THE MEDIA BUSINESS: ADVERTISING; Chanel makes a big pitch for a new perfume aimed at young women, its toughest market.

FOR the last 81 years, the Chanel name has carried a special resonance for women 30 and older, who have made Chanel No. 5 the world's leading fragrance. But the younger market has proved elusive for Chanel, a state of affairs it intends to change with the introduction of its latest fragrance appealing to 20-somethings. Chanel's name for the new fragrance -- Chance -- is fitting. To capture the fancy of this fickle group of women of ages 18 to 29, Chanel is giving Chance the biggest marketing push in the company's history -- with an introductory budget estimated at more than $12 million. Chanel is flinging itself into a market already crowded by competitors' earlier entrants, like Happy by Clinique and CK One from Calvin Klein. Chanel's aggressive plans are self-explanatory, industry observers said. ''Young consumers are the lifeblood of the beauty industry,'' said Irma Zandl, president of the Zandl Group in New York, a consulting company that specializes in the under-30 age category. ''A brand not recruiting teens or young adults is just getting old.''