1 ORGANIC CHEMISTRY

2 Types of Organic Compounds 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

3 Isomerism Isomers have identical composition but different structuresIsomers have identical composition but different structures Two forms of isomerismTwo forms of isomerism –Constitutional (or structural) –Stereoisomerism ConstitutionalConstitutional –Same empirical formula but different atom- to-atom connections StereoisomerismStereoisomerism –Same atom-to-atom connections but different arrangement in space.

4 Structural Isomers

5 Cis-2-butene Stereoisomers: Geometric Geometric isomers can occur when there is a C=C double bond. Trans-2-butene

6 Optical isomers are molecules with non-superimposable mirror images.Optical isomers are molecules with non-superimposable mirror images. Such molecules are called CHIRALSuch molecules are called CHIRAL Pairs of chiral molecules are enantiomers.Pairs of chiral molecules are enantiomers. Chiral molecules in solution can rotate the plane of plane polarized light.Chiral molecules in solution can rotate the plane of plane polarized light. Stereoisomers: Optical

7 Chiral Compounds and Polarized Light

8 Stereoisomers Isomers Chirality generally occurs when a C atom has 4 different groups attached. Lactic acid

9 Stereoisomers Isomers Lactic acid isomers are nonsuperimposable

10 Chirality: Handedness in Nature These molecules are non-superimposable mirror images.

11 Chirality: Handedness in Nature These amino acids are non- superimposable mirror images.

12 Stereoisomers in Nature Right- and left- handed seashells The DNA here is right-handed

13 Compounds of C and HCompounds of C and H Subgroups:Subgroups: –Alkanes: C-C single bonds –Alkenes: C=C double bonds –Alkynes: carbon-carbon triple bonds –Aromatic: based on benzene Hydrocarbons

14 Alkanes have the general formula C n H 2n+2Alkanes have the general formula C n H 2n+2 CH 4 = methaneCH 4 = methane C 2 H 6 = ethaneC 2 H 6 = ethane C 3 H 8 = propaneC 3 H 8 = propane C 4 H 10 = butaneC 4 H 10 = butane C 5 H 12 = pentaneC 5 H 12 = pentane Hydrocarbons

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16 Methane Hydrate, CH 4 (H 2 O) x

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18 Gas hydrates have been known for many years, and combustion of a sample of methane hydrate is seen on the front cover. Recently, however, vast deposits of methane hydrate were discovered deep within sediments on the floor of the world’s oceans. How these deposits were formed is a mystery. But what is important is their size. It is estimated that the global methane hydrate deposits contain approximately tons of carbon, or about twice the combined amount in all reserves of coal, oil, and conventional natural gas. Now if scientists and engineers could only solve the problem of extracting the methane conveniently and safely! Methane Hydrate, CH 4 (H 2 O) x

19 Hydrocarbons & Structural Isomerism C 5 H 12 has 3 structural isomers. C 6 H 14 has 5 C 7 H 14 has 9 C 5 H 12 has 3 structural isomers. C 6 H 14 has 5 C 7 H 14 has 9 Isomers of C 5 H 12 ? Note names of isomers

20 Alkanes are colorless gases, liquids, and solids Generally unreactive (but undergo combustion) Not polar (or low polarity) and so are not soluble in water. Hydrocarbons: Alkanes

21 All compounds are flexible. Cyclohexane, C 6 H 12, has interconverting “chair” and “boat” forms. Hydrocarbons: Cycloalkanes

22 Alkenes: Compounds with C=C Double Bonds How many isomers are possible for a compound with the formula C 4 H 8 ?How many isomers are possible for a compound with the formula C 4 H 8 ?

23 Alkenes— Many Occur Naturally

24 Reactions of Alkenes: ADDITION REACTIONS Alkenes are unsaturated — more bonds can form to the C atomsAlkenes are unsaturated — more bonds can form to the C atoms Molecules such as Br 2, H 2, HCl, HBr, and H 2 O add to the double bondMolecules such as Br 2, H 2, HCl, HBr, and H 2 O add to the double bond

25 An Addition Reaction The fat in bacon is partially unsaturated. The fat adds Br 2 to the C=C bonds.The fat in bacon is partially unsaturated. The fat adds Br 2 to the C=C bonds. Fats can be “hydrogenated” with H 2.Fats can be “hydrogenated” with H 2. Fat placed in Br 2 vapor

26 An Addition Reaction Fat placed in Br 2 vapor

27 An Addition Reaction Fats can be “hydrogenated” with H 2.Fats can be “hydrogenated” with H 2. Peanut butter has partially hydrogenated vegetable oil.

