Synthesis method of DTPA (diethylene triamine pentacetic acid) penta-sodium salt

Abstract

The invention discloses a synthesis method of a DTPA (diethylene triamine pentacetic acid) penta-sodium salt, and belongs to the field of chemical synthesis. The synthesis method comprises the following steps: dissolving chloroacetic acid into deionized water to obtain a chloroacetic acid solution; adding diethylene triamine into the chloroacetic acid solution for reaction, and maintaining the temperature of a solution reaction system at -20-30 DEG C; slowly adding 2 / 5 to 3 / 5 of sodium hydroxide into the solution reaction system, controlling the reaction temperature at -20-30 DEG C; slowly adding the remaining sodium hydroxide into the reaction system, and controlling the reaction temperature at 30-60 DEG C, and preserving heat and reacting for 2-5 hours after the sodium hydroxide is completely added; adjusting the pH of the reaction system in the step 4) to 11.5, cooling to room temperature, and filtering. According to the synthesis method, the yield of the DTPA penta-sodium salt is improved; in the synthesis process, the reaction is relatively stable and the reaction time is shortened by controlling the alkali dripping speed and the reaction temperature.

Description

Technical field: [0001] The invention relates to the field of chemical industry, in particular to a method for synthesizing DTPA pentasodium salt. Background technique: [0002] Diethylenetriaminepentaacetic acid (DTPA) is an important aminocarboxyl complexing agent, and its pentasodium salt is often used in practical applications. The effect of eliminating color-forming metal ions is very obvious, and it is widely used in textile, dyeing, chemical process control and other aspects. Since the stability and antioxidant capacity of the chelate formed by DTPA and transition metal ions are stronger than those of ethylenediaminetetraacetic acid (EDTA), it can chelate metal ions such as calcium, magnesium, iron, manganese in water, and reduce the impact of metal ions , so it is widely used in the bleaching process of wood pulp. [0003] The DTPA industrial production method has following two kinds at present: the first kind of method is the chloroacetic acid method, CN101607921A...

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Problems solved by technology

[0003] The DTPA industrial production method has following two kinds at present: the first kind of method is the chloroacetic acid method, CN101607921A a kind of preparation method of diethylenetriaminepentaacetic acid, the research of pentasodium diethylenetriaminepentaacetic acid synthetic technique ("Chemical Industry and Engineering Technology" (2008.29. (1). 18-19)), DTPA chelating agent and its manufacture ("Paper and Paper" (2005.3.63-64)), DTPA synthesis process ("Paper Chemicals" (1997.9 ( 4) .7-10)), the synthesis of papermaking chemical DTPA ("China Paper" (1997.5.68-69)) and other documents have introduced this method, which uses chloroacetic acid, diethylenetriamine and hydrogen oxidation Synthesis of raw materials such as sodium or sodium carbonate has a relatively simple process, but a large amount of by-product sodium chloride will be produced during the production process, and the obtained DTPA crude product needs to be desalted and purified. In addition, chloroacetic acid is easy to hydrolyze during the production process, which seriously affects DTPA Yield

[0004] The second method is the sodium cyanide method, the research on the synthesis method of DTPA ("Leather Chemical Industry" (2002.19. (5). 26-28)), the synthesis of diethylenetriaminepentaacetic acid ("Chemical Industry and Engineering Technology" ( 2006.27.(6).24-25)) and other documents introduced this method, using sodium cyanide, formaldehyde and diethylenetriamine and other raw materials to synthesize. The advantages of this method are simple operation, low cost, good product quality, and no Sodium chloride is produced as a by-product, but this method uses highly toxic cyanide as a raw material, making production management difficult to control

[0005] At present, most domestic production of DTPA adopts the chloroacetic acid method, and the yield is low. The yield reported in the literature is mostly below 80%. In addition, the impurity content is high, the salt content is high, and the refining process is backward, so it cannot compete with similar foreign products in the market.

[0006] Above-mentioned chloroacetic acid method reaction equation is as follows, and wherein formula 1, 2 are target reaction equations, but in actual production, when lye is added dropwise, the local concentration of lye may be too large and easily cause the hydrolysis failure of sodium chloroacetate, formula 3 is Sodium chloroacetate is hydrolyzed under strong alkaline conditions to generate sodium glycolate and sodium chloride. As the pH value of the solution system rises further in the later stage, the hydrolysis of sodium chloroacetate may be intensified

Sodium carbonate can also be used in the chloroacetic acid neutralization step, but at a higher cost

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