Phosphonium borate

Phosphonium salts, which are generally stable in the form of iodide and tetraphenyl-borate crystalline solids, are frequently purified by recrystallization. Where this is not possible, thick-layer chromatography (0.2-1 mm Kieselguhr, silica) may afford a satisfactory method of purification12,13. In this manner, analysis using secondary ion mass spectrometry (SIMS) has a detection limit 10-50 ng per spot14. 

Probably, the same mechanism is involved in the conversion of 2-benzopyrylium formates 10 into indenes 118 on heating in formic acid (Section III,C,2), or in the formation of indanes 214 on heating the fluoro-borate 178 in hydrochloric acid with phosphorus or in glacial acetic acid with phosphonium iodide (71CB2984). The primary step of this conversion includes the addition of a hydride anion then the intermediate isochro-mene of type 107 becomes protonated and takes part in further transformations. 

Ionic liquids (IL) are salts melting at low temperatures, and represent a novel class of solvents with non-molecular ionic character. In contrast to a classical molten salt, which is a high-melting, highly viscous, and very corrosive medium, an ionic liquid is already liquid at temperatures below 100 °C and is of relatively low viscosity [4]. In most cases, ionic liquids consist of combinations of cations such as ammonium, phosphonium, imidazolium, or pyridinium with anions such as halides, phosphates, borates, sulfonates, or sulfates. The combination of cation and anion has a great influence on the physical properties of the resulting ionic liquid. By careful choice of cation and anion it is possible to fine tune the properties of the ionic liquid and provide a tailor-made solution for each task (Fig. 1), and this is why ionic liquids are often referred to as designer solvents or materials. 

Methyl-4,6-diphenylphosphorm A suspension of 2-methyl-4,6-diphenylpyrylium fluoro-borate (2.1 g, 6.3 mmoles) in 1-butanol (50 ml) is heated with phosphonium iodide (2.6 g, 16 mmoles) at 110-120° for 24 h. The solvent is removed, the residue taken up in benzene, and this solution is washed several times with water, dried over calcium chloride, and concentrated. When the residue is rubbed with ethanol and cooled the product crystallizes recrystallization from a little ethanol gives material (945 mg) melting at 79-81°. 

PEPTIDE SYNTHESIS M-Oxo-bis[tris(dimethylamino)phosphonium] bistetrafluoro-borate. 

Synthesis of Poly[lsobutylene-co-(4-Methylstyrenyl, Triphenyl Phosphonium Tetraphenyl Borate)]... 

Mechanical Behavior. The ionomers, - poly[Isobutylene-co-(4-methyl styrenyl, triphenyl phosphonium bromide or tetraphenyl borate)] were found to be different in physical appearance(hard and strong) and tougher than the starting material, the Exxpro elastomer. The mechanical properties of these quaternary phosphonium... 

Figure 2. NMR Data, Poly[Isobutylene-co-(4-methylstyrenyl, triphenyl phosphonium tetraphenyl borate)]...

Scheme 77.70 Stoichiometric reaction of phosphonium borate with imine.

I 77 Frustrated Lewis Pairs A Metal-Free Strategy for Hydrogenation Catalysis Table 11.1 Catalytic hydrogenation of imines with phosphonium borate catalysts [45]. 

Scheme 11.11 Catalytic hydrogenation of imine using phosphonium borate catalyst.

Scheme 11.12 Reaction of phosphonium borate with benzaldehyde.

Scheme 11.16 Synthesis and reduction ofenamine by ethylene-linked phosphonium borate.

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