Chemistry 121 Winter Introduction to Organic Chemistry and Biochemistry Instructor Dr. Upali Siriwardane (Ph.D. Ohio State) E-mail: upali@latech.edu Office: 311 Carson Taylor Hall ; Phone: 318-257-4941; Contact me trough e-mail if you have questions Online Tests on Following days December 16, 2016: Test 1 (Chapters 12-13) January 23, 2017 : Test 2 (Chapters 14-16) February 10, 2017 : Test 3 (Chapters 17-19) February 22, 2017 : Test 4 (Chapters 20-22) February 23, 2017: Make Up Exam: Chapters 12-22)

GHW Questions GHW#3 CHEM 121 Winter 16

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 12.10 Classification of Carbon Atoms, 358 12.11 Branched-Chain Alkyl Groups, 359 12.12 Cycloalkanes, 361 12.13 IUPAC Nomenclature for Cycloalkanes, 362 12.14 Isomerism in Cycloalkanes, 363 12.15 Sources of Alkanes and Cycloalkanes, 365 12.16 Physical Properties of Alkanes and Cycloalkanes, 367 12.17 Chemical Properties of Alkanes and Cycloalkanes, 368 12.18 Halogenated Alkanes and Cycloalkanes, 371 CHEM 121 Winter 15

Chapter 13. Unsaturated Hydrocarbons 13.2 Characteristics of Alkenes and Cycloalkenes, 385 13.3 IUPAC Nomenclature for Alkenes and Cycloalkenes, 386 13.4 Line-Angle Structural Formulas for Alkenes, 389 13.5 Constitutional Isomerism in Alkenes, 390 13.6 Cis-Trans Isomerism in Alkenes, 391 13.7 Naturally Occurring Alkenes, 394 13.8 Physical Properties of Alkenes and Cycloalkenes, 396 13.9 Chemical Reactions of Alkenes, 396 13.10 Polymerization of Alkenes: Addition Polymers, 402 13.11 Alkynes, 406 13.12 Aromatic Hydrocarbons, 408 13.13 Names for Aromatic Hydrocarbons, 410 13.14 Aromatic Hydrocarbons: Physical Properties and Sources, 413 13.15 Chemical Reactions of Aromatic Hydrocarbons, 413 13.16 Fused-Ring Aromatic Hydrocarbons, 414 CHEM 121 Winter 16

Isomerism Skeleton Position Functional group geometric conformational 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 16

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

1. Write the name of names and units of unsaturation for the hydrocarbons (alkane, alkene, alkyne and arene) with following general formula. CnH2n+2 CnH2n CnH2n-2 CnHn Name a) ______ b) ____ c) ____ d) ___ Unit of unsat. a) ______ b) ____ c) ____ d) ___ CHEM 121 Winter 16

2. Draw all constitutional isomers of butane: C4H10. CHEM 121 Winter 16

3. Names of following cycloalknes: CHEM 121 Winter 16

4. Complete the following reactions of alkanes. a) Combustion: C5H12(g) + 8 O2(g)  ___CO2(g) + ___H2O(g) ii) C4H10(g) + ___ O2(g)  ___CO2(g) + ___H2O(g) b) Halogenations: (substitution reaction to form alkyl halides) CHEM 121 Winter 16

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 16

Chapter 13 – Unsaturated Hydrocarbons I. Alkenes and Alkynes Alkenes Alkynes

Chapter 13 – Unsaturated Hydrocarbons III. Aromatic Compounds

Unsaturated Hydrocarbons: Alkenes Alkynes Arenes ethene ethyne benzene C2H4 C2H2 C6H6 CnH2n CnH2n-2 CnHn unsaturated unsaturated Aromatic alkene alkyne Arene Chapters 13 Chapters 13 Chapter 13 CHEM 121 Winter 16

Units of Unsaturation: Alkenes Alkynes Arenes ethene ethyne benzene C2H4 C2H2 C6H6 CnH2n CnH2n-2 CnHn Units of Unsaturation CnH2n+2 CnH2n+2 CnH2n+2 (6-4)/2 =1 (6-2)/2 =2 (14-6)/2 =4 one double = one triple  three double = 1 ring CHEM 121 Winter 16

Nomenclature of Alkenes: Common Names Some alkenes, particularly low-molecular-weight ones, are known almost exclusively by their common names CHEM 121 Winter 16

Nomenclature (IUPAC) of Alkenes and Alkynes HOW TO Name an Alkene or Alkyne Find the longest chain that contains both C atoms of the double or triple bond. Step [1] 4 C’s in longest chain 6 C’s in longest chain butane ----> butene hexane ----> hexyne

