Theoretical study of the furfuryl benzoate and furfuryl acetate pyrolysis

Abstract

In the present work, the pyrolysis reaction mechanism of both furfuryl benzoate and furfuryl acetate was evaluated at the M06/6‐311++g(d,p) level. The uncommon methylenecyclobutenone compound and either the benzoic or the acetic acid were determined as the products of a multistep process consisting in two [3 + 3] rearrangements and a subsequent hydrogen α‐elimination step, through a cyclic 5‐membered transition state (TS), being the latter the rate‐limiting step for both reactants. Furthermore, a deeper analysis on the basis of the reaction force formalism showed that the TS is formed in two stages: The first one is characterized by the weakening of the C─O bond, and the second one is where the H atom is transferred from the C atom to its nearest O atom. The H─O bond formation was determined to contribute the most to the electronic activity occurring during the TS formation as suggested by a reaction electronic flux analysis. Accordingly, natural bond orbital calculations showed that the most significant changes occur in the charge distribution of the O and H atoms. Finally, a negligible effect of the substituting group on the reaction was determined since similar activation energies were obtained for the pyrolysis of furfuryl benzoate and furfuryl acetate; however, a minor difference was evidenced in the reaction force results. In this sense, the structural contribution to the activation energy is larger than the electronic one for the furfuryl benzoate reaction, w1SR>w2SR, whereas the opposite is observed for the furfuryl acetate reaction, w1SR>w2SR.

Efficient Dehydration of C6–10-α,ω-Alkanediols to Alkadienes as Catalyzed by Aliphatic Acids

“…Further, pyrolysis of esters may also produce olefins, and this route benefits from less side reactions such as rearrangement and isomerization. ,, In 1959, Froemsdorf reported the first example of pyrolysis of n-butyl acetate to 1-butene at 500 °C . Up till now, however, there are only a few reports on the preparation of alkadiene via the pyrolysis of ester.…”