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Organic Chemistry Organic Chemistry: The chemistry of carbon and carbon-based compounds Organic Chemistry in everyday life: Smells & tastes: fruits, chocolate,

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Presentation on theme: "Organic Chemistry Organic Chemistry: The chemistry of carbon and carbon-based compounds Organic Chemistry in everyday life: Smells & tastes: fruits, chocolate,"— Presentation transcript:

1 Organic Chemistry Organic Chemistry: The chemistry of carbon and carbon-based compounds Organic Chemistry in everyday life: Smells & tastes: fruits, chocolate, fish, mint Medications: Aspirin, Tylenol, Decongestants, Sedatives Addictive substances: Caffeine, Nicotine, Alcohol, Narcotics Hormones/Neurotransmitters: Adrenaline, Epinephrine Food/Nutrients: Carbohydrates, Protein, Fat, Vitamins Genetics: DNA, RNA Consumer products: Plastics, Nylon, Rayon, Polyester

2 Drawing Organic Structures Butane: C 4 H 10 CH 3 CH 2 CH 2 CH 3 CH 3 (CH 2 ) 2 CH 3 Shortcuts make structures easier & faster to draw Line Structure Only shows bonds C atoms assumed at each end and intersection of bonds H atoms not shown Assume 4 bonds to each C Fulfill C’s 4 bonds by adding H’s Lewis Structure Condensed Structures Carbon Atoms

3 Types of Organic Compounds Classified according to functional group Alkane Alkene Alkyne Haloalkane Alcohol Ether Ketone Aldehyde Carboxylic acid Amine Amino acid Amide

4 Big Idea in Organic Chemistry Structure controls Function Each functional group has predictable reactivity

5 Alkanes or Paraffins All C atoms are tetrahedral and sp 3 hybridized (only C-C single bonds) General formula = C n H 2n+2 (CH 4, C 2 H 6, C 3 H 8, C 4 H 10, etc.) Can have linear or branched alkanes C 5 H 12 Same molecular formula, different structure: structural isomers Branches are called substituents Primary (1°) carbon atom:bound toone other C atom Secondary (2°) C atom:bound to2 other C atoms Tertiary (3°) C atom: ”3 ” Quaternary (4°) C atom: ”4 ” 3° 1° 2°

6 Names of Linear Alkanes and Alkyl Substituents AlkaneAlkyl substituents # of C atoms CH 4 CH 3 CH 3 CH 2 CH 3 CH 3 CH 2 CH 2 CH 3 -CH 3 -CH 2 CH 3 -CH 2 CH 2 CH 3 Methyl Ethyl Propyl etc. Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane Root: number of C atoms Suffix: functional group (-ane for alkanes) (-yl for alkyl groups)

7 CH H H H Methane CH 4 H C CCC H H H H HHH H H Butane C 4 H 10 Butyl -C 4 H 9 Methyl -CH 3 CH H H ? R H C CCC H H H H HHH H ? Where R = any other C atom or arrangement of C atoms R

8 First Ten Hydrocarbons: Properties Name Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane CH 4 C 2 H 6 C 3 H 8 C 4 H 10 C 5 H 12 C 6 H 14 C 7 H 16 C 8 H 18 C 9 H 20 C 10 H 22 Number of Carbon Atoms Molecular Formula Melting Point, o C # of Isomers Boiling Point, o C

9 Properties of Alkanes Compound Methane Ethane Propane Butane Pentane MW Boiling point (°C) Linear Alkanes: C atoms: gas at room temp C atoms: liquid at room temp >15 C atoms: solid at room temp Larger molecular weight → Stronger London dispersion forces Nonpolar → only London Dispersion Forces IMF Formula CH 4 C 2 H 6 C 3 H 8 C 4 H 10 C 5 H 12

10 Fractional Distillation of Crude Oil Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 429

11 Naming Branched Alkanes (IUPAC) 1.Root name: name of longest continuous C chain (parent chain) 2 equally long? Choose the one with more branches 2.Number C atoms in chain, starting at end with first branch 3.Identify substituents, give each a number (C it is connected to) Two or more identical substituents: use prefixes (di-, tri-, tetra-, etc.) 4.List substituents alphabetically before root name Do not alphabetize prefixes 5.Punctuation:commas separate numbers from each other hyphens separate numbers from names no space between last substituent & root name 4-ethyl-3,5-dimethyloctane ethyl 3-methyl and 5-methyl = 3,5-dimethyl Octane

12 Common Names of other Alkyl Substituents isopropyl isobutyl sec-butyl tert-butyl alphabetized as “i” alphabetized as “b” R R R R R R R R Remember that R = any carbon chain “iso” indicates symmetry 3 carbons 4 carbons 2o2o 2o2o Secondary carbonTertiary carbon 3o3o 3o3o

13 H CH H H C CC H H HHH C H H H 2 - methylbutane butane Naming Practice Expanded Structure Line Structure

14 H C CCC H H CH 3 H H H C C H H H H H hexane 3,3-dimethyl hexane 4,4-dimethyl Lowest sum of numbers is correct Naming Practice Line Structure

