| abstract |
The invention relates to naphthol derivatives of the general formula I n<IMAGE>n in which n n R<1>, R<2> and R<3> are identical or different and each represents hydrogen or an alkyl or alkoxy group, where at least one of the radicals is a (C8-C30)-alkyl or alkoxy radical, n R<4> denotes hydrogen or an alkyl group, n R<5> denotes a nitro group, an alkyl group substituted by halogen, a cyano group, a sulphonamide group or an alkylsulphonyl group, n X denotes nitrogen or the radical CR<6> and n Y denotes sulphur or the radical CR<7> = CR<8>, in which n R<6>, R<7> and R<8> are identical or different and each denotes hydrogen, halogen, a nitro group, a cyano group, an alkyl or haloalkyl group or an alkylsulphonyl group, n a method for their preparation and their use as a pH indicator or in methods and compositions for determining an ion in an aqueous liquid. |