| 摘要 |
<p>Novel hemiacetals of the formula II <IMAGE> are described in which R' is an aliphatic or cycloaliphatic radical, Ar represents an unsubstituted or substituted mononuclear or polynuclear radical having aromatic or heteroaromatic character and, if appropriate, having non-polar, weakly polar or basic substituents and/or chromophoric groups or groups inducing fluorescence or luminescence. At least one of the substituents X<1>, X<2> and X<3>, preferably all three of the substituents mentioned, must be powerful electron-attracting substituents and are selected from the group of the fluorine atoms, chlorine atoms, bromine atoms or nitro groups, preferably fluorine atoms. The hemiacetals are formed reversibly from the corresponding keto compounds upon contact with an alcohol of the formula R'OH, and during this reaction the absorption of light in the ultraviolet, visible or infra-red range changes, or a fluorescence or luminescence originates or is quenched. Devices containing the keto compounds act as optical sensors for the determination of the alcohols mentioned.</p> |
