With boric anhydride

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. 

Crystals of magnetic oxide have been obtained in a variety of ways, such as by calcination of sodium carbonate and ferrous chloride 1 by fusion of potassium sulphate and iron phosphate 2 by the action of hydrogen chloride upon heated ferrous oxide 3 and by ignition of ferrous fluoride with boric anhydride.4... 

Boron carbide can be prepared in a hydrogen-Ar plasma, using (1) amorphous boron and carbon powders (2) an anode made of a mixture of graphite with boric anhydride (or borax) and a graphite cathode, or (3) a mixture of BCI3-CH4 Boron... 

In 1702 Homberg prepared the free acid from borax and called it sal sedativum. In 1747 Baron discovered that borax is a compound of soda and sal sedativum in other words, it is a salt and with the establishment of Lavoisier s system of nomenclature, introduced in conjunction with de Morveau, Berthollet, and Fourcroy in 1787, the incorrect appellation sal sedativum gave place to boracic add, subsequently shortened to boric acid. Lavoisier regarded it as an oxide. The news reaching Paris early in 1808 that Davy had, in the previous October, isolated the alkali metals potassium and sodium stimulated chemists generally to attempt the isolation of other metals. Gay-Lussac and Thenard prepared potassium that year (1808) by a new process, namely heating potash with metallic iron, a method which Davy himself subsequently adopted as more convenient than his own electrolytic one. The potassium was now heated with boric anhydride in a copper tube and, after cooling,... 

Made a crystalline l crylH in colunihatc l y fusing with boric anhydride, the i)reci itate ol t,lined by precipitating ix>tassiuni culiinibate with lierylliinn cliloridc. Found comi ositi( n, 6.24 per cent. IJeO, 8<>/jo per cent. Cb,0 . 

Acetylacetone stirred with boric anhydride, then added to a soln. of vanillin and tributyl borate in dry ethyl acetate, stirred ca. 1 hr. with intermittent drop-wise addition of n-butylamine, stirring continued 4 hrs., and allowed to stand overnight curcumin. Y 80%. F. e. s. H. J. J. Pabon, R. 83, 379 (1964). 

The 3(a)- and 8(jS)-solanidanols on treatment with boric anhydride produced the same A for A )-solanidene, which was hydrogenated to solanidane.r Similarly the two aiZosolanidanols gave the same A - (or A )-allosolanidene, reducible to oZiosolanidane. The chief characteristics of these ten substances and their interrelationships are summarised in the following table — ... 

Prepared by condensing p-chlorophenol with phlhalic anhydride in sulphuric acid solution in the presence of boric acid. The chlorine atom is replaced by hydroxyl during the condensation. It can also be prepared by oxidation of anthraquinone or 1-hydroxyanthraquinone by means of sulphuric acid in the presence of mercury(ll) sulphate and boric acid. 

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). 

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. 

On the other hand, the reaction of 3-,sec-aminophenols (71) with phthalic anhydride does not give the corresponding keto acids (72). The keto acids (72) having a secondary amino group at 4-position are prepared by the reaction of 3-sec-aminophenols (71) with phthalimide at 150-220°C in the presence of boric acid, followed by hydrolysis of the intermediate carboxamide with aqueous sodium hydroxide (Eq. 3). 

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 ... 

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

Of practical interest are the last two techniques for producing trialkylbo-rates. It should be noted however, that the industrial reaction of boric anhydride with alcohols is fraught with difficulties. E.g., when powderlike boric anhydride is introduced into alcohol, clumps should be broken lest they kill the reaction. If boric anhydride is used in the form of pieces, the reaction should be conducted under an increased pressure and alcohol should be dehydrated beforehand. Thus, the most technological method is to obtain trialkyl(aryl)borates by the interaction of boric acid with alcohols. 

Similarly to trimethylborate, the reaction of a corresponding alcohol with boric acid or boric anhydride yields other trialkylborates triethyl-, tri-n-propyl-, tri-n-butyl-, tri-sec-butyl-, tri-tret-butyl-, tri-n-pentyl-, triisopen-... 

Reduction of sugars into alditols is effected by treatment with sodium borohydride, and acetylation by treatment with acetic anhydride containing sulphuric acid (2%) at 80°C for 15 h [436] or for 4 h by refluxing with a mixture of acetic anhydride and pyridine (1 1) [437]. The excess of reducing agent is usually decomposed prior to the acylation by treatment with an acid. The boric acid so produced should be removed, as it forms a complex with alditols and retards the acylation. Polar stationary phases (e.g., Carbowax 20M), on which strong sorption and decomposition of the derivatives occur, are not very suitable for the GC separation of acetates. Carbowax 20M modified with terephthalic acid and XE-60 provides good results, but some derivatives do not separate. 

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