3,3,3 Trifluoropropene

Heterogeneous vapor-phase fluorination of a chlorocarbon or chlorohydrocarbon with HP over a supported metal catalyst is an alternative to the hquid phase process. Salts of chromium, nickel, cobalt or iron on an A1P. support are considered viable catalysts in pellet or fluidized powder form. This process can be used to manufacture CPC-11 and CPC-12, but is hampered by the formation of over-fluorinated by-products with Httle to no commercial value. The most effective appHcation for vapor-phase fluorination is where all the halogens are to be replaced by fluorine, as in manufacture of 3,3,3-trifluoropropene [677-21 ] (14) for use in polyfluorosiHcones. 

Monomer Production. The key industrial monomer is 2,4,6-trimethyl-2,4,6-tris-(3,3,3-trifluoropropyl)cyclotrisiloxane [2374-14-3] which is produced by the hydrosilylation of 3,3,3-trifluoropropene [677-21-4] with methyldichlorosilane [75-54-7] cataly2ed by various platinum and other noble metal compounds (eq. 3). 

A similar mechanism operates in the reaction of 3,3,3-trifluoropropene with benzene and aluminum chloride [12 13] Perfluorophenylpropene undergoes intramolecular electrophilic attack m a rare example of ring closure at a C -F bond [14] (equation 11)... 

Ester enolates react with 3,3,3-trifluoropropene by an Sf,2 -ty pe process to gi ve 5 5 difluoro-4-pentenoic acid esters [130] (equation 112)... 

Table 3-2. Detailed Data for Identification of 1,1,2-Trichloro-3,3,3-trifluoropropene...

A first evaluation of complex 71a by Blechert et al. revealed that its catalytic activity differs significantly from that of the monophosphine complex 56d [49b]. In particular, 71a appears to have a much stronger tendency to promote cross metathesis rather than RCM. Follow-up studies by the same group demonstrate that 71a allows the cross metathesis of electron-deficient alkenes with excellent yields and chemoselectivities [50]. For instance, alkene 72 undergoes selective cross metathesis with 3,3,3-trifluoropropene to give 73 in excellent yield and selectivity. Precatalyst 56d, under identical conditions, furnishes a mixture of 73 and the homodimer of 72 (Scheme 17) [50a]. While 56d was found to be active in the cross metathesis involving acrylates, it failed with acrylonitrile [51]. With 71a, this problem can be overcome, as illustrated for the conversion of 72—>74 (Scheme 17) [50b]. 

The easy homolysis of C-Br bond in CBr4 allowed us to conduct the radical chain reaction of CBr4 with 3,3,3-trifluoropropene under common conditions (benzoyl peroxide), although in this case the strong electrophiles are used as reagents (an addend and a monomer), i.e. a very unfavorable combination of polar factors for proceeding the process takes place (ref. 6). 

Trifluoropropene is a compound of special interest in this series. Some transformations of the intermediate telomer radicals had been observed in this case, which prompted to study this reaction in more details. In addition to telomers C6H5CH2(CH2CHCp3)nBr (T Br, n = 1,2), the authors have found compound PhCH=CHCH(CF3)CH2CH2Cp3 and explained its formation by rearrangement of the intermediate radical with two monomer units followed by easy... 

There is still another situation that leads to second order spectra and this one usually cannot be anticipated. For example, take a look at the proton spectrum of 3,3,3-trifluoropropene in Fig. 2.9. This spectrum is not the simple one that one would expect for a monosubstituted ethylene. However, the second order nature of this spectrum can be understood after examining the fluorine-decoupled spectrum, which is given in Fig. 2.10. The decoupled spectrum displays the expected multiplets from the ABC system, each proton appearing as a doublet of doublets. The second order spectrum seen in Fig. 2.9 derives from the fact that the protons at 5.98 and 5.93 are seen from the 19F frequency as... 

The fluorine NMR spectrum of 3,3,3-trifluoropropene (Fig. 5.11) provides a good example of the doublet observed for the trifluoro-... 

Proton and carbon spectra of 3,3,3-trifluoropropene are provided in Figs. 5.12 and 5.13 as specific examples of such spectra. The proton spectrum is more complicated than one would have expected based on a first-order analysis. However, a fluorine-decoupled spectrum becomes first order, as was depicted and discussed in Chapter 2, Section 2.3.5, Figs. 2.9 and 2.10. 