15 Isomers The fat dog shook himself, and then rolled over on the wet rug. The dog shook the fat rug, then rolled over and wet on himself. These two statements use the same words... but have very different meanings! OR Likewise, isomers may have the same formula, but have very different structures…

16 Structural Isomers of C 4 H 10 2-methylpropane or

17 Structural Isomer Practice On piece of your own paper, draw AND name ALL of the isomers for the following alkanes: Formulas # isomers If you complete that, try to draw and name all of the isomers for octane (C 8 H 18 ). There are 18 of them! Some of your drawings may look different, but they are only different structures (isomers) if they also have different names Pentane Hexane Heptane C 5 H 12 C 6 H 14 C 7 H

18 Structural Isomers: Pentane (C 5 H 12 ) pentane 2-methylbutane 2,2-dimethylpropane

19 Structural Isomers: Hexane (C 6 H 14 ) hexane 2-methylpentane 3-methylpentane 2,3-dimethylbutane 2,2-dimethylbutane

20 Structural Isomers: Heptane (C 7 H 16 ) heptane 2-methylhexane 3-methylhexane 2,2-dimethylpentane 2,3-dimethylpentane

21 Structural Isomers: Heptane (C 7 H 16 ) 2,4-dimethylpentane 3,3-dimethylpentane 3-ethylpentane 2,2,3-trimethylbutane

22 Comparing Structural Isomers C 5 H 12 (Same formula, different structure) More branching → weaker London dispersion forces 36.0pentane methylbutane 9.52,2-dimethylpropane Boiling point (°C) Name Structure BP/MP of Linear alkanes > BP/MP of branched alkanes

23 Chemical Bingo: Naming Review There are 27 structures or names drawn on the next slide. Select 24 of them to be placed on your bingo card. Because of space issues, I would number each bingo square and then list the names or structures on a separate sheet of paper If I give you a name, you must match it to a structure. If I give you a structure, you must match it to a name Any bingo winner will be awarded 1 bonus point on the quiz (5% pts)

24 Chemical Bingo: Alkanes isopropylsec-butyl tert-butylisobutyl decanenonane 2,3,4,5-tetramethylhexane 3,4-diethylhexane 3,5-diethyl-4-isopropylheptane 4-tert-butyl-3,5-dimethylheptane 4-ethyl-2,2,3,5,6,6-hexamethylheptane Any isomer of C 5 H 12 Any isomer of C 6 H 14 Any isomer of C 7 H 16

25 Reactions of Alkanes Combustion exothermic reaction alkanes used as fuel source C 4 H 10 + ___ O 2  ___ CO 2 + ___ H 2 O / 2 Incomplete Combustion with insufficient O 2 produces CO Poor ventilation, cigarettes C 4 H 10 + ___ O 2  ___ CO + ___ H 2 O 4 5 9/29/2 CO is poisonous because it binds to the hemoglobin in the blood, preventing the absorption of O 2

26 Radical Halogenation Terms Mechanism –How the reaction occurs through multiple steps (most reactions actually occur in many steps) Chain Reaction –Reactions that occur on their own after some initiating event Free Radicals –Atoms that have one free electron—highly reactive

27 Radical Halogenation Terms Mechanism –How the reaction occurs through multiple steps (most reactions actually occur in many steps) Chain Reaction –Reactions that occur on their own after some initiating event Free Radicals –Atoms that have one free electron—highly reactive (denoted with a dot next to atom)

28 Radical Halogenation Terms Initiation Step –Step where a bond is split by heat/light, producing free radicals Propagation Step –Step where free radicals react with non- radicals, producing more free radicals and continuing the “chain reaction” Termination Step –Step where free radicals react with each other, producing non-radicals and terminating the “chain reaction”

29 Radical Halogenation Terms Initiation Step –Step where a bond is split by heat/light, producing free radicals Propagation Step –Step where free radicals react with non- radicals, producing more free radicals and continuing the “chain reaction” Termination Step –Step where free radicals react with each other, producing non-radicals and terminating the “chain reaction”

30 Initiation Propagation Termination Reactions of Alkanes Radical Halogenation of Alkanes Mechanism (chain reaction): Step 1Cl 2 ⇌ Cl· + Cl · Step 2Cl· + CH 4  CH 3 · + HCl Step 3CH 3 · + Cl 2  CH 3 Cl + Cl· Step 4Cl· + Cl·  Cl 2 Overall reaction: CH 4 + Cl 2  CH 3 Cl + HCl Halogenated product is a haloalkane Naming: halogen atom is a substituent, replace –ine ending with –o -F fluoro-Cl chloro-Br bromo-I iodo  chloromethane hh (Free Radicals) Why not 1-chloromethane? Type of Step CH 4 + Cl 2  CH 3 Cl + HCl

31 Radical Halogenation of Alkanes Halogen substitutes for hydrogen in alkane →multiple results CH 4 CH 3 ClCH 2 Cl 2 CHCl 3 CCl 4 Cl 2  Cl 2  Cl 2  Cl 2  Compound CH 3 Cl CH 2 Cl 2 CHCl 3 CCl 4 IUPAC Name Chloromethane Dichloromethane Trichloromethane Tetrachloromethane Common Name Methyl chloride Methylene chