Background and overview[1]
1-Benzothiophene-3(2H)-one is an organic intermediate that can be prepared by reacting 2-carboxymethylthiobenzoic acid as a starting material. It can be used to prepare Fluorescent Red 5B. Fluorescent Red 5B is a bluish red oil-soluble solvent pigment with good heat resistance, light resistance, high tinting power and bright color; it can be used for coloring a variety of resins.
Preparation[1]
Synthesis of 1-benzothiophene-3(2H)-one: Weigh 38kg of 2-carboxymethylthiobenzoic acid and 33kg of sodium hydroxide according to the proportion, and mix the above raw materials evenly in a closed-loop kettle. , heated to 180°C, and then performed a ring-closing reaction. The reaction time of the ring-closing reaction was 9 hours. After the ring-closing reaction is completed, add 75kg of water to dilute. The diluted solution is subjected to solid-liquid separation, insoluble matter is removed and the filtrate is collected to prepare an aqueous solution of 1-benzothiophene-3(2H)-one.
Apply[1]
1-benzothiophene-3(2H)-one can be used to prepare fluorescent red solvent pigments: transfer the 1-benzothiophene-3(2H)-one aqueous solution to the oxidation kettle, and add 1-benzothiophene-3(2H)-one to the oxidation kettle. Air was introduced into the aqueous solution of 3(2H)-ketone, heated to 90°C, and then an oxidation reaction was performed. The reaction time of the oxidation reaction was 14 hours. After the oxidation reaction is completed, the temperature is lowered to 35°C, and a filter cake is obtained after solid-liquid separation. The filter cake is washed with water until neutral, and dried to obtain a fluorescent red solvent pigment.
Main reference materials
[1]CN201910806039.5 Fluorescent red solvent pigment and preparation method thereof
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