28 Alkynes Alkynes have carbon-carbon triple bonds.Alkynes have carbon-carbon triple bonds. C 2 H 2 : common name = acetylene systematic name = ethyneC 2 H 2 : common name = acetylene systematic name = ethyne Preparation: CaC 2 (s) + H 2 O(liq) --> C 2 H 2 (g) + Ca(OH) 2 (s) ∆H f o (C 2 H 2, g) = kJ/mol Preparation: CaC 2 (s) + H 2 O(liq) --> C 2 H 2 (g) + Ca(OH) 2 (s) ∆H f o (C 2 H 2, g) = kJ/mol ∆H rxn for C 2 H 2 + O 2 = –1300 kJ/mol

29 Aromatic Compounds Benzene, C 6 H 6, in the top 25 chemicals produced in the U.S.Benzene, C 6 H 6, in the top 25 chemicals produced in the U.S. Starting point for hundreds of other compounds.Starting point for hundreds of other compounds.

30 Resonance in Benzene C 6 H 6 has two resonance structures with alternating double bonds.C 6 H 6 has two resonance structures with alternating double bonds. The π electrons are delocalized over the ring.The π electrons are delocalized over the ring.

31 Resonance in Benzene CC bond order is _______________CC bond order is _______________ C–C single bond = 154 pm C=C bond = 134 pmC–C single bond = 154 pm C=C bond = 134 pm CC bonds in benzene = 139 pmCC bonds in benzene = 139 pm π electrons delocalized

32 Other Aromatic Hydrocarbons TolueneNaphthalene

33 Benzene Derivatives Aniline C 6 H 5 NH 2 Phenol C 6 H 5 OH TNT trinitrotoluene C 6 H 4 CH 3 (NO 2 ) 3

34 Naming Benzene Derivatives 1,4-dimethylbenzene Common name: Para-xylene

35 Reactions of Aromatics SubstitutionsSubstitutions — not additions — are typical. AlCl 3 is a catalyst. Catalysts typically used in aromatic substitutions.

36 Functional Groups See CD-ROM Screens 11.5 & 11.6

37 Alcohols Characterized by –OH groupCharacterized by –OH group Name: add –ol to name of hydrocarbonName: add –ol to name of hydrocarbon Methanol Butanol

38 Structures of Alcohols C 3 H 5 OH: how many structural isomers? Naming: Add -ol to name of 3-C hydrocarbon. Indicate position of OH with number.

39 Alcohol Properties Alcohols are a derivative of waterAlcohols are a derivative of water Many alcohols dissolve in waterMany alcohols dissolve in water Methanol dissolves in water. Butanol is NOT soluble in water.

40 “Sterno” Alcohols burn in airAlcohols burn in air A mixture of ethanol + calcium acetate = STERNOA mixture of ethanol + calcium acetate = STERNO

41 GLYCOLS Alcohols with Two OH Groups Propylene glycol Ethylene glycol

42 Alcohol Reactions Screen 11.6 Substitution Elimination—the reverse of addition

43 Sugars: Related to Alcohols Sugars are carbohydrates, compounds with the formula C x (H 2 O) y.Sugars are carbohydrates, compounds with the formula C x (H 2 O) y. What is the difference between  and  D-glucose?

44 Sucrose and Ribose

45 AminesAmines Alcohols are derivatives of H 2 O (R–OH) and amines are derivatives of NH 3. Methylamine Dimethylamine Trimethylamine

46 AminesAmines Amines generally have terrible odors! Cadaverine Pyridine

47 AminesAmines Amines, like NH 3, are bases

48 AminesAmines Many natural products and drugs (such as nicotine and cocaine) are bases. Nicotine H+H+H+H+

49 Compounds with Carbonyl Group AldehydeAldehyde Carboxylic acid KetoneKetone

50 Structures of Aldehydes Cinnamaldehyde Odors from aldehydes and ketones

51 Carboxylic Acids Benzoic acid Carboxylic acid group with acidic H + All are WEAK acids Acetic acid Acids are found in many natural substances: bread, fruits, milk, wine

52 Carboxylic Acids Formic acid, HCO 2 H, gives the sting to ants. Aspirin, acetylsalicylic acid

53 Acids + Alcohols --> ESTERS Esters have generally pleasant odors

54 Acids + Alcohols --> ESTERS One of the important reactions in nature!

55 Acids + Alcohols --> ESTERS

56 Glycerol Alcohol with 3 OH Groups Combine this with long chain acids > ??? Fatty acids ---> fats and oils Combine this with long chain acids > ??? Fatty acids ---> fats and oils

