Hexion Specialty Chemicals, Inc., an Apollo Management L.P. portfolio company, announced the signing of a definitive agreement to acquire Huntsman Corporation in an all-cash transaction valued at approximately $10.6 billion, including assumption of debt.       Under the terms of the agreement, Huntsman stockholders will receive $28 in cash for each outstanding Huntsman share of common stock. The Huntsman Board of Directors unanimously approved the agreement and recommended that Huntsman stockh...