reactions of unsaturated hydrocarbons combustion complete combustion c 3 h 6 + o 2 → co 2 + h 2 o...
TRANSCRIPT
Reactions of Unsaturated Hydrocarbons
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
CH3 – CH = CH2
+ Cl2
+ Br2
Solution is on the next slide
Addition on Alkene
Addition on Alkyne
• Alkynes produce dihaloalkenes or tetrahaloalkanes
CH3 – C ≡ C – CH3
CH3 – CH2 – C ≡ CH
+ Cl2
+ Br2
Solution is on the next slide
Addition on Alkyne
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
H2C=CH2 + H2 Heat, catalyst
H HH-C-C-H H H
Hydrogenation
CH3 – C ≡ C – CH3
CH3 – CH2 – C ≡ CH
CH3 – CH = CH2 + H2
+ H2
+ H2
Solution is on the next slide
Hydrogenation
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
Hydration
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
H2C=CH2 + HX H HH-C-C-H H X
HC=CH + HX
H-C=C-H H X
H XH-C- C-H H X
+ HX
Addition of HX on Asymmetrical Alkenes
• Markovnikov’s Rule applies
CH3 – CH2 – CH = CH2 + HBr