The way to obtain benzyl alcohol

 

(57) Abstract:

Upon receipt of benzyl alcohol by alkaline hydrolysis of benzyl chloride in aqueous medium at elevated temperature to separate water-salt layer, which is treated in one or two stages diversilobum ether, which is the byproduct of the synthesis step and the waste stage rectification, when the mass ratio (5 - 10) : 1. table 1.

The invention relates to a method for producing benzyl alcohol used in the production of basic organic synthesis, textile, paint, medical industry.

The existing method for producing benzyl alcohol is based on the hydrolysis of benzyl chloride with aqueous solutions of alkaline agent is sodium hydroxide, sodium carbonate or their mixtures (Century. And. Isagulyan Synthetic fragrances. - Yerevan, 1974, S. 184; L. M. Solow and L. A. Kheifets. Fragrant substances and intermediates of perfumery-cosmetic production.- M.: Chemistry, 1990, S. 21).

Also known is a method of obtaining benzyl alcohol by saponification of benzyl chloride aqueous alkaline solution at a temperature of 150-350oC and elevated pressure sufficient to maintain the reacting substances in the liquid phase, and p is(Patent UK N 1341113, class. C 07 C 31/16, 1973).

The disadvantage of this method is the low selectivity of the process is the formation of undesirable by-product of benzaldehyde reaches 10-15% of benzyl alcohol.

To simplify the process of technology saponification benzyl chloride is carried out at a temperature of 100-110oC in the presence of acute water vapor (Ed.St. USSR N 550376, class C 07 C 31/16, 1975).

The disadvantage of this method is the formation of increased amounts of sewage in the form of water-salt solutions as the concentration of the alkaline agents is limited by their low values (from 2 to 17%) and an increase in the concentration leads to the formation of increased amounts of side - products of the synthesis of benzaldehyde, dibenzylamino ether, and the solubility of benzyl alcohol in water is significant at the 20oC 4 wt.%, that reduces the output by 10-20 wt.%.

The invention solves the problem of improving the technology of production of benzyl alcohol, expressed in increasing the yield of benzyl alcohol, the reduction of energy consumption.

Obtain a technical result, the proposed method is achieved by treating the water-salt layer phase synthesis of benzyl alcohol dicale.

The proposed method is as follows. In a reactor with a stirrer (or another device that provides good mixing of the components) load water-salt layer and dibenzylamine ether (VAT residue). The mixture is stirred at room temperature for one hour, defend 1.5 - 2 hours and share. The lower water-salt layer is directed in the collection of treated wastewater, and to the organic layer, add a new portion of the crude solution and are processed in the above mode. The process is conducted until reaching 13-20% of the content of benzyl alcohol in diversilobum ether, after which the mixture is directed to one of the existing stages of the process of rectification with the original raw, the synthesis of benzoylacetate or simple Stripping.

The invention is illustrated by the following examples.

Example 1. To 500 g of water-salt solution with a content of benzyl alcohol to 3.25% poured 100 g of dimensional ether containing 0.2% alcohol, the mixture is stirred for 0.5 hour, defend 1 hour. Obtain 115 g of the organic layer with 13,0% content of benzyl alcohol and 484,5 g of water-alcohol solution with an alcohol content of 0.3%. The degree of purification of 91%.

Example 2. To the organic layer of example 1 prili the content of benzyl alcohol to 20.9% and 488,4 g of a water-salt solution with a concentration of alcohol of 1.0 wt.%. The degree of purification 69.6 per cent.

Example 3. 500 g of a water-salt solution containing 1.3% of alcohol, treated with 50 g of dimensional ether content of benzyl alcohol 3,55%. Get 494,4 g of water-salt layer and of 55.5 grams organic, in which the alcohol concentration is equal to 0.18 and 13,28%, respectively. The degree of purification of water-salt solution to 86.3%.

Example 4. To the organic layer of example 3, poured a fresh portion of water-salt solution of example 3. Mix, defend, share. Get 60.1 g of organic and 495,3 g of water-salt layer with a content of benzyl alcohol 19,95 and 0.38%, respectively. The degree of purification 71,0%.

Example 5. 500 g of a water-salt solution with a content of benzyl alcohol to 0.75% treated with 70 g of dimensional ether with an alcohol concentration of 0.15%. Get 73,6 g of organic and 496,2 water-salt layer with a content of benzyl alcohol in them 4,56 and 0.1%, respectively. The degree of purification was 86.7%.

Example 6. To the organic layer of example 5 is poured new batch (500g) water-salt solution composition of example 5. Receive the following number of layers and their content of benzyl alcohol - 76,0 and 497,5 and 8.16 g and 0.18%, respectively. The degree of purification 76,2%.

Example 7. To the organic layer note the layers and their content of benzyl alcohol - 78,4 and 497,5 g and 11.0 and 0.27%, respectively. The degree of purification 64,28%.

Example 8. To the water-salt solution of example 7 poured a fresh portion of dimensional ether (70 g). After treatment you receive the following number of layers with the content of benzyl alcohol 496,5 and 70.9 g and 0.08 and a 1.45%. The degree of purification 70,15%.

Example 9. Water-salt solution of example 8 is treated with a fresh portion of dimensional ether. After treatment you receive the following number of layers with the content of benzyl alcohol 492,0 and 58,0 g and 0.28 and 14.0%. The degree of extraction of 85%.

From these examples and the table shows that the single treatment of water-salt solution diversilobum ether (examples 1, 3, 5, 9) provides 85-90% recovery of benzyl alcohol, the latter increases when the ratio is changed (examples 9 and 1) from 10:1 to 5:1.

The increase in the number of water-salt solution with respect to dibenzylamino ether resulted in further decrease in efficiency of the process decreases below the specified value to the irrational technological costs (increase in the volume of extractant, the energy consumption for regeneration).

The re-use of the extractant prob obtain benzyl alcohol by alkaline hydrolysis of benzyl chloride in aqueous medium at elevated temperature with branch water-salt solution, characterized in that the water-salt solution process diversilobum ether, waste stage of rectification and byproduct stage of the synthesis, at a mass ratio of 5 - 10 : 1 in one or two stages.

 

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