Ester pyrolysis of carbonates: bis(benzene hydrate) carbonate as potential precursor for monomeric carbonic acid

• Published in: European Journal of Organic Chemistry
• Main Author: Bucher, G.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2010
• Subjects: Carbonic acid
• Online Access: http://eprints.gla.ac.uk/36936/

The twofold ester pyrolysis of carbonates, yielding monomeric carbonic acid, was investigated by computational methods. By comparison with CCSD(T)/cc-pVTZ//B3LYP/ccpVTZ benchmark calculations, the M05-2X method was found to give the most accurate reaction enthalpies among the DFT methods employed. While the first ester pyrolysis of diethyl carbonate, (E)-bis(acetdldoxime) carbonate or diN,N-dimethylhydroxylaniine carbonate will yield the corresponding monocarbonates, these highly labile compounds are predicted to decay via alternative reaction channels that result in the formation of carbon dioxide. Due to competing O-O bond homolyis reactions, dialkyl diperoxycarbonates are predicted to afford at best moderate yields of monomeric carbonic acid upon flash vacuum pyrolysis. The carbonate derived frorn "benzene hydrate" (cyclohexa-2,4-dien-l-ol), however, is predicted to be an ideal precursor for monomeric carbonic acid, undergoing ester pyrolysis in a very facile reaction, with no competing bond homolysis processes.