3 - Methyl-7 - Dialkylamino-1 ,4 - O Phthalazinone -2 - Ketone Acid Condensation

Some 5-dialkyIamino-2-nitrosophenols have been synthesized from the raw material m-aminophenol by N-alkylation, nitrosation with dimethyl sulphate, diethyl sulphate, propyl bromide, butyl bromide respectively.3-methyl-7-dialkylamino-l,4-benzoxazin-2-ones was obtained from these compounds by reduction and cyclization.3-Methyl-7-dialkylamino-l,4-benzoxazin-2-ones are very useful in synthesis of new type fluorescence dyes. The absorption and emission bands of benzoxazinone dyes prepared from these compounds could be changed in a wide range with substituted group and solvent effect.A novel class of dyes were prepared by condensation of 3-methyl-7-dialkylamino-l,4-benzoxazin-2-ones with squaric acid. These novel squarylium dyes have the same characteristics as the conventional squarylium dyes, such as narrow absorptive band, high molar absorptivity, relative stability and minimal absorption of visible light. They are more useful for laser-protective.