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Reactions of Unsaturated Hydrocarbons. Combustion. Complete combustion C 3 H 6 + O 2 → CO 2 + H 2 O Incomplete combustion C 3 H 6 + O 2 → C + CO + CO 2 + H 2 O. Combustion. Complete combustion
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Combustion • Complete combustion C3H6 + O2→ CO2 + H2O • Incomplete combustion C3H6 + O2→ C + CO + CO2 + H2O
Combustion • Complete combustion 2 C3H6 + 9 O2→ 6 CO2 + 6 H2O • Incomplete combustion C3H6 + 3 O2→ C + CO + CO2 + 3 H2O
Addition Reactions • Take place on unsaturated compounds because they contain double or triple bond • Two atoms are added to carbons joined in multiple bond • What can be added? • X2 H2 H2O HX
Addition • Addition of halogen • Alkenes form dihaloalkanes CH3–CH = CH – CH3 + Cl2 CH3–CH = CH2 + Br2 Solution is on the next slide
Addition on Alkyne • Alkynes produce dihaloalkenes or tetrahaloalkanes CH3– C ≡ C – CH3 + Cl2 CH3– CH2–C ≡ CH + Br2 Solution is on the next slide
H2C=CH2 + H2 H H H-C-C-H H H Heat, catalyst Addition • Addition of Hydrogen • Catalysts normally used such as Pt, Pd or Ni • Known as Hydrogenation • Alkene becomes an alkane • Alkyne becomes and alkene or alkane
Hydrogenation CH3– C ≡ C – CH3 + H2 CH3–CH = CH2 + H2 CH3– CH2–C ≡ CH + H2 Solution is on the next slide
Addition • Addition of Water • Occurs in the presence of acid (H+) • Known as Hydration • Alkene becomes an alcohol • Alkynes do not produce alcohols this way! (produces ketone or aldehyde)
Hydration CH3– CH =CH – CH3 + H2O
Addition of H2O on Asymmetrical Alkenes • Asymmetrical alkenes – an alkenes that has different groups on either side of the double bond CH3–CH = CH – CH3 symmetric CH3– CH2–CH = CH2 asymmetric
Markovnikov’s Rule • States that the carbon with most hydrogen atoms receives even more hydrogen atoms in an addition reaction • According to the Markovnikov’s rule, the addition of two asymmetrical reactants forms primarily one product. • Only small amount of the other isomer is found.
CH3– CH2–CH =CH2 + H2O CH3–CH =CH2 + H2O Solution is on the next slide
H H H-C-C-H H X H X H-C- C-H H X H2C=CH2 + HX HC=CH + HX H-C=C-H H X + HX Addition • Addition of Hydrogen Halides (HX) • HX = HCl, HBr, HI (Not HF) • Alkene becomes an alkyl Halide • Alkynes form monohalo alkenes or dihaloalkanes with the halogens on the same carbon
Addition of HX on Asymmetrical Alkenes • Markovnikov’s Rule applies CH3– CH2–CH = CH2 + HBr