A kind of preparation technology of 2-methyl-4-chlorophenoxyacetic acid

Abstract

The invention discloses a 2-methyl-4-chlorophenoxyacetic acid preparation technology. The technology is characterized in that a series of reactions comprising a condensation reaction of o-cresol, sodium hydroxide and water, a sodium modifying reaction of sodium hypochlorite, an acidulation reaction of hydrochloric acid and the like are carried out, and the pH value of 2-methyl-4-chlorophenoxyacetic acid in the acidulation reaction of hydrochloric acid is 5, so production and use demands are satisfied. The above improved technology substitutes a traditional technology utilizing pure benzene and chlorine, so the safety of 2-methyl-4-chlorophenoxyacetic acid in the preparation is increased. An o-cresol recovery operation is added for recovering o-cresol used in the above reaction, a platinum resistance thermometer arranged in a condensation reaction vessel is used for detecting the temperature in the condensation reaction vessel in the late stage of the above reactions, an enamel reaction vessel heating vessel body connected with the enamel reaction vessel is controlled when the temperature of the platinum resistance thermometer is higher than preset 90DEG C, and o-cresol for recovery is obtained through an enamel condenser connected with the enamel reaction vessel to improve the resource utilization rate.

Description

technical field [0001] The invention relates to a preparation process of 2-methane-4-chlorophenoxyacetic acid, in particular to a preparation process of 2-methane-4-chlorophenoxyacetic acid with high safety factor during processing. Background technique [0002] 2-methyl-4-chlorophenoxyacetic acid has always been one of the common herbicide varieties worldwide because of its low dosage and low cost. At the same time, 2-methyl-4-chlorophenoxyacetic acid has a small solubility in water and is easily Soluble in organic solvents such as ethanol and benzene, but its sodium salt and amine salt are easily soluble in water. In addition, it can also be used as a plant growth regulator to prevent tomato, cotton, pineapple, etc. from falling flowers and fruits and forming seedless fruits. [0003] At present, the preparation of 2-methyl-4-chlorophenoxyacetic acid often adopts the following method: first, under the condition of below 30 degrees Celsius, use chloroacetic acid and sodium ...

AI Technical Summary

Problems solved by technology

However, using the above method to prepare 2-methyl-4-chlorophenoxyacetic acid, due to the use of pure benzene and chlorine in the process, pure benzene may cause cancer, may cause hereditary gene damage, is highly flammable, and irritates the eyes and skin. Chlorine gas is a yellow-green toxic gas with a strong pungent smell, so there are consequences of a series of reactions such as the damage of work clothes caused by human error and the poisoning of operators during the preparation process.

In addition, in the preparation process of 2-methyl-4-chlorophenoxyacetic acid, sodium o-cresate has the generation of waste caused by untimely recovery.

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