Transcript Chemistry 30 – Organic Chemistry

Chemistry 30 – Organic
Chemistry - Part 2
To accompany
Inquiry into Chemistry
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
• Do questions 1a, 2, and 3, page 589
Organic Chemistry – 15.1 – Types of Organic
Reactions
• B Addition Reactions
Y
C=C
+ Y–Z
Z
-C–C-
Product has more
bonds! Addition
• Addition can occur with alkene or alkyne:
•
•
•
•
+
+
+
+
water (HOH)
hydrogen (H2)
hydrogen halide (HX)
halogen (X2)
alcohol
alkane
alkyl halide
alkyl halide
see
page
590-1
Organic Chemistry – 15.1 – Types of Organic
Reactions
A fat molecule:
=
O
CH2 – O – C - R
R′
H
O
CH – O – C – R
fats are triesters!
H
H
C=C
H
O
CH2 – O – C - R
=
• Read about trans fats on
page 592
cis
linkage
C=C
=
• Your text has numerous
examples of addition
reactions on page 590
and 591
R′
trans
linkage
Organic Chemistry – 15.1 – Types of Organic
Reactions
• C Elimination Reactions
Y
Z
-C–C-
C=C
+ Y–Z
• 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
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
-C–Y
+
A–Z
-C–Z
+
A-Y
• Examples pages 593 and 594
• Note that for halogens + alkanes, reaction is
very slow (essentially doesn’t occur) without
presence of ultraviolet light
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
R - C – OH
carboxylic
acid
+
HO - R′
alcohol
H2SO4
catalyst
O
=
=
O
R - C – O - R′ + HOH
ester
water
• Esterification is a type of elimination reaction –
water is produced
Organic Chemistry – 15.1 – Types of Organic
Reactions
• Example:
=
O
CH3 – CH2 – C – O - H +
H - O-CH3
H2SO4
Organic Chemistry – 15.1 – Types of Organic
Reactions
• Example:
CH3 – CH2 – C – O - H +
H - O-CH3
H2SO4
O
CH3 – CH2 – C – O – CH3
=
=
O
+ HOH
methyl propanoate
• I prefer to write it in reverse direction (alcohol
1st) to make naming ester easier
H2SO4
O
=
=
CH3 – O – H +
O
H – O – C – CH2 – CH3
CH3 – O – C – CH2 – CH3 + HOH
methyl propanoate
now 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
Reactants
Hydrocarbon* ene or yne +
HOH, X2, HX,
+ O2
or H2
Products
CO2(g) +
H2O(g) or (l)
Elimination
Substitution
Esterification
alcohol or
alkyl halide
alkane or
alcohol +
aromatic + X2 carboxylic
acid
alcohol, alkyl alkene + HOH alkyl halide
halide*,
or HX
alkane
ester +
water
Other
triple or
double to
single
single to
double
acid
catalyst
needed
Other
more bonds*
fewer bonds*
slow; needs
uv light
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 polymerization
the 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
Cl
2
2
2
2
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:
Pt
C2H6(g)
CH2=CH2(g) + H2(g)
ethane
ethene
• Ethene is used to produce ethylene glycol
(ethane-1,2-diol), polyethylene, and
polyvinyl chloride
Organic Chemistry – 15.2 – Polymers and the
Petrochemical Industry
• Manufacture of PVC (polyvinyl chloride):
Step 1:
Cl Cl
C=C
(g) + Cl2(g)
reaction type?
- C – C - (g)
• Step 2:
Cl
Cl Cl
- C – C – (g)
C = C
(g)
+
HCl(g)
reaction type?
HCl from step 2 reacted with more ethene to
Cl Cl
produce more
-C–C-
Organic Chemistry – 15.2 – Polymers and the
Petrochemical Industry
• Step 3:
Cl
n
C=C
Cl
Cl
Cl
………. - C – C – C – C – C – C - ……….
polyvinyl chloride
Organic Chemistry – 15.2 – Polymers and the
Petrochemical Industry
• Heath and Environmental Concerns:
Cl
C=C
• 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 toxic
Biggest source: people burning their own
garbage
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
Organic Chemistry – 15.2 – Polymers and the
Petrochemical Industry