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[Chemical Knowledge]：Production and manufacturing method and process flow of o-cresolphthalein

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The manufacturing method
of o-cresolphthalein
o-cresolphthalein (o-cresolphthalein) is an organic compound widely used in the field of chemical production raw materials, mainly used as acid-base indicator and metal complexing agent. This article will introduce the manufacturing method of o-cresolphthalein in detail.

1. raw materials and equipment

1. raw materials: o-cresol, phthalic anhydride, sulfuric acid, sodium hydroxide, ethanol.
2. Equipment: reaction kettle, stirrer, condenser, water separator, filter, oven, grinding machine.

2. manufacturing steps

1. esterification reaction: the o-cresol and phthalic anhydride according to a certain molar ratio into the reaction kettle, adding an appropriate amount of sulfuric acid as a catalyst, start the stirrer and condenser, heating to a certain temperature, esterification reaction. Moisture generated during the reaction is discharged through the water separator.
2. Neutralization reaction: After the esterification reaction is completed, the reaction solution is cooled to room temperature, an appropriate amount of sodium hydroxide solution is added, and the pH value is adjusted to neutral, so that the sulfuric acid catalyst is completely neutralized.
3. Extraction and washing: The neutralized reaction solution was poured into a separatory funnel, an appropriate amount of ethanol was added, and the mixture was shaken thoroughly for extraction. After standing and layering, the upper ethanol phase was poured out, and new ethanol was added for washing. The operation was repeated several times until the washing was clean.
4. Drying and crystallization: The washed ethanol solution of o-cresolphthalein is poured into an oven, and the ethanol is evaporated by heating to obtain crude o-cresolphthalein. The crude product was ground to a powder and recrystallized with an appropriate amount of ethanol to obtain pure o-cresolphthalein.

3. precautions

1. During the esterification reaction, the temperature and pH value should be strictly controlled to avoid the occurrence of side reactions.
2. During the extraction and washing process, ensure sufficient shaking and standing time for sufficient separation and washing.
3. In the process of drying and crystallization, the oven temperature and the evaporation rate of ethanol should be controlled to avoid product decomposition or agglomeration.

4. Yield and Purity

The o-cresolphthalein product with high yield and high purity can be obtained by the above production method. The specific yield and purity are related to the operating conditions, raw material purity and other factors.

5. safety and environmental protection

in the production process, pay attention to abide by the safety operation procedures, to avoid the occurrence of fire, poisoning and other accidents. At the same time, it is necessary to strengthen environmental protection treatment of waste water and waste gas to reduce environmental pollution.

In summary, the manufacturing method of o-cresolphthalein involves multiple chemical reactions and operation steps, and the reaction conditions and operation process need to be strictly controlled to ensure the quality and yield of the product. At the same time, it is necessary to strengthen safety and environmental protection management to ensure the smooth progress of the production process.

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