Search

The title compound was synthesized at a near-quantitative yield using the nucleophilic aromatic substitution of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with perfluoropyridine (PFP). The purity and structure were determined by NMR (1H, 13C, 19F), GC-EIMS, and single-crystal X-ray crystallography. [ABSTRACT FROM AUTHOR]

The title compound was synthesized in near quantitative yields via initial nucleophilic aromatic substitution of pentafluoropyridine (PFP) with 4-(2-bromoethyl)phenol as a versatile precursor for ionic liquids (ILs). The purity and structure were determined using 1H, 13C, and 19F NMR and GC-EIMS. [ABSTRACT FROM AUTHOR]

Reaction of triplet O2 with the bridged dipotassium dicyclopentadienyl salt, ansa-[(CHBut)2(Ph2C5H2)2]K2(THF)3 1, in dry MeCN facilitated an intramolecular cyclopentadienyl ring-C to ring-C bond formation and the precipitation of the crude product 4,5-di-tert-butyl-1,3,6,8-tetraphenyl-4,5,8a,8b-tetrahydro-as-indacene 2 as an off-white solid in a 73% yield (>95% pure, 1H NMR). Characterization of 2 was carried out using multinuclear NMR spectroscopy (1H and 13C), single-crystal X-ray crystallography, FTIR spectroscopy, and thermal analytical techniques (SDT, DSC). The molecular structure consisted of a rigid, C2-symmetric six-membered ring in a chair conformation with four of the ring-C atoms fused to 1,3-diphenylcyclopentadiene rings and the other two ring-C atoms substituted with trans di-axial But groups. [ABSTRACT FROM AUTHOR]

The title compound was synthesized in near-quantitative yield using nucleophilic aromatic substitution of 4,4′-(hexafluoroisopropylidene)diphenol (BPAF) with perfluoropyridine (PFP). The purity and structure were determined by NMR (1H, 13C, 19F), GC–EIMS, and single-crystal X-ray crystallography. [ABSTRACT FROM AUTHOR]

Improving the performance of composite energetic materials comprised of a solid metal fuel and a source of oxidizer (known as thermites) has long been pursued as thermites for pyrolant flares and rocket propellants. The performance of thermites, involving aluminum as the fuel, can be dramatically improved by utilizing nanometer-sized aluminum particles (nAl) leading to vastly higher reaction velocities, owing to the high surface area of nAl. Despite the benefits of the increased surface area, there are still several problems inherent to nanoscale reactants including particle aggregation, and higher viscosity composited materials. The higher viscosity of nAl composites is cumbersome for processing with inert polymer binder formulations, especially at the high mass loadings of metal fuel necessary for industry standards. In order to improve the viscosity of high mass loaded nAl energetics, the surface of the nAl was passivated with covalently bound monolayers of perfluorinated carboxylic acids (PFCAs) utilizing a novel fluorinated solvent washing technique. This work also details the quantitative binding of these monolayers using infrared spectroscopy, in addition to the energetic output from calorimetric and thermogravimetric analysis. Dataset: Supplementary file of thermal analysis Dataset License: CC-BY [ABSTRACT FROM AUTHOR]

Improvements to fluoropolymer processing techniques by way of utilizing nanoparticles as drop-in processing aids have pronounced effects on bulk composite properties. In this work, we prepared fluoroalkyl-silanized silica nanoparticles (F-SiNPs, ca. 200 nm) that were solvent-blended with polyvinylenedifluoride (PVDF) in order to prepare composites with varying weight fractions. We demonstrated that the ability to functionalize SiNPs with long fluoroalkylchains that induced co-crystallization with the PVDF matrix, resulting in uniform particle dispersion and improved interlaminate adhesion. This was quantitatively investigated using calorimetry and thermogravimetric analysis, which showed a decrease in the bulk crystallinity of the virgin PVDF from 37% to 10% with minimal 10 wt % F-SiNP loading, rendering a nearly amorphous PVDF. Additional discussions in this work include the effects of various bare and fluoroalkyl-functionalized SiNP loadings on the amorphous and crystalline domains of the PVDF matrix, as well as thermal decomposition. [ABSTRACT FROM AUTHOR]

Perfluoropyridine (PFPy) is an organofluorine compound that has been employed for a variety of applications, from straightforward chemical synthesis to more advanced functions, such as fluorinated networks and polymers. This can be directly attributed to the highly reactive nature of PFPy, especially towards nucleophilic aromatic substitution (SNAr). The aim of this review is to highlight the discovery and synthesis of PFPy, discuss its reactive nature towards SNAr, and to summarize known reports of the utilization and thermal analysis of PFPy containing fluoropolymers and fluorinated network materials. [ABSTRACT FROM AUTHOR]

Perfluoroaromatics, such as perfluoropyridine and perfluorobenzene, are privileged synthetic scaffolds in organofluorine methodology, undergoing a series of regioselective substitution reactions with a variety of nucleophiles. This unique chemical behavior allows for the synthesis of many perfluoroaromatic derived molecules with unique and diverse architectures. Recently, it has been demonstrated that perfluoropyridine and perfluorobenzene can be utilized as precursors for a variety of materials, ranging from high performance polyaryl ethers to promising drug scaffolds. In this work, using density functional theory, we investigate the possibility of perfluoropyrimidine, perfluoropyridazine, and perfluoropyrazine participating in similar substitution reactions. We have found that the first nucleophilic addition of a phenoxide group substitution on perfluoropyrimidine and on perfluoropyridazine would happen at a site para to one of the nitrogen atoms. While previous literature points to mesomeric effects as the primary cause of this phenomenon, our work demonstrates that this effect is enhanced by the fact that the transition states for these reactions result in bond angles that allow the phenoxide to π-complex with the electron-deficient diazine ring. The second substitution on perfluoropyrimidine and on perfluoropyridazine is most likely to happen at the site para to the other nitrogen. The second substitution on perfluoropyrazine is most likely to happen at the site para to the first substitution. The activation energies for these reactions are in line with those reported for perfluoropyridine and suggest that these platforms may also be worth investigation in the lab as possible monomers for high performance polymers. [ABSTRACT FROM AUTHOR]

Since initially being reported, fluorinated silica nanometer-sized particles (F-SiNPs) have gained much interest in the scientific community, due to their unique properties. These properties, include, low surface energies, increased mechanical strength, thermal robustness, and chemical resistance, and are a direct result of the incorporation of fluorine with a nanometer-sized silica network. This review aims to summarize the synthetic methods that have, and are still, being utilized to prepare these specialized materials. Following this, applications for F-SiNPs, with an emphasis on recent examples, will be presented in further detail. [ABSTRACT FROM AUTHOR]