Boric acid and sodium borate

Buffers contain mixtures of weak acids and their salts (i.e., the conjugate bases of acids), or mixtures of weak bases and their conjugate acids. Typical buffer systems used in pharmaceutical dosage forms include mixtures of boric acid and sodium borate, acetic acid and sodium acetate, and sodium acid phosphate and disodium phosphate. The reason for the buffering action of a weak acid, HA (e.g., acetic acid) and its ionized salt, A" (e.g., sodium acetate) is that A" ions from the salt combine with the added hydrogen ions, removing them from solution as undissociated weak acid. 

Due to their low dehydration temperatures and water solubilities, boric acid and sodium borates (borax pentahydrate and borax decahydrate) are mostly used as fire retardants in wood/cellulosic products such as timbers, plywood, particle board, wood fiber, paper products, and cotton products. In recent years, boric acid has also been used as fire retardant in epoxy intumescent coating, pheno-lics, urethane foam, and so on. When necessary, boric acid can be coated with silicone oil such as silicone to alleviate its water solubility in water-based coating. 

BORIC ACID AND SODIUM BORATE (Blinx, Collyrium)... 

Boric acid and sodium borate have been used for many years in a variety of products as antiseptics and fungistatic agents in baby talcum powder. Boric acid powder (99%) is still used as a pesticide against ants and cockroaches. In the past, repeated and indiscriminate application of boric acid to broken or abraded skin resulted in many cases of severe poisoning. Epidemics have also occurred after boric acid was mistakenly added to infant formula or used in food preparation. Although chronic toxicity seldom occurs now, acute ingestion by children at home is common. 

The pH 9.18 buffer has a composition of 0.01 m sodium tetraborate decahydrate (Na2B4O7-10H2O). In solution this salt hydrolyzes to form boric acid and sodium borate. It has good stability toward... 

A unique Hquid—Hquid extraction process for manufacturing boric acid from sodium borate brines has been operated at Seades Lake, Trona, California, by the North American Chemical Co. since 1962. Both potassium sulfate and sodium sulfate are produced as coproducts in this process. 

Reactions with acids and bases produce borates with varying Na20/B203 mole ratios. While acids produce borates with Na20/B203 mole ratios less than 0.5, their ratio is greater than 0.5 with bases. Treatment with sulfuric acid produces boric acid and sodium sulfate ... 

Optically active 2,3-diacyl glycerols (9) can also be prepared from the intermediate (3) in the sequence above.3 Thus (3) is treated with triphenylmethyl chloride and pyridine in chloroform to give 1-O-triphenylmethyl-j/i-glycerol-2,3-carbonate (6). The carbonate group is then hydrolyzed with dilute sodium hydroxide in ethanol to give (7). This is acylated as usual (8) finally the protective group is hydrolyzed with boric acid and trimethyl borate (Matheson, Coleman and Bell). 

Electrolytic dielectrics include metal oxides, aqueous-based liquid electrolytes, and non-aqueous-based liquid electrolytes. The most commonly used metal oxides are aluminum oxide, tantalum pentoxide, and niobium oxide. A typical aqueous-based liquid electrolyte contains boric acid or sodium borate in aqueous solution with various sugars or ethylene glycol to retard evaporation. Eor example, there are three major types of water-based electrolytes for aluminum electrolytic capacitors standard water-based (with 40% to 70% water), those containing ethylene glycol (with less than 25% water), and dipropyl ketone (with less than 25% water). 

For the most part boric acid esters are quantitated by hydrolysis in hot water followed by determination of the amount of boron by the mannitol titration (see Boron compounds, boric oxide, boric acid and borates). Separation of and measuring mixtures of borate esters can be difficult. Any water present causes hydrolysis and in mixtures, as a result of transesterification, it is possible to have a number of borate esters present. For some borate esters, such as triethanolamine borate, hydrolysis is sufftciendy slow that quantitation by hydrolysis and titration cannot be done. In these cases, a sodium carbonate fusion is necessary. 

Volatile boron compounds, especially boranes, are usually more toxic than boric acid or soluble borates (Table 29.9) (NAS 1980). However, there is little commercial production of synthetic boranes, except for sodium borohydride — one of the least toxic boranes (Sprague 1972). Boron trifluoride is a gas used as a catalyst in several industrial systems, but on exposure to moisture in air, it reacts to form a stable dihydride (Rusch etal. 1986). Eor boric oxide dusts, occupational exposures to 4.1 mg/m (range 1.2 to 8.5) are associated with eye irritation dryness of mouth, nose and throat sore throat and cough (Garabrant et al. 1984). 

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