Superior activity and selectivity of multifunctional catalyst Pd-DTP@ZIF-8 in one pot synthesis of 3-phenyl propyl benzoate

• Published in: Inorganica Chimica Acta Vol. 490; pp. 282 - 293
• Main Authors: Malkar, Radhika S., Yadav, Ganapati D.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2019; Elsevier Science Ltd
• Subjects: 3-Phenyl propyl benzoate; Alcohol; Anhydrides; Benzoic anhydride; Catalysis; Catalysts; Chemical synthesis; Cinnamyl alcohol; Copper; Esterification; Hydrogenation; In situ leaching; Leaching; Metal-organic frameworks; MOF; Nickel; One pot synthesis; Palladium; Selectivity; Thermal stability; Zeolites; ZIF-8; ZIF-8; MOF; 3-Phenyl propyl benzoate; Hydrogenation; Cinnamyl alcohol; Benzoic anhydride; One pot synthesis
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2019.03.012

[Display omitted] •Preparation of multifunctional ZIF-8 possessing acidic (dodecatungstophosphoric acid-DTP) and metal sites (Pd°).•One pot synthesis of 3-phenyl propyl benzoate over 5% Pd-DTP@ZIF-8 from cinnamyl alcohol and benzoic anhydride.•Pd, Ni and Cu were screened for selective hydrogenation of cinnamyl benzoate.•Fresh and spent catalyst was fully characterized.•Catalyst was active, thermally stable and reusable up to 3 cycles. The catalytic efficiency of zeolitic imidazolate framework (ZIF-8) has been explored by making it multifunctional. Dual active sites were incorporated such as acid (dodecatungstophosphoric acid, DTP) and metal (Pd°) to prepare 5% Pd-DTP@ZIF-8. DTP was encapsulated inside the cage of ZIF-8 by in-situ and bottle around the ship approach whereas Pd was loaded ex-situ by simple wet impregnation method. The catalytic efficiency was tested for one pot synthesis of 3-phenyl propyl benzoate (3-PPB), a perfumery compound, from cinnamyl alcohol and benzoic anhydride. Trans-esterification of cinnamyl alcohol with benzoic anhydride gives cinnamyl benzoate which on further hydrogenation gives 3-PPB. Three different supports were screened such as ZIF-8, K10 and MCF out of which ZIF-8 showed the maximum activity because of its high surface area and smaller pore diameter. Further Pd, Ni and Cu metals were studied for selective hydrogenation of CC bond among which 5% Pd-DTP@ZIF-8 gave almost 98% conversion of cinnamyl benzoate to 3-PPB with 93% selectivity. Fresh and spent catalysts were characterized by various techniques. 5% Pd-DTP@ZIF-8 showed anti-leaching property with great thermal stability. The turn over frequency and turn over number of the catalyst was observed to be 0.058 s−1 and 835, respectively. A kinetic model was developed with good fit using LHHW mechanism and the activation energy calculated as 17.45 kcal/mol for hydrogenation step. Thus, the reaction was found to be kinetically controlled. The entire process is green.