title: Synthesis of defined endocrine-disrupting nonylphenol isomers for biological and environmental studies.
abstract: Nonylphenols are very important environmentally relevant substances in the focus of the world-wide endocrine disrupter research for over 25 years. Thus, they are among the 10 priority hazardous substances of the new European Union Water Framework Directive. They consist of a very complex mixture of isomers representing therefore a multi-component problem like dioxins or PCBs. As estrogenic effect and degradation behavior in the environment of individual 4-nonylphenols are heavily dependent on the structure and bulkiness of the side chain, it is absolutely necessary to consider the nonylphenol problem from an isomer-specific viewpoint. Therefore a range of 28 differently branched nonylphenol isomers were synthesized for biological and environmental studies. Nonylphenols with a quaternary alpha-carbon, like 4-(1,1,3,4-tetramethylpentyl)phenol (4-NP(95)) and 4-(1-ethyl-1,3,3-trimethylbutyl)phenol (4-NP(170)), were obtained by Friedel-Crafts alkylation of anisole with tertiary nonyl bromides and demethylation with BI(3). Nonylphenols with a tertiary alpha-carbon, such as 4-(1,2-dimethylheptyl)phenol (4-NP(10)) and 4-(1,2,4-trimethylhexyl)phenol (4-NP(41)), were accessible via coupling of p-methoxyphenylmagnesium bromide with ketones. Nonylphenols bearing a quaternary beta-carbon, like 4-(2,2-dimethylheptyl)phenol (4-NP(15)) and 4-(1,2,2-trimethylhexyl)phenol (4-NP(39)), were synthesized starting from 4'-methoxyisobutyrophenone. The compounds were characterized by GC-MS and NMR-spectroscopy. The individual isomers were designated according to the Juelich Nomenclature.
authors.affiliation: Institute of Chemistry and Dynamics of the Geosphere, ICG-3: Phytosphere, Research Centre Juelich, D-52425 Juelich, Germany.
authors.forename: Roswitha M
authors.initials: RM
authors.lastname: Boehme
authors.forename: Thomas
authors.initials: T
authors.lastname: Andries
authors.forename: Karl Heinz
authors.initials: KH
authors.lastname: Dötz
authors.forename: Bjoern
authors.initials: B
authors.lastname: Thiele
authors.forename: Klaus
authors.initials: K
authors.lastname: Guenther
mesh_terms: D052244:Endocrine Disruptors / Q000138:chemical synthesis* / Q000737:chemistry; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000138:chemical synthesis* / Q000737:chemistry; D007536:Isomerism; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry*
chemical_list: D052244:Endocrine Disruptors; D004785:Environmental Pollutants; D010636:Phenols; C025256:nonylphenol