Trifluoropropene, 20 241-242 3-Trifluoroacety 1-17 -camphorate, 6 98 Triflates, cross-coupling of organoboranes with, 73 651 Triflic acid, 22 598 Tri-Flo separator, 76 634 Trifluoroacetylacetone molecular formula, 5 712t Trifluoroacetyl chloride... 

In a subsequent study, the additivity assumption (dose addition) was tested, using the similarly acting nephrotoxicants tetrachloroethylene, trichloroethylene, hexachloro-1,3-butadiene (HCBD), and l,l,2-trichloro-3,3,3-trifluoropropene (Jonker et al. 1996). The compounds were given to female rats by daily oral gavage for 32 days either alone, at the LONEL and NONEL (= LONEL/4), or in combinations of four (at the NONEL and LONEL/2) or three (at the LONEL/3) (see Table 10.9). 

Recently, 3,3,3-trifluoro-2-propenyl zinc reagent has been prepared by the reaction of 2-bromo-3,3,3-trifluoropropene with Zn(Ag) and TMEDA in THF in good yield [169]. TMEDA is essential to the preparation of this zinc reagent, presumably by formation of a chelate structure which can stabilize the zinc reagent (Scheme 58). 

The absolute configuration of other compounds [CF3CH(OH)R R=Me, Et, Bu, C7H15] was determined from S-(-)-trifluoropropene oxide, which was produced from the direct oxidation of 3,3,3-trifluoropropene with microorganism. 

Thechloro- and bromofluorination of vinyl chloride, 1,2-dichloroethene, trichloroethene, 1,2-dichlorodifluoroethene, and letrafluoroethene give good and for 3,3.3-trifluoropropene quantitative yields of the addition products. 

The reactions of a-unsaturated alkanecarboxylic acids with sulfur tetrafluoride are usually accompanied by polymerization and other side reactions and give poor yields of trifluoroal-kencs. Although acrylic acid is reported to give 3,3,3-trifluoropropene in 45 % yield,41 numerous attempts by the author to repeat this reaction have failed. 

The reaction of 3,3,3-trifluoropropene with a sulfur tetrafluoride/hydrogen fluoride/disul-fur dichloride system proceeds at 20 C to give a mixture of diastereomers of bis[2-fluoro-l-(tri-fluoromethyl)ethyl] sulfide (18) in high yield.243... 

The use of solvent has also proved to be necessary in the fluorination of 3,3,3-trichloro-l-phenylpropene18 and l-(4-bromophenyl)-3,3,3-trichloropropene19 with antimony(III) fluoride. 3,3,3-Trifluoro-l-phenylpropene and l-(4-bromophenyl)-3,3,3-trifluoropropene are obtained in 80 and 65% yield, respectively, by refluxing the reactants in dioxane for 7 hours. Tarring occurs in the absence of solvent.15... 

A 1-L, 3-necked, round-bottomed flask was equipped with magnetic stirrer, pressure-equalizing addition funnel with N2 inlet, low temperature thermometer, and a Friedrich condenser with N, outlet. The outlet was attached to two traps in series. The first was cooled in a Dewar of salt/ice water (- 15 C) and the second in a Dewar of dry ice/i-PrOH (— 78 C). 2-Bromo-3,3,3-trifluoropropene (50 g, 0.286 mol) and hexane (250 mL) were added to the flask. 1.6 M BuLi in hexane (190 mL, 0.304 mol, commercial) was added to the addition funnel. The flask was cooled with a hexane slush bath by addition of liquid N2 until the temperature of the solution inside the flask was - 85 °C. Then the BuLi soln was added over a period of 25 min at such a rate that the temperature remained below - 80 C. The slightly cloudy, yellowish solution was allowed to stir for an additional 10 min. Then, the hexane slush was removed, Upon reaching - 30 C, a gelatinous precipitate formed and the temperature rapidly rose to 28 "C. The volatile product was removed from solution by heating the mixture at reflux for 30 min with a slow flow of N2 through the system. The product was obtained from the dry ice trap yield 21 g (97%). 

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