Process for producing asymmetric hypomethyl dye
A kind of technology of alkyl group and nitro group, applied in the field of preparing asymmetric methine dyes
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Embodiment 1
[0049] Under nitrogen, 46.2 g of methyl 1,3,3-trimethyl-2-methyleneindoline-5-carboxylate were dissolved in 100 ml of n-butanol. Add 34.8 g of 1-phenyl-3-methyl-5-pyrazolone and stir for about 10 minutes. After adding 22.0 g of trimethyl orthoformate and 1 ml of glacial acetic acid, the mixture was refluxed at (102-105° C.) for 5 hours. A further 3 g of trimethyl orthoformate were then added, after which a further 10 hours of reflux were performed. The batch was cooled with stirring, followed by stirring for 2 hours. It was then filtered by applying vacuum, and the filter cake was washed with 200 ml of methanol, then 500 ml of hot water, and dried at 80° C. under reduced pressure.
[0050] 78.8 g of dye was isolated, which was >98.5% asymmetric methine dye of formula 1 below. This dye gives plastics such as polystyrene a vivid orange finish dyeing. In the absence of the glacial acetic acid catalyst, the yield was reduced by about 4%.
[0051] Formula 1 ...
Embodiment 2
[0052] Example 2 Example 1 was repeated using 41.8 g of 1-phenyl-3-methyl-5-pyrrolidone and 31 g of methyl orthoformate. 85.9 g of a dye mixture containing about 92% of the asymmetric methine dye of formula 1 and about 8% of the symmetric methine dye of the formula below were isolated. When used for the spin dyeing of plastics such as polystyrene, this dye mixture gave a vivid orange coloration, however it was significantly yellower than that produced by the dye prepared according to Example 1.
Embodiment 3
[0054] Under a nitrogen atmosphere, 46.2 g of methyl 1,3,3-trimethyl-2-methyleneindoline-5-carboxylate was dissolved in 100 ml of n-butanol. Add 61.6 g of pyrazolone and stir for about 10 minutes.
[0055] After adding 22.0 g of trimethyl orthoformate, the mixture was refluxed at (102-105° C.) for 5 hours. A further 3 g of trimethyl orthoformate were then added, followed by a further 10 hours of reflux. The batch was cooled with stirring and then stirred for 2 hours. It was then filtered by applying a vacuum and the filter cake was washed with 200 ml methanol and then 500 ml hot water and dried at 80° C. under reduced pressure.
[0056] Recrystallization from butanol afforded 100.6 g of the dye of formula 2, ie 91.6% of theory.
[0057] Formula 2
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