Why was camphor difficult for chemists to identify correctly?

Identifying the structure of camphor was a significant challenge for 19th-century chemists because the methods available at the time relied entirely on studying chemical reactions.12

Chemists determined structures by observing sequences of reactions and inferring the original substance's structure based on the associated changes. This process was often ambiguous, as multiple potential structures could be considered consistent with the available experimental data. Consequently, more than 30 different structures were proposed for camphor before its correct configuration was finally established.2

Modern analytical techniques, such as nuclear magnetic resonance (NMR), mass spectrometry, and X-ray crystallography, have since replaced the need for relying solely on complex reaction sequences, making the determination of such molecular structures a routine task today.2