Introduction to Organic Chemistry and Biochemistry Instructor Dr. Upali Siriwardane (Ph.D. Ohio State) Office: 311 Carson Taylor Hall ; Phone: ; Office Hours: MTW 8: :00 am; ThF 9: :00 am 1:00 - 2:00 pm. December 19, 2014: Test 1 (Chapters 12-13) January 26, 2015: Test 2 (Chapters 14-16) February 13, 2015: Test 3 (Chapters 17-19) March 2, 2015: Test 4 (Chapters 20-22) March 3, 2015: Make Up Exam: Chapters 12-22) Bring Scantron Sheet 882-E Chemistry 121(001) Winter CHEM 121 Winter 15

GHW Questions GHW#3 CHEM 121 Winter 152

Chapter 12. Saturated Hydrocarbons  12.1 Organic and Inorganic Compounds, 341  12.2 Bonding Characteristics of the Carbon Atom, 342  12.3 Hydrocarbons and Hydrocarbon Derivatives, 342  12.4 Alkanes: Acyclic Saturated Hydrocarbons, 343  12.5 Structural Formulas, 344  12.6 Alkane Isomerism, 346  12.7 Conformations of Alkanes, 348  12.8 IUPAC Nomenclature for Alkanes, 350  12.9 Line-Angle Structural Formulas for Alkanes, 356  Classification of Carbon Atoms, 358  Branched-Chain Alkyl Groups, 359  Cycloalkanes, 361  IUPAC Nomenclature for Cycloalkanes, 362  Isomerism in Cycloalkanes, 363  Sources of Alkanes and Cycloalkanes, 365  Physical Properties of Alkanes and Cycloalkanes, 367  Chemical Properties of Alkanes and Cycloalkanes, 368  Halogenated Alkanes and Cycloalkanes, 371 CHEM 121 Winter 153

Chapter 13. Unsaturated Hydrocarbons 13.1 Unsaturated Hydrocarbons, Characteristics of Alkenes and Cycloalkenes, IUPAC Nomenclature for Alkenes and Cycloalkenes, Line-Angle Structural Formulas for Alkenes, Constitutional Isomerism in Alkenes, Cis-Trans Isomerism in Alkenes, Naturally Occurring Alkenes, Physical Properties of Alkenes and Cycloalkenes, Chemical Reactions of Alkenes, Polymerization of Alkenes: Addition Polymers, Alkynes, Aromatic Hydrocarbons, Names for Aromatic Hydrocarbons, Aromatic Hydrocarbons: Physical Properties and Sources, Chemical Reactions of Aromatic Hydrocarbons, Fused-Ring Aromatic Hydrocarbons, 414 CHEM 121 Winter 154

etheneethyne benzene C 2 H 4 C 2 H 2 C 6 H 6 C n H 2n C n H 2n  2 C n H n unsaturatedunsaturated Aromatic alkenealkyne Arene Chapters 13 Chapters 13 Chapter 13 Unsaturated Hydrocarbons: Alkenes Alkynes Arenes CHEM 121 Winter 155

etheneethyne benzene C 2 H 4 C 2 H 2 C 6 H 6 C n H 2n C n H 2n  2 C n H n Units of Unsaturation C n H 2n+2 C n H 2n  C n H 2n+2 (6-4)/2 =1(6-2)/2 =2(14-6)/2 =4 one double = one triple  three double = 1 ring Units of Unsaturation: Alkenes Alkynes Arenes CHEM 121 Winter 156

1. Write the name of names and units of unsaturation for the hydrocarbons (alkane, alkene, alkyne and arene) with following general formula. C n H 2n+2 C n H 2n C n H 2n-2 C n H n Name a) ______ b) ____ c) ____ d) ___ Unit of unsat. a) ______ b) ____ c) ____ d) ___ CHEM 121 Winter 157

Isomerism Isomers Isomers - different compounds having the same molecular formula but different structural formulas There are two type of Isomers: Constitutional isomerism: Different connections among atoms in the Skeleton Position Functional group Stereoisomerism: Same connectivity among atoms, but these atoms differ in spatial orientation geometric conformational optical CHEM 121 Winter 158

