A-Trifluoromethyl acrylates

Of a large number of possible fluorinated acrylates, the homopolymers and copolymers of fluoroalkyl acrylates and methacrylates are the most suitable for practical applications. They are used in the manufacture of plastic lightguides (optical fibers) resists water-, oil-, and dirt-repellent coatings and other advanced applications [14]. Several rather complex methods to prepare the a-fluoroalkyl monomers (e.g., a-phenyl fluoroacrylates, a-(trifluoromethyl) acrylic and its esters, esters of perfluoromethacrylic acid) exist and are discussed in some detail in [14]. Generally, a-fluoroacrylates polymerize more readily than corresponding nonfluorinated acrylates and methacrylates, mostly by free radical mechanism [15], Copolymerization of fluoroacrylates has been carried out in bulk, solution, or emulsion initiated with peroxides, azobisisobutyronitrile, or y-irradiation [16]. Fluoroalkyl methacrylates and acrylates also polymerize by anionic mechanism, but the polymerization rates are considerably slower than those of radical polymerization [17]. 

Fractional precipitation Poly(methyl a-(trifluoromethyl)acrylate)... 

To a solution of ( )-1-methoxy-2-methyl-3-(trimethylsiloxy)buta-l,3-diene (lOg, 54mmol) in CIljClj (25 mL) was added a solution of 2,2.2-trifluoroethyl 2-(trifluoromethyl)acrylate (11.8g, 54mmol) in CH2CI2 (15mL) at 0 C under argon, and the solution was stirred for 3 min. After evaporation of the solvent, MeOH (30 mL) and TsOH (2 g, 10.5 mmol) were added at 0 C. The resulting solution was stirred at the same temperature for 1.5 h. F.vaporation of the solvent and vacuum distillation of the residue gave 13 yield 16.5 g (87%) bp 88 C/3 Torr. 

A-(hexyl acrylate)-A-ethylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide... 

As described in detail later, the polymers for use in 157 nm lithography universally contain fluorine because only fluoropolymers provide low enough absorption at 157 nm. The acid group of choice is hexafluoroisopropanol, which has a pKa similar to that of phenol, as mentioned earlier. Several platforms are available (Fig. 41) 1) tetrafluoroethylene-norbornene,2) 2-trifluoromethyl-acrylate-norbornene, 3) 2-trifluromethylacrylate-styrene, 4) 2-trifluoromethy-lacrylate-vinyl ether, 5) all-norbornene, 6) methacrylate, and 7) cyclopolymers. 

Terbutylazine was another example of a triazine herbicide, which was used for MIP synthesis. In otdet to test the ability of different functional monomers to form strong interactions with terbutylazine, a combinatorial approach was used. Thus, MAA, 2-(trifluoromethyl) acrylic acid (TFMAA), hydroxyethyl methacrylate (HEM), methyl methacrylate (MMA), N-vinyl-a-pytrolidone (NVP) and 4-vinylpytidine (4VP) were used for polymer preparation. In dichloromethane, MAA and TFMAA appeared to be the best monomets able to fotm the terbutilazine-specific functional sites. 

Aziridination of a-trifluoromethyl-substituted acrylates such as 137 can be accomplished with ethyl nosyloxycarbamate. With a weak base such as calcium oxide, a Michael adduct is obtained (138), but with sodium hydride Michael addition is followed by cychzation with extrusion of nosylate ion to give 139. ... 

Matsui et al. [162] first reported the preparation of molecularly imprinted monoliths based on functional monomer such as methacrylic acid or 2-trifluoromethyl-acrylic acid via in situ polymerization. The reaction mixture consisting of monomer, cross-linker (ethylene glycol dimethacrylate), porogenic solvents (cyclohexanol and 1-dodecanol), initiator, and template molecule was degassed and poured into a column where the polymerization took place. When reaction is completed, the template molecule and the porogenic solvents were extracted with methanol and acetic acid resulting in monoliths with molecular recognition in the separation of positional isomers of diaminonaphthalene and phenylalanine anilide enantiomers. 

Matsui, J. Takeuchi, T. A molecularly imprinted polymer rod as nicotine-selective affinity media prepared with 2-(trifluoromethyl)acrylic add. Anal. Comm. 1997, 34 (7), 199-200. 

