Article
Chemistry, Multidisciplinary
Matthieu Balas, Asma Mayoufi, Richard Villanneau, Franck Launay
Summary: Since its first report in the early 1990s, Mukaiyama-type aerobic epoxidation involving the presence of an aldehyde as an electron donor is considered as an interesting oxidation reaction. Among the various metal catalysts efficient for this process, salen-type complexes have many advantages: i) cheap Schiff-base ligands can be easily synthesized and functionalized, ii) their metal complexes are described with most transition metals from the periodic table and iii) these compounds are also efficient for the catalytic formation of cyclic carbonates from epoxides and CO2, which makes them ideal candidates for the oxidative carboxylation of alkenes. The present work aimed at revisiting the aerobic oxidation of styrene using Cr(iii) and Mn(iii) salen complexes in the presence of isobutyraldehyde with the idea to further use these complexes (without any work-up), as co-catalysts for the formation of styrene carbonate under CO2 pressure. However, contrary to what is often described in the literature, the present study showed that the introduction of a metal catalyst is not necessary for the epoxidation of styrene at 80 degrees C in benzonitrile. In our hands, yields of ca. 15% of styrene carbonate were obtained from styrene using O-2 (3.5 bar) and CO2 (11 bar) as reagents in the presence of isobutyraldehyde (2.5 eq), tetrabutylammonium bromide (ca. 2 mol%) and the Cr(iii) salen complex (ca. 1 mol%). Apparently, the oxidation of Cr(iii) to Cr(vi) species in the presence of O-2 and isobutyraldehyde is detrimental to the kinetics of the tetrabutylammonium bromide-catalyzed cycloaddition of CO2 to styrene oxide.
REACTION CHEMISTRY & ENGINEERING
(2023)
Article
Engineering, Environmental
Yufei Han, Zhe Li, Mengru Zhang, Fei Han, Zhe Liu, Weizhi Zhou
Summary: A cobalt-substituted alpha-FeOOH catalyst (FeCox) was synthesized using a simple coprecipitation method. The substitution of cobalt greatly enhanced the activation of peroxymonosulfate (PMS) and improved the removal efficiency of tetracycline (TC) as a model pollutant. The introduction of cobalt led to a change in the activation pathway of alpha-FeOOH, resulting in singlet oxygen (O-1(2)) becoming the dominant reactive oxygen species (ROS) in the reaction system. The excellent catalytic performance of FeCo10 was attributed to the structural defects caused by cobalt substitution, which increased the hydroxyl sites and electron transmission capacity of the catalyst.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Derik Wilbers, Joseph Brehm, Richard J. Lewis, Jacqueline van Marwijk, Thomas E. Davies, David J. Morgan, Diederik J. Opperman, Martha S. Smit, Miguel Alcalde, Athanasios Kotsiopoulos, Susan T. L. Harrison, Graham J. Hutchings, Simon J. Freakley
Summary: The combination of heterogeneous catalysis and biocatalysis to form one-pot reaction cascades allows the integration of enzymatic transformations into existing chemical infrastructure. The use of peroxygenases for clean C-H activation in such tandem systems requires a constant supply of low-level hydrogen peroxide. The in situ generation of oxidants from cheap reactants at industrial scale shows potential for highly active cascade processes.
Article
Chemistry, Multidisciplinary
Panxia Zhao, Jie Chen, Nana Ma, Jingfei Chen, Xiangquan Qin, Chuanfei Liu, Fuquan Yao, Lishan Yao, Longyi Jin, Zhiqi Cong
Summary: The study demonstrates the efficient H2O2-dependent (R)-enantioselective epoxidation of unfunctionalized styrene and its derivatives by site-mutated variants of a unique non-natural P450BM3 peroxygenase in combination with a dual-functional small molecule. The synergistic use of protein engineering and an exogenous DFSM represents an effective strategy to control the enantioselectivity of styrene epoxidation, significantly expanding the chemical scope of P450 enzymes as useful bio-oxidative catalysts.
Article
Chemistry, Physical
Qingping Ke, Shuai Fang, Jun Tang, Fengfeng Li, Chuantao Ning, Zhicheng Tang, Qiang Ling, Xiangchun Liu, Ping Cui
Summary: In this study, perovskite LaSrCoFeO6 (LSCF) was used as a heterogeneous and visible-light catalyst for the epoxidation of styrene under aerobic conditions. LSCF exhibited high catalytic activity and selectivity, with the formation of O-1(2) species proposed as reactive oxygen species for the reaction. The reaction rate over LSCF catalyst was found to be 50 mmol·g(cat)(-1)·h(-1), and the conversion and selectivity of styrene oxide reached 99.9% and 80.3%, respectively.
