SU116927A1 - The method of purification of aromatic hydrocarbons - Google Patents

Description

Aromatic hydrocarbons with aliphatic side chains can be oxidized in the liquid phase at 50-300 ° under pressure and with the use of catalysts. However, hydrocarbons of different origins and different pretreatments, despite their identical or very similar chemical and physical characteristics, are not equally oxidized, more easily, or more difficult. Various methods are known to increase the oxidability of such hydrocarbons. Thus, for example, there is a known method for increasing the oxidation capacity of xylenes by treatment with aluminum chloride at elevated temperatures, as well as purification with concentrated sulfuric acid followed by treatment using metallic sodium or potassium.

A disadvantage of the known methods is a loss of at least 510%.

processed aromatic hydrocarbon, significant consumption of chemicals.

The described method of purification of aromatic hydrocarbons increases their ability to oxidize, is simpler and is not accompanied by their isomerization. A feature of the method is that the raw hydrocarbons are treated with formaldehyde in an amount of from 0.05 to 10 mol. % in the presence of a strong acid from 0.01 to 10 mol. % followed by neutralization of the reaction mixture and mechanical separation of salt and condensation products.

Instead of formaldehyde, compounds that release formaldehyde under these conditions can be used.

Example 1. 1060 g (10 moles) of 96% p-xylene obtained by freezing from a fraction of the xylene coal tar is stirred for 4 hours. at 20 ° С 5 g of 35% water methanol ratio № 116927

Formaldehyde alignment (about 0.05 moles of formaldehyde) and 10 g (about 0.1 mol) of concentrated sulfuric acid. The mixture is then decanted from the gummy slag and the xylene phase is stirred for 14 hours (14 g (about 0.1 mol) anhydrous potassium carbonate). The filtered product is distilled and then oxidized with air at 70 atm and 180 °. The injected oxygen is completely consumed for oxidation. Under these oxidation conditions, unrefined p-xylene does not receive oxygen, while refined with 10 percent by volume concentrated sulfuric acid, washed with water, neutralized with potassium carbonate, and distilled p-xylene absorbs 60 to 80% of the injected oxygen.

Example 2. 1060 g (10 moles of 96% p-xylene is stirred at 20 for 4 hours with 0.75 g (0.025 mol) of trioxymethylene and 1 g (about 0.01 mol) of concentrated sulfuric acid. Then, in the reaction 5 g (about 0.05 mol) of powdered anhydrous sodium carbonate are added. The product is filtered and distilled. When the product is oxidized at 180 ° and a pressure of 70 atm, all the oxygen taken in the reaction is absorbed by the product.

Example 3. 1320 g (10 moles) of freshly distilled tetrahydronaphthalene are mixed at 20 ° for 4 hours. with 2 g (about 0.025 mol) formaldehyde dimethyl acetal, 8.5 g (about 0.05 mol) p-tolFFlsulfonic acid. Then 10 g (about 0.1 mol) of anhydrous sodium carbonate are added to the reaction mixture. After filtration and distillation, 500 g of the product obtained is oxidized at 75 ° and normal pressure with air in the amount of 100 norms, l / h.

In 5 hours An iodometric titration of the oxidized product shows about 15% tetraline hydroperoxide. Peroxidized tetralip during oxidation under the same conditions shows the content of the oxidized product only in an amount of 9%.

Subject invention

Claims (2)

1. A method for purifying aromatic hydrocarbons, characterized in that, in order to increase their ability to oxidize, raw hydrocarbons are treated with formaldehyde in an amount of from 0.05 to 10 mol. % in the presence of a strong acid from 0.01 to 10 mol. % followed by neutralization of the reaction mixture and mechanical separation of salt and condensation products. 2. A method according to Claim 1, characterized in that instead of formaldehyde, compounds are used that release formaldehyde under these conditions.