John C. Kotz Paul M. Treichel John Townsend http://academic.cengage.com/kotz Chapter 10 Carbon: More Than Just Another Element John C. Kotz • State University of New York, College at Oneonta 2 Important – Read Before Using Slides in Class Instructor: This PowerPoint presentation contains photos and figures from the text, as well as selected animations and videos. For animations and videos to run properly, we recommend that you run this PowerPoint presentation from the PowerLecture disc inserted in your computer. Also, for the mathematical symbols to display properly, you must install the supplied font called “Symb_chm,” supplied as a cross-platform TrueType font in the “Font_for_Lectures” folder in the "Media" folder on this disc. If you prefer to customize the presentation or run it without the PowerLecture disc inserted, the animations and videos will only run properly if you also copy the associated animation and video files for each chapter onto your computer. 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Thank you. © 2009 Brooks/Cole - Cengage ORGANIC CHEMISTRY © 2009 Brooks/Cole - Cengage 3 4 cinnamaldehyde eugenol © 2009 Brooks/Cole - Cengage 5 Types of Organic Compounds • Vast majority of over 20 million known compounds are based on C: organic compounds. • Generally contain C and H + other elements • Great variety of compounds © 2009 Brooks/Cole - Cengage Isomerism • Isomers have identical composition but different structures • Two forms of isomerism – Constitutional (or structural) – Stereoisomerism • Constitutional – Same empirical formula but different atomto-atom connections • Stereoisomerism – Same atom-to-atom connections but different arrangement in space. © 2009 Brooks/Cole - Cengage 6 7 Structural Isomers © 2009 Brooks/Cole - Cengage 8 Stereoisomers: Geometric Geometric isomers can occur when there is a C=C double bond. Cis-2-butene © 2009 Brooks/Cole - Cengage Trans-2-butene 9 Stereoisomers: Optical • Optical isomers are molecules with non-superimposable mirror images. • Such molecules are called CHIRAL • Pairs of chiral molecules are enantiomers. • Chiral molecules in solution can rotate the plane of plane polarized light. © 2009 Brooks/Cole - Cengage 10 Chiral Compounds—Polarized Light © 2009 Brooks/Cole - Cengage 11 Stereoisomers Isomers Chirality generally occurs when a C atom has 4 different groups attached. Lactic acid © 2009 Brooks/Cole - Cengage Stereoisomers Isomers Lactic acid isomers are nonsuperimposable © 2009 Brooks/Cole - Cengage 12 Chirality: Handedness in Nature These molecules are non-superimposable mirror images. © 2009 Brooks/Cole - Cengage 13 Chirality: Handedness in Nature These amino acids are nonsuperimposable mirror images. © 2009 Brooks/Cole - Cengage 14 Stereoisomers in Nature Right- and lefthanded seashells The DNA here is right-handed © 2009 Brooks/Cole - Cengage 15 16 The egg cases of the whelk have a righthanded twist. © 2009 Brooks/Cole - Cengage 17 Hydrocarbons • Compounds of C and H • Subgroups: – Alkanes: C-C single bonds – Alkenes: C=C double bonds – Alkynes: carbon-carbon