Elements of Unsaturation:Heteroatoms Halogens replace hydrogen atoms in hydrocarbons,so when calculating unsaturations, count halides as hydrogen atoms. Single bond oxygen does not change the C:H ratio, so ignore oxygen in the formula. Nitrogen is trivalent,so it acts like half a carbon. Add the number of nitrogen atoms when calculating unsaturations. H OH NH2 3H+1Br≈4H 4H 4C,6H 2C+1N,5H 2013 Pearson Education Inc. 0 Elements of Unsaturation: Heteroatoms • Halogens replace hydrogen atoms in hydrocarbons, so when calculating unsaturations, count halides as hydrogen atoms. • Single bond oxygen does not change the C:H ratio, so ignore oxygen in the formula. • Nitrogen is trivalent, so it acts like half a carbon. Add the number of nitrogen atoms when calculating unsaturations. 10 © 2013 Pearson Education Inc. H H H Br 3 H + 1 Br ≈ 4 H H H H OH 4 H H O H H 4 C, 6 H H H H NH2 2 C + 1 N, 5 H