Low Pressure Koch Reaction by Cu(CO)_n⁺-H₂SO₄-H₃PO₄-H₂O Catalyst (Part 5)

Structural Analysis of Branched tert-Tridecanoic Acids Obtained in the Low Pressure Koch Reaction of Branched Dodecenes

Abstract

Low pressure Koch reaction of branched dodecenes (two species of butene trimers) with Cu(CO)_n⁺-H₂SO₄-H₃PO₄-H₂O catalyst was performed under mild conditions (12°C, 1.6MPa). The structures of these branched dodecenes and tert-tridecanoic acids produced were determined using GC-MS and NMR spectroscopy. Although triisobutylene concentrations of branched dodecenes were different, the compositions of the obtained tert-tridecanoic acids were closely similar. As the results of structural analysis, it was confirmed that the main isomer of tert-tridecanoic acids was 2-t-butyl-2, 5, 5-trimethylhexanoic acid which had 25-40% of tert-tridecanoic acids, and that every tert-tridecanoic acid had t-butyl group in its alkyl groups and one of three alkyl groups was methyl or ethyl group as its structural characteristics. And a mechanism of Cu(CO)_n⁺-catalyzed hydrocarboxylation of branched dodecenes was proposed on the basis of the structures of the reactants and the products.