Boric anhydride

Boric anhydride. This is a powerful and efficient desiccant and will absorb up to about 25 per cent, of its weight of water. It is useful for drying formic acid. 

The selectivity to alcohol in LPO may be significantly increased when boric acid, meta-hotic acid, or boric anhydride is present in stoichiometric amounts (2). The boron compounds appear to convert alkyUiydroperoxides to alkyl borates and may also intercept alkylperoxy radicals, converting them to alkylperoxyboron compounds these are later converted to alkyl borates. The alkyl borates are resistant to further oxidation they are hydrolyzed to recover alcohols. 

Diphenylamine can also be produced by passing the vapors of aniline over a catalyst such as alumina, or alumina impregnated with ammonium fluoride (17). The reaction is carried out at 480°C and about 700 kPa (7 atm). Conversion per pass, expressed as parts diphenylamine per 100 parts of reactor effluent, is low (18—22%), and the unconverted aniline must be recycled. Other catalysts disclosed for the vapor-phase process are alumina modified with boron trifluoride (18), and alumina activated with boric acid or boric anhydride (19). 

The Guerbet reaction (386—389) involving condensation of ethanol in the presence of sodium ethoxide, catalyzed by potassium hydroxide and boric anhydride (390,391) or alkaline phosphates (392), gives / -butanol [71-36-3]. ... 

Boric anhydride. (Prepared by melting boric acid in an air oven at a high temperature, cooling in a desiccator, and powdering.) Mainly used for drying formic acid. 

Rapid procedure Dry over anhydrous K2CO3 for 24h, followed by further drying for 24h over 3A molecular sieves or boric anhydride, followed by distn. Alternatively, stir over P2O5 (5% w/v) for 24h then distil. However this last method is not suitable for use in reactions with very acid sensitive compounds. 

Fractionally distd under reduced pressure. Dried with sodium and again fractionally distd or refluxed with boric anhydride and distd (b 195-205°/5mm), the distillate being neutralised with NaOH and again fractionally distd. Also purified by distn from Raney nickel and by preparative GLC. 

Bofsaure, /. boric acid. anhydrid, n. boric anhydride (B2O3). -seife, f. boric-acid soap. Weinstein, m. = Boraxweinstein. 

Borate. Dehydration is the first reaction occurring on heating the borate as in the case of the phosphate but at a much lower temperature (130-270 C, step 1 Figure 17). Boric acid heated alone in the same conditions in TG, eliminates water between 80-300 C in two main overlapping steps with maximum rate at 170 and 190 C corresponding to formation of metaboric acid and boric anhydride respectively ... 

Synonyms Boric anhydride boron sesquiox-ide boron trioxide fused boric acid... 

Synonyms boric anhydride boron oxide diboron trioxide... 

Preparation,—1. By strongly heating boric anhydride with calcic fluoride —... 

Dextrose Polymers and Their Nitrates. Dextrose (d-glucose) polymers can be obtd by heating dextrose or polysaccharides composed of dextrose units, in the presence of catalysts, such as boric anhydride, or boric acid. The resulting solid products are light in color and have a high 8 wide degree of... 

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