Although the nucleophilic alkylation of aromatics has recently been achieved with a variety of potent main group reagents, all of this reactivity is limited to a stoichiometric regime. We now report that the ytterbium(II) hydride, [BDI YbH] (BDI = CH[C(CH )NDipp] , Dipp = 2,6-diisopropylphenyl), reacts with ethene and propene to provide the ytterbium(II) n-alkyls, [BDI YbR] (R = Et or Pr), both of which alkylate benzene at room temperature. Density functional theory (DFT) calculations indicate that this latter process operates through the nucleophilic (S 2) displacement of hydride, while the resultant regeneration of [BDI YbH] facilitates further reaction with ethene or propene and enables the direct catalytic (anti-Markovnikov) hydroarylation of both alkenes with a benzene C-H bond. Dipp Dipp Dipp Dipp 2 3 2 2 N 2

Bisphenol-a is an estrogenic compound which is a degradation product of the polymer bisphenol-a glycidyl methacrylate (BIS-GMA) used in dental materials. Human exposure to bisphenol-a may also arise from epoxy resins used as coatings in food and beverage cans. Bisphenol-a is an industrial pollutant and has been detected in atmospheric fallout and surface waters, which may also contribute to exposure. Therefore, a study was undertaken to estimate potential exposure from composite resin dental materials, from canned foods and beverages and from ambient air. Applying probabilistic exposure assessment methods, and using available data and information on the release of bisphenol-a from dental composites, on bisphenol-a concentrations in canned foods, canned beverages and ambient air, total adult exposure was estimated for the Canadian population. Calculations indicated that mean total exposure from all sources was about 65 times lower than a tolerable daily intake (TDI) for bisphenol-a derived by Health Canada to address potential estrogenic effects of this compound. Maximum estimated exposure was also less than this TDI. On average, composite resin dental materials and canned foods contributed approximately equally to total exposure whereas canned beer, canned soft drinks and ambient air were relatively insignificant sources of exposure.

Although the nucleophilic alkylation of aromatics has recently been achieved with a variety of potent main group reagents, all of this reactivity is limited to a stoichiometric regime. We now report that the ytterbium(II) hydride, [BDI YbH] (BDI = CH[C(CH )NDipp] , Dipp = 2,6-diisopropylphenyl), reacts with ethene and propene to provide the ytterbium(II) n-alkyls, [BDI YbR] (R = Et or Pr), both of which alkylate benzene at room temperature. Density functional theory (DFT) calculations indicate that this latter process operates through the nucleophilic (S 2) displacement of hydride, while the resultant regeneration of [BDI YbH] facilitates further reaction with ethene or propene and enables the direct catalytic (anti-Markovnikov) hydroarylation of both alkenes with a benzene C-H bond. Dipp Dipp Dipp Dipp 2 3 2 2 N 2