Preparation Method of Guanidine Thiocyanate|CAS:593-84-0|

Guanidine salts are widely used in the production of biomedicine, dyes and resin components. Free guanidine is a crystalline organic base, the alkalinity is equivalent to the strength of sodium hydroxide. Free guanidine is not stable enough to be stored easily, so it is sold in the market in the form of salt in practical applications. Common guanidine salts include: guanidine hydrochloride, guanidine thiocyanate, guanidine carbonate, guanidine phosphate and so on. Among them, guanidine hydrochloride and guanidine thiocyanate are common guanidine salts in nucleic acid extraction lysis solutions. They not only provide a high-salt environment, but also inactivate nucleases, release nucleic acids, and protect nucleic acid molecules, especially in the process of extracting all RNA from samples. Compared with guanidine hydrochloride, guanidine thiocyanate is more complete, which makes the detection results more rapid and accurate. Therefore, in this application field, the demand for high-purity guanidine thiocyanate is greater.

Among the currently known technologies for synthesizing guanidine thiocyanate: Patent US2700056 prepares guanidine thiocyanate by heating ammonium thiocyanate. This direct synthesis method requires higher temperature and pressure, and requires high equipment; used in patent CN103058889A Guanidine carbonate is used as a raw material to produce guanidine thiocyanate. This method uses a carbonate exchange method, which has problems of efficiency and economy. In order to overcome the shortcomings of the current technology, Yacoo adopts a salt exchange method to prepare guanidine thiocyanate. The specific preparation steps are as follows:

1. Add solvent, guanidine hydrochloride, and thiocyanate (alkali metal thiocyanate or ammonium thiocyanate) to the reaction flask in sequence, stir and mix thoroughly, and react for 2.5h-3.5h while stirring at 60℃-75℃, filter the crystals to obtain the reaction solution, where in the molar ratio of guanidine hydrochloride to the thiocyanate is 1:0.8-1.3, the weight ratio of solvent to guanidine hydrochloride is 8-10:9.5-10, and the solvent is water, One or more combinations of alcohol solvents (methanol, ethanol, isopropanol) and aprotic organic solvents (dimethyl sulfoxide or acetone).

2. Add the reaction liquid to the pre-cooled reaction flask, stir and filter, and then filter to obtain a solid.

3. Dissolve the solid in water, heat to 50℃, add activated carbon, stir and filter to obtain a filtrate.

4. Place the filtrate in the freezer overnight, then filter and dry to obtain guanidine thiocyanate.

The salt exchange method is adopted, the reaction process is lower than 80°C, and no gas is released during the preparation process, which is superior to the existing synthesis method (which requires high temperature, high pressure and other reaction conditions, and there is gas release during preparation). The preparation process of the invention is more controllable and environmentally friendly in the production process, has lower product cost, high production efficiency and good product quality.

References

CN112209856A A preparation method of guanidine thiocyanate