triple bonds – Aromatic: based on benzene © 2009 Brooks/Cole - Cengage 18 Hydrocarbons • Alkanes have the general formula CnH2n+2 • CH4 = methane • C2H6 = ethane • C3H8 = propane • C4H10 = butane • C5H12 = pentane © 2009 Brooks/Cole - Cengage 19 © 2009 Brooks/Cole - Cengage Methane Hydrate, CH4(H2O)x © 2009 Brooks/Cole - Cengage 20 CH3CH2 CH2CH2 CH3 Pentane Hydrocarbons & Structural Isomerism 21 CH3 CH3CHCH2CH3 2-Methylbutane CH3 H3CCCH3 CH3 2,2-Dimethylpropane Note names of isomers © 2009 Brooks/Cole - Cengage Isomers of C5H12? C5H12 has 3 structural isomers. C6H14 has 5 C7H14 has 9 22 Hydrocarbons: Alkanes Alkanes are colorless gases, liquids, and solids Generally unreactive (but undergo combustion) Not polar (or low polarity) and so are not soluble in water. © 2009 Brooks/Cole - Cengage 23 Hydrocarbons: Cycloalkanes All compounds are flexible. Cyclohexane, C6H12, has interconverting “chair” and “boat” forms. Axial H ato m H H 4 H H Eq u ator ial H atom H 5 6 2 3 H H H H 1 HH Chair form © 2009 Brooks/Cole - Cengage 4 H H 1 H 6 5 H 3 H 2 H H H H H H H Boat form H H H H 5 4 H 3 HH H H 1 6 H H 2 H Chair form H 24 Alkenes: Compounds with C=C Double Bonds • How many isomers are possible for a compound with the formula C4H8? 3 4 CH2CH3 H 1 C H 1 C 2 C H 3 CH3 H 1-butene © 2009 Brooks/Cole - Cengage H 1 H3C 2 C 4 CH3 2 C CH3 2-methylpropene (isobutene) H 4 CH3 H 3 C 2 C H cis-2-butene 1 H3 C 3 C H trans-2-butene 25 Alkenes— Many Occur Naturally © 2009 Brooks/Cole - Cengage 26 Reactions of Alkenes: ADDITION REACTIONS • Alkenes are unsaturated — more bonds can form to the C atoms • Molecules such as Br2, H2, HCl, HBr, and H2O add to the double bond H C C + Br2 H H H © 2009 Brooks/Cole - Cengage Br Br H C C H H H 1,2-dibromoethane An Addition Reaction Fat placed in Br2 vapor • The fat in bacon is partially unsaturated. The fat adds Br2 to the C=C bonds. • Fats can be “hydrogenated” with H2. © 2009 Brooks/Cole - Cengage 27 An Addition Reaction Fat placed in Br2 vapor PLAY MOVIE © 2009 Brooks/Cole - Cengage 28 An Addition Reaction • Fats can be “hydrogenated” with H2. PLAY MOVIE Peanut butter has partially hydrogenated vegetable oil. © 2009 Brooks/Cole - Cengage 29 30 CH3(CH2)7CH=CH(CH2)7CO2H Trans Fatty Acids tend to raise total blood cholesterol © 2009 Brooks/Cole - Cengage 31 Trans Fatty Acids Food Percentages of TransFatty Acids Butter Soft Margarine Hard Margarine Vegetable Oils, Including Safflower, Sunflower, and Soy Beef burger, Fried or Grilled Chocolate Cake with Icing © 2009 Brooks/Cole - Cengage 3.6 5.2 12.4 0 0.8 7.1 Alkynes • Alkynes have carbon-carbon triple bonds. • C2H2: common name = acetylene systematic name = ethyne Preparation: CaC2(s) + H2O(liq) --> C2H2 (g) + Ca(OH)2(s) ∆fHo(C2H2, g) = +226.7 kJ/mol ∆rH for C2H2 + O2 = –1300 kJ/mol © 2009 Brooks/Cole - Cengage 32 33 Aromatic Compounds • Benzene, C6H6, in the top 25 chemicals produced in the U.S. • Starting point for hundreds of other compounds. © 2009 Brooks/Cole - Cengage 34 Resonance in Benzene • C6H6 has two resonance structures with alternating double bonds. • The π