Article
Chemistry, Physical
Fengfeng Li, Jun Tang, Qingping Ke, Yun Guo, Minh Ngoc Ha, Chao Wan, Zhiping Lei, Jing Gu, Qiang Ling, Van Noi Nguyen, Wangcheng Zhan
Summary: A photothermal catalytic approach using LaSrCoxFe2-xO6 double perovskite materials as catalysts has been developed for efficient epoxidation of styrene. Singlet oxygen was identified as the key reactive oxygen species, and the mechanism involves a combination of photothermal and solvation effects to generate hot electrons, holes, superoxides, and singlet oxygen species.
Article
Chemistry, Multidisciplinary
Sii Hong Lau, Meredith A. Borden, Talia J. Steiman, Lucy S. Wang, Marvin Parasram, Abigail G. Doyle
Summary: This study introduces a Ni/photoredox-catalyzed enantioselective reductive coupling of styrene oxides and aryl iodides, yielding enantioenriched 2,2-diarylalcohols. Analysis shows that enantioselectivity is correlated with the electronic properties of the ligands, with more electron-donating ligands leading to higher ee values. Experimental and computational studies support the hypothesis that reductive elimination is enantiodetermining and ligand electronic properties affect enantioselectivity by altering the position of the transition state structure.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Physical
Hu Xiao, Shuang Dong, Yan Liu, Xiao-Qiong Pei, Hui Lin, Zhong-Liu Wu
Summary: New (R)-selective styrene monooxygenases have been identified, showing high enantioselectivity in converting styrene analogues into (R)-epoxides with purity up to >99% ee. Site 46 was identified as a critical residue affecting the enantioselectivity of SMOs, providing a valuable green alternative for the synthesis of enantiopure (R)-epoxides.
CATALYSIS SCIENCE & TECHNOLOGY
(2021)
Article
Chemistry, Physical
Yu-Jhang Lu, Damodar Janmanchi, Thiyagarajan Natarajan, Zhi-Han Lin, Wondemagegn H. Wanna, I-Jui Hsu, Der-Lii M. Tzou, Tigist Ayalew Abay, Steve S-F Yu
Summary: We investigated the catalytic epoxidation of cyclohexene and styrene using AgCN powder as a catalyst in CH3CN. The reaction mixtures separated into organic and aqueous layers easily. We achieved high selectivity in the production of cyclohexene oxide and styrene oxide. The AgCN particles could be recycled and reused through various analytical techniques.
Article
Chemistry, Physical
Dianwen Hu, Xiaojing Song, Hao Zhang, Xinyu Chang, Chen Zhao, Mingjun Jia
Summary: Catalytic epoxidation of styrene with molecular oxygen using transition metal monosubstituted heteropolyacid compounds encapsulated in UiO-66 frameworks shows high catalytic activity and selectivity, with Co-HPA@UiO-66 exhibiting the best performance under mild conditions. The hybrid composite catalyst efficiently converts styrene derivatives to epoxides through the activation of in-situ generated acylperoxy radical intermediate.
MOLECULAR CATALYSIS
(2021)
Article
Chemistry, Applied
Ferran Sabate, Jose Luis Jorda, Maria J. Sabater
Summary: In this study, a fraction of structural Mn cations in cryptomelane oxide K-OMS2 were replaced by different cationic dopants, resulting in the weakening of the Mn-O bond and the production of oxygen vacancy defects. The most active catalyst was found to be the ruthenium doped cryptomelane oxide, which exhibited a higher reducibility and a more weakened Mn-O bond force constant value. All the doping processes enhanced the alcohol conversion and showed a high selectivity towards the aldehyde.
