Electrochemical properties of new organic radical materials for lithium secondary batteries

The use of ionic liquid (IL)-supported organic radicals as cathode-active materials in lithium secondary batteries is reported in this article. Two different types of IL-supported organic radicals based on the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) radical and imidazolium hexafluorophosphate IL were synthesized. The first type is a mono-radical with one unit of TEMPO and the second is a symmetrical di-radical with 2 U of TEMPO; both are viscous liquids at 25 °C. The radicals exhibit electrochemical activity at ∼3.5 V versus Li/Li⁺ as revealed in the cyclic voltammetry tests. The organic radical batteries (ORBs) with these materials as the cathode, a lithium metal anode and 1 M LiPF₆ in EC/DMC electrolyte exhibited good performance at room temperature during the charge–discharge and cycling tests. The batteries exhibited specific capacities of 59 and 80 mAh g⁻¹ at 1 C-rate with the mono- and di-radicals as the cathodes, respectively, resulting in 100% utilization of the materials. The performance degradation with increasing C-rate is very minimal for the ORBs, thus demonstrating good rate capability.     

Selective Light Supported Oxidation of Hexoses Using Air as Oxidant – Synthesis of Tetrahydroxyazepanes

Unprotected alkyl glycosides have been oxidized using air as oxidant and copper(I) chloride/TEMPO as the catalytic system. The primary hydroxy group in the 6 position is selectively transformed into an aldehyde equivalent. The process was optimized by irradiation with visible light. Without further purification and with high yields, the resulting lactols have been transformed into tetrahydroxyazepane.     

A Mild TEMPO‐Catalyzed Aerobic Oxidative Conversion of Aldehydes into Nitriles

An efficient method to prepare nitriles from aldehydes using hexamethyldisilazane (HMDS) as the nitrogen source has been developed. The reactions were performed with 2,2,6,6‐tetramethylpiperidine l‐oxyl (TEMPO) as the catalyst, NaNO₂ or TBN as the co‐catalyst, and molecular oxygen as the terminal oxidant under mild conditions. A variety of aromatic, heteroaromatic, aliphatic and allylic aldehydes could be converted into their corresponding nitriles in good to excellent yields.

     

Effect of Thermal Treatment on the Properties of TEMPO Oxidized Cellulose Film for the Flexible Substrate of Solar Cell

The 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose film (TOCF) has been attempted to be used as a substrate in electronic and optoelectronic devices, but the changes in the TOCF properties before and after annealing treatment have usually been neglected during device fabrication. In this study, TOCF was treated in different atmospheres (air, vacuum, and N₂) and at different temperatures, and the properties were investigated. The results indicate that the optical properties are slightly affected by atmosphere and temperature; only slight transmittance loss and haze increase have been observed when TOCF is exposed to an air atmosphere at temperatures of above 120℃. In contrast to the slight effects on the optical properties, cellulose degradation and a loss of film strength have been observed regardless of the atmosphere used when placed at temperatures of above 100℃. Specifically, TOCF was exposed to air, followed by N₂ and vacuum atmospheres. Additional Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) results showed that increasing the temperature had no significant effect on the structure of TOCF. Therefore, the annealing temperature should be controlled at a temperature of lower than 100℃ and a vacuum atmosphere is preferred.     

Mg（OH）_2/硅藻土催化合成2,2,6,6-四甲基哌啶氮氧自由基（TEMPO）

该文采用DOE实验设计方案进行实验,通过Minitab数据分析软件找出影响合成反应的主要因子是反应温度和投料比;然后结合单因素法分析得到合成2,2,6,6-四甲基哌啶氮氧自由基（TEMPO）最适宜的工艺条件为：pH=7.5,双氧水滴加时间为2 h,催化剂用量为0.20 g,反应温度为70℃,H2O2和2,2,6,6-四甲基哌啶（TEMP）的投料比为2.5∶1。在此工艺条件下合成TEMPO的得率为94.15%,产品纯度为100%。     

TEMPO选择性催化氧化对纸浆成纸性能的影响

通过以TEMPO为媒介的氧化反应,纸浆纤维素的非结晶区和结晶区表面C6的伯羟基被选择性氧化为醛基或羧基,而不会引起纤维的晶体尺寸和聚合度的变化。2,2,6,6四甲基哌啶氧化物自由基（TEMPO）-NaClO-NaBr作为一种新的选择性催化氧化体系,主要研究了该体系对纸浆纤维的氧化过程。结果表明：在适宜的反应条件温度40℃、pH=9．5、NaClO用量为0．4mmol／g下,经TEMPO-NaClO-NaBr表面化学改性氧化的纸浆,其成纸干抗张强度提高25％左右,湿抗张强度提高90％左右。同时耐破度可提高约57％,对撕裂度影响较小。     

Novel 2,2,6,6‐Tetramethylpiperidine 1‐Oxyl–Iodobenzene Hybrid Catalyst for Oxidation of Primary Alcohols to Carboxylic Acids

Novel bifunctional hybrid‐type catalysts bearing 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and iodobenzene moieties ( 1a and 1b ) were developed and used for the environmentally benign oxidation of primary alcohols to carboxylic acids. Reaction of primary alcohols 2 with a catalytic amount of 1 in the presence of peracetic acid as a co‐oxidant under mild conditions gave the corresponding carboxylic acids 3 in excellent yields.     

Post‐polymerization modification by nitroxide radical coupling

Post‐polymerization modification is an attractive approach to extend applications and convert commodity plastics into products with new, desirable and tunable properties. Among the post‐polymerization modification methods, the nitroxide radical coupling (NRC) reaction has been shown to be a convenient and versatile way to graft specific functionalities onto polymer chains and to control the onset and yield of polymer crosslinking during peroxide‐initiated processes. The use of 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and its derivatives as controllers of scorch in crosslinking and as functionalizers in functionalization reactions is thoroughly described. Examples are also given of graft polymerization from macroalkoxyamines generated by NRC and grafting of nitroxides by irradiation processes. In addition, in this review we attempt to demonstrate the broad applications of the NRC reaction in the preparation of polymers with a multitude of functionalities and elaborate architectures. The examples discussed here concern the use of atom transfer and single electron transfer NRC reactions to design a variety of polymers with asymmetrical structure and the use of the radical crossover reaction, based on the alkoxyamine dynamic covalent bond, to generate reversible polymer structures and switchable functional polymers. © 2018 Society of Chemical Industry     

Aryl Ketone-Catalyzed Light-Driven Radical Oxy-Functionalization of Non-Acidic C(sp3)−H Bonds Enabled by Triple Role of TEMPO

A light-driven radical oxy-functionalization of non-acidic aliphatic and benzylic C(sp³)−H bonds was achieved with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) in a single-step by employing an aryl ketone as a sole catalyst. The transformation was initiated by homolysis of a C(sp³)−H bond in the starting substance by the photo-excited aryl ketone. The derived carbon radical was then promptly trapped by TEMPO leading to the formation of the TEMPO-adduct. The derived TEMPO-adduct is synthetically versatile as an alcohol equivalent since it can be readily converted to the corresponding ketone by oxidation and to the corresponding alcohol by reduction. The key to realizing the present catalytic reaction relies on the distinctive triple role of TEMPO, which acts as the precursor of the oxygen functionality, the oxidant to regenerate the aryl ketone, and the protective group for the derived TEMPO-adduct from over-oxidation.