Preparation method of dimethyldiallylammonium chloride

Abstract

The invention discloses a preparation method of dimethyldiallylammonium chloride, which comprises the following steps: in a continuous pipeline type reactor, keeping the temperature at 15-35 DEG C, reacting a dimethylamine water solution having a flow rate of u kg / h and chloropropene having a flow rate of 1.27-1.54u / n kg / h until the free amine concentration is lower than 3.8*10<-4> mol / g, wherein the pH value is controlled at 7.0-12.0 in the reaction process; then, regulating the reaction temperature to 35-60 DEG C, controlling the pH value of the reaction solution at 8.5-12.0, and further reacting until the free amine concentration is 5.1*10<-5> mol / g; and after the reaction is finished, further performing post treatment, and purifying to obtain dimethyldiallylammonium chloride. According to the invention, a continuous method is used, so that no evacuation problem exists, and nitrogen gas gap substitution is not required; through the on-line control on the pH value, the dropwise adding amount of the liquid alkali is controlled, thereby maximally relieving the hydrolysis of the chloropropene, improving the product yield and reducing the production of three wastes; and due to continuous production, all operating parameters are constant, and a DCS (distributed control system) can be used to perform full-automatic control. Thus, the error and deviation caused by artificial operation can be eliminated, and the product quality is more stable.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a preparation method of dimethyl diallyl ammonium chloride. Background technique [0002] Allyl chloride and liquid caustic soda are used in the production process of dimethyl diallyl ammonium chloride (DMDAAC for short). The traditional interstitial process is to add liquid caustic at one time, which instantly makes the pH value very high, and the high pH value is beneficial to allyl chloride. The hydrolyzate, allyl alcohol (a polymerization chain transfer agent, toxic) has a serious inhibitory effect on the subsequent polymerization of DMDAAC. In order to slow down the negative effect of allyl alcohol on subsequent applications, the traditional process has adopted separation measures. Separation The wastewater containing allyl alcohol or the exhaust gas containing allyl alcohol in the separation process are all three wastes treatment problems. In addition,...

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Problems solved by technology

[0002] Allyl chloride and liquid caustic soda are used in the production process of dimethyl diallyl ammonium chloride (DMDAAC for short). The traditional interstitial process is to add liquid caustic soda at one time, which instantly makes the pH value very high, and the high pH value is beneficial to allyl chloride. The hydrolyzate, allyl alcohol (a polymerization chain transfer agent, toxic) has a serious inhibitory effect on the subsequent polymerization of DMDAAC. In order to slow down the negative effect of allyl alcohol on subsequent applications, the traditional process has adopted separation measures. Separation The wastewater containing allyl alcohol or the exhaust gas containing allyl alcohol in the separation process are all three wastes treatment problems. In addition, the hydrolysis of allyl chloride also reduces the product yield, so reducing the hydrolysis of allyl chloride has greater industrial significance

[0004] Although DMDAAC has entered large-scale production, the design of the device is still simply scaled up according to the old gap method. The gap method production process has the following problems: ①The quality is poor in repeatability, and the polymerization activity of each batch of products is different, which directly affects downstream applications. ; ② The gap method frequently vents and feeds materials, so that a large amount of oxygen-containing air enters the reaction system, so that the raw materials dimethylamine, chloropropene and intermediate product allyl dimethylamine are oxidized, resulting in high color of the product and reducing the Product quality; ③The operating parameters of the gap method are highly dependent on human beings. Occasional human errors and human working conditions will become obstacles to product quality stability

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