Article
Engineering, Chemical
Yuxin Wu, Zhuo Chen, Fajun Wang, Jianhong Xu, Yundong Wang
Summary: The study focused on a highly efficient microreaction system for epoxidation of styrene, achieving high conversion and excellent product selectivity. Various factors such as temperature, residence time, catalyst molar fraction, MeCN/t-BuOH molar ratio, H2O2 flow rate, and buffer solution were investigated. A kinetic equation was established based on experimental data, aiding in verifying the rationality of the reaction mechanism and optimizing experimental conditions.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Chemistry, Inorganic & Nuclear
Xavier Kesse, Clemence Sicard, Nathalie Steunou, Jean-Pierre Mahy, Remy Ricoux
Summary: A new biocatalyst MP8@MIL-101(Cr/Fe) was synthesized by immobilizing Microperoxidase 8 (MP8) within MIL-101(Cr/Fe) metal-organic framework. The characterization of MIL-101(Cr/Fe) and MP8@MIL-101(Cr/Fe) was done using PXRD, FTIR spectroscopy, and TGA. The catalytic activity of MP8@MIL-101(Cr/Fe) for styrene oxidation using H2O2 and tBuOOH was investigated under different reaction conditions and compared to MP8 alone. MP8@MIL-101(Cr/Fe) showed approximately 3 times higher efficiency and approximately 50% selectivity for styrene oxide compared to MP8 alone.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Palli Sitaramulu, Kamma Yogendra, Silligandla Nazeer, Ramineni Kishore, Benjaram M. Reddy, Tumula Venkateshwar Rao
Summary: CeO2, Bi2O3, and ceria-bismuth mixed oxide (Ce0.8Bi0.2O2, Ce0.7Bi0.3O2, and Ce0.5Bi0.5O2) catalysts have been prepared using a coprecipitation method and characterized using various physicochemical characterization techniques. The Bi-doped ceria (Ce0.7Bi0.3O2) catalyst showed superior catalytic activity for styrene oxidation and epoxide product selectivity due to higher oxygen vacancies and redox behavior. Optimization of catalytic activity parameters such as temperature, reaction time, catalyst amount, substrate/oxidant ratio, and solvent nature was performed to improve the conversion of styrene and selectivity towards styrene epoxide.
NEW JOURNAL OF CHEMISTRY
(2023)
Article
Chemistry, Applied
Zhanyu Zhang, Jun Tang, Junbao Chen, Peixin Cui, Siyu Jiao, Wei Yi, Qingping Ke, Hengquan Yang
Summary: In this study, MnOx nanocatalysts with abundant oxygen vacancies were prepared using reverse-micelle as a template and endowed with an amphiphilic surface through post-modification. These catalysts were utilized to formulate Pickering emulsion and create compartmentalized droplet microreactors for the epoxidation of styrene. The oxygen defects on MnOx improved the chemisorption of t-butylhydroperoxide and facilitated the formation of superoxide radicals for the synthesis of styrene oxide. The compartmentalization effects from Pickering emulsion droplets enhanced the radical reaction path, resulting in higher selectivity and catalytic efficiency.
Article
Green & Sustainable Science & Technology
Arindam Kuila, Peddy V. C. Rao, Nettem V. Choudary, SriGanesh Gandham, Harshad R. Velankar
ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY
(2015)
Article
Chemistry, Multidisciplinary
Velu Jeyalakshmi, Rajaram Mahalakshmy, Kanaparthi Ramesh, Peddy V. C. Rao, Nettem V. Choudary, Gandham Sri Ganesh, Kandasamy Thirunavukkarasu, Konda Ramasamy Krishnamurthy, Balasubramanian Viswanathan
Article
Energy & Fuels
P. K. Sahoo, B. P. Prajwal, Siva Kalyan Dasetty, M. John, B. L. Newalkar, N. V. Choudary, K. G. Ayappa
Article
Chemistry, Applied
Sumit V. Jadhav, Krishna Mohan Jinka, Hari C. Bajaj
Article
Engineering, Chemical
Kun Liu, Krishna M. Jinka, Joseph E. Remias, Kunlei Liu
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2013)
Article
Chemistry, Applied
N. V. Choudary, B. L. Newalkar
JOURNAL OF POROUS MATERIALS
(2011)
Review
Engineering, Chemical
Saptarshi Ray, Peddy V. C. Rao, Nettem V. Choudary
LUBRICATION SCIENCE
(2012)
Article
Chemistry, Applied
K. Agarwal, M. John, S. Pai, B. L. Newalkar, R. Bhargava, N. V. Choudary
MICROPOROUS AND MESOPOROUS MATERIALS
(2010)
Article
Energy & Fuels
T. Chiranjeevi, N. Ravichander, D. T. Gokak, V. Ravikumar, N. V. Choudary
PETROLEUM SCIENCE AND TECHNOLOGY
(2014)
Article
Chemistry, Applied
Krishna Mohan Jinka, Hari C. Bajaj, Raksh V. Jasra, Eko Adi Prasetyanto, Sang-Eon Park
TOPICS IN CATALYSIS
(2010)
Article
Chemistry, Multidisciplinary
G. Pritika, T. Chiranjeevi, D. T. Gokak, N. V. Choudary
INDIAN JOURNAL OF CHEMISTRY SECTION A-INORGANIC BIO-INORGANIC PHYSICAL THEORETICAL & ANALYTICAL CHEMISTRY
(2013)
Article
Materials Science, Characterization & Testing
Jaya Rawat, P. V. C. Rao, N. D. Raut, N. V. Choudary
MATERIALS PERFORMANCE
(2010)
Article
Chemistry, Multidisciplinary
Rajagopalan Prabu, Arindam Kuila, Raman Ravishankar, Peddy V. C. Rao, Nettem V. Choudary, Harshad R. Velankar
