The core component of DBDMH (link:https://www.bloomtechz.com/basic-chemicals/raw-materials/dbdmh-cas-77-48-5.html) is dibromohydrin, a derivative of hydantoin and white or light yellow crystalline powder. It is a new type of high-efficiency disinfectant with a wide bactericidal spectrum, strong bactericidal effect, mild performance, and can be decomposed into carbon dioxide, nitrogen and water. The downside is that it dissolves very slowly in water. As a bactericide and algicide, it can effectively kill various bacteria, fungi, viruses, algae, hepatitis virus, Escherichia coli, Staphylococcus aureus, gonorrhea, cholera, Salmonella typhimurium, etc. It can be widely used in disinfection of public places, surface disinfection of environmental objects, disinfection of sanitary products, and food preservation: in aquaculture, it can effectively prevent and control various bacterial and fungal diseases such as fish, turtles, crabs, shrimps, frogs, and shellfish. Diseases; Disinfect and sterilize industrial water, tap water, domestic sewage, and swimming pools.
Because of its wide range of uses, many researchers have studied the product. In order to increase the yield of the product, scientists have carried out various attempts to improve the purity of the product. Here we list four common synthetic methods for 1,3-Dibromo-5,5-dimethylhydantoin (DBDMH):
1. Hydrobrominated urea method:
This method is one of the common methods for synthesizing DBDMH. The steps are as follows:
1.1. Prepare anhydrous acetic acid or methyl chloride solution:
In a dry reaction kettle, add an appropriate amount of anhydrous acetic acid or methyl chloride. Note that the choice of anhydrous solvent depends on experimental conditions and reaction performance.
1.2. Dissolving urea:
Add urea gradually to anhydrous acetic acid or methyl chloride until saturation is reached. The dissolution of urea can be accelerated by stirring and controlling the dissolution temperature at 0-5 degrees Celsius.
1.3. Add liquid bromine:
Slowly and steadily add bromine dropwise to anhydrous acetic acid or methyl chloride dissolved in urea. The best addition rate is to add bromine to the reaction system in the form of trickle flow. At the same time, keep the temperature of the reaction system within the range of 0-5 degrees Celsius.
1.4. Stirring and holding time of the reaction mixture:
During the gradual addition of bromine to the reaction system, the mixture was gently stirred using a stirrer. Stirring of the reaction mixture was continued for 2-4 hours to ensure sufficient reaction.
1.5. Collection of sediment:
At the end of the reaction, you will observe the formation of a white solid precipitate in the reaction mixture, which is the 1,3-Dibromo-5,5-dimethylhydantoin product.
The reaction mixture was filtered using a filter unit to isolate a solid precipitate.
1.6. Wash the solid product:
The resulting solid product was washed with cold ethanol. This step is to remove remaining bromine and other impurities.
Cold ethanol was added to the solid product, stirred and filtered.
This washing step can be repeated several times to ensure the purity of the solid product.
1.7. Drying and purification:
Put the washed solid product into a vacuum desiccator and dry it at an appropriate temperature. This can help remove residual ethanol and moisture, and obtain pure 1,3-Dibromo-5,5-dimethylhydantoin crystals.
In the end, you will get pure DBDMH crystals.
2. Tetrabromocyclospendine method:
The method uses tetrabromocycloclidinone as a raw material to synthesize DBDMH. The steps are as follows:
2.1. Preparation of Bromocyclopentadienylacetone (DMDHPA):
- In a reaction kettle, add an appropriate amount of cyclopentadiene and acetone, add a catalyst (such as borane, etc.), and obtain DMDHPA by heating and reacting. This step can be performed by a known method.
2.2. Reaction with bromine:
- In a dry reaction vessel, add DMDHPA and bromine.
- Heat the reaction system to an appropriate temperature (usually in the range of 60-100 degrees Celsius), and stir the reaction mixture to promote the reaction.
- During the reaction, it was observed that bromine reacted with DMDHPA to generate 1,3-Dibromo-5,5-dimethylhydantoin.
2.3. Isolate the product:
- After the reaction is over, the reaction mixture is cooled and diluted with an appropriate amount of water.
