Fluoride effects

International Symposium on Fluorides, "Fluorides Effects on Vegetation, Animals and Humans." Paragon Press, Salt Lake City, UT, 1983. 

The reaction of an a-halo carbonyl compound with zinc, tin, or indium together with an aldehyde in water gave a direct cross-aldol reaction product (Eq. 8.90).226,227 A direct Reformatsky-type reaction occurred when an aromatic aldehyde reacted with an a-bromo ester in water mediated by zinc in low yields. Recently, it was found that such a reaction mediated by indium was successful and was promoted by son-ication (Eq. 8.91).228 The combination of BiCl3-Al,229 CdCl2-Sm,230 and Zn-Et3B-Eb0231 is also an effective mediator. Bismuth metal, upon activation by zinc fluoride, effected the crossed aldol reaction between a-bromo carbonyl compounds and aldehydes in aqueous media. The reaction was found to be regiospecific and syn-diastereoselective (Eq. 8.92).232... 

Landis, F A. and Moore, R. B. 2000. Blends of a perfluorosulfonate ionomer with poly(vinylidene fluoride) Effect of counterion type on phase separation and crystal morphology. Macromolecules 33 6031-6041. 

The selectivities and activities of this reaction were greatly improved by running the catalysis solvent-free and by adding cocatalytic amounts of Schwesinger-type fluorides ( naked fluoride , e.g. phosphacenium-fluoride-P2 13) [14]. The fluoride effect is pronounced both in terms of activity and enantioselectivity (even inverting the sense of enantioselection in one example see Table 6.1). 

Fe3S4 clusters, 38 17-22 fluoride effect, lattice energies and, 1 218 formal of transition metal atoms, 27 71-72... 

M.R. Karagas, J.A. Baron, J.A. Barrett, S.J. Jacobsen, Patterns of fracture among United States elderly Geographic and fluoride effects, Ann. Epidemiol. 6 (1996) 209-216. 

Elsair, J., R. Merad, R. Denine, M. Azzouz, K. Khelfat, M. Hamrour, B. Alamir, S. Benah, and M. Reggabi. 1981. Boron as antidote to fluoride effect on bones and claws in subacute intoxication of rabbits. Eluoride 14 21-29. 

The fluorination of polyfluorocyclohexenes with antimony(V) fluoride proceeds under much more severe temperature conditions ( 150 C) than with vanadium(V) fluoride (see Section 12.4.2). In these reactions antimony(V) fluoride effects both the oxidative addition of fluorine and the substitution of vinyl chlorine atoms by fluorine.48... 

F. Rubel Jr., The removal of excess fluoride from drinking water by the activated alumina method, in J.L. Shupe, H.B. Peterson, N.C. Leone (Eds.), Fluoride Effects on Vegetation, Animals and Humans, Paragon Press, Salt Lake city, 1983, pp. 345-349. 

Fluoride effects on the thyroid can be observed on many different levels. Of particular importance relating to G-protein activation is the ability of AlFx to clone the role of thyroid-stimulating hormone (TSH). Allgeier with coworkers [113] demonstrated that TSH led to the activation of two forms of Gs (Gs short and Gs long) as well as of Gq and Gil, demonstrating that signaling pathways induced by TSH already bifurcate in the course of the receptor-G-protein interaction and concluded that TSH activation is mediated by Gq/11 and Gs, respectively. 

Sheldon and co-workers have circumvented this problem to some extent by three approaches 46 the use of sulfuric acid to reduce the pH, by addition of ammonium fluoride and by addition of ammonia. Ammonia stabilizes monomeric chromium(III) species via the formation of amine complexes, and the fluoride effects dissolution of the silica at near-neutral pH. The three catalysts that were synthesized were evaluated in the oxidative cleavage of styrene with 35% m/m hydrogen peroxide in 1,2-dichloroethane at 70 °C (Table 4.4). The... 

Smith, F.A., Fluorides in everyday life, in Fluorides Effects on Vegetation, Animals and Humans, Shupe, J.L., Peterson, H.B., and Leone, N.C., Eds., Paragon Press, Inc., Salt Lake City, UT, 1983, p. 7. 

Ti-F bond [182.5(5) pm], which as expected is shorter than the Ti-Cl bond of 17 [228.4(3) pm] [12]. We were of course interested in the catalytic properties of 24 in comparison with triflate 23. In the presence of 23, allylsilane 5 adds smoothly to benzaldehyde the product is, however, racemic. Most probably the catalyst is tri-methylsilyl triflate, which is formed according to pathway B (Scheme 2, cf. [4a]). On the contrary, no reaction between benzaldehyde and allyl silane 5 is observed in the presence of fluoride 24. As we observed earlier, all cyclopentadienyltitanium TADDOLates studied catalyzed the conversion of benzaldehyde 25 with salt-free (i-PrO),TiCH3 26 to 2-phenylethanol 27 [11]. In this case the titanium fluoride effect was indeed very pronounced, as at -78 °C 0,5 % of 24 afforded 60 % of product 27 in 17 h with 78 % ee with 2 % of 24 the induction is 93 % ee. 

Furthermore, Nicolaou, Kunz, and Vozny independently reported that glycosyl fluorides effectively reacted with a variety of free alcohols and silyl ethers using BF3Et20 as an activator to give the corresponding O-glycosides in good yields (O Scheme 25) [58,59,60,61]. 

Cobanera A, Morasso A, White E, et al. Xylitol-sodium fluoride effect on plaque. / Dent Res 1987 66 814. 

Parker, C.M., R.P Sharma, and J.L. Shupe. 1979. The interaction of dietary vitamin C, protein, and calcium with fluoride effects in guinea pigs in relation to breakings. Clin. Tox. 15 301. 

The data in table 3a also suggest that the presence of fluoride in the test toothpastes had little or no effect on the proportion of calculus-formers at the end of the trials. This finding is consistent with the observation of Jin and Yip in then-recent review of calculus [16]. They implied that the cause was a balance of fluoride effects on potential factors that could promote or inhibit calculus formation. 

Gibson s method 4 is based on the principle that ammonium hydrogen fluoride effects the complete decomposition of beryl at a low temperature, even if the mineral is only coarsely ground. Much of the silica is volatilized as ammonium fluosilicate and the beryllium and aluminium converted first to fluorides, then sulfates. The former is separated by solution in (NH COs. 

---