Oklahoma City -based Tronox Inc. filed for bankruptcy protection on Monday, saying it cannot cope with the environmental and litigation liabilities its former parent, Kerr-McGee Corp. , saddled the chemical company with when it spun it off in 2006.

The Chapter 11 filing by Tronox, the world’s third-largest producer of whitening pigment titanium dioxide, covers only the company’s U.S. operations. Trono...