Synthesis of branched para-nonylphenol isomers: occurrence and quantification in two commercial mixtures.

Eight tertiary nonanols were synthesized via Grignard reaction and coupled by Friedel-Crafts alkylation with phenol to the corresponding nonylphenols. Six branched para-nonylphenols (NP) were obtained: 4-(3'-methyl-3'-octyl)phenol (33NP), 4-(2'-methyl-2'-octyl)phenol (22NP), 4-(2',5'-dimethyl-2'-heptyl)phenol (252NP), 4-(2',5',5'-trimethyl-2'-hexyl)phenol (2552NP), 4-(2',4'-dimethyl-2'-heptyl)phenol (242NP) and 4-(4'-ethyl-2'-methyl-2'-hexyl)phenol (4E22NP). Their structures were confirmed by GC-MS and NMR spectroscopy. These six isomers as well as the earlier synthesized 4-(3',5'-dimethyl-3'-heptyl)phenol (353NP), 4-(3',6'-dimethyl-3'-heptyl)phenol (363NP) and 4-(2',6'-dimethyl-2'-heptyl)phenol (262NP) were compared with commercial NP mixtures purchased from Acros and Fluka by GC-MS (equipped with a 100 m polysiloxane column). The analyses revealed that all obtained isomers are occurring in different quantities in both commercial NP mixtures.