Reactions of Organic Compounds I

1. Reactions of Organic Compounds I SCH4U Spring 2012

2. Reactions of Alkanes • Combustion • Alkanes + Oxygen  Carbon Dioxide and Water • C2H6 + 7/2 O2 2CO2 + 3H2O • Reaction with halogen (X) • Needs heat or UV light • Alkane + X2  Halogen Alkane + HX • C2H6 + Cl2  C2H5Cl + HCl (only one Cl atom is substituted)

3. Reactions of Alkenes • Addition • Combustion • Alkenes react with oxygen to form carbon dioxide and water • C2H4 + 3O2 2CO2 + 2H2O • Halogenation • Occurs at room temperature • Alkenes + Halogen  Halogen Alkane • C2H4 + Cl2  C2H4Cl2

4. Reactions of Alkenes • Hydrogenation • Occurs with heat and catalyst • Alkenes + Hydrogen  Alkane • C2H4 + H2  C2H6 • Reaction with hydrogen halides • Occurs at room temperature • C2H4 + HCl  C2H5Cl • Hydration • Uses sulphuric acid as catalyst • C2H4 + H2O  C2H5OH

5. Reactions of Alkenes • Markovnikov’s rule • When an asymmetrical atom is added across a double bond, the hydrogen adds to the carbon with the most hydrogens already attached to it • E.g.

6. Reactions of Alkynes • Same as alkenes • Combustion • One mole alkyne + one mole of (X2 or H2 or HX or H2O)  alkene • One mole alkyne + two moles of (X2 or H2 or HX or H2O)  alkane • Follow Markovnikov’s rule

7. Reactions of Benzene • Substitution (only one atom is substituted) • React with Halogens • Use catalyst • Nitration • Use Nitric and sulphuric acid (HNO3/H2SO4) • Produces NO2 group

8. Reactions of Benzene • Reaction with alkyl halide • Use catalyst

9. Reactions of alkyl halides • Combustion • Substitution • The X group in R-X is replaced by a different group • E.g. R-X + H2O  R-OH + HX

10. Reactions of Alkyl Halides • E.g. alkyl halide is heated with a concentrated solution of ammonia in ethanol • CH3-CH2-Br + NH3 CH3-CH2-NH2 + HBr (primary amine) • CH3-CH2-NH2 + CH3-CH2-Br  CH3-CH2-NH-CH2-CH3 + HBr (secondary amine)

11. Reactions of Alkyl Halides • Elimination • H-X are eliminated from R-X; the product is very often an alkene