Oleum boric acid

Dichloroanthraqoinone. Orange-yellow cryst. from AcOH. Mj>. 187 5°. Sol. PhN02, Py, hot CjH, hot AcOH. Spar, sol. EtOH, EtjO, li in. 10% oleum + boric acid at 200° —> quinizarin. 

Dihydroxyanthraquinone. This anthraquinone, also known as quinizarin [81-64-1] (29), is of great importance in manufacturing disperse, acid, and vat dyes. It is manufactured by condensation of phthalic anhydride (27) with 4-chlorophenol [106-48-9] (28) in oleum in the presence of boric acid or boron trifluoride (40,41). Improved processes for reducing waste acid have been reported (42), and yield is around 80% on the basis of 4-chlorophenol. 

One of the few strong acids is tetrafhydrogen sulfato)boric acid HB(HS04)4 solutions of this can be obtained by dissolving boric acid in oleum ... 

This compound is obtained from phthalic acid and p-chlorophenol with sulfuric acid in the presence of boric acid. The intermediate product is quinizarin, which is sulfonated in oleum or with sodium hydrogen sulfite and oxidants to form 89 ... 

To prepare boron trifluoride, mix 50 g of potassium fluoborate and 9 g of boric acid anhydride in flask 3, and pour 25 ml of anhydrous sulphuric acid into the mixture. Prepare the anhydrous sulphuric acid by adding the relevant amount of 65 % oleum to a 96 % sulphuric acid solution carefully, wear eye protection ). 

In a 100-mL, two-necked flask, 4.80 g (77.8 mmol) boric acid, H3B03, is dissolved in 20 mL cone. H2S04 (96 wt %) 20 mL of oleum (65 wt % S03) is added dropwise. The reaction mixture is heated to 60°C and kept 45 min under a vacuum (10 2 Torr) to remove excessive sulfur trioxide. 3.0 g... 

The increase in acidity is, however, limited to H0 = —13.6 as a result of insoluble complexes that precipitate when the concentration of the boric acid approaches 30mol%. Figure 2.4 shows the composition-related acidity increase for the system in comparison with oleum. 

The only known strong acid of the sulphuric acid system is tetra(hydro-gensulphato)boric acid, HB(HS04)4, which may be obtained in solution in sulphuric acid by dissolving boric add in oleum in the amount required by equation (4) (Flowers et al., 1956). 

The manufacture of boron trifluoride proceeds either discontinuously by reacting borates with fluorspar and oleum or continuously by reacting, for example, hydrogen fluoride with boric acid in the presence of sulfuric acid, to bind the water formed ... 

The species H[B(H804)4] has not been isolated as a pure compound, but a solution of this acid can be prepared by dissolving boric acid in oleum (equation 8.51) (see Section 15.9) and can be titrated conductometrically against a solution of a strong base such as KH8O4 (equation 8.52). 

In sulfonating hydroxyanthraquinones, boric acid is often added to block the free phenolic group by the formation of boric esters, thereby inhibiting oxidation as a destructive side reaction. Sodium sulfate is also added to such sulfonation mixtures presumably pyrosulfate is formed, which is more moderate in its action than oleum. 

The cyclohexanone oxime obtained by any of these processes (1, 2,4, 6, and 7, in Figure 2.11) is converted to caprolactam by the Beckmann rearrangement in oleum. The resulting caprolactam sulfate is neutralized with ammonia and purified. The neutralization process yields about 2 + 0.2 kg of ammonium sulfate/kg of caprolactam. The lactam purification may entail extraction with organic solvents (toluene, benzene, chlorinated aliphatic hydrocarbons) followed by extraction of the organic solution with water and subsequent isolation of the lactam by either crystallization or distillation. Newer developments are concerned with the gas-phase catalytic rearrangement of cyclohexanone oxime using a boric acid on carbon catalyst in a fluidized-bed operation [122],... 

This reaction was first reported by Bohn in 1889 and subsequently by Schmidt in 1891. It is the introduction of hydroxyl groups into anthraquinone molecules containing at least one hydroxyl group by the oxidizing action of fuming sulfuric acid (i.e., oleum). Therefore, it is generally known as the Bohn-Schmidt reaction. It is reported that if boric acid is added to the reaction mixture, then ordinary concentrated sulfuric acid can be used instead of the oleum, and boric acid can form esters with hydroxyanthraquinones to prevent the further oxidation. In addition, selenium, selenium oxide, and mercury can be added as catalytic agents. ... 

There are only a few known substances which act as acids in sulphuric acid. Even perchloric acid, the strongest mineral acid in water, is undissociated in sulphuric acid despite the high dielectric constant. Disulphuric acid and higher polysulphuric acids are definitely acidic as well as the complex acid HB(HS04)4, which is obtained by dissolving boric acid in oleum o. 

---