Synthetic preparation process of a new type of refined guanidine hydrochloride

Guanidine hydrochloride is often used as an intermediate in medicines, pesticides, dyes and other organic compounds, it is also an important raw material for sulfonamides and folic acid; it can be used as a strong denaturants in the extraction of total RNA from cells. The proportion of traditional refined guanidine hydrochloride synthetic preparation process is simple, and the operation in each process is not strict: such as mixing impurities during stirring, temperature is difficult to observe, and weighing is inaccurate. Both of them lead to the problem that the low purity of the Guanidine HCL and the incomplete reaction. Then how to solve these problems?


Researchers have developed a new guanidine hydrochloride synthetic preparation process, which solves the shortcomings of the prior part. As a preference, the following steps are included:


1. Ratio: (1) dicyandiamide 350g, ammonium chloride 450g, ammonium carbonate 50g, (2) dicyandiamide 168g: ammonium chloride 203g: ammonium carbonate 19g; weighting by electronic precision balance, one prefabricated, another reserved.
2. Preparation, adding the pre-formed raw materials to the reaction kettle with electric heating function, adding the spare raw materials to the porcelain quality cup (high-temperature disinfection after washing and drying before operation), and uniformly stirring the raw materials in reaction kettle through the non-front glass rod. The raw materials in the porcelain cup are are added to the reaction kettle after the raw materials in that are uniformly stirred;
3, heating, the reactor is heated to 170°C±5°C, and monitored by a temperature sensor;
4. The synthesis reaction is carried out in a reactor environment of 170°C±5°C for three hours;

5. Preparation was completed, and the reaction vessel was opened to obtain 385 g of hydrazine hydrochloride.


The preparation process not only has a precise ratio, the reaction temperature is convenient for observation and control, no impurity is mixed during stirring, the reaction is complete, and the prepared guanidine hydrochloride is also high in purity.


Edited by Suzhou Yacoo Science Co., Ltd.

Preparation Of Graphene Using Guanidine Hydrochloride As Reducing Agent

Guanidine hydrochloride, which is often used as an intermediate in medicines, pesticides, dyes and other organic compounds, is an important raw material for sulfonamides and folic acid; it can be used as a strong denaturants in the extraction of total RNA from cells, and used for denaturation and complexation of proteins. It can be used as an antistatic agent for synthetic fibers. In addition, it can also be used as a reducing agent to prepare graphene.

Graphene is a two-dimensional crystal composed of carbon atoms with only one layer of atomic thickness. It is an ultra-thin material with high strength and toughness. It has a large breaking strength which is 200 times more than steel. It has 20% stretching range and excellent electrical conductivity.

Due to its unique quantum effect and excellent electrical, thermal and mechanical properties, graphene has broad application in nanoelectronic devices and integrated circuits, flexible electronic devices, ultra-high sensitive sensor devices and other new electronic devices, composite materials, solar cells, super capacitors, hydrogen storage materials, etc.

The Existing Preparation Method

At present, preparation methods of graphene mainly include physical mechanical stripping method, vapor deposition method and chemical method. Mechanical methods include micro-mechanical stripping methods, epitaxial growth methods and heating of SiC. It is difficult to prepare graphene with large area and uniformly thick.

Compared with physical methods, chemical method for preparing graphene has a high yield. It has the advantages of simple preparation method, low cost and large-scale production, and thus becomes a common method for preparing graphene. However, in the reduction of graphene oxide, the selected reducing agents are mainly hydrazine hydrate and its derivatives, NaBH4, p-phenylenediamine, sulfur compounds, etc. Most of the reducing agents are toxic and explosive, which is not conducive to large scale production.

Therefore, it is necessary to develop a simple, efficient, low-cost and environmentally friendly method.

The researchers developed a method for preparing graphene with guanidine hydrochloride (CAS 50-01-1) as a reducing agent [1]:

(1) Dispersing graphene oxide in water, treating with a cell disrupter for 20~90min and then continuing ultrasonic for 10~60min to obtain a uniformly dispersed graphene oxide with a concentration of 0.1~10mg/mL;

(2) Adding soluble polymer (one of polyvinylpyrrolidone, polyacrylamide, polyvinyl alcohol, polyethylene glycol, hydroxymethyl cellulose, polyacrylic acid) to the graphene oxide dispersion, ultrasonic dispersion 5~30min, a mixed solution of polymer and graphene oxide is obtained, and the mass concentration of the soluble polymer in the mixed solution is 0.01~0.1 mg/mL;

(3) Adding guanidine hydrochloride to the above mixed solution, the mass ratio of guanidine hydrochloride to graphene oxide is 10:1~100:1, and adding alkaline solution (10%~28% ammonium hydroxide, 0.1~5mol/L NaOH solution, 0.1~5mol/L KOH solution) to adjust the pH to 8~12, stir in the oil bath (60~100°C), the reaction time is 1~5h. The water-soluble graphene is obtained by centrifuging and washing.

The preparation method has the advantages of simple preparation process, low equipment requirement, and easy preparation of graphene in large quantities; the presence of the soluble high molecular polymer greatly improves the water solubility of the graphene, and is also beneficial to the further preparation of the graphene film. Guanidine hydrochloride (Guanidinium chloride) can be used as a reducing agent to prepare graphene which can be stably dispersed in an aqueous solution, and the prepared graphene can be used for constructing sensor and electrical device.

Reference

[1] Ma Qi, Song Jinping, Guo Yong, et al. A method for preparing graphene with guanidine hydrochloride as a reducing agent. CN104261393B, 29 June 2016.

Edited by Suzhou Yacoo Science Co., Ltd.