Constitutional Isomers Positional (Chp. 12) Skeletal (Chp. 12) Enantiomers (Optical) (Chp. 16) Functional (Chp. 14) Stereoisomers Conformational (Chp.12)Geometric (Chp. 13) CHEM 121 Winter 159

2. Draw all constitutional isomers of butane: C 4 H 10. CHEM 121 Winter 1510

3. Names of following cycloalknes : CHEM 121 Winter 1511

4. Complete the following reactions of alkanes. a) Combustion: i) C 5 H 12 (g) + 8 O 2 (g)  ___CO 2 (g) + ___H 2 O(g) ii) C 4 H 10 (g) + ___ O 2 (g)  ___CO 2 (g) + ___H 2 O(g) b) Halogenations: (substitution reaction to form alkyl halides) CHEM 121 Winter 1512

Unsaturated hydrocarbons Hydrocarbons with carbon-carbon double bonds and triple bonds double bonds: alkenes triple bonds: alkynes three alternating double bond in 6 carbon ring: aromatics CHEM 121 Winter 1513

Unsaturated Hydrocarbons in Use Acetylene: Welding Beta-carotene is in carrots sex pheromones in insect control involves luring insect into a trap. involves luring insect into a trap. Ethene is the hormone that causes tomatoes to ripen. CHEM 121 Winter 1514

etheneethyne benzene C 2 H 4 C 2 H 2 C 6 H 6 C n H 2n C n H 2n  2 C n H n unsaturatedunsaturated Aromatic alkenealkyne Arene Chapters 13 Chapters 13 Chapter 13 Unsaturated Hydrocarbons: Unsaturated Hydrocarbons: Alkenes Alkynes Arenes CHEM 121 Winter 1515

Nomenclature of Alkenes: Common Names Some alkenes, particularly low-molecular-weight ones, are known almost exclusively by their common names CHEM 121 Winter 1516

IUPAC Nomenclature of Alkynes ynuse the infix -yn- to show the presence of a carbon- carbon triple bond number the parent chain to give the 1st carbon of the triple bond the lower number follow IUPAC rules for numbering and naming substituents CHEM 121 Winter 1517

Example of IUPAC Nomenclature of Alkenes Cycloalkanes CHEM 121 Winter 1518

Naturally Occurring Alkenes Cis-Trans Isomerism – vitamin A has five double bonds – four of the five can show cis-trans isomerism – vitamin A is the all-trans isomer CHEM 121 Winter 1519

Naturally Occurring Alkenes: The Terpenes Terpene: a compound whose carbon skeleton can be divided into two or more units identical with the carbon skeleton of isoprene CHEM 121 Winter 1520

Terpenes with isoprene units CHEM 121 Winter 1521

Terpenes: Polymers of Isopren Terpenes: Polymers of Isoprene myrcenemyrcene, C 10 H 16, a component of bayberry wax and oils of bay and verbena mentholmenthol, from peppermint CHEM 121 Winter 1522

Terpenes Vitamin A Vitamin A (retinol) the four isoprene units in vitamin A are shown in red they are linked head to tail, and cross linked at one point (the blue bond) to give the six-membered ring CHEM 121 Winter 1523

5) How many isoprene units a in the following natural product? CHEM 121 Winter 1524

6) Give common name or/and IUPAC names of following compounds a) b) c) d) CHEM 121 Winter 1525

Cis and trans Geometrical isomers of alkenes cis two groups are said to be located cis to each other if they lie on the same side of a plane with respect to the double bond. trans If they are on opposite sides, their relative position is described as trans. CHEM 121 Winter 1526

Cis-Trans Isomerism Dienes, trienes, and polyenes n 2 n for an alkene with n carbon-carbon double bonds, each of which can show cis-trans isomerism, 2 n cis-trans isomers are possible consider 2,4-heptadiene; it has four cis-trans isomers, two of which are drawn here CHEM 121 Winter 1527

6) Give common name or/and IUPAC names of following compounds e) f) g) h) i) CHEM 121 Winter 1528

Physical Properties Alkenes and alkynes are nonpolar compounds the only attractive forces between their molecules are dispersion forces Their physical properties are similar to those of alkanes of similar carbon skeletons those that are liquid at room temperature are less dense than water (1.0 g/m L) they dissolve in each other and in nonpolar organic solvents they are insoluble in water CHEM 121 Winter 1529

