| abstract |
NEW MATERIAL:A spiropyran compound expressed by formula I (A is bivalent organic residue; B is naphthyl or biphenyl; X is C or S substituted by two alkyl groups). EXAMPLE:1-[2-(alpha-Naphthoyloxy)ethyl]-3,3-dimethyl-6'-nitrospiroindo linobenzpopy ran. USE:Useful as photochromic materials for printing, recording, decoration, etc., having excellent fatigue resistance of coloring and decoloring by light. Resins obtained by blending the compound therein are advantageously usable in optical elements having color changing properties, e.g. sunglasses, photometers or curtains. PREPARATION:A compound expressed by formula II is condensed with 5- nitrosalicylaldehyde or a compound expressed by formula III is reacted with naphthalene or biphenyl derivative to afford the aimed compound formula I. |