| 摘要 |
NEW MATERIAL:The fluorene compound of formula I (R1 is 5-8C alkyl; R2-R4 are 1-8C alkyl; n is 4 or 5). EXAMPLE:3-(Diethylamino)-6-(N-methyl-N-isoamylamino)fluorene spiro(9,3')-6'- pyrrolidinophthalide. USE:Useful as an electron-donative color-developing agent having absorption in near infrared region. It develops blue to green color when brought into contact with an acidic substance such as acid clay, phenolic resin or phenolic compound and exhibits absorption in near infrared region of about 700-1000nm wavelength. The developed color image has excellent light fastness, gives a heat-sensitive recording paper having excellent whiteness of highlight and prevents reading error. It has high rate of color development and gives a developed color image having high fastnesses such as water-resistance and moist-heat resistance. PREPARATION:The compound of formula I can be produced by diazotizing a compound of formula II in an inorganic acid at -5-10 deg.C, cyclizing at 10-130 deg.C under stirring and neutralizing with an alkali. |
