Organocatalyst Promoted Efficient Synthesis of Carboxylic Acid Esters and its Application as Plasticizer for Polyvinyl Chloride

The present work is related to the synthesis of a carboxylic acid ester using lab synthesized triphenylphosphonium triflate catalyst and its application as a plasticizer for polyvinyl chloride (PVC) processing. The high thermal stability of this organocatalyst allows the synthesis of terephthalic acid di-esters with high boiling alcohols such as 1-butanol, 2-ethyl hexanol with higher yield in the range of 55-97 %. Different ester derivatives like dioctyl phthalate (DOP), dioctyl terephthalate (DOTP), n-butyl benzoate, dibutyl terephthalate, dibutyl phthalate, and di-dodecanol terephthalate have been synthesized using triphenylphosphonium triflate organocatalyst. These synthesized ester derivatives are characterized using 1H NMR, GC-MS and HPLC. The purity of different synthesized esters was in the range of 80-99 %. The synthesized Dioctyl terephthalate (DOTP) was used as a plasticizer in PVC and compared the results with commercial DOP plasticizer performance for PVC. The PVC/DOTP composition exhibited comparable performance in terms of mechanical properties like tensile and flexural strength and modulus. No significant change found in hardness and impact strength of both the compositions. Ease of processing observed in case of PVC/DOTP composition due to lower torque as compared to PVC/DOP composition. This indicates DOTP can be a potential alternative to the traditional dioctyl phthalate (DOP) plasticizer for PVC processing. Novel energy efficient process has been developed for diester synthesis using reusable organocatalyst. Developed process required lower reaction time and temperature as compared to conventional process. One of the synthesized ester derivative, dioctyl terephthalate (DOTP) used as plasticizer for PVC processing and compared with the PVC/DOP composition. Both the compositions showed comparable performance.image