Optimization of the terpineol synthesis from turpentine oil using p−toluenesulfonic acid catalyst

Abstract

P-Toluenesulfonic acid (PTSA) has been identified as a promising homogeneous acid catalyst for the direct hydration of α-pinene (AP), which accounts for approximately 82 % of Vietnam turpentine oil, to produce terpineol. The efficiency of this transformation is influenced by multiple parameters, including the relative molar ratios of reactants, catalyst, and solvent, as well as reaction temperature and time. To support the expansion of this process into industrial applications, this study employed Response Surface Methodology (RSM), a statistical optimization approach, to identify the optimal reaction conditions. In the context of optimized conditions: The molar ratio of AP/PTSA was 1:1, H₂O/PTSA was 26:1, and IPA/PTSA was 5:1. The process was conducted at 66 °C for 2.5 h, resulting in a high AP conversion of 98 % and a total terpineol selectivity of 50 %, with α-terpineol accounting for 46 %. Notably, the PTSA catalyst exhibited high levels of activity even after three reuse cycles, thereby substantiating its recyclability. These findings underscore the process as a cost-effective, environmentally friendly, and technically viable route for industrial-scale terpineol production from turpentine oil.