Borate salts

Alcohols react with boric acid with elimination of water to form borate esters, B(OR)3. A wide variety of borate salts and complexes have been prepared by the reaction of boric acid and inorganic bases, amines, and heavy-metal cations or oxyanions (44,45). Fusion with metal oxides yields... 

A number of boron chemicals are prepared directly from boric acid. These include synthetic inorganic borate salts, boron phosphate, fluoborates, boron ttihaHdes, borate esters, boron carbide, and metal aHoys such as ferroboron [11108-67-1]. 

The polyions postulated in solution all have known structural analogues in crystalline borate salts. Investigations of the Raman (66) and B nmr (67) spectra of borate solutions have confirmed the presence of three of these species the triborate (3), B202(0H) 4, tetraborate (4), [B40 (0H) 4], and pentaborate (5) B O (OH) 4, polyanions. Skeletal stmctures were assigned based on coincidences between the solution spectra and those soHd borates for which definitive stmctural data are available (52). These same ions have been postulated to be present in alkah metal borate glasses as well. 

Borate salts or complexes of virtually every metal have been prepared. For most metals, a series of hydrated and anhydrous compounds maybe obtained by varying the starting materials and/or reaction conditions. Some have achieved commercial importance. 

Copper, Manganese, and Cobalt Borates. Borate salts of copper, manganese, and cobalt ate precipitated when borax is added to aqueous solutions of the metal(Il) sulfates or chlorides (152). However, these materials are no longer produced commercially. 

Thermal decomposition of solid estrone 2- and 4- diazonium fluoro-borate salts leads to 2- and 4-fluoroestradiol. ... 

A recent adaptation of the procedure employing perchlorate and fluoro-borate salts has been reported by Leonard and Paukstelis (J5). This report includes proof of structure by direct comparison to iminium salts prepared by protonation of enamines. The general reaction reported was that of a ketone or aldehyde with a secondary amine perchlorate to give iminium salts. A large structural variety of carbonyl compounds and several amine... 

The monocation tris(diethylether) ethylzinc is formed from diethyl zinc as a tetrakis(penta-fluorophenyl)borate salt.85 Longer-chain linear and cyclic ether complexes (2) of zinc alkyls have also been observed. The reaction between zinc dialkyls and primary amines gives a number of structurally diverse products dependent on the reaction conditions and the amine.86 The... 

Figure 7. Schematic representation of the microenvironment of the cationic PSD diOC16(3) in a potassium sensor before (A) and after (B) extraction of potassium from the aqueous into the lipophilic membrane phase. The sensor membrane is composed of valinomycin, diOC16(3) and a lipophilic borate salt dissolved in plasticized PVC.

Another important bioanalytical application of voltammetric ISEs is the detection of polyions (see also above). A technique using cyclic voltammetry on micropipette electrodes filled with the organic electrolyte solutions in 1,2-dichloroethane was successfully applied for the detection of protamine [65] in saline solution and heparin in undiluted sheep plasma samples [66]. Protamine transport was facilitated with dino-nylnaphthalenesulfonic acid (DNNS). As a heparin-selective component the tetrakis-(4-chlorophenyl)borate salt of trimethyloctadecyl ammonium was used. 

Note that the photolysis of various pyridinium borate salts at — 78°C (to prevent thermal reaction) affords the same methyl-transfer products as obtained in thermal reactions (i.e., equation 44). 

The same authors <2000J(P1)3584> studied the reactivity of 2 toward benzenediazonium (chloride or tetrafluoro-borate) salts. No diazo coupling took place under neutral or slightly acidic conditions. However, under basic conditions (NaOH in H20/MeOH), a mixture of 62 and 63 was obtained. This result clearly indicates that the diazo coupling takes place through the anion of 62 which arises from the base-catalyzed methanolysis of amide 2 in which the pyrrole ring is obviously not nucleophilic enough. 

KC8 also affords a borate salt, but in this case it is uniquely dimerized with a relatively long (1.83(2) A) B-B bond, which is caused, no doubt, by the presence of adjacent negative charges and the four-coordination of the boron atoms. Reduction of 2,6-Trip2H3C6BBr2 with sodium gave the 9-borafluorenyl radical anion salt, which was characterized by EPR and elemental analysis.67... 

