Fluoride-free systems

Mowery and DeShong used the commercially available hypervalent silicate complex TBAT as a phenylating agent for the cross-coupling reaction with allylic esters. They later reported on the use of the same organosilane for the coupling with aryl iodides and triflates and electron-deficient aryl bromides. The reactions were catalyzed by either Pd(dba)2 or [Pd(allyl)Cl]2 without the need of added phosphine ligands. 

Denmark and Ober reported on the use of GS2GO3 in combination with water for the palladium-catalyzed cross-coupling of aryl iodides and bromides with aryl silanols. Although the system was not very general, since ligands, ratios, and solvents varied depending on the substrate, good yields were obtained in most cases. 

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The results of varying silanolate concentration show two regions with distinct slopes. This can be interpreted either as a change in mechanism, or a switch in the TLS of the same mechanism. It is immediately apparent that the mechanism diverges from that of TBAF-promoted reactions. A change to zeroth-order behavior in silanolate is evidence of an intramolecular transmetallation step. The proposed mechanism for this fluoride-free system is therefore shown in Figure 7.5. 

Corma A, Navarro MT, Rey F, Valencia S. Synthesis of pure polymorph C of Beta zeolite in a fluoride-free system. Chem Commun 2001 1486-7. 

The original DEBS 1-TE cell-free system allowed several other features of polyketide chain extension to be examined by using well-known inhibitors of specific enzyme activities. Incubation of DEBS 1 -TE with the serine protease inhibitor phenylmethylsulfonyl fluoride (PMSF) resulted in a significant decrease in biosynthetic activity. This result emphasized the mechanistic similarity between the targeted TE domain and the serine protease enzymes. Addition of the fatty acid inhibitor cerulenin [38] also reduced production of the lactone, consistent with the evolutionary kinship between these two classes of enzymes. Inhibition of DEBS 1+TE by cerulenin was also reported [33],... 

Anionic metal-free initiation was successfully applied to both aliphatic and aromatic cyclic carbonates. This method is based on the reaction of a silyl ether with fluoride anions, for example, tetrabutyl ammonium fluoride (BU4NF) or tris (dimethylamino)sulfonium trimethylsilyl difluoride (TASF, [(CH3)2N]3 SSi(CH3)3p2), to produce an anion with a tetrabutyl ammonium or tris(dimethylamino)sulfonium counterion. The metal-free system is an efficient initiator for neopentyl carbonate polymerization. ... 

Eiji Shirakawa and Tamio Hayashi of Kyoto University also used (Chem. Lett. 2008,37, 654) a Co catalyst to promote the coupling of aryl and alkenyl Grignard reagents with enol triflates such as 11. Alois Fiirstner of the Max-Planck-lnstitut, MilUieim optimized (Chem. Commun. 2008, 2873) promoters for the Pd-catalyzed StiUe-Migata coupling of iodo alk-enes such as 14 with alkenyl stannanes such as 15 to give 16. It is particularly noteworthy that their system is fluoride free. 

Resin-modified glass—ionomer lining and restorative materials add a multifunctional acidic monomer to the poly(acryhc acid) [9003-01 Hquid component of the system. Once the glass powder and Hquid are mixed, setting can proceed by the acid—glass—ionomer reaction or the added monomer can be polymerized by a free-radical mechanism to rapidly fix the material in place (74,75). The cured material stiH retains the fluoride releasing capabiHties of a glass—ionomer. 

Some early examples involving microwave-assisted solvent-free Sonogashira couplings using palladium powder doped on alumina/potassium fluoride as catalyst were described by Kabalka and coworkers (Scheme 4.4) [150], In addition, this novel catalytic system has been used in microwave-assisted solvent-free Sonogashira coupling-cyclization of ortho-iodophenol with terminal alkynes, and similarly of ortho-ethynylphenols with aromatic iodides, to generate 2-substituted benzo[b]furans... 

Another specialty area is coil coating, which involves coating metal coils by continuous operation. Modern roller systems afford speeds of up to 200 m/min. Most coils are made of cold-rolled and surface treated steel, aluminum, or alloys of the latter with manganese or magnesium. Coating systems are based on alkyd or acrylic resins, oil-free polyester, silicone-modified polyester or acrylic resin, poly(vinylidene fluoride), or poly(vinyl fluoride). Water-reducible systems, mainly based on acrylic resins, have been developed for aluminum as well as for steel coils [21-24], Drying is carried out by continuous operation in gas- or oil-heated multichamber ovens. 

Very pure Nb may be obtained by electrowinning from 02-free molten salt system (double fluorides or chlorides). 

AEA also concluded that the agent offgas/scrubbing systems could be fabricated from stainless steel, while the agent anolyte and catholyte circuits should be lined with materials resistant to corrosion by free fluoride, e.g., PTFE or PFA. 

Gel polymer lithium-ion batteries replace the conventional liquid electrolytes with an advanced polymer electrolyte membrane. These cells can be packed in lightweight plastic packages as they do not have any free electrolytes and they can be fabricated in any desired shape and size. They are now increasingly becoming an alternative to liquid-electrolyte lithium-ion batteries, and several battery manufacturers. such as Sanyo. Sony, and Panasonic have started commercial production.Song et al. have recently reviewed the present state of gel-type polymer electrolyte technology for lithium-ion batteries. They focused on four plasticized systems, which have received particular attention from a practical viewpoint, i.e.. poly(ethylene oxide) (PEO). poly (acrylonitrile) (PAN). ° poly (methyl methacrylate) (PMMA). - and poly(vinylidene fluoride) (PVdF) based electrolytes. ... 

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