Novel perfluoropolyethers containing 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole blocks: synthesis and characterization

Peroxidic perfluoropolyethers (PFPEs) are industrial intermediates used by Solvay Solexis for the preparation of different classes of (per)fluoropolyethers (Fomblin^®, Galden^®, Solvera^®, Fluorolink^®). The chemistry of these peroxidic compounds has been recently exploited for the synthesis of novel PFPE block copolymers. In the present work we report the synthesis, the structural and physical-chemical characterization of block copolymers obtained by the reaction of peroxidic PFPEs with 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole, a cyclic homopolymerizable perfluoroolefin. These block copolymers combine the most attractive properties of the PFPEs, like the excellent lubrication, the high thermal stability and the optical transparency, with new specific properties which are related to the perfluorodioxolenic blocks.     

Di-block copolymer stabilized methyl methacrylate based polyHIPEs: Influence of hydrophilic and hydrophobic co-monomers on morphology,wettability and thermal properties

Due to intermediate hydrophobicity of methyl methacrylate (MMA) monomer in water, it is difficult to prepare its stable water in oil high internal phase emulsion (HIPE). Moreover, the addition of fully hydrophilic co-monomer such as 2-hydroxyethyl methacrylate (HEMA) in MMA monomer makes it further troublesome to stabilize these emulsions. This paper addresses the preparation of such type of difficult to prepare emulsions via addition of an amphiphilic fluorinated di-block copolymer (FDB), poly(2-dimethylamino)ethylmethacrylate-b-poly(trifluoroethyl methacrylate) (PDMAEMA-b-PTFEMA) as stabilizer. Interestingly, HEMA and/or HFBA (hexa fluorobutyl acrylate) as co-monomers were successfully added to impart some special properties such as thermodynamic stability, desired amphiphilicity to the final polyHIPEs. Fluorinated blocks in FDB anchored well at oil/water interface of HIPE, offering enough hydrophobicity to the comparatively hydrophilic monomers and in turn providing resistance against coalescence. MMA polyHIPEs were found to be fully hydrophobic just by replacing HEMA co-monomer with HFBA. Due to superb inherent hydrophobic nature of fluorine atoms, MMA-HFBA polyHIPEs showed remarkable water contact angle of 139°. Furthermore, the addition of fluorinated co-monomer in MMA based HIPEs significantly improved thermal stabilities of these materials with improvement in degradation temperature from 305 °C to 360 °C.     

The physical properties of alkene-terminated liquid crystal molecules/E8 mixture and the electro-optical properties as they doped in polymer-dispersed liquid crystal systems

Effects of the content of fluorinated alkene-terminated liquid crystal (LC) molecules on the physical properties of the fluorinated alkene-terminated LC/E8 mixture were studied. The morphology and electro-optical properties as they doped in polymer-dispersed liquid crystal (PDLC) films were investigated. The detailed discussion of the obtained results is given. As a result, comparing with the physical properties of the series of LC mixtures with the same content of the analogous fully saturated compounds doped with E8, we find that the birefringence is significantly larger for the LC mixture with the alkene-terminated materials. Both fluorinated alkene-terminated LC molecules and the analogous fully saturated compounds doped with E8 reduce the driving voltage of PDLC films. Moreover, PDLC films with the fluorinated alkene-terminated LC molecules possessed higher contrast ratio and faster response time than that of the PDLC films prepared by adding the same mass fraction of the analogous fully saturated compounds. Thus, the ability to manipulate physical properties of LC mixture and electro-optical properties of PDLC films by changing the LC molecular structures may have future relevance for new LC structures design and applications of PDLC films.     

Photoredox mediated annelation of iododifluoromethylated alcohols with 1,1-diarylethylenes

A method for the synthesis of 3,3-difluorotetrahydrofurans from iododifluoromethylated alcohols and 1,1-diarylethylenes is described. The reaction is performed under irradiation with 400?nm light emitting diodes in the presence of a cationic iridium(III) photocatalyst, [Ir(ppy)₂(dtbbpy)]PF₆, substoichiometric amounts of triphenylphosphine and sodium trifluoroacetate as a base.     

An efficient Fe(III)-catalyzed 1,6-conjugate addition of para-quinone methides with fluorinated silyl enol ethers toward β,β-diaryl α-fluorinated ketones

Reported here is a highly efficient 1,6-conjugate addition of fluorinated silyl enol ethers to para-quinone methides, allowing facile access to a range of β,β-diaryl α-fluorinated ketones with good to high yields. Fe(OTf)₃ was identified as the optimal catalyst, with the loading of 3?mol%. Notably, this represent the first 1,6-conjugate addition with fluorinated silyl enol ethers. The synthetic potential of the resulting adducts is also demonstrated.     

Regioselective remote CH fluoroalkylselenolation of 8-aminoquinolines

Herein, the direct C-5 fluoroalkylselenolation of 8-aminoquinolines is described. The Pd-catalyzed reaction is performed with the in situ generated fluoroalkylselenyl chloride and various 8-aminoquinoline amides or sulfonamides. The desired products were formed in moderate to excellent yields.     

Cycloadditions between methyl (Z)-2-bromo-4,4,4-trifluoro-2-butenoate and various tosylacetamides: Synthesis of trifluoromethylated pyroglutamates and 2-pyridones derivatives

Cycloaddition reactions between methyl (Z)-2-bromo-4,4,4-trifluoro-2-butenoate and various 2-tosylacetamides are described. Various 2-tosylacetamides react with methyl (Z)-2-bromo-4,4,4-trifluoro-2-butenoate in the presence of NaH at room temperature in one step to form trifluoromethylated pyroglutamates as single diastereomers. However, employing the same reactants using t-BuOK as base at ?78?°C results in the formation of trifluoromethylated 2-pyridones. A ring-closure mechanism is proposed for the reaction.     

氨及其氟取代物与氟化氢形成氢键络合物的系列理论研究

采用ａｂ ｉｎｉｔｉｏ方法，在６－３１Ｇ水平上，对ＮＨ３…ＮＦ、ＮＨ２Ｆ…ＨＦ、ＮＦ３…ＨＦ４种氢键络合物的５组构型进行了一系列能量梯度法的构型优化和能量计算，取得到关于这些分子络合物的结构特征，氢键键能与键级，单体电荷迁移量等信息，分析，比较得出了在每种构型下各体系的重要物理量随氟基数的递变规律，并探讨了氟基的诱导效应对上述体系氢键作用的影响。     

Etude DFT du mécanisme des réactions de cycloaddition dipolaire-1,3 de la C,N-diphénylnitrone avec des dipolarophiles fluorés de type éthylénique et acétylénique

Structures and energetics of reactants, transition states and cycloadducts of cycloadditions of nitrone with three-fluorinated dipolarophiles have been investigated with the density functional theory method B3LYP/6-31G^*. Analysis of the results on the different reaction pathways shows that the reaction takes place along a concerted mechanism and proceeds more or less synchronously. The FMO analysis shows a strong HOMO_dipole-LUMO_{dipolarophile} interaction as the principal reason for the reactivity in these 1,3-dipolar cycloaddition reactions. Regioselectivity of the products of the reaction is predicted reliably by our calculations, the results provide a good prediction of the relatives rates observed experimentally as the dipolarophiles are varied.     

Reaction of α-halogen substituted β-ethoxyvinyl trifluoromethyl ketones with 2-aminopyridine: new route to trifluoroacetyl-containing heterocycles

The reaction of α-halosubstituted β-ethoxyvinyl trifluoromethyl ketones with 2-aminopyridine gives 3-trifluoroacetyl imidazo[1,2-a]pyridine and 3-halo-1,1,1-trifluoro-4-(2-pyridinylamino)-3-buten-2-ones. The product ratio depends on the nature of the α-halogen atom and the solvent.