Hydrazine sulfate, also known as hydrazine sulfate, is a red scaly crystal or rhombic crystal. The relative density is 1.37, the melting point is 254 ℃, and the decomposition occurs when heating is continued. It is slightly soluble in cold water and easily soluble in hot water. The aqueous solution is acidic and insoluble in ethanol and ether. It is very stable in the air and susceptible to alkali and oxidant. It has strong reducibility. Hydrazine produced by oxidizing ammonia with sodium hypochlorite is prepared by reacting with sulfuric acid, or directly by reacting hydrazine with sulfuric acid. It is used for the gravimetric determination of nickel, cobalt and cadmium, the purification of rare metals and the separation of polonium and tellurium, as well as the precipitation of chlorate, hypochlorite and carboxyl compounds. It is also used for the preparation of isoniazid, furacilin, parahydrazine, anhydrous hydrazine, etc. it is also used as a reducing agent, insecticide and sterilization agent.
Preparation of hydrazine sulfate:
Method 1: sodium hypochlorite was prepared by the reaction of chlorine and sodium hydroxide, then reacted with ammonia to prepare hydrazine hydrate, finally dehydrated to prepare hydrazine, and then reacted with sulfuric acid to prepare hydrazine sulfate.
Method 2: hydrazine sulfate was synthesized from hydrazine hydrate by dropping concentrated sulfuric acid. The specific steps are as follows:
1) Dilute a certain amount of hydrazine hydrate (80%) and then add it into a four necked flask, and slowly cool it in a low-temperature bath.
2) Add 98% concentrated sulfuric acid into the dropping funnel and slowly drop it into the four necked flask, keep the temperature in the flask at about 0-10 ℃, and measure its pH with a pH test paper. The dropping can be stopped when the pH value is 5-7.
3) Cool the solution slowly, stir it slowly, and then keep it for 2 h. white solid can be settled.
4) Add proper amount of methanol into the mixed solution, precipitate and filter to obtain hydrazine sulfate solid.
Method 3: a preparation method of hydrazine sulfate, comprising the following steps:
S1. Using butanone and ammonia as raw materials, air as oxidant, PdCl2 and CuCl2 as catalysts, formamide and sodium bromide as cocatalysts to synthesize butanone and nitrogen;
S2. Separating an upper oil phase containing butanone and nitrogen and an aqueous phase containing a catalyst;
S3. The pH value of the separated oil phase is adjusted to 1-4 with acid, and butanone and nitrogen are acid hydrolyzed into hydrazine salt and butanone;
S4. Adjust the pH value of the solution containing hydrazine salt to 9-12, neutralize the hydrazine salt with alkali to generate hydrazine hydrate, evaporate all hydrazine hydrate and water in the solution, and distill the condensate into hydrazine hydrate solution;
S5. Hydrazine sulfate is prepared by adding concentrated sulfuric acid to hydrazine hydrate, and the product hydrazine sulfate is obtained by cooling crystallization, suction filtration, washing and drying.
Method 4: a preparation method of high-grade pure hydrazine sulfate. The specific preparation steps are as follows: (1) add pure water into the glass lined reactor, slowly add 98% sulfuric acid under stirring and cooling, add 80% hydrazine hydrate at 70-80 ℃ after adding, and filter while hot, wherein the mass ratio of pure water, 98% sulfuric acid and 80% hydrazine hydrate is 10:10:4; (2) The filtrate is adjusted to pH = 4-5 with sulfuric acid or hydrazine hydrate, and stirred for 20-60min. When the pH is unchanged, it is cooled and crystallized to 25 ℃, centrifuged and crystallized, washed with absolute ethanol, and air dried at room temperature to obtain the finished product; The preparation method is simple in process. On the basis of industrial method, a preparation method of chemical reagent hydrazine sulfate has been developed. The product quality reaches the high-grade purity standard and is suitable for the needs of large-scale industrial production.
Hydrazine sulfate is mainly used as a raw material for manufacturing pharmaceuticals and industrial grade azodiisobutyronitrile. It can also be used as a reducing agent, mainly used as a reagent for metal surface treatment and analysis, and also for the purification of rare metals. In agriculture, it is mainly used as insecticide and disinfectant. Its application examples are as follows:
1. Determination of Trace Selenium by hydrazine sulfate Turbidimetry
Selenium is a necessary trace element for many organisms, including human beings. It has many physiological functions such as anti-cancer, anti-oxidation and antagonizing harmful heavy metals. Studies have shown that many malignant diseases are closely related to selenium deficiency, such as thyroid cancer, colorectal cancer, chronic pneumonia, pulmonary tuberculosis, Keshan disease, Kashin Beck disease, reproductive system diseases and so on. Because most of our country is located in the low selenium belt and the content of selenium in the soil is low, people pay more and more attention to increasing the intake of selenium through food and medicine. However, the dose range of selenium poisoning is very narrow, so it has important practical significance to determine the content of selenium in food and medicine.
2. For preparing 4-methylpyrazole
Methylpyrazole is an alcohol dehydrogenase inhibitor approved by the US FDA and produced by orphan medical in early 1998. It is mainly used to rescue alcohols such as ethylene glycol, ethanol and methanol. Firstly, the concentrated sulfuric acid and hydrazine hydrate are used as raw materials to produce hydrazine sulfate by heating and refluxing; Then, sulfuric acid, hydrazine sulfate and potassium iodide are added to the reactor, isobutyraldehyde is added under the condition of continuous stirring for heating and refluxing reaction. After the reaction, the pH of the reaction solution is adjusted to 7, and then the solvent is extracted, dried and evaporated in order to obtain the crude 4-methylpyrazole; Subjecting the obtained crude product to primary vacuum distillation for purification; After the initial purification, the product was added to the mixed liquid of ethyl acetate and petroleum ether for recrystallization, and finally, it was distilled again under reduced pressure to obtain 4-methylpyrazole refined product. The 4-methylpyrazole prepared by the invention can be operated under normal pressure, the preparation method is simple, and is conducive to industrial production; The purity of 4-methylpyrazole is high, and the content of single impurity is less than 0.1%, which fully meets the quality requirements.