Summary of Physical State of Unsaturated Hydrocarbons CHEM 121 Winter 1530

Reactions of Unsaturated Hydrocarbons CHEM 121 Winter 1531

Chemical Reactions of Alkenes 1) Combustion: Alkenes are very flammable and the combustion products are carbon dioxide and water. 2) Addition Reactions: Atoms or group of atoms are added to each a carbon atom of a multiple bond. Two different reactants are involved. a) Symmetric Addition Reactions : Hydrogenation reaction: hydrogenation a hydrogen atom is added to each carbon atom of a double bond. Catalyst (usually Ni or Pt) is needed. Halogenation reaction : In alkene halogenation a halogen atom is added to each carbon atom of a double bond. No catalyst is needed. b) Asymmetric Addition Reactions: both reactants (H-X (X= Cl, OH)) and the alkene need to be asymmetric c) Polymerization of Alkenes: Addition Polymers Polymers are macromolecules in which small units (monomers) are repeated again and again. CHEM 121 Winter 1532

Markovnikov’s Rule When an unsymmetrical molecule HQ (e.g., H-Cl, H-OH, H-F) reacts with an unsymmetrical alkene, the hydrogen atom from the HQ becomes attached to the unsaturated carbon atom that already has the most hydrogen atoms CHEM 121 Winter 1533

CHEM 121 Winter 1534

Hydration Addition of water to the double bond. Textbook page86. CHEM 121 Winter 1535

CHEM 121 Winter 1536

7) Complete the reactions of following alkenes CHEM 121 Winter 1537

7) Complete the reactions of following alkenes CHEM 121 Winter 1538

CHEM 121 Winter 1539

CHEM 121 Winter 1540

Aromatic hydrocarbons Aromatic hydrocarbons - organic compounds that had aromas and had different chemical properties from alkane Benzene is the parent compound for the aromatic hydrocarbons. Textbook, page90. Consider benzene. C 6 H 6 CHEM 121 Winter 1541

13 | 42 Space-filling and ball- and-stick models for the structure of benzene. Unsaturated Hydrocarbons cont’d CHEM 121 Winter 15

Resonance Structures of Benzene Resonance structures or contributing structures = when two or more structure can be drawn for a compound. In this case, the real structure is something between the proposed structures. CHEM 121 Winter 1543

Naming Aromatic Hydroarbons. Monosubstituted benzenes: Ar-CH 2 CH 3 ethylbenzene Ar-CH 2 -CH 2 -CH 2 -CH 3 butylbenzene Ar-CH 3 (methylbenzene) toluene Ar-X (halobenzene) bromobenzene, Ar-NO 2 nitrobenzene Ar-SO 3 H benzenesulfonic acid Ar-NH 2 a nitrile substituent X CHEM 121 Winter 1544

CHEM 121 Winter 1545

Nomenclature Disubstituted benzenes locate substituents by numbering or use the locators ortho (1,2-), meta (1,3-), and para (1,4-) Where one group imparts a special name, name the compound as a derivative of that molecule CHEM 121 Winter 1546

Nomenclature Polysubstituted benzenes – with three or more substituents, number the atoms of the ring – if one group imparts a special name, it becomes the parent name – if no group imparts a special name, number to give the smallest set of numbers, and then list alphabetically CHEM 121 Winter 1547

Disubstituted benzenes: 2,6-dibromotoluene p-diethylbenzene 3,5-dinitrotoluene p-cholonitrobenzene o-nitrobenzenesulfonic acid 4-benzyl-1-octene m-cyanotoluene CHEM 121 Winter 1548

8) Match the following names of aromatic hydrocarbons (arenes) to following structures: Anisole, Aniline, Phenol, Benzoic acid, Toluene, Nitrobenzene. Complete the reactions of following alkenes _________ _________ _________ CHEM 121 Winter 1549

9. Give the names of the following disubstituted aromatic hydrocarbons. _________ _________ _________ _________ CHEM 121 Winter 1550

10) Complete the following chemical reactions of aromatic hydrocarbons. CHEM 121 Winter 1551