SPIRO(INDOLINE-2,2'-2H'-CHROMENE)PHOTOCHROMIC COMPOUNDS

摘要

Photochromic compounds having the formula WHEREIN R1 is a member selected from the group consisting of an alkyl group, a substituted alkyl group, and an aralkyl group; wherein R2 and R3 each is a member selected from the group consisting of an alkyl group and a phenyl group; and, wherein R4 is a member selected from the group consisting of an alkyl group, a nitro group, a halogen atom, an aldehyde group, an alkoxyl group, a carboxyl group, and a carboxylic acid ester group; said alkyl group having from one to five carbon atoms are disclosed. The compounds are useful in recording media where their ability to change color on activation with ultraviolet light is advantageous.