- A CONTINUOUS PROCESS FOR THE SYNTHESIS OF AZO DYES INVOLVING IN-SITU GENERATION OF DIAZONIUM SALTS
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The present disclosure provides a continuous process for the synthesis coupled compounds of diazonium salts including azo dyes involving in-situ generation of diazonium salts. It further discloses a set up to carry out the process for the synthesis of coupled compounds of diazonium salts.
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Paragraph 0051; 0059
(2021/05/21)
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- Method of preparing solvent red 24
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The invention discloses a method of preparing solvent red 24. The method comprises the steps of: feeding ortho-toluidine and methanol into a reactor, dropwise adding 30wt% of hydrochloric acid at 20-25 DEG C, cooling to 2-5 DEG C, dropwise adding 40wt% of sodium nitrite solution, performing thermal insulation for 3h, heating to a room temperature for thermal insulation for 2h, adding soft water, performing stirring and filtering, washing till a pH (potential of hydrogen) of filtrate is neutral, performing drying, feeding ortho-toluidine, the soft water and a single coupling material into the reactor, dropwise adding 30wt% of hydrochloric acid at 20-25 DEG C, cooling to 2-5 DEG C, dropwise adding 20wt% of sodium nitrite solution, performing thermal insulation for 4h, dropwise adding a mixedsolution of 2-naphthol and 5% alkaline liquor at 2-5 DEG C, performing thermal insulation for 2h, regulating the pH, performing thermal insulation for 5h, re-measuring the pH, performing filtering, and repeatedly cleaning and drying a filter cake. According to the method, reaction time is shortened; a reaction is relatively thorough; a product yield is increased by approximately 30%; almost no byproduct is generated; and a product is excellent in color light and strength.
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Paragraph 0016; 0031; 0034; 0035; 0036; 0037
(2018/11/03)
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