Tetraphenylboron salts

Figure 3. Electron transfer rate in C-1,4 in THF as the function of concentration of tetraphenylboron salts ( and A) - experimental values for TPB-Na and TPB-TBA, respectively [39] (solid line) - theoretical values from the AMS A theory [22].

Melting points of the organic tetraphenylboron salts may be used in the identification of many of these compounds (58,59). 

Diphenylmanganese, prepared from phenylmagnesium bromide and Mn(II) chloride, with but-2-yne in diethyl (31%) and the corresponding complex (10%), isolated as the tetraphenylboron salt . 

Dimesitylcobalt(II) (prepared from mesitylmagnesium bromide and C0CI2) reacts at — 30°C in THF with but-2-yne . The bis-hexamethylbenzenecobalt(I) 71 complex is isolated as halide, picrate and tetraphenylboron salts. This complex is... 

Table I. Electron Transfer Rates in 1,4-ee-BCN in THF in the Presence of Various Tetraphenylboron Salts ...

A soln. of allyldiethylammonium tetraphenylboron salt in methylene chloride added to bis(triphenylphosphine)(ethylene)platinum in the same solvent, and allowed to stand 5 min. at room temp. -> diethylamine. Y ca. 100%. F. e. s. H. Kurosawa, J. Organometal. Chem. 112, 369 (1976) deallylation of acylamines with palladous acetate-cupric acetate-NaCl and related reagents s. M. Mori and Y. Ban, Chem. Pharm. Bull. 24, 1992 (1976). 

We can also mention the gravimetric determinations of protonated amines and quaternary ammoniums as tetraphenylboron salts (see above). Furthermore, alkaloids seem to have been the subject of the greatest number of this type of gravimetric determination. Usually, the precipitation of tetraphenylboron salts is carried out in the range 3 < pH < 5. Gravimetric determinations of alkaloids as phosphotungstates and reineckates have also been proposed. 

A completely new approach to the determination of small amounts of nitrogenous bases (including tropine alkaloids) in aqueous solutions such as eye-drops and injections has been published by Johnson and King. Precipitation with tetraphenylboron at pH 3-7 is used the excess of the latter is then determined by back-titration with a standard solution of quaternary ammonium salt to a visual end-point. Melting-points of the organic tetraphenylboron salts may be used in the identification of many of these compounds. An assay, including standardisation of reagents, can be completed in half an hour and the accuracy of the method was shown to compare very favourably with that of many of the official methods for the compounds examined. 

For the identification of amines acylation methods (acetylation, benzoylation, 3,5-dinitrobezoylation), reaction with p-toluenesulfonyl chloride, preparation of substituted thioureas, diazotization and coupling (for aromatic primary amines), and the preparation of salts (picrates, tetraphenylboron salts) are most commonly used. 

The detection and the identification of nitrogen compounds can be carried out by converting them to tetraphenylboron salts (66, 67) ... 

Perchloric acid Dipicrylamine Sodium tetraphenylboron + acetic acid White precipitate of potassium perchlorate Orange-red complex precipitate (NH4+ interferes) sensitivity, 3 pg of K White precipitate of the potassium salt... 

A few experiments were carried out with living polystyrene solutions containing sodium perchlorate or sodium tetraphenylboron (6). These salts had no effect on the rate of polymerization, although their concentration exceeded by... 

Solvation and Shift Reagents.—The solvation parameters for a series of alcohols have been determined using the n.m.r. chemical shift of tris-n-butylphosphine oxide. Ion pair association between tetraphenylboron and cationic centres was used to study the electronic structure of aminonaphthylphosphonium salts (24 X = Ph4B ). Shift reagents have been used in the conformational analysis of adenosine phosphates and aromatic solvent induced shifts to probe the stereochemistry of butadienylphosphonates and their polymers. The geometries of difluorophosphine derivatives were evaluated from liquid crystal n.m.r. studies with the aid of electron diffraction. ... 

We are strictly content with studying quantitative determinations with tetraphenyl-boron ion (TPB) ( 6115)46 . Its sodium and lithium salts are soluble in water. Its rubidium, cesium, potassium, and ammonium salts are very poorly soluble. The solubility product of potassium tetraphenylboron is Als(K(C6H5)4B) = 2.25 x 10 . Likewise, numerous quaternary ammoniums and protonated amines form slightly soluble salts with tetraphenylboron ion according to the reaction... 

Of the usual processes employed for the determination of potassium that by means of perchloric acid is the most suitable. Procedures have been described using tetraphenylboron as precipitant (see p. 31) but it should be remembered that this method is subject to considerable interference, especially when ammonium salts are present. 

Other solvents, which lead exclusively to radical derived products from the photolysis of diazonium salts, include formic acid and dimethylformamide. Anions can also act as donors in the photochemical electron transfer process here, the efficiency increases with decreasing electrochemical oxidation potential of the anion. Tetraphenylboron ion is a good electron donor, while fluoroborate is a poor donor. ... 

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