Fluorination derivatives

The most important of the halogenated derivatives of acetic acid is chloroacetic acid. Fluorine, chlorine, bromine, and iodine derivatives are all known, as are mixed halogenated acids. For a discussion of the fluorine derivatives see Fluorine compounds, organic. 

Many different processes using HF as a reactant or source of fluorine are employed in the manufacture of fluorinated chemical derivatives. In many cases the chemistry employed is complex and in some cases proprietary. Electrochemical fluorination techniques and gaseous fluorine derived from HF are used in some of these appHcations. 

Diels-Alder reactions, 4, 842 flash vapour phase pyrolysis, 4, 846 reactions with 6-dimethylaminofuKenov, 4, 844 reactions with JV,n-diphenylnitrone, 4, 841 reactions with mesitonitrile oxide, 4, 841 structure, 4, 715, 725 synthesis, 4, 725, 767-769, 930 theoretical methods, 4, 3 tricarbonyl iron complexes, 4, 847 dipole moments, 4, 716 n-directing effect, 4, 44 2,5-disubstituted synthesis, 4, 116-117 from l,3-dithiolylium-4-olates, 6, 826 electrocyclization, 4, 748-750 electron bombardment, 4, 739 electronic deformation, 4, 722-723 electronic structure, 4, 715 electrophilic substitution, 4, 43, 44, 717-719, 751 directing effects, 4, 752-753 fluorescence spectra, 4, 735-736 fluorinated derivatives, 4, 679 H NMR, 4, 731 Friedel-Crafts acylation, 4, 777 with fused six-membered heterocyclic rings, 4, 973-1036 fused small rings structure, 4, 720-721 gas phase UV spectrum, 4, 734 H NMR, 4, 7, 728-731, 939 solvent effects, 4, 730 substituent constants, 4, 731 halo... 

Hydrogen fluoride adds to more complex molecules, such as unsaturated steroids, to give fluorinated derivatives [/, 8] Low temperatures and inert diluents, such as tetrahydrofuran or methylene chloride, are generally employed. With bicyclic unsaturated terpenes, rearrangements often accompany addition to the double bond [/]. 

Several flaoraza reagents shown in Tables 3a and 3b (B, C, E, F, J, and K) are reactive enough to fluorinate an aromatic ring (Table 1). The ortho isomer predominates in the o/mlp mixture Reagent K has been used to prepare fluorinated derivatives of tyrosine and estradiol [77 (equation 35) (Table 1, entry 10)... 

The Reforrnatsku reaction of a-halogenated carboxylic esters with silylated cyanohydrins combined with an intramolecular acylation reaction gives fluorinated derivatives of tetronic acid [28] (equation 17) It is noteworthy to mention that this particular reaction sequence only proceeds with ultrasonic irradiation A very... 

Thermally unfavorable [2-1-2] cycloadditions often can be promoted photo chemically [136,137,138], some examples for fluorinated derivatives are given in equations 60-62... 

The different nucleophilicities of 3,5-dimethyl- and 3,5-bis(trifluoromethyl) pyrazoles are shown by their reactions widi lraas-[Rh(CO)Cl(Ph3P)2]. The dimethyl derivative gives die dinuclear species similar to 111. The less nucleophilic fluorine derivative gives 116, where die pyrazole ring is monodentate. The fluoro compound similar to 111 [L2 = (CO)2l may be obtained in the absence... 

Other fluorinated derivatives of acetylacetone are trifluoroacetylacetone (CF3COCH2COCH3) and hexafluoroacetylacetone (CF3COCH2COCF3), which form stable volatile chelates with aluminium, beryllium, chromium(III) and a number of other metal ions. These reagents have consequently been used for the solvent extraction of such metal ions, with subsequent separation and analysis by gas chromatography [see Section 9.2(2)]. 

Fluorinated derivatives of 191 have been prepared from chlorofluoro-pyridine carboxylic acids (92JMC518). 

Halogen atoms can be stereoselectively introduced by ring-opening of y-azir-idinyl-a,P-enoates (Scheme 2.39). Treatment of 149 with diethylaminosulfur tri-fluoride (DAST) results in stereospecific ring-opening to yield fluorinated derivative 150 [59]. A related stereoselective conversion of y-aziridinyl-a,P-enoates 151 into allyl halides 152 by use of lithium halide in the presence of Amberlyst 15 was also reported recently [60]. 

MeCN, r.t., 24 h) gave, respectively, a mixture of fluorinated derivatives 287 (67%) and 290 (6%), and 290 (54%) and 287 (11%). In each case, the minor products were formed by C-5 epimerization of the starting compounds prior to the displacement, followed by fluorination. Reduction (NaBHJ of 287 and 290, followed by hydrolysis, gave an anomeric mixture of 5-deoxy-5-fluoro-L-idofuranose (from 287) and 5-deoxy-5-fluoro-D-glucofuranose... 

Figure 8.7 Thermal behavior of no fluorinated complexes [AuCI (CNC6H40C H2 + i)] (labeled as no F), and the corresponding fluorinated derivatives 6a (F-3) and 6b (F-2).