electrons are delocalized over the ring. H C HC H C C C H H CH H H C C H C C H CH C H Resonance structures of benzene, C6 H6 © 2009 Brooks/Cole - Cengage H C HC H C C C H H CH Abbreviated representation of resonance structures 35 Resonance in Benzene • CC bond order is _______________ • C–C single bond = 154 pm C=C bond = 134 pm • CC bonds in benzene = 139 pm π electrons delocalized © 2009 Brooks/Cole - Cengage 36 Bonding in Benzene © 2009 Brooks/Cole - Cengage 37 Other Aromatic Hydrocarbons Toluene © 2009 Brooks/Cole - Cengage Naphthalene Benzene Derivatives 38 Aniline Phenol C6H5NH2 TNT trinitrotoluene C6H5OH C6H4CH3(NO2)3 © 2009 Brooks/Cole - Cengage Naming Benzene Derivatives Cl 1 6 2 3 5 4 39 Ortho to Cl Meta to Cl Para to Cl 1,4-dimethylbenzene Common name: Para-xylene © 2009 Brooks/Cole - Cengage 40 Reactions of Aromatics • Substitutions — not additions — are typical. CH3 + CH3Cl AlCl3 AlCl3 is a catalyst. Catalysts typically used in aromatic substitutions. © 2009 Brooks/Cole - Cengage + HCl 41 Functional Groups See Chemistry Now, Chapter 10 © 2009 Brooks/Cole - Cengage 42 Alcohols • Characterized by –OH group • Name: add –ol to name of hydrocarbon Methanol Butanol © 2009 Brooks/Cole - Cengage 43 Structures of Alcohols C3H5OH: how many structural isomers? H H H H C C C H H H 1-propanol OH H H OH H C C C H H H H 2-propanol Naming: Add -ol to name of 3-C hydrocarbon. Indicate position of OH with number. © 2009 Brooks/Cole - Cengage 44 Alcohol Properties • Alcohols are a derivative of water • Many alcohols dissolve in water Methanol dissolves in water. © 2009 Brooks/Cole - Cengage Butanol is NOT soluble in water. 45 “Sterno” • Alcohols burn in air • A mixture of ethanol + calcium acetate = STERNO © 2009 Brooks/Cole - Cengage GLYCOLS Alcohols with Two OH Groups Ethylene glycol © 2009 Brooks/Cole - Cengage 46 47 Alcohol Reactions Screen 11.6 PLAY MOVIE Substitution © 2009 Brooks/Cole - Cengage PLAY MOVIE Elimination—the reverse of addition 48 TYPES OF ALCOHOLS H Primary R C OH CH3 CH2 OH, ethanol H CH3 R Secondary R C OH R R C R © 2009 Brooks/Cole - Cengage H3 C C H H Tertiary rubbing alcohol OH OH 49 More Alcohol Reactions H H C H C OH ( ) + Oxidizin g agent H H H Eth anol H O C C H ( ) H Acetaldehyde + Oxidizin g agent Ethanol is a PRIMARY ALCOHOL. It is oxidized to an ALDEHYDE and then to an ACID. © 2009 Brooks/Cole - Cengage H H O C C OH ( ) H Acetic acid 50 More Alcohol Reactions OH R—C—R' H Secondary alcohol oxidizing agent O R—C—R' Ketone (–R and –R' are organic groups. They may be the same or different.) SECONDARY ALCOHOLS are oxidized to KETONES — and reaction stops there. © 2009 Brooks/Cole - Cengage 51 Sugars: Related to Alcohols • Sugars are carbohydrates, compounds with the formula Cx(H2O)y. CHO H OH 4 HO HO 5 3 H H OH 2 H 3 H OH 4 H OH 5 H HO 2 HO 1 OH OH a-D-glucose H 1 CH2OH H OH 4 HO HO 5 HO 1 3 H H 2 OH H b-D-glucose Open chain form What is the difference between a and b D-glucose? © 2009 Brooks/Cole - Cengage OH 52 Sucrose and Ribose H OH HO HO HO HO H OH O H H CH2OH H HO Fructose H © 2009 Brooks/Cole - Cengage O