| abstract |
Hemiacetals are disclosed which correspond to the following formula II <IMAGE> II in which R' is an aliphatic or cycloaliphatic residue, Ar is an unsubstituted or substituted monocyclic or polycyclic aromatic or heteroaromatic residue and X1, X2 and X3 are selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, fluoro, chloro, bromo and nitro, wherein however at least one of said substituents has to be selected from the stated halo atoms or nitro. The hemiacetals are formed reversibly from an alcohol and a corresponding keto compound and the hemiacetals of formula II differ from the corresponding keto compounds as to their light absorption in the ultraviolet, visible or infrared range, or a fluorescence or luminescence is created or quenched when the keto compound is converted into the hemiacetal of formula II. Said reaction can be performed in sensors which are used for the optical determination of alcohols. |