Example of IUPAC Nomenclature of Alkenes Cycloalkanes CHEM 121 Winter 16

Nomenclature of Alkenes and Alkynes HOW TO Name an Alkene or Alkyne Number the carbon chain from the end that gives the multiple bond the lower number. Step [2] 1-butene 2-hexyne

IUPAC Nomenclature of Alkynes use 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 16

Unsaturated Hydrocarbons in Use Acetylene: Welding Beta-carotene is in carrots sex pheromones in insect control involves luring insect into a trap. Ethene is the hormone that causes tomatoes to ripen. CHEM 121 Winter 16

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 16

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 16

Terpenes with isoprene units CHEM 121 Winter 16

Terpenes: Polymers of Isoprene myrcene, C10H16, a component of bayberry wax and oils of bay and verbena menthol, from peppermint CHEM 121 Winter 16

Terpenes 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 16

5) How many isoprene units a in the following natural product? CHEM 121 Winter 16

6) Give common name or/and IUPAC names of following compounds a) b) c) CHEM 121 Winter 16

Cis and trans Geometrical isomers of alkenes 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. If they are on opposite sides, their relative position is described as trans. CHEM 121 Winter 16

Isomerism in Unsaturated Hydrocarbons II. Stereoisomers Geometrical 2-butene A. Cis/trans isomers

Cis-Trans Isomerism Dienes, trienes, and polyenes for an alkene with n carbon-carbon double bonds, each of which can show cis-trans isomerism, 2n cis-trans isomers are possible consider 2,4-heptadiene; it has four cis-trans isomers, two of which are drawn here CHEM 121 Winter 16

6) Give common name or/and IUPAC names of following compounds e) f) h) i) CHEM 121 Winter 16

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 16

Summary of Physical State of Unsaturated Hydrocarbons CHEM 121 Winter 16

Reactions of Unsaturated Hydrocarbons CHEM 121 Winter 16

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 16

Reactions of Unsaturated Hydrocarbons III. Reactions of Alkenes Addition Reactions 1. Hydrogenation

Chapter 13 – Unsaturated Hydrocarbons 2. Halogenation 3. Hydrohalogenation

Addition Reactions of Alkenes 4. Markovnikov’s Rule C2 is bonded to 1 H C1 is bonded to 2 H’s C1 has more H’s, so it will bond to the H from HCl. 2-Chloropropane is the only product formed.

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 16

Addition Reactions of Alkenes 5. Hydration this C has no H’s CH3 CH3 H2SO4 OH + H OH H H H this C has 1 H only product

Addition Reactions of Alkenes

Hydration Addition of water to the double bond. Textbook page86. CHEM 121 Winter 16

7) Complete the reactions of following alkenes CHEM 121 Winter 16

7) Complete the reactions of following alkenes CHEM 121 Winter 16

Polymerization of Alkenes CHEM 121 Winter 16

CHEM 121 Winter 16

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. C6H6 CHEM 121 Winter 16

Chapter 13 – Unsaturated Hydrocarbons III. Aromatic Compounds

Unsaturated Hydrocarbons cont’d Space-filling and ball-and-stick models for the structure of benzene. CHEM 121 Winter 16

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 16

Nomenclature of Aromatic Compounds 1. One substituent

Chapter 13 – Unsaturated Hydrocarbons 2. Disubstituted Benzenes

3. Polysubstituted Benzenes ortho-xylene o-xylene 1,2-dimethylbenzene meta-xylene m-xylene 1,3-dimethylbenzene para-xylene p-xylene 1,4-dimethylbenzene 3. Polysubstituted Benzenes 4-chloro-1-ethyl-2-propylbenzene

2,5-dichloroaniline Some common drugs that contain benzene rings are:

Naming Aromatic Hydroarbons. Monosubstituted benzenes: Ar-CH2CH3 ethylbenzene Ar-CH2-CH2-CH2-CH3 butylbenzene Ar-CH3 (methylbenzene) toluene Ar-X (halobenzene) bromobenzene, Ar-NO2 nitrobenzene Ar-SO3H benzenesulfonic acid Ar-NH2 a nitrile substituent X CHEM 121 Winter 16

CHEM 121 Winter 16

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 16

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 16

Disubstituted benzenes: 2,6-dibromotoluene p-diethylbenzene 3,5-dinitrotoluene p-cholonitrobenzene o-nitrobenzenesulfonic acid 4-benzyl-1-octene m-cyanotoluene CHEM 121 Winter 16

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 16

9. Give the names of the following disubstituted aromatic hydrocarbons.   _________ _________ _________ _________ CHEM 121 Winter 16

Reactions of Aromatic Hydrocarbons No Addition Reactions Show substitution Reactions CHEM 121 Winter 15

10) Complete the following chemical reactions of aromatic hydrocarbons. CHEM 121 Winter 16