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105 results about "2,4-Dichlorophenoxyacetic acid" patented technology

2,4-Dichlorophenoxyacetic acid (usually called 2,4-D) is an organic compound with the chemical formula C₈H₆Cl₂O₃. It is a systemic herbicide which selectively kills most broadleaf weeds by causing uncontrolled growth in them, but leaves most grasses such as cereals, lawn turf, and grassland relatively unaffected.

Preparation method and device of 2,4-dichlorphenoxyacetic acid

The invention provides a preparation method and device of 2,4-dichlorphenoxyacetic acid. The preparation method provided by the invention is used for solving the technical problems of heavy pollution, low yield, low content and high cost of the existing synthetic method of 2,4-dichlorphenoxyacetic acid; in the process of synthesizing the 2,4-dichlorphenoxyacetic acid, a special dropwise adding reactor is employed to dropwise add chloroacetic acid and caustic soda liquid simultaneously so that sodium chloroacetate generated through a reaction reacts with sodium phenate before hydrolysis; as lots of heat is released by the reaction between the chloroacetic acid and the caustic soda liquid, the reaction heat needed by condensing the sodium chloroacetate and the sodium phenate is just guaranteed; and independent preparation of brine ice which needs to be consumed to keep the sodium chloroacetate at a low temperature and heating required by a condensation reaction are also avoided. According to the invention, non-reacting phenol is recovered and wastewater is recovered to reduce the amount of the wastewater; and the wastewater contains no phenol and thus is easier to treat; and the preparation method provided by the invention can be applied to synthesis of 2,4-dichlorphenoxyacetic acid and analogues.
Owner:威海韩孚生化药业有限公司

Method for controlling continuous reaction crystal size of 2,4-dichlorphenoxyacetic acid

The invention relates to a method for controlling a continuous reaction crystal size of a herbicide 2,4-dichlorphenoxyacetic acid. The method comprises the following steps: (1) preparing a 80-100 DEG C saturated or nearly saturated solution of a 2,4-dichlorphenoxyacetic acid salt, and 10-38% hydrochloric acid respectively; (2) in a crystallizer, continuously adding the 2,4-dichlorphenoxyacetic acid salt solution and the hydrochloric acid prepared in the step (1), wherein a molar ratio of the 2,4-dichlorphenoxyacetic acid salt to hydrochloric acid is 1 to (1-1.2), controlling the crystallization temperature at 20-60 DEG C, controlling the retention time to 2-10 hours, continuously discharging the material to an after-treatment process to obtain the 2,4-dichlorphenoxyacetic acid product. According to the crystal size control method disclosed by the invention, the 2,4-dichlorphenoxyacetic acid salt is dissolved at a high temperature, the 2,4-dichlorphenoxyacetic acid salt solution and hydrochloric acid are subjected to a continuous reaction crystallization process in the crystallizer at a low temperature, so that the problems that the 2,4-dichlorphenoxyacetic acid product produced by the process of performing acidification reaction at a high temperature and then cooling for crystallizing is low in purity and small in crystal size and easily causes equipment corrosion are solved. The method has the advantages that the prepared produce has a great crystal size and a high purity, energy consumption is low, equipment corrosion is hardly caused, the operation is simplified and the process is easily controlled automatically.
Owner:TIANJIN UNIV OF SCI & TECH +1
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