Anhydrous tetrabutylammonium fluoride

Tetrabutylammonium fluoride (TBAF) is prepared at low temperature by nucleophilic aromatic substitution of hexafluorobenzene with tetrabutylammonium cyanide. Adventitious water is scavenged during this synthesis by the generated hexacyanobenzene, which readily adds water under basic conditions. Contrary to expectations, TBAF is stable to Hofmann elimination in polar aprotic solvents under anhydrous conditions. Added hydroxylic solvents are shown to catalyze the decomposition of TBAF and to catalyze proton exchange with DMSO. The synthetic utility of this salt is described briefly.     

Fluorodenitrations using tetrabutylammonium fluoride

Fluoroaromatics are prepared in good yield under mild conditions using the tetrabutylammonium fluoride promoted fluorodenitration of nitroaromatics.     

Spectroscopic evidence for medium controlled hydrogen bond inhibition of resonance delocalization of charge in complexes of tetrabutylammonium fluoride with phenols

Infrared spectra of tetrabutylammonium fluoride complexes of both 4-cyanophenol and methyl-4-hydroxybenzoate but not 3-cyanophenol reveal the presence of two distinct types of hydrogen bond corresponding to charge localized and partially charge delocalized forms. The latter only occur in polar aprotic protophilic solvents at low temperatures. The activation energies for the interconversion of the two forms reflect the relative abilities of the two groups to delocalize charge through resonance. The chemical shifts of the aromatic protons of the complexes are also medium dependent although the precise nature of this medium dependence is less easily understood.     

Removal of 9-fluorenylmethyloxycarbonyl (Fmoc) group with tetrabutylammonium fluoride

Tetrabutylammonium fluoride in N, N-dimethylformamide (DMF) is an effective alternative to the piperidine reagent for the removal of 9-fluorenylmethyloxycarbonyl (Fmoc) group in the solid phase peptide synthesis.     

Properties of tetrabutylammonium fluoride applied to silica gel

Conclusions The effect of the surface concentration of Bu₄NF applied to silica gel and Aerosil on its catalytic capacity in condensation of benzaldehyde with fluorene was studied. The capacity of the Bu₄NF applied to the support to pass into DMF solution was determined by the ionometric method. In the case of monolayer application of Bu₄NF on silica gel, catalysis of the model reaction is heterogeneous in character.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 375–378, February, 1988.     

Addition of benzyltrimethylsilane to imines triggered by tetrabutylammonium fluoride

The addition of benzyltrimethylsilane 2 to imines 1 triggered by TBAF in the presence of 4A molecular sieves gave rise to the corresponding α-benzylated amines 3 in good yields. Moderate to high diastereoselectivity was obtained in the reactions of tert-butanesulfinyl imines with 2.     

Photopolymerization of vinyl fluoride

The photopolymerization of vinyl fluoride, in the presence of peroxide, was studied in dimethyl sulfoxide (DMSO) solution and in bulk. It was found that high rates of reaction could be obtained in spite of the fact that the polymer precipitates at an early stage. By continuous supply of monomer the precipitated polymer was converted into a transparent bulk polymer.     

Copolymers of vinyl fluoride

Vinyl fluoride was polymerized by photochemical initiation in a continuous-flow cylindrical reactor at room temperature and at pressures of up to 30 atm. Copolymers with vinyl acetate were prepared in order to improve the solubility and processability of poly(vinyl fluoride) (PVF). The copolymers were hydrolyzed to the corresponding vinyl alcohol copolymers and yielded hydrophilic films that are strong and flexible only when swollen by water. It was found that on hydrolysis the T_g, T_m, and heat of fusion as well as degree of crystallinity increased. It was suggested that PVF and the copolymers with vinyl alcohol are isomorphous.     

The heats of fusion of tetrabutylammonium fluoride ionic clathrate hydrates

Two ionic clathrate hydrates with different structures are formed in the binary system tetrabutylammonium fluoride–water, namely tetragonal structure-I hydrate (TS-I) (n-С₄H₉)₄NF · 32.8H₂O, and cubic superstructure-I hydrate (CSS-I) (n-С₄H₉)₄NF · 29.7H₂O. The heats of fusion (ΔH_f) of these polyhydrates were measured calorimetrically with differential scanning calorimeter. For TS-I polyhydrate ΔH_f = (204.8 ± 2.3) kJ/mol hydrate, for CSS-I hydrate ΔH_f = (177.5 ± 3.1) kJ/mol polyhydrate. The change of water molecules energy state in the water lattices of TS-I and CSS-I polyhydrates are discussed.     

Catalytic effect of tetrabutylammonium fluoride in the preparation of secoribo-nucleosides

A general and rapid procedure is developed for the preparation of secoribo-nucleoside analogues. Bu₄NF has a marked effect on the condensation of guanine ( 5 ) with 2-(chloromethoxy)ethyl benzoate ( 2 ) or 1-halo-2-(chloromethoxy)ethanes 12 and 16 . Condensation and deprotection of the acyl protecting group and nucleophilic displacement of the halogen atoms to yield 9-[(2-hydroxyethoxy)methyl] guanine ( 9 ) occurred in one step.     

Kinetics of vinyl fluoride polymerization

Vinyl fluoride was polymerized, at low temperatures and pressures, by photo- and γ-ray initiation. The kinetics of this heterogeneous polymerization reaction was studied and a general scheme was proposed to explain the experimental results. The scheme is based on the assumption that the main site of the polymerization is in the “polymer phase.” The solvent used determines the rate of the reaction by its effect on the swelling of the polymer. The degree of polymerization is determined mainly by transfer reactions.     

Photolysis of vinyl bromides in the presence of tetrabutylammonium azide: trapping of a vinyl cation with azide ion

Vinyl cations generated by the title photolysis gave vinyl azides by capture of an azide ion and their further photolyses resulted in the formation of cycloaddition-products via nitrile ylides derived from the corresponding azirines.     

Benzylation of cellulose in the solvent dimethylsulfoxide/tetrabutylammonium fluoride trihydrate

The cellulose solvent dimethylsulfoxide/tetrabutylammonium fluoride trihydrate (TBAF·3 H₂O) was studied as reaction medium for the synthesis of benzyl cellulose (BC) by treating the dissolved polymer with benzyl chloride in the presence of solid NaOH or aqueous NaOH solution. BC samples with degree of substitution (DS) between 0.40 and 2.85 were accessible applying different molar ratios. The studies show that both the TBAF·3 H₂O concentration and the molar ratio of the reagents to repeating unit influence the DS. The solubility of the BC synthesized in a different way, however, of comparable DS is different. Structural analyses were carried out by means of FTIR-, ¹H- and ¹³C NMR spectroscopy. SEC measurements revealed polymer aggregation in samples of low DS synthesized in a solvent containing 9.0% TBAF·3 H₂O. At higher concentration of TBAF·3 H₂O in the solvent, the BC samples obtained do not form aggregates. BC of high DS is crystalline and shows thermotropic liquid crystalline behavior as analyzed by means of DSC. Melting point and degradation temperature are not related to the DS.