Method for recovering hydroxyacetate from waste water of phenoxyacetic acid pesticides

A technology of glycolic acid esters and phenoxyacetic acids, which is applied in the preparation of carboxylic acid esters, chemical instruments and methods, and the preparation of organic compounds, and can solve the problems of low conversion rate, high price, and uneconomical industrial production.

Inactive Publication Date: 2015-07-01
SHANGHAI TAIHE INT TRADE CO LTD +1
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  • Abstract
  • Description
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Problems solved by technology

The disadvantage of the first method is that the conversion rate is low, resulting in a low utilization rate of raw materials; the disadvantage of the second method is that the price of the halogenated hydrocarbon used is generally higher than that of the corresponding alcohol, and it will consume at least an equivalent amount of alkali to promote the reaction and produce new solid waste, making industrial production very uneconomical

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Wastewater concentration

[0027] Concentrate 20kg of wastewater step by step under 95°C (vacuum 40mmHg), first concentrate to 10% solid content and filter to obtain salt and concentrate 1. Concentrate 1 further at 95°C (vacuum 40mmHg) To the solid content of 10%, filter to obtain salt and concentrate 2, then concentrate 2 at 95 degrees (vacuum 40mmHg) to a constant weight, filter to obtain salt and concentrate 3 (1.04 kg).

Embodiment 2

[0029] Preparation of methyl glycolate

[0030] The concentrated solution 3 was mixed with 0.76 kg of benzene and 0.62 kg of methanol, and 0.126 kg of sulfuric acid was slowly added dropwise, reacted at 60 degrees for 36 hours, and cooled to room temperature to obtain a reaction solution containing methyl glycolate, methanol, benzene and sulfuric acid. The reaction liquid was rectified, and the reflux ratio was set to 1:3. First, the bottom temperature was raised to 30 degrees, the vacuum degree was 20 mm Hg, and the rectification to obtain the front distillate, and then the bottom of the still was heated to 70 degrees, the vacuum degree was 20 mm Hg, 301 g of methyl glycolate was obtained by distillation.

Embodiment 3

[0032] Preparation of tert-butyl glycolate

[0033] Mix concentrate 3 with 0.76 kg of toluene and 1.71 kg of tert-butanol, slowly add 0.2 kg of p-toluenesulfonic acid in batches, react at 90 degrees for 48 hours, and cool to room temperature to obtain tert-butyl glycolate, tert-butanol, A reaction liquid of toluene and sulfuric acid. The reaction liquid was cooled to 20 degrees, washed with 1.5 kg of water and separated to obtain the organic phase, which was rectified, and the reflux ratio was set to 1:2. First, the bottom temperature of the kettle was raised to 60 degrees, and the vacuum degree was 20 mm Hg. Obtain the front distillate, and then heat up to 180 degrees to rectify to obtain 372 g of tert-butyl glycolate.

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Abstract

The invention relates to a method for recovering hydroxyacetate from waste water of phenoxyacetic acid pesticides. The method comprises the following steps: subjecting waste water in production of the phenoxyacetic acid pesticides to concentration and desalting under the conditions of pressure reduction and heating so as to obtain concentrated waste water mother liquor containing glycolic acid; and treating the concentrated waste water mother liquor under acidic or alkaline conditions so as to recover hydroxyacetate. Compared with the prior art, the invention has the following advantages: glycolic acid is converted into hydroxyacetate instead of direct extraction since the content of glycolic acid in the waste water is low and glycolic acid cannot be extracted by using a conventional extraction method after complete drying of water by distillation in the presence of water as glycolic acid decomposes at 100 DEG C and is intermiscible with water; thus, the disadvantages that glycolic acid easily decomposes at a high temperature and is hard to separate and purify are overcome, and conversion of glycolic acid into hydroxyacetate enables loss caused by decomposition of glycolic acid to be avoided and recovery efficiency to be improved.

Description

Technical field [0001] The invention belongs to the field of pesticide waste water recycling and utilization, and particularly relates to a method for recovering glycolic acid esters from phenoxyacetic acid pesticide waste water. Background technique [0002] The synthesis process of phenoxyacetic acid pesticides all go through the condensation process of chloroacetic acid and phenol. In this process, excess chloroacetic acid will be hydrolyzed to produce glycolic acid. [0003] At present, domestic manufacturers of phenoxyacetic acid pesticides all produce a large amount of high COD (mainly glycolic acid produced by the hydrolysis of sodium chloroacetate) wastewater. The treatment of these wastewaters will produce a large amount of high COD solid waste, which not only greatly increases the cost of the three wastes treatment, but also pollutes the environment. However, glycolic acid ester is an important fine chemical intermediate, which is widely used in adhesive, dyeing, textile...

Claims

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Application Information

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IPC IPC(8): C07C69/675C07C67/10
Inventor 王海波汪淼谢思勉田晓宏张照军
Owner SHANGHAI TAIHE INT TRADE CO LTD
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