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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