Acrobat does not have a tool to do this automatically. A TOC is usually created in the application in which you created your document before you convert to PDF. If you already have a PDF document (e.g. assembled from a number of different documents), then I would create a table of contents in e.g. MS Word, then convert that document into PDF, insert it at the beginning of my existing PDF document and then create the links manually in this new table of contents. There are solutions available that can convert a bookmarks hierarchy into a table of contents, but none of them free as far as I know. The one that I have first hand experience with is the Debenu PDF Aerialist (http://www.debenu.com/products/desktop/debenu-pdf-aerialist/).
Karl Heinz Kremer
PDF Acrobatics Without a Net
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