Matsui, J. Doblhoff-Dier, O. Takeuchi, T. 2-(trifluoromethyl)acrylic acid a novel functional monomer in non-covalent molecular imprinting. Anal Chim. Acta 1997, 343 (1-2), 1. ... 

The BAP functional monomer was prepared by 2,6-diamino pyridine and acryloyl chloride in triethylamine-chloroform solution (54% yield) [37]. Cyclobarbital-imprinted copolymers were prepared by the following procedure BAP (Immol), template cyclobarbital (0.5 mmol) and EGDA cross-linker (20 mmol) were dissolved in CHCI3. In the presence of a radical initiator, 2,2-azo (2,4-dimethylvaleronitrile), radical copolymerization was performed in N2 atmosphere with a two-step process for 6 h at 40°C and then for 3 h at 90°C. The obtained polymer was ground and sieved in the range of 26-63 pm. Selectivity of the cyclobarbital-imprinted polymer was assessed by chromatographic analysis for 5-barbiturates. They also used BAP monomer to imprint antitumor active compound of 5-fluorouracil (5-FU) [36]. The 5-FU imprinted polymers showed a higher afihnity for 5-FU than for 5-FU derivatives. The BAP imprinted polymer was prepared in the presence of a co-monomer, 2-(trifluoromethyl)-acrylic acid. 

An MIP adsorbent is prepared for the extraction of 7-diethylamino-4-methyl-coumarin (Fig. 3). The print molecule, 7-diethylamino-4-methylcoumarin (4 mmol, 0.925 g), a functional monomer, 2-(trifluoromethyl) acrylic acid (12 mmol, 1.681 g), a cross-linking monomer, ethylene glycol dimethacrylate (60 mmol, 11.893 g) and a polymerization initiator, 2,2 -azobis(2,4-dimethylvaleronitrile) (0.140 g) are dissolved in anhydrous toluene (18 mL) in a 50-mL borosilicate PYREX tube.The solution is briefly purged with dry nitrogen for 5 min and sealed with a screw cap. The PYREX tube is transferred to a water bath preset at 45°C and maintained for 16 h. After polymerization, the polymer monolith is taken from the PYREX tube and fractured. This is further ground with a mechanical mortar (Retsch, Haan, ERG) and wet-sieved with 5% ethanol (v/v), and subjected to repetitive sedimentation in... 

The Michael addition reactions of nitro compounds such as nitromethane to CF3-containing acrylates such as ethyl (E)-ethyl 3-(trifluoromethyl)acrylate using a microflow reactor (channel width 100 pm, depth ca. 40 pm and length 80 mm flow rate 1 pi min ) has been reported. The reactions proceed smoothly in the presence of DBU as a base to afford the corresponding Michael adducts without any detectable formation of polymeric byproducts (Table 5.3) [11]. 

Takeuchi and co-workers (18) coupled combinatorial techniques with molecular imprinted polymers to develop sensors for triazine herbicides. The library consisted of a 7 x 7 array containing different fractions of monomers methacrylic acid (MAA) and 2-(trifluoromethyl)acrylic acid (TFMAA) with constant concentrations of the imprint molecules ametryn or atrazine. After UV-initiated polymerization, the products from the sensor library were characterized by HPLC measurement of herbicide concentration. The receptor efficiency was observed to vary with monomer type the atrazine receptor efficiency increased with MAA composition and the ametryn receptor was enhanced by increased fractions of TFMAA. Although only monomer concentration was varied in the hbraries, the authors conclude that the CM synthetic approach would be usefiil in analyzing other variables such as solvent, cross-linking agent, and polymerization conditions to produce optimum molecularly imprinted polymer sensors. 

There are, however, several highly reactive vinyl monomers such as 2-(trifluoromethyl) acrylates and 2-cyanoacrylates that undergo anionic polymerizations in the presence of even weak bases. The photoinitiated anionic polymerizations of these monomers have been achieved using a number of photosensitive metal complexes. For example, the irradiation of alkali salts containing the trans-[Cr(NH3)2(NCS)4] anion at wavelengths in the range of 350-532 nm releases the thiocyanate anion (SCN"). As depicted in Scheme 34, the thiocyanate anion is capable of initiating the anionic chain polymerization of ethyl 2-cyanoacrylate. ... 

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