Post on 30-Dec-2015
Organic Chemistry – 15.1 – Types of Organic Reactions
• A Combustion Reactions
• We will focus on complete combustions:hydrocarbon + O2(g) CO2(g) + H2O(g) + energy
• Cellular respiration is a complete combustion (but H2O(l) is produced)
• Many hydrocarbon derivatives also undergo complete combustion
Organic Chemistry – 15.1 – Types of Organic Reactions
• B Addition Reactions
Product has more bonds! AdditionC =
C + Y – Z - C – C
-
Y Z
seepage590-1
• Addition can occur with alkene or alkyne:
• + water (HOH) alcohol• + hydrogen (H2) alkane• + hydrogen halide (HX) alkyl
halide• + halogen (X2) alkyl
halide
Organic Chemistry – 15.1 – Types of Organic Reactions
• Your text has numerous examples of addition reactions on page 590 and 591
• Read about trans fats on page 592
C = C
C = C
CH2 – O – C - R
CH2 – O – C - R
CH – O – C – R
R′
R′
=
=
=
O
O
O
H H
H
H
A fat molecule:
trans linkage
cis linkage
fats are triesters!
Organic Chemistry – 15.1 – Types of Organic Reactions
• C Elimination Reactions
• Essentially the reverse of addition – less bonds
• Alcohols undergo elimination to produce water and an alkene
• Alkyl halides can undergo elimination to produce alkene and hydrogen halide
C = C
+ Y – Z - C – C -
Y Z
Examples on page 593
Organic Chemistry – 15.1 – Types of Organic Reactions
• D Substitution Reactions
• Like name implies, something leaves and is replaced by something else
• Examples pages 593 and 594
• Note that for halogens + alkanes, reaction is very slow (essentially doesn’t occur) without presence of ultraviolet light
- C – Y + A – Z - C – Z + A - Y
Organic Chemistry – 15.1 – Types of Organic Reactions
• Aromatics + halogens will undergo substitution, not addition
Organic Chemistry – 15.1 – Types of Organic Reactions
• E Esterification
• Esterification is a type of elimination reaction – water is produced
R - C – OH
=
O
+ HO - R′
R - C – O - R′
=
O
+ HOHcarboxyli
cacid
alcohol
ester
water
H2SO4
catalyst
Organic Chemistry – 15.1 – Types of Organic Reactions
• Example:
CH3 – CH2 – C – O - H + H - O-CH3
=
O H2SO
4
Organic Chemistry – 15.1 – Types of Organic Reactions
• Example:
=
O CH3 – CH2 – C – O – CH3 + HOH
CH3 – CH2 – C – O - H + H - O-CH3
=
O H2SO
4
methyl propanoate • I prefer to write it in reverse direction
(alcohol 1st) to make naming ester easier
CH3 – O – H + H – O – C – CH2 – CH3 CH3 – O – C – CH2 – CH3 + HOH
=O =O H2SO
4 methyl propanoatenow ester is written in order
of name
Organic Chemistry – 15.1 – Types of Organic Reactions
• Further esterfication examples on page 595 – 6
• Other examples page 596
• Do Practice Problems 1 – 3, page 596 – 7
• Do WS 15.1.5
• Do Investigation 15.A, page 597
Organic Chemistry – 15.1 – Types of Organic Reactions
• Summary:Reaction type
Complete Combustion
Addition Elimination Substitution Esteri-fication
Reactants Hydrocarbon* + O2
ene or yne + HOH, X2, HX, or H2
alcohol or alkyl halide
alkane or aromatic + X2
alcohol + carboxylic acid
Products CO2(g) + H2O(g) or (l)
alcohol, alkyl halide*, alkane
alkene + HOH or HX
alkyl halide ester + water
Other triple or double to single
single to double
slow; needs uv light
acid catalyst needed
Other more bonds*
fewer bonds*
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Bromine test for double bonds
• Bromine, Br2, forms a brown solution (remember electrolysis of KBr(aq)
• If Br2(aq) is mixed with an alkene or alkyne, addition will occur and the brown colour will disappear in the aqueous layer
• If Br2(aq) is mixed with an alkane or aromatic, substitution (slow) will occur and the aqueous layer will remain brown…………..
Organic Chemistry – 15.1 – Types of Organic Reactions
• Read “Octane-Enhancing Compounds” page 599 and
• “Replacing CFC’s” page 600
• Section 15.1 – oral review – question 1 - reaction type
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Polymer: a large long chain molecule with repeating units of small molecules called monomers
• Plastics: polymers that can be heated and shaped into specific shapes and forms
• Plastics are always synthetic, though not all polymers are synthetic
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Addition polymerizationthe reaction is an addition reaction as studied earlier
• Example: polyethylene
CH2=CH2 + CH2=CH2 -CH2-CH2-CH2-CH2- + CH2=CH2
- CH2 – CH2 – CH2 – CH2 – CH2 – CH2 – and on and on
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Other addition polymers:
2 2
2
2
2 2
Cl Cl
Cl
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Condensation polymerization – water produced
• polyesters and nylons
• polyester example:
ester linkage
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• nylon example:
amide linkage: same type of bond present between amino acids in proteins
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Do Practice Problems page 606, questions 7-10
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Ethene (ethylene) is required for the manufacture of many substances in Alberta’s petrochemical industry
• Ethane, obtained from petroleum refining is “cracked” to produce ethene by catalytic cracking:C2H6(g) CH2=CH2(g) + H2(g)
ethane ethene• Ethene is used to produce ethylene glycol
(ethane-1,2-diol), polyethylene, and polyvinyl chloride
Pt
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Manufacture of PVC (polyvinyl chloride):Step 1:
• Step 2:
C = C (g) + Cl2(g) - C – C - (g)
Cl Cl reaction type?
Cl Cl - C – C – (g) C = C (g) +
HCl(g)
Cl
reaction type?
HCl from step 2 reacted with more ethene to produce more Cl C
l - C – C -
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Step 3:Cl n C = C ………. - C – C – C – C – C – C -
……….
Cl
Cl
Cl
polyvinyl chloride
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Heath and Environmental Concerns:
• Vinyl chloride: was found in the 1970’s to be carcinogenic. Workers protected today by government legislation
• Manufacture and disposal of PVC may produce dioxins – highly toxicBiggest source: people burning their own garbage
Cl C = C
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Plastics do not decay or rot – problems?
• Today: recycling programs – manufacture of useful products from recycled plastics
• Note: recycling is not the cure-all. Reducing and reusing are better solutions. Why?
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Natural Polymers
• Carbohydrates: (monomer-glucose) cellulose, starch, glycogen
• Proteins: (monomer-amino acids)
• DNA
Organic Chemistry – 15.2 – Polymers and the Petrochemical Industry
• Section 15.2 Review, page 614, question 1-6