Hexafluoro-2-isopropanol

In fluorinated alcohols such as 2,2,2-trifluoroethanol and 1,1,1,3,3,3-hexafluoro-isopropanol, only alkoxy-de-diazoniation and substitution by the anion of the diazonium salt are observed (Sec. 8.3), because these alcohols are extremely weak nucleophiles. 

Numerous technologically important polymers, for example, many crystalline polyolefins are soluble only at the elevated temperature. Consequently, the high-temperature SEC instruments were designed, in which also dissolution and filtration of samples is performed at elevated temperature. Some SEC eluents such as hexafluoro isopropanol are very expensive, other ones are very aggressive—the extremes represent concentrated sulfuric acid [150] or hexamethyl phosphorotriamide [151] used as the mobile phase for some polyamides or cresols for polyesters [152]. Many biopolymers solicit the appropriate environment (eluent) and/or temperature of experiment below the ambient value to prevent their denaturation. Some polymers rapidly degrade in solution, for example, poly(hydroxy butyrate). These are to be separated as rapidly as possible and the data obtained should be corrected. 

Di- and tri-chlorobenzenes are used as the high-boiling-point eluents in SEC of polyolefins and the highly polar solvents such as poisonous and expensive hexafluoro isopropanol in SEC of polyesters and polyamides. Some unusual SEC eluents are mentioned in Section 16.4.3. 

Finally, two interesting systems with nonconventional solvents were reported. One uses the ionic liquid 1-butyl-3-imidazolium tetrafluoroborate ([BMIM][BF4]), giving results quite similar to those in CH2C12 with a large excess of pyridine, with good conversion and selectivity for the diepoxide (entry 8) [61]. The other nonconventional solvent used is the fluorous solvent hexafluoro-isopropanol. In the presence of 2,2 -bipyridine, this system gives full conversion and selectivity at a very low catalyst loading of 0.1 mol% (entry 9) [62],... 

The best yields, up to 99%, were obtained in hexafluoro-isopropanol but acetonitrile and methanol were also satisfactory. The role of the salt was to enhance the formation of the radical species involved bringing about a significant increase in reaction yield furan and 2,5-dimethylfuran in methanol were converted into 2,5-dimethoxy-2,5-dihydrofurans. The use of PhI(py+)22TfO in acetonitrile-water provided better results [130]. 

Hence, the initial reactions were conducted using BINOL-phosphate 5 in combination with various achiral Brpnsted acids, including pro-tonated pyridine derivatives, alcohols and acids. Best enantioselectiv-ities were observed with the addition of carbonic acids, phenol and hexafluoro isopropanol which provided the isoquinuclidines 28 with up to 88% ee. Further explorations concentrated on varying the reaction parameters including different protected imines, catalyst load-... 

Figure 19.6 shows the CP/MAS NMR spectra of unannealed A-PVA films prepared from aqueous, dimethyl sulphoxide (DMSO) and hexafluoro-isopropanol (HFIP) solutions [41]. It is found that the relative intensities of the CH triplet of the sample prepared from the aqueous solution are signifi-... 

When this same tetrol was condensed with 1,4-cyclohexanedione in n-butyl ether in the presence of a trace of jv-toluenesulfonic acid, a nearly quantitative yield of a white polymer VII was obtained. This material did not melt, but was soluble in hexa-fluoroisopropanol and had an [n] of 0.04 dl/g (25 , hexafluoro-isopropanol). This polymer VII was found to be highly crystalline by X-ray powder pattern and had a T. in the DTA apparatus of 400°. 1/Z... 

After a 0.2-g sample was added to 40 ml of hexafluoro-isopropanol, the mixture was stirred overnight and filtered. 

The product obtained after washing and drying of the reactor product is a white, semi-crystalline powder soluble in only very few exotic solvents i.e. hexafluoro-isopropanol (HFIPA) and meta-cresol. The presence of a crystalline phase in PK copolymer, as indicated by X-ray diffraction (XRD) analysis, is confirmed by a clear fusion effect measured during heating the sample in the DSC showing a Tm-value of about 258 C and a heat of fusion effect (Hfl-value) of about 152 J/g. 

Random copolymers of norbornene methyl-cyclopentyl ester and norbornene hexafluoro-isopropanol... 

Polyglycolide (PGA) Purasorb PG Lactcl PGA Medi.sorb 1(X)PGA PURAC BPI Alkermes Inc Semi-crystalline T j 225-2.30 °C Tg 35-40 °C Soluble in hexafluoro-isopropanol MW >100,000 Tensile strength >68 MPa % Elongation 15-20 Modulus 6.9 GPa... 

An alternative approach to 157 nm resist development was presented, employing fluoroaromatic polymers, that represent an evolutionary step in resist materials development. Both partially blocked and copolymers of 4-hexafluoro-isopropanol styrene have been synthesized and characterized. Both absorb less than 4/C at 157 nm. Both the acetals and die t-B(X blocking groups lower the absorbance further and the 100% blocked HFIP/BOM has an extrapolated O.D. of 2.06/D. Thermal properties were also measured and shown to te dependent upon the degree of blocldng as is the case in PHS-based resists. 

When phenols such as 72 are treated with (diacetoxyiodo)benzene in hexafluoro-isopropanol, phenoxenium ions 73 are produced. A subsequent 1,2-shift involving the migration of the more electron-rich substituent produces a dienone 74 (Scheme 22) [20, 21]. Although the allyl group appears to be the best substituent for the 1,2-shift, the reaction can also be performed with an alkyl or aryl group as the migrating substituent. The process also extends to bicyclic phenols 75, yielding dienones of type 76 as reaction products. 

Tetrol Polymer yield m M.p. (°C) Decomposition point rc) Intrinsic viscosity hexafluoro-isopropanol (dl/gm 25 0... 

GPC chromatograms were obtained from solutions prepared in either diehloromethane (DCM) or hexafluoro-isopropanol (HFIP). Samples for both DCM and HFIP were obtained from blends which were initially dissolved in TCE for NMR analysis. Polycarbonate standards were used for calibration of DCM chromatograms. HFIP chromatograms were calibrated with Polybutyleneterephthalate standards. 

Analysis of annealed samples by Gel-permeation-chromatography (GPC) in both dichloromethane (DCM) and hexafluoro-isopropanol (HFIP) revealed further details on how PC and PET behave during transesterification. Molecular weights were followed in both media by the peak positions in the chromatograms (Mp). 

Room temperature fluorocarbon-containing solvents, such as 2,2,2-trifluoroethanol (TFE) and hexafluoro-2-isopropanol (HFIP)... 

Room Temperature Fluorinated Solvents, Such as 2,2,2-trifluoroethanol and Hexafluoro-2-isopropanol... 

Hexafluoro-2-isopropanol (HFIP) with 0.05M Sodium Trifluoroacetic Acid 0.35 mL/min 30 C... 

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