2021)
Article
Polymer Science
Alastair Little, Alan M. Wemyss, David M. Haddleton, Bowen Tan, Zhaoyang Sun, Yang Ji, Chaoying Wan
Summary: The study investigates the effects of various reaction conditions on the synthesis of PLGA25, showing how factors such as reaction temperature, initiator concentration, and catalyst concentration impact the molecular weight, monomer conversion, and thermal properties.
Article
Chemistry, Physical
Paulraj Arunkumar, Sampath Gayathri, Aruliah Rajasekar, Shanmugam Senthil Kumar, Sathish Kumar Kamaraj, Jong Hun Han
Summary: Manipulating metal valence states and porosity in metal-organic frameworks (MOFs) using alloying techniques enables the creation of high-valent metal sites and pore environments, which can enhance catalytic activity for sensing applications.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2024)
Article
Chemistry, Organic
Kazuho Sakai, Yusuke Yagi, Nobuyoshi Nomura
Summary: A novel method for the synthesis of highly isotactic poly(racemic lactic acid) [P(rac-LAA)] from racemic 2,2,5-trimethyl-1,3-dioxolan-4-one using achiral homosalen-Al catalysts is reported. The polymerization involves stereoselective ring opening and deacetonation. The effects of substituents on the catalyst regarding polymerization rates, polydispersity, and iso-stereoselectivity of P(rac-LAA) were studied, and the isopropyl-substituted homosalen-Al catalyst yielded the highest isotacticity (Pm = 0.96), moderate molecular weight (Mn = 6,200), and broad polydispersity (PDI = 2.20). Differential scanning calorimetric analysis indicated that the polymer was semicrystalline with a melting temperature of 156 degrees C.
Article
Chemistry, Physical
Leah Ford, Alexander Spanos, Nicholas A. A. Brunelli
Summary: Sn-Beta is a complex catalyst with multiple types of active sites, and its activity can be calculated using site quantification experiments. This study connects site quantification experiments with spectroscopic measurements to explain the differences in catalytic activity between materials crystallized for different amounts of time. The activity difference between Sn-Beta-200-10d and Sn-Beta-200-40d can be attributed to the reduced fraction of high-activity sites. Combining site quantification experiments with NMR techniques allows for the establishment of a synthesis-structure-activity relationship that has the potential to improve the performance of Sn-Beta.
Article
Chemistry, Physical
Alexander P. Spanos, Aamena Parulkar, Nicholas A. Brunelli
Summary: Enhancement of catalytic performance of zeolites can be achieved by controlling catalytic sites and reaction environment. Experimental results show that a hydrophobic framework is beneficial for alcohol ring opening of epoxides, with hydrophobic materials demonstrating higher turnover frequencies than hydrophilic catalysts under certain reaction conditions.
JOURNAL OF CATALYSIS
(2021)
Article
Polymer Science
Rachele N. Carafa, Kristy Halnan, R. Stephen Wylie, Daniel A. Foucher, Alan J. Lough, Ian Manners, Andrew R. McWilliams
Summary: A series of cyclic thionylphosphazenes were prepared and studied for their susceptibility to ring-opening polymerization with Lewis acid catalysts at ambient temperatures through both density functional theory calculations and experimental investigations. The results suggest that thionylphosphazenes exhibit sensitivity and reversibility to the Lewis acid-catalyzed polymerization reactions at room temperature.
Article
Polymer Science
Yuejia Zhu, Yongzhu Hu, Zhenjiang Li, Bo Liu, Yuanyuan Qu, Zhihao Zhang, Tianfo Guo, Yongqiang Li, Luoyu Gao, Kai Guo
Summary: By introducing 3-amino-1,2,4-benzo-thiadiazine-1,1-dioxide (ABTD) as a bidentate H-bond donor and triethylamine (TEA) as a mild Lewis base, successful control of polylactide (PLA) with predictable molecular weights and extremely narrow dispersities was achieved in room temperature solutions.
EUROPEAN POLYMER JOURNAL
(2021)
Review
Polymer Science
Chengjian Zhang, Xiaowei Geng, Xinghong Zhang, Yves Gnanou, Xiaoshuang Feng
Summary: Sensitivity to environmental concerns and the demand for metal-free polymeric materials have driven research towards breakthroughs in organocatalytic polymerizations. Triethyl borane (TEB) has been discovered as an exceptional Lewis acid, serving to generate ate complexes and activate epoxides. Lewis pairs consisting of alkyl boranes combined with onium salts or organic bases have demonstrated unprecedented versatility for (co)polymerizations of oxygenated monomers, producing various oxygenated polymers. This review summarizes the progress made in TEB-mediated polymerization systems and proposes future challenges in organocatalytic synthesis.
PROGRESS IN POLYMER SCIENCE
(2023)
Article
Chemistry, Organic
Xiu-Mei Kan, Jie Zhu, Pin-Hua Li, Zhi-Chuan Wu, Pei-Jun Yang
Summary: An efficient synthesis of g-amino ethers was achieved by Cu(OTf)2-catalyzed ring-opening of 2-aryl N-tosylazetidines with phenols. This reaction exhibited excellent yields and regio-selectivities, low catalyst loading, mild reaction conditions, and good scalability. One product was transformed into the drug molecule (+/-)-fluoxetine via a two-step procedure.
Article
Multidisciplinary Sciences
Marvin L. Frisch, Sebastian Polarz
Summary: The integration of strong Lewis acids into surfactants can lead to the development of surfactants that actively reduce the size of dirt, thereby enhancing catalytic efficiency.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Physical
Ruite Lai, Qidong Hou, Guanjie Yu, Chao Xie, Hengli Qian, Tianliang Xia, Xinyu Bai, Yao Tang, Mian Laiq Ur Rehman, Meiting Ju
Summary: In this study, a Sn doped zirconium phosphate catalyst was developed for the efficient isomerization of dihydroxyacetone into lactic acid in water. The catalyst exhibited high activity and reusability, while preventing leaching of ions. The excellent catalytic performance was attributed to the accelerated conversion of pyruvaldehyde to lactic acid by the strong Lewis acid sites.
CATALYSIS COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Parth Patel, Raj Kumar Tak, Bhavesh Parmar, Shilpa Dabas, Brijesh Patel, Eringathodi Suresh, Noor-ul H. Khan, Saravanan Subramanian
Summary: The study introduces a nitrogen-rich sulfonated carbon catalyst derived from an inexpensive precursor for the synthesis of bioactive vicinal diols. The well-characterized catalyst exhibits wide generality and can be reused for four cycles without loss of activity under mild reaction conditions.
Article
Engineering, Chemical
Arianna Zanoni, Flavio Tollini, Cora Casiraghi, Giuseppe Storti, Mattia Sponchioni, Davide Moscatelli
Summary: Engineered polylactic acid (PLA) nanoparticles synthesized from oligo(lactic acid) macromonomers have been studied for controlled drug delivery. This study compares the synthesis of PLA-based macromonomers via ring-opening polymerization (ROP) and direct polycondensation of lactic acid in the presence of 2-hydroxyethyl methacrylate (HEMA). It is found that polycondensation is a valuable alternative to ROP for macromonomers with an average chain length of up to 4, while ROP remains the main route for longer chains requiring strict control over the chain length distribution.
CANADIAN JOURNAL OF CHEMICAL ENGINEERING
(2023)