DCE interface in the presence of TPBCl [43,82]. The accumulation of products of the redox reactions were followed by spectrophotometry in situ, and quantitative relationships were obtained between the accumulation of products and the charge transfer across the interface. These results confirmed the higher stability of this anion in comparison to TPB . It was also reported that the redox potential of TPBCP is 0.51V more positive than (see Fig. 3). However, the redox stability of the chlorinated derivative of tetra-phenylborate is not sufficient in the presence of highly reactive species such as photoex-cited water-soluble porphyrins. Fermin et al. have shown that TPBCP can be oxidized by adsorbed zinc tetrakis-(carboxyphenyl)porphyrin at the water-DCE interface under illumination [50]. Under these conditions, the fully fluorinated derivative TPFB has proved to be extremely stable and consequently ideal for photoinduced ET studies [49,83]. Another anion which exhibits high redox stability is PFg- however, its solubility in the water phase restricts the positive end of the ideally polarizable window to < —0.2V [85]. 

Lloyd, R. V. Wood, D. E. Free-radicals in an adamantane matrix. 8. EPR and INDO study of benzyl, anilino, and phenoxy radicals and their fluorinated derivatives. J. Am. 

In 1994, we reported the dispersion polymerization of MM A in supercritical C02 [103]. This work represents the first successful dispersion polymerization of a lipophilic monomer in a supercritical fluid continuous phase. In these experiments, we took advantage of the amphiphilic nature of the homopolymer PFOA to effect the polymerization of MMA to high conversions (>90%) and high degrees of polymerization (> 3000) in supercritical C02. These polymerizations were conducted in C02 at 65 °C and 207 bar, and AIBN or a fluorinated derivative of AIBN were employed as the initiators. The results from the AIBN initiated polymerizations are shown in Table 3. The spherical polymer particles which resulted from these dispersion polymerizations were isolated by simply venting the C02 from the reaction mixture. Scanning electron microscopy showed that the product consisted of spheres in the pm size range with a narrow particle size distribution (see Fig. 7). In contrast, reactions which were performed in the absence of PFOA resulted in relatively low conversion and molar masses. Moreover, the polymer which resulted from these precipitation... 

The two O -alkylated guanosine derivatives (117) shown in Figure 28, do not demonstrate a perpendicularity of hydrocarbon and base, presumably because the hydrocarbon is much smaller. However, again the nucleoside has the syn-conformation. This perpendicularity, however, is found for the acetylamino fluorine derivative. 

Our calculations showed that the first step, cyclization of the nitrene to an azabicyclo[4.1.0]heptatriene, is rate-determining. Our calculated barriers for cyclization of four fluorinated derivatives of lb are given in Table 6.87 The CASPT2/cc-pVDZ barrier of 13.4 kcal/mol for cyclization of 2,6-difluoro-phenylnitrene (10b) is 4.1 kcal/mol higher than the barrier computed for lb -+ 2b. In contrast, the calculated barriers to rearrangement of 3,5-difluoro-phenylnitrene (lOe) and 4-fluorophenylnitrene (10c) are very similar to that computed for unsubstituted phenylnitrene (lb). These computational results are consistent with the observed reluctance of pentafluorophenylnitrene (10a) and 2,6-difluorophenylnitrene (10b) to rearrange,48 1 81 83 and with the relative ease... 

Reaction of the thia-amino acid 392 with trifluoroacetic anhydride gave the 2,2,2-trifluoro-l-[7-(trifluoromethyl)-l//-pyrrolo[l,2-c]-[l,3]thiazol-6-yl] ethanone pyrrole 395. The formation of the pyrrole can be rationalized by a sequence involving trifluoroacetylation of the enamine 392 affording dione 393 followed by loss of water and carbon dioxide to give the aromatic product 395. These decarboxylations afford fluorinated derivatives of heterocyclic skeletons known to exhibit interesting biological activity (Scheme 58) <2000T7267>. 

Powdery PNT-N was obtained when the unfluorinated compound was refluxed in diphenyl ether solution. When the temperature was raised to 196°C for 24 h, the amount of solid increased with time and there was no observable change in the appearance ofthe solid. However, in the case ofPNT-F, a black solid formed suddenly between 120- 150°C, and no additional solid formed even when the temperature was increased to 190°C. Apparently the fluorinated derivative reacts much more rapidly and exothermically than the hydrocarbon analogue. Care should be exercised when heating such compounds in sealed glass tubes. 

Fluorine derivatives. See Morphactins Fluorine ores, 77 854-855 Fluorine perchlorate, 18 279 Fluorine production, 9 635... 

Within the field of Lewis adducts, we naturally studied the conformational analysis of the parent borazane complex, H3N BH3, and of its fluorinated derivatives (13) and showed that, with respect to their preferred conformation, there is no determinant AEN-.iH spatial term analogous to the AEP...H term discussed above relative to F3P BH3. 

Figure 11. Epoxide ring opening reactions of the fluorinated derivatives of dibenzo[a,h]acridine-8,9-epoxide. Figure adapted from reference 27. 

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