H a-D-Glucose OH H OH H H H Deoxyribose, the sugar in the OH H DNA CH2 OH backbone. O Amines 53 Alcohols are derivatives of H2O (R–OH) and amines are derivatives of NH3. Methylamine © 2009 Brooks/Cole - Cengage Dimethylamine Trimethylamine Amines 54 Amines generally have terrible odors! Cadaverine Pyridine © 2009 Brooks/Cole - Cengage Amines 55 Amines, like NH3, are bases 2 C6H5NH2 (aq) + H2SO4(aq) Aniline © 2009 Brooks/Cole - Cengage 2 C6H5NH3 +(aq) + SO42-(aq) Anilinium ion Amines 56 Many natural products and drugs (such as nicotine and cocaine) are bases. H+ © 2009 Brooks/Cole - Cengage Nicotine 57 O C Aldehyde © 2009 Brooks/Cole - Cengage Compounds with Carbonyl Group Carboxylic acid Ketone 58 Structures of Aldehydes Cinnamaldehyde © 2009 Brooks/Cole - Cengage Odors from aldehydes and ketones Carboxylic Acids Acetic acid Acids are found in many natural substances: bread, fruits, milk, wine © 2009 Brooks/Cole - Cengage 59 Benzoic acid Carboxylic acid group with acidic H+ All are WEAK acids Carboxylic Acids 60 H O C O O Formic acid, HCO2H, gives the sting to ants. © 2009 Brooks/Cole - Cengage C CH3 O Aspirin, acetylsalicylic acid 61 Acids + Alcohols --> ESTERS Esters have generally pleasant odors © 2009 Brooks/Cole - Cengage 62 Acids + Alcohols --> ESTERS O O CH 3COH + CH 3CH 2OH Acetic acid H+ CH 3COCH 2CH 3 + H 2O Ethyl acetate Ethanol O O RC—O—H + R'—O—H Carboxylic acid Alcohol H+ RC—O—R' + H 2O Ester One of the important reactions in nature! © 2009 Brooks/Cole - Cengage 63 Acids + Alcohols --> ESTERS 3-methylbutanol Acetic acid O H3C C CH3 O CH2 CH2CHCH3 3-methylbutylacetate Many fruits such as bananas and strawberries contain esters. © 2009 Brooks/Cole - Cengage Glycerol Alcohol with 3 OH Groups Combine this with long chain acids f ??? Fatty acids f fats and oils © 2009 Brooks/Cole - Cengage 64 65 Fats and Oils H2 C HC H2 C O O CR O O CR O O CR What is the functional group in a fat or oil? © 2009 Brooks/Cole - Cengage R = organic group with NO C=C bonds C12 = Lauric acid C16 = Palmitic acid C18 = Stearic acid R = organic group WITH C=C bonds C18 = oleic acid H2 C HC H2 C O O CR O O CR O O CR 66 Fats and Oils Fats with C=C bonds are usually LIQUDS Oleic acid: a monounsaturated fatty acid C=C bond © 2009 Brooks/Cole - Cengage H2 C HC H2 C O O CR O O CR O O CR 67 Fats and Oils Fats with saturated acids (no C=C bonds) are SOLIDS. Saturated fats are more common in animals. © 2009 Brooks/Cole - Cengage 68 Fats and Polar Bears • Bears gorge on blubber in the winter. • During the summer bears rely on stored fat for energy. • Burn 1-1.5 kg of fat per day. • Water for metabolism comes from fat burning. © 2009 Brooks/Cole - Cengage 69 Trans Fatty Acids • Oleic acid is a mono–unsaturated cisfatty acid • Trans fatty acids have deleterious health effects. • Trans fatty acids raise plasma LDL cholesterol and lower HDL levels. C=C bond © 2009 Brooks/Cole - Cengage 70 Fats and Oils: Saponification Glyceryl stearate, a fat + NaOH O CH2 O CR O + 3 NaOH CH O CR O CH2 O CR R = —(CH2 )16CH3 CH2 OŃ H CH OŃ H CH2 OŃ H Glycerol © 2009 Brooks/Cole - Cengage O + 3 RCŃ O- Na+ Sodium stearate, a soap 71 Acids + Amines --> AMIDES N-methylacetamide © 2009 Brooks/Cole - Cengage 72 Acids + Amines --> AMIDES H C H H H O H O C C C C C C N C H H H H Amide link Acetaminophen Tylenol, Datril, Momentum, ... © 2009 Brooks/Cole - Cengage 73 Alpha-Amino Acids H2N H O C C OH R Amine H Alanine H3C © 2009 Brooks/Cole - Cengage C Chiral a-carbon NH3 CO2 Acid 74 Peptides and Proteins O H 3N OŠ H CH3 Alanine HOCH 2 H 3N + H OŠ O Serine peptide bond – H2O H HOCH2 H H 3N O N H O OŠ CH3 Adding more peptide links ---> PROTEIN © 2009 Brooks/Cole - Cengage Polymers • Giant molecules made by joining many small molecules called monomers • Average production is 150 kg per person annually in the U.S. © 2009 Brooks/Cole - Cengage 75 76 Polymer Classifications • Thermoplastics (polyethylene) soften and flow when heated • Thermosetting plastics — soft initially but set to solid when heated. Cannot be resoftened. • Other classification: plastics, fibers, elastomers, coatings, adhesives © 2009 Brooks/Cole - Cengage 77 Polymer Preparation • Addition polymers — directly adding monomer units together • Condensation polymers — combining monomer units and splitting out a small water (water) © 2009 Brooks/Cole - Cengage Polyethylene: Addition Polymer n H2 C CH2 Ethylene H H C C H H n Polyethylene A polymer with a molar mass of 1e6 has about 360,000 units. © 2009 Brooks/Cole - Cengage 78 Mechanism of Addition Polymerization PLAY MOVIE © 2009 Brooks/Cole - Cengage 79 80 Types of Polyethylene Linear, high density PE (HDPE) Branched, low density PE, LDPE © 2009 Brooks/Cole - Cengage Cross-linked PE, CLPE 81 Types of Polyethylene Polymers based on Substituted Ethylenes, CH2=CHX CH2CH OH CH2CH n polyvinyl alcohol CH2CH OCCH3 n O polyvinyl acetate n polystyrene Table 10.12: others are PVC, acrylonitrile, polypropylene, polymethyl methacrylate © 2009 Brooks/Cole - Cengage Polystyrene • Polystyrene is nonpolar material and dissolves in organic solvents. • PS foam is mostly air, and when it dissolves it collapses to a much smaller volume. © 2009 Brooks/Cole - Cengage 82 83 Slime! Slime is polyvinylalcohol cross-linked with boric acid © 2009 Brooks/Cole - Cengage Bubble Gum! A copolymer Styrene + butadiene © 2009 Brooks/Cole - Cengage 84 85 Condensation Polymers O n HOC O COH + n HOCH2CH2OH terephthalic acid O C ethylene glycol O COCH2CH2O + H2 O n Polyethylene terephthalate (PET), a polyester © 2009 Brooks/Cole - Cengage 86 Polyesters, PET Jackets made from recycled PET soda bottles © 2009 Brooks/Cole - Cengage Soda bottles, mylar film. 87 Polyesters: Mechanism PLAY MOVIE © 2009 Brooks/Cole - Cengage 88 Polyamides: Nylon PLAY MOVIE © 2009 Brooks/Cole - Cengage 89 Polyamides: Nylon •Each monomer has 6 C atoms in its chain. •A polyamide link forms on elimination of HCl •Result = nylon 66 •Proteins are polyamides © 2009 Brooks/Cole - Cengage Polymer Recycling Symbols LDPE = HDPE = PP = V= © 2009 Brooks/Cole - Cengage Low density PE = 0.910-0.925 g/cm3 High density PE = 0.941-0.965 Polypropylene = 0.90 PVC (Vinyl chloride) = 1.30-1.58 90