Sulfuric acids camphor treatment

For an excellent formal treatment of the Wagner-Meenvein rearrangements of camphor in sulfuric acid, which makes extensive use of C labeling, see O. R. Rodig and R. J. Sysko, J. Am. Chem. Soc., 94, 6475 (1972). 

Camphor-3-sulfonic acid may also be obtained (73% yield) by treatment of camphor with sulfur trioxide-dioxan at —35 °C, followed by standing the reaction mixture at room temperature (4 hours) and neutralization with sodium hydroxide. This reaction and that with methyl chlorosulfonate probably proceed via the enolic form of the ketone. The formation of 8- and 10-camphorsulfonic acids is considered to involve Wagner and Nemetkin rearrangements of the carbocations formed in the acidic media. ... 

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