Ammonium tetraphenylborate

Ammonium may be determined by predpitation with sodium tetraphenylborate as the sparingly soluble ammonium tetraphenylborate NH4[B(C6H5)4], using a similar procedure to that described for potassium it is dried at 100°C, For further details of the reagent, including interferences, notably potassium, rubidium, and caesium, see Section 11.38,... 

Ammonium tetraphenylborate [14637-34-4] M 337.3, m ca 220°(dec). Dissolve in aqueous Me2CO and allow crystn to proceed slowly otherwise very small crystals are formed. No trace of Me2CO was left after drying at 120° 53 19 1957]. The salt was ppted from dilute AcOH soln of sodium... 

One final and useful correlation can be obtained from an investigation of the salt tri-isoamyl-n-butyl ammonium tetraphenylborate, and application of Stoke s Law (46). Coplan and Fuoss (47) have shown that the single ion conductances Xq and Aq for this salt are equal (to within 1 %), i.e. AJ = Aq = A0/2. Thus in principle it is possible to obtain single ion conductances for any species using this as a reference electrolyte [e.g. see Ref. (26)]. Furthermore, the corresponding Stoke s radii can then be estimated,... 

Ion pair dissociation constants for a wide variety of hexachloroantimonate salts in methylene chloride are shown in Table 4, together with that for the highly symmetric salt tri-isoamyl-n-butyl>ammonium tetraphenylborate. 

Data for equivalent conductances at infinite dilution A0, and in particular single ion contributions AJ and Aq, have been deliberately excluded from this report being of more interest to the electrochemist than to the polymer kinetidst. However, it is worthwhile pointing out that conductance data on tri-isoamyl-n-butyl ammonium tetraphenylborate and hexachloroantimonate in CH2C1 has been obtained (26), allowing single ion conductances for all the ions in Tables 4 and 5 to be estimated. Thus the effective Stoke s radii (r and r ) can be calculated (as outlined in Section III.B) and compared with the effective interionic distance (r+ and 6 ) in the ion pairs, as calculated from the simplified Denison and Ramsey equation. This correlation is displayed in Table 6. 

About a 50-ml. quantity of dry ammonia is condensed into the Schlenk tube which is cooled with a Dry Ice-methanol bath. The reaction mixture is stirred with a magnetic stirrer. The Schlenk tube containing the red solution may be left conveniently in the bath overnight. The bath warms up very slowly, and the ammonia can evaporate without further precautions. After removal of ammonia, the yellow solid residue is dissolved in about 30 ml. of water and the solution filtered into an excess of a concentrated solution of sodium tetraphenylborate. The yellow precipitate is collected and dried under high vacuum. The crude product is stirred with several portions of dichloro-methane until the filtrate is almost colorless and only a small quantity of white ammonium tetraphenylborate remains on the filter. Pentane is then added dropwise until no more precipitate separates. After the purification is repeated and the precipitate is dried under high vacuum, the pure product is obtained in about 40% yield, based on CsHsFeCCO Cl. Anal. Calcd. C, 72.55 H, 5.50 Fe, 10.88 N, 2.73. Found C, 73.04 H, 6.05 Fe, 11.04 N, 2.68. 

Supercritical carbon dioxide (SCCO2) has a dielectric constant e = 1.6 (cyclohexane e = 2.0), and even though tetrakis(decyl)ammonium tetraphenylborate has some solubility in SCCO2, the conductivity is too low for practical electrochemistry [442]. 1,1,1,2-Tetrafluoroethane (HFC 134a) has a higher polarity in the supercritically state, and well-behaved CV may be obtained with TBACIO4 a potential window of about 9 V has been obtained [443]. 

It is true that ionic compounds such as [NH j fBtC H,) ]" are known in which there are no extremely active metals or nonmetals. Nevertheless, the above statement is lor all practical purposes correct, and we can consider compounds such as ammonium tetraphenylborate to result from the particular covalent bonding properties of nitrogen and boron. 

Solid-phase extraction of various analyte complexes on e.g. microcrystalline naphthalene (Ni [23] and Cu [24] with nitroso-R salt and tetradecyldimethylbenzylammonium chloride), ammonium tetraphenylborate-naphthalene (U with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol) [25], chitin column (Cr(VI) with 1,5-diphenylcarbazide) [26], strong anion-exchange cartridge (Cr(VI) at pH 8) [27], Cig cartridge (CL-azo dye) [28] and minicolumn (As with ammonium diethyl dithiophosphate) [29], silica modified chemically with A-allyl- or A-phenyl-TV -propylthiourea (OSO4) [30] and Sephadex DEAE A-25 (chloride form) (V with Eriochrome Cyanine R) [31] prior to the spectrophotometric determination has recently been reported. The application of solid-phase spectrophotometry to determine nitrite and nitrate in water samples has recently been described [32]. 

Preconcentration of Pd in the form of the complex with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol on a column packed with ammonium tetraphenylborate-naphthalene sorbent was described [1,2]. The method has been applied to the determination of Pd in catalysts, alloys and biological materials [1]. The detection limit of 15 ppb was achieved using third derivative spectrophotometric measurement [2]. 

Ammonium tetraphenylborate-naphthalene adsorbent was proposed for the preconcentration and determination of traces of uranium in standard alloys using 2-(5-bromo-... 

Zinc (and Cu) in brass and tap water were determined with the use of zincon after preliminary preconcentration on Chelex-100 column [3]. The application of V-hydroxy-AW-diphenylbenzamidine and diphenylcarbazone to the determination of zinc in airborne dust particulates has been described [4]. Trace amounts of zinc in standard alloys, environmental and pharmaceutical samples were determined by fourth derivative spectrophotometry using PAN as a reagent and ammonium tetraphenylborate supported on naphthalene as an adsorbent [5]. The detection limit was 9.5 ng ml Zn. Submicrogram amounts of zinc in water and rock samples were determined with 5-(2 -carbomethoxyphenyl)azo-8-quinolinol in the anionic micellar medium of sodium dodecyl sulfate [6]. 

Examples of the use of TGA in the literature include monitoring the decomposition of potassium and ammonium tetraphenylborates, the characterisation of chromatographic stationary phases and the identification of polymers in forensic cases. 

The other alkali metals do not give a precipitate even if present in a high concentration compared to potassium, but ammonium will give an ammonium tetraphenylborate precipitate identical to potassiimi tetraphenylborate. Of less importance is that a precipitate is also formed with rubidium, caesium, thallium, silver, and some organic nitrogen substances. Other references add copper and mercury as being capable of giving a positive reaction with tetraphenylborate. ... 

Ammonium tetraphenylborate [14637-34-4] M 337.3, m ca 220"(dec). Dissolve it in aqueous Me2CO and allow crystallisation to proceed slowly otherwise very small crystals are formed. No trace of Me2CO is left in the crystals after drying at 120° [Davies Staveley Trans Faraday Soc 53 19 1957]. Also, the salt can be precipitated from a dilute AcOH solution of sodium tetraphenylborane in the presence of NH ions. After standing for 5 minutes, the precipitate is filtered off onto a sintered porcelain cmcible, washed with very dilute AcOH and dried at room temperature for at least 24 hours [Vendlandt.4na/ Chem 28 1001 1956]. Alternatively, a solution of sodium tetraphenylborane (5% excess) in H2O is added to NH4CI solution. After 5 minutes the precipitate is collected, washed several times with H2O and recrystallised from aqueous Me2CO. [Howick Vf)mm.Analyt ChimActa 19 342 1958, Beilstein 16 IV 1625.]... 

BTPPATPB (Bis[triphenylphosphoranylidene]ammonium tetraphenylborate) (47) TPAsDCC (tetraphenylarsonium3,3 -commo-bis[undecahydro-l,2-dicarba-3-cobalta-chosododecarborate]) (48) ... 

C2aH23B306, D-Mannitol tris(benzeneboronic) ester, 43B, 820 C2aH2aBN, Ammonium tetraphenylborate, 46B, 627... 

Cb oHb 2BN7Ni 3O8, Tris(N-ethylenebis(salicylideneiminato)nickel-(II)) ammonium tetraphenylborate tetrahydrofuran solvate, 42B, 756... 

With discoveries of boron-based cocatalysts such as triphenyl-boron, ammonium tetraphenylborate salts, and finally pentafiuorophenyl derivatives of borate [B(C6H5)4] , olefin polymerization catalysis was developed without a reliance on alkylaluminum species. Although the activity with nonfiuori-nated boron-based cocatalysts was invariably low, the fiuorinated analogs exhibited olefin polymerization behavior similar to that of metallocene/MAO catalyst systems. The boron and borate compoimds are typically used in a 1 1 molar ratio with transition metal (stoichiometric or near stoichiometric). Because these activators do not alkylate the transition metal, the metallocene precatalyst employed must already bear alkyl groups. Thus, zirconocene dimethyl species combine with boron or borate activators to nerate active cationic polymerization catalysts. Figure 8 shows typical activation reactions with borate (a, b) and boron (c) activators. 

BTPPATPB is bis(triphenylphosphoranylidene)ammonium tetraphenylborate TEATPBCl is tetraethylammonium tetrakis[4-chlorophenyl]borate)... 

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