57 Fats and Oils R = organic group with NO C=C bonds C 12 = Lauric acid C 16 = Palmitic acid C 18 = Stearic acid R = organic group with NO C=C bonds C 12 = Lauric acid C 16 = Palmitic acid C 18 = Stearic acid R = organic group with C=C bonds C 18 = oleic acid R = organic group with C=C bonds C 18 = oleic acid What is the functional group in a fat or oil?

58 Fats and Oils Fats with C=C bonds are usually LIQUDS Oleic acid: a monounsaturated fatty acid C=C bond

59 Fats and Oils Fats with saturated acids (no C=C bonds) are SOLIDS. Saturated fats are more common in animals.

60 Fats and Polar Bears Bears gorge on blubber in the winter.Bears gorge on blubber in the winter. During the summer bears rely on stored fat for energy.During the summer bears rely on stored fat for energy. Burn kg of fat per day.Burn kg of fat per day. Water for metabolism comes from fat burning.Water for metabolism comes from fat burning. Bears gorge on blubber in the winter.Bears gorge on blubber in the winter. During the summer bears rely on stored fat for energy.During the summer bears rely on stored fat for energy. Burn kg of fat per day.Burn kg of fat per day. Water for metabolism comes from fat burning.Water for metabolism comes from fat burning.

61 Trans Fatty Acids Oleic acid is a mono–unsaturated cis- fatty acidOleic acid is a mono–unsaturated cis- fatty acid Trans fatty acids have deleterious health effects.Trans fatty acids have deleterious health effects. Trans fatty acids raise plasma LDL cholesterol and lower HDL levels.Trans fatty acids raise plasma LDL cholesterol and lower HDL levels. C=C bond

62 Fats and Oils: Saponification

63 Acids + Amines --> AMIDES N-methylacetamide

64 Acetoaminophen Tylenol, Datril, Momentum,... Acetoaminophen

65 Alpha-Amino Acids

66 Peptides and Proteins Adding more peptide links ---> PROTEIN

67 PolymersPolymers Giant molecules made by joining many small molecules called monomersGiant molecules made by joining many small molecules called monomers Average production is 150 kg per person annually in the U.S.Average production is 150 kg per person annually in the U.S.

68 Polymer Classifications Thermoplastics (polyethylene) soften and flow when heatedThermoplastics (polyethylene) soften and flow when heated Thermosetting plastics — soft initially but set to solid when heated. Cannot be resoftened.Thermosetting plastics — soft initially but set to solid when heated. Cannot be resoftened. Other classification: plastics, fibers, elastomers, coatings, adhesivesOther classification: plastics, fibers, elastomers, coatings, adhesives

69 Polymer Preparation Addition polymers — directly adding monomer units togetherAddition polymers — directly adding monomer units together Condensation polymers — combining monomer units and splitting out a small water (water)Condensation polymers — combining monomer units and splitting out a small water (water)

70 Polyethylene: Addition Polymer EthylenePolyethylene A polymer with a molar mass of 1e6 has about 36,0000 units.

71 Mechanism of Addition Polymerization

72 Types of Polyethylene Linear, high density PE (HDPE) Branched, low density PE, LDPE Cross-linked PE, CLPE

73 Types of Polyethylene Table 11.12: others are PVC, acrylonitrile, polypropylene, polymethyl methacrylate

74 Polystyrene Polystyrene is nonpolar material and dissolves in organic solvents.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.PS foam is mostly air, and when it dissolves it collapses to a much smaller volume.

75 Slime! Slime is polyvinylalcohol cross-linked with boric acid

76 Condensation Polymers

77 Polyesters, PET Jackets made from recycled PET soda bottles Soda bottles, mylar film.

78 Polyesters: Mechanism

79 Polyamides: Nylon

80 Each monomer has 6 C atoms in its chain.Each monomer has 6 C atoms in its chain. A polyamide link forms on elmination of HClA polyamide link forms on elmination of HCl Result = nylon 66Result = nylon 66 Proteins are polyamidesProteins are polyamides

81 Polymer Recycling Symbols LDPE = Low density PE = g/cm 3 HDPE = High density PE = PP = Polypropylene = 0.90 V = PVC (Vinyl chloride) =