- The product 1,3-Dibromo-5,5-dimethylhydantoin will precipitate as a solid precipitate.
- Separate and collect the solid product using a filtration device.
2.4. Purification and drying:
- The collected solid product may contain impurities that require purification.
- Recrystallization can be performed using solvents such as diethyl ether or chloroform to remove impurities.
- Vacuum drying the pure product to remove residual solvent and moisture to obtain pure 1,3-Dibromo-5,5-dimethylhydantoin.
3. p-toluenesulfonic acid method:
The method prepares DBDMH by reacting p-toluenesulfonic acid and hydrobromic acid. The steps are as follows:
3.1. Preparation of 5,5-dimethylcyclopentadienylacetone (DMDHPA):
- In a reaction kettle, add appropriate amount of cyclopentadiene and acetone, and add catalyst (such as borane, etc.) at the same time.
- The cyclization reaction is carried out by heating the reaction to generate 5,5-dimethylcyclopentadienylacetone (DMDHPA).
- This step can be performed using known methods.
3.2. Reaction with bromine:
- Dissolve p-toluenesulfonic acid in a sufficient amount of acetonitrile.
- Add DMDHPA to the reaction vessel and slowly add bromine dropwise.
- It is recommended to perform the reaction under temperature control, usually in the range of 0-10 degrees Celsius.
- As the reaction proceeds, bromine is observed to react with DMDHPA to form 1,3-Dibromo-5,5-dimethylhydantoin.
3.3. Isolation of the product:
- After the reaction is finished, dilute the reaction mixture, and appropriate amount of acetonitrile or deionized water can be used.
- The product 1,3-Dibromo-5,5-dimethylhydantoin will precipitate as a solid precipitate.
- Separate and collect the solid product using a filtration device.
3.4. Purification and drying:
- The collected solid product may contain impurities that require purification.
- Recrystallization can be performed using solvents such as diethyl ether or chloroform to remove impurities.
- Vacuum drying the pure product to remove residual solvent and moisture to obtain pure 1,3-Dibromo-5,5-dimethylhydantoin.
4. Pyridine method:
The method uses pyridine as a raw material to synthesize DBDMH. The steps are as follows:
4.1. Preparation of pyridine-2,4-dicarboxylic acid:
- In a reaction flask, mix pyridine and formic acid and add catalyst (eg pyrophosphate triester).
- The reaction is usually carried out at a higher temperature, such as a boiling reaction.
- After the reaction is complete, pyridine-2,4-dicarboxylic acid is obtained.
4.2. Reaction with sodium nitrite:
- Dissolve pyridine-2,4-dicarboxylic acid in sufficient solvent such as chloroform.
- Add appropriate amount of sodium nitrite to adjust the pH value.
- Stir the reactants at low temperature.
- As the reaction proceeds, production of nitrosopyridine compounds is observed.
4.3. Bromination reaction:
- Transfer the reactants to another container.
- Add appropriate amount of cuprous bromide (CuBr2) as catalyst.
- As the reaction proceeds, a substitution reaction of nitrosopyridine with bromine is observed to form a bromopyridine compound.
4.4. Isolation of the product:
- After the reaction is finished, dilute the reaction mixture, and appropriate amount of ethyl acetate can be used.
- Adjust the pH, usually with sodium bicarbonate (NaHCO3) solution.
- Separate the organic and aqueous phases and collect the organic phase.
4.5. Purification and drying:
- Remove the solvent from the organic phase using a rotary evaporator to obtain the bromopyridine compound.
- For the purification of bromopyridine, methods such as recrystallization or column chromatography can be used.
- Vacuum drying the pure product to remove residual solvent and moisture to obtain pure 1,3-Dibromo-5,5-dimethylhydantoin.
These are brief descriptions of four common synthetic methods for 1,3-Dibromo-5,5-dimethylhydantoin (DBDMH). Please note that when performing these chemical synthesis reactions in the laboratory, you must strictly follow the safe operating procedures of chemical experiments and ensure that they are carried out under appropriate conditions. If you need more detailed and specific chemical information, please refer to relevant chemical literature and professional materials.