I recently did a reaction in the lab where 10-camphor sulfonic acid was used as the catalyst instead of something more conventional like hydrochloric acid or sulfuric acid. Dry acetontrile was used as a solvent. The scheme is shown below:
I'm not too sure why it is used. My initial thoughts are it's due to the solubility of 10-CSA in water/organic solvents. Alongside this using a conventional acid such as hydrochloric acid, the water content of the acid may affect the equilibrium. Although 10-CSA still has water in it, it would not be comparable to hydrochloric or sulfuric acid. 10-CSA also is quite bulky, which could provide some selectivity on which positions are deprotonated, although I don't see this as being likely due to its conjugate base having such a high pKa. Aside from this what else could be plausible explanation for the usage of 10-CSA?