Structure Elucidation Of C-80, C-81 And C-82 Isoprenoid Tetraacids Responsible For Naphthenate Deposition In Crude Oil Production

A series of C-80 isoprenoid 20-bis-16,16'-biphytanyl tetraacids has previously been found to be responsible for calcium naphthenate scaling in crude oil processing. This paper describes the structure elucidation by high-field NMR spectroscopy of the structures of the series of homologous C-80 tetraacids containing 4-8 five-membered rings. In addition, the structures of methyl-substituted C-81 and C-82 analogues containing 7 and 8 five-membered rings have been determined for the first time. The biosynthetic implications are discussed.