Manufacturing method of o-cresolphthalein
o-cresolphthalein (o-cresolphthalein) is an organic compound widely used in the field of raw materials for chemical production, mainly used as acid-base indicator and metal complexing agent. This article will introduce the manufacturing method of o-cresolphthalein in detail.
I. Raw materials and equipment
1. Raw materials: o-cresol, phthalic anhydride, sulfuric acid, sodium hydroxide, ethanol.
2. Equipment: reactor, stirrer, condenser, water separator, filter, oven, grinder.
2. Manufacturing steps
1. Esterification reaction: add o-cresol and phthalic anhydride into the reaction kettle according to a certain molar ratio, add an appropriate amount of sulfuric acid as a catalyst, turn on the stirrer and condenser, and heat up to a certain temperature to carry out the esterification reaction. The water produced during the reaction is discharged through a water separator.
2. Neutralization reaction: After the esterification reaction, cool the reaction solution to room temperature, add appropriate amount of sodium hydroxide solution and adjust the pH to neutral, so that the sulfuric acid catalyst is completely neutralized.
3. Extraction and washing: Pour the neutralized reaction solution into a partition funnel, add appropriate amount of ethanol, and extract with sufficient shaking. After the stratification, the upper ethanol phase is poured out and new ethanol is added for washing, and the operation is repeated several times until it is washed clean.
4. Drying and crystallization: The washed o-cresolphthalein ethanol solution was poured into an oven and heated to evaporate the ethanol to obtain the o-cresolphthalein crude product. Grind the crude product into powder and recrystallize it with appropriate amount of ethanol to get pure o-cresolphthalein.
III. Precautions
1. During the esterification reaction, the temperature and pH should be strictly controlled to avoid the occurrence of side reactions.
2. During extraction and washing, ensure sufficient shaking and standing time for adequate separation and washing.
3. In the drying and crystallization process, the oven temperature and the evaporation rate of ethanol should be controlled to avoid decomposition or agglomeration of the product.
4. Yield and purity
By the above manufacturing method, the o-cresolphthalein product with high yield and high purity can be obtained. The specific yield and purity are related to the operating conditions, purity of raw materials and other factors.
V. Safety and environmental protection
In the production process, it is necessary to pay attention to the safety operation procedures to avoid fire, poisoning and other accidents. At the same time, it is necessary to strengthen the environmental protection management of waste water and waste gas to reduce the pollution of the environment.
In conclusion, the manufacturing method of o-cresolphthalein involves several chemical reactions and operational steps, which need to strictly control the reaction conditions and operation process to ensure the quality and yield of the product. At the same time, safety and environmental protection management should be strengthened to ensure the smooth progress of the production process.
