WILMINGTON, Del. — Chemical maker Huntsman Corporation says an outside appraisal firm believes a proposed $6.5 billion buyout by Hexion Specialty Chemicals would result in a solvent combined entity.

Huntsman says in a filing Friday with the Securities and Exchange Commission that it expects to ask American Appraisal for a formal opinion at the appropriate time.

Huntsman and Hexion are in a courtroom battle in Delaware that will decide whether Hexion should be held to its buyout commitment. Hexion says Huntsman's deteriorating finances make the deal no longer viable. It's suing Huntsman to free itself from the deal and a $325 million breakup fee.

Hexion officials describe the timing of Huntsman's SEC filing as "peculiar." They say Huntsman doesn't have a solvency certificate demanded by two banks that would finance the leveraged buyout.