Lithium Chelatophosphates. If the work of Barthel et al. and Angell et al. on various borate-based salts could be viewed as the structural modification of a perhalogenated borate salt (LiBF4) that was already used in commercial lithium ion cells, then similar modifications were also carried out on the more popular salt LiPFe. the industry standard of lithium ion cell electrolytes. 

When the monosilylated precursor 26 was reacted in a similar manner with LiBH4 according to Scheme 11, the resulting product was the solvent-free lithium borate salt 27 (74% yield). This compound could be recrystallized from -hexane. 

The catalytic activity of the oxoisoindolium salt 54 and 55 was compared to that of trityl tetrakis[pentafluorophenyl]borate salts in the addition reaction of enol acetate to benzaldehyde and glycosylation reaction (Scheme 59) [151, 152]. 

The most efficient system devised by Monsanto uses electrodes fabricated from carbon steel plate, electro-coated on one face with cadmium. These are stacked in parallel so that the electrolyte can be pumped through the gap between successive plates. Overall tire system forms a series of electrochemical cells with a cadmium cathode and a carbon steel anode. Each plate of metal forms the cathode of one cell and the anode of the next in the stack. Electric current is passed across the stack. The electrolyte contains phosphate and borate salts as corrosion inhibitors, EDTA to chelate any cadmium and iron ions generated by corrosion together with hex-amethylenebis(ethyldibutylammonium) phosphate to provide the necessary telraal-kylammonium ions. This electrolyte circulates through the cell from a reservoir and there is provision for the introduction of acjylonitrile and water as feedstock. The overall cell reaction is ... 

The reaction of borate salts with hydrogen peroxide in alkaline aqueous solution results in formation of peroxoborates. This reaction is rapid and occurs by nucleophilic attack of the perhydroxyl anion on boric acid,... 

In general, most alkali borates are soluble, whereas most other borates are insoluble. Table 7.1 presents the names, formulas, states, solubilities, and standard free energies of a number of the more important simple inorganic species of B. All borate salts are white unless they contain a colored cation. 

Free-radical photoinitiators are classified by their chemical nature as type I and type II however, there are a few systems with different chemistry, e.g., borate salt initiators that depend on inter-/intramolecular electron transfer,i that do not fit into either category. 

The silicon analogs of carbocations have been reported a number of times [131], but there is only one confirmed sighting to date, the highly hindered trimesitylsilicenium ion as its tetrakis(pentafluorophenyl)borate salt [132] ... 

The checkers observed the separation of a heavy, white precipitate presumed to be a borate salt during the addition of hydrogen peroxide. After the three-phase mixture had been stirred at room temperature for 3 hr, the liquid layers were decanted into a separatory funnel. The solid remaining in the flask was washed with two 75-mL portions of ether and these washings were used to extract the aqueous layer. 

A very important advance was made in 1927, with the disclosure24 by Balz and Schiemann of a new synthetic route (which has ever since been named after them) from an arylamine to an aryl fluoride. After diazotization in the normal way, the readily available tetrafluoroboric acid, or a tetrafluoroborate salt, was added to precipitate the insoluble diazonium tetrafluoro-borate salt. This was then dried and heated it decomposed (usually at 100-150°C) to give a good yield of the corresponding aryl fluoride. 

The bulky methylaluminoxane anion stabilizes the coordinatively unsaturated metal cation. Stabilization by noncoordinating anions such as carbosilane dendrimers is also viable.571 Aluminoxanes, however, are required to be used in large excess to be effective. Alternatively, the active catalyst can also be prepared by reacting a metal dialkyl with fluorinated boranes, borate salts or aluminate salts. 

Imidate salts are 0-alkyl derivatives of tertiary amides. Being activated tertiary amides, they are extremely reactive towards nucleophiles. There is instantaneous reaction with hydroxide ion they also react rapidly at room temperature with water under acidic conditions. When an imidate fluoro-borate salt such as 43 reacts with sodium hydroxide, it gives sodium fluoro-borate and the tetrahedral intermediate 44 which breaks down in an irrevers-... 

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