Pure Guanidine Hydrochloride CAS 50-01-1

A method for purifying pharmaceutical grade guanidine hydrochloride, which comprises the following steps: (a) under normal pressure, add 500 g of water into the mixer, then add 1200 g of crude guanidine hydrochloride, stir at 60 ° C for 30 min, stir evenly and then pump into a coarse filter to remove mechanical impurities and incompletely dissolved solid particles to obtain Guanidine hydrochloride crude guanidine aqueous solution; (b) The crude guanidine hydrochloride aqueous solution obtained by removing mechanical impurities and incompletely dissolved solid particle impurities through a coarse filter is pumped into an ultrasonic crystallization system for continuous and cyclic treatment to obtain guanidine hydrochloride clear liquid to induce the precipitation of fine impurities (the ultrasonic crystallization system adopts Continuous treatment type, which has an internal circulation system to recycle the crude guanidine hydrochloride aqueous solution) to obtain guanidine hydrochloride clear liquid; the operation control parameters of the ultrasonic crystallization system are: temperature 60 ° C, pressure and normal pressure, hydraulic residence time 60min and The frequency of the ultrasonic power source is 20KHz; the above-mentioned ultrasonic crystallization system adopts self-developed equipment, as shown in Figure 2, including a static component 1, an ultrasonic-induced crystallization component 2 and a filter press 3. The ultrasonic-induced crystallization assembly 2 includes a liquid inlet pipe 22 for feeding the crude guanidine hydrochloride aqueous solution, and a plurality of ultrasonic crystallizers 21 (three in this embodiment, three in this embodiment, one end of the liquid inlet pipe 22 and a plurality of ultrasonic crystallizers 21 connected in series through the pipes. The specific number can be selected according to actual needs) and a liquid outlet pipe 23 with one end connected to the ultrasonic crystallizer 21 (the most downstream one, which is defined according to the flow direction of the crude guanidine hydrochloride aqueous solution); the static component 1 includes a static tank 10. The clear liquid outlet pipe 11 whose one end communicates with the upper end of the stationary tank 10, and the impurity enrichment liquid outlet pipe 12 whose one end is communicated with the lower end of the stationary tank 10, is installed in the stationary tank 10 and has one end connected to the lower end of the stationary tank 10. The liquid conduit 13 connected to the other end of the liquid outlet pipe 23 and the conical separator assembly 14 installed in the static tank 10 and matched with the liquid conduit 13 (the conical separator assembly 14 is arranged in the liquid conduit). The bottom of the other end of the tube 13 communicates with it, including a central tube and a conical baffle installed on the side wall of the central tube and communicated with it. The effluent of the component is buffered and then introduced into the stationary tank 10, so that impurities can be gradually enriched to the bottom of the stationary tank 10; at this time, the level of the guanidine hydrochloride clear liquid in the stationary tank 10 rises and passes The liquid outlet pipe 11 overflows or discharges); the filter press 3 is respectively connected with the other end of the impurity-enriched liquid outlet pipe 12 and the middle of the liquid inlet pipe 22 through the pipeline, and is used to filter the impurity-enriched liquid after pressure filtration. The filtrate is re-introduced into the liquid inlet pipeline 22 for recycling, and the filter cake produced by the pressure filtration can be outsourced; (c) Pump the guanidine hydrochloride clear liquid that has been induced to remove impurities by the ultrasonic crystallization system into the precision filter to remove the fine impurity grains not completely removed by the ultrasonic crystallization system; then pump the guanidine hydrochloride solution that has passed through the precision filter into the decolorizer , in order to remove the trace amount of cyanamide impurities dissolved in the solution to obtain a refined guanidine hydrochloride solution, the process conditions of the decolorizer are: temperature 60 ℃, pressure 0.15MPa (G) and hydraulic residence time 30min; (d) pumping the purified guanidine hydrochloride solution into the finished product crystallizer for crystallization and purification; separating the crystals and drying to obtain pharmaceutical grade guanidine hydrochloride; the yield is 85% (calculated as crude guanidine) and the purity is 99.7%.