Simulation of radical polymerization of methyl methacrylate at room temperature using a tertiary amine/BPO initiating system

2015 ◽  
Vol 6 (31) ◽  
pp. 5719-5727 ◽  
Author(s):  
Alexander Zoller ◽  
Didier Gigmes ◽  
Yohann Guillaneuf
Keyword(s):  
Methyl Methacrylate ◽  
Radical Polymerization ◽  
Free Volume ◽  
Tertiary Amine ◽  
Room Temperature ◽  
Empirical Models ◽  
Side Reactions ◽  
System P

A model was developed for the polymerization of methyl methacrylate at room temperature. The model used both free volume and empirical models for propagation, termination and several side reactions.

scholarly journals Hierarchically porous π-conjugated polyHIPE as a heterogeneous photoinitiator for free radical polymerization under visible light

2014 ◽  
Vol 5 (11) ◽  
pp. 3559-3562 ◽  
Author(s):  
Zi Jun Wang ◽  
Katharina Landfester ◽  
Kai A. I. Zhang
Keyword(s):  
Free Radical ◽  
Visible Light ◽  
Methyl Methacrylate ◽  
Energy Saving ◽  
Radical Polymerization ◽  
Room Temperature ◽  
Free Radical Polymerization ◽  
Light Bulb ◽  
Household Energy ◽  
Hierarchically Porous

A hierarchically porous π-conjugated polyHIPE was used as a heterogeneous visible light photoinitiator for the radical polymerization of methyl methacrylate (MMA) under a household energy saving light bulb at room temperature.

A Facile, Efficient and Selective Deprotection of P - Methoxy Benzyl Ethers Using Zinc (II) Trifluoromethanesulfonate

2019 ◽  
Vol 16 (12) ◽  
pp. 955-958
Author(s):  
Reddymasu Sireesha ◽  
Reddymasu Sreenivasulu ◽  
Choragudi Chandrasekhar ◽  
Mannam Subba Rao
Keyword(s):  
Room Temperature ◽  
Protecting Groups ◽  
Side Reactions ◽  
Reaction Conditions ◽  
Acid Sensitivity ◽  
Time Period ◽  
Protective Groups ◽  
Benzyl Ethers ◽  
Last Stage ◽  
Zinc Triflate

: Deprotection is significant and conducted over mild reaction conditions, in order to restrict any more side reactions with sensitive functional groups as well as racemization or epimerization of stereo center because the protective groups are often cleaved at last stage in the synthesis. P - Methoxy benzyl (PMB) ether appears unique due to its easy introduction and removal than the other benzyl ether protecting groups. A facile, efficient and highly selective cleavage of P - methoxy benzyl ethers was reported by using 20 mole% Zinc (II) Trifluoromethanesulfonate at room temperature in acetonitrile solvent over 15-120 min. time period. To study the generality of this methodology, several PMB ethers were prepared from a variety of substrates having different protecting groups and subjected to deprotection of PMB ethers using Zn(OTf)2 in acetonitrile. In this methodology, zinc triflate cleaves only PMB ethers without affecting acid sensitivity, base sensitivity and also chiral epoxide groups.

Photocontrolled iodine-mediated reversible-deactivation radical polymerization with a semifluorinated alternating copolymer as the macroinitiator

2020 ◽  
Vol 11 (47) ◽  
pp. 7497-7505
Author(s):  
Jiannan Cheng ◽  
Kai Tu ◽  
Enjie He ◽  
Jinying Wang ◽  
Lifen Zhang ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Radical Polymerization ◽  
Room Temperature ◽  
Blue Led ◽  
Led Light ◽  
Alternating Copolymers ◽  
Alternating Copolymer ◽  
Reversible Deactivation ◽  
Novel Strategy ◽  
Reversible Deactivation Radical Polymerization

A novel strategy for preparing block copolymers with semifluorinated alternating copolymers as macroinitiators was established by photocontrolled iodine-mediated RDRP under irradiation with blue LED light at room temperature.

scholarly journals Lithium-mediated Ferration of Fluoroarenes

2020 ◽  
Vol 74 (11) ◽  
pp. 866-870
Author(s):  
Lewis C. H. Maddock ◽  
Alan Kennedy ◽  
Eva Hevia
Keyword(s):  
Hydrogen Atom ◽  
Organometallic Chemistry ◽  
Room Temperature ◽  
Structural Elucidation ◽  
Side Reactions ◽  
Metal Base ◽  
Lithium Amide ◽  
Mixed Metal ◽  
Important Challenge

While fluoroaryl fragments are ubiquitous in many pharmaceuticals, the deprotonation of fluoroarenes using organolithium bases constitutes an important challenge in polar organometallic chemistry. This has been widely attributed to the low stability of the in situ generated aryl lithium intermediates that even at –78 °C can undergo unwanted side reactions. Herein, pairing lithium amide LiHMDS (HMDS = N{SiMe3}2) with FeII(HMDS)2 enables the selective deprotonation at room temperature of pentafluorobenzene and 1,3,5-trifluorobenzene via the mixed-metal base [(dioxane)LiFe(HMDS)3] (1) (dioxane = 1,4-dioxane). Structural elucidation of the organometallic intermediates [(dioxane)Li(HMDS)2Fe(ArF)] (ArF = C6F5, 2; 1,3,5-F3-C6H2, 3) prior electrophilic interception demonstrates that these deprotonations are actually ferrations, with Fe occupying the position previously filled by a hydrogen atom. Notwithstanding, the presence of lithium is essential for the reactions to take place as Fe II (HMDS)2 on its own is completely inert towards the metallation of these substrates. Interestingly 2 and 3 are thermally stable and they do not undergo benzyne formation via LiF elimination.

scholarly journals Understanding Sulfur Redox Mechanisms in Different Electrolytes for Room-Temperature Na–S Batteries

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Hanwen Liu ◽  
Wei-Hong Lai ◽  
Qiuran Yang ◽  
Yaojie Lei ◽  
Can Wu ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Surface ◽  
Reversible Capacity ◽  
High Loading ◽  
Side Reactions ◽  
Liquid Sulfur ◽  
Shuttle Effect ◽  
Loading Ratio ◽  
Solid Liquid ◽  
Sulfur Cathodes

Abstract This work reports influence of two different electrolytes, carbonate ester and ether electrolytes, on the sulfur redox reactions in room-temperature Na–S batteries. Two sulfur cathodes with different S loading ratio and status are investigated. A sulfur-rich composite with most sulfur dispersed on the surface of a carbon host can realize a high loading ratio (72% S). In contrast, a confined sulfur sample can encapsulate S into the pores of the carbon host with a low loading ratio (44% S). In carbonate ester electrolyte, only the sulfur trapped in porous structures is active via ‘solid–solid’ behavior during cycling. The S cathode with high surface sulfur shows poor reversible capacity because of the severe side reactions between the surface polysulfides and the carbonate ester solvents. To improve the capacity of the sulfur-rich cathode, ether electrolyte with NaNO3 additive is explored to realize a ‘solid–liquid’ sulfur redox process and confine the shuttle effect of the dissolved polysulfides. As a result, the sulfur-rich cathode achieved high reversible capacity (483 mAh g−1), corresponding to a specific energy of 362 Wh kg−1 after 200 cycles, shedding light on the use of ether electrolyte for high-loading sulfur cathode.

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