LEVERKUSEN, Germany (March 3)—Bayer A.G. has opted to keep its Rhein Chemie Rheinau GmbH subsidiary, a spokesman for Leverkusen-based Bayer has confirmed. The decision ends a 15-month bid to find a buyer for the unit, which supplies chemicals to the rubber, polyurethane, plastics and lubricant industries. Bayer hinted in December it would retain Rhein Chemie after a deal to sell the unit to U.S. equity firm Advent International Corp. fell through. Boston-based Advent had offered to pay about $200 million for the firm and assume certain of its debts. Mannheim-based Rhein Chemie likely is to continue to operate as an independent unit, rather than become part of the newly launched Bayer Polymers A.G. structure, a Bayer spokesman indicated. With annual sales of around $330 million, Rhein Chemie employs 1,100.