Phospho sulfonic acid as an efficient and recyclable solid acid catalyst for the solvent-free preparation of acylals

- Phospho sulfonic acid (PSA) is synthesized and well characterized.
- The PSA is an excellent solid acid catalyst for the protection of aldehydes with acetic anhydride.
- No chromatographic separations are needed to obtain the protected products.
- The solid acid PSA catalyst is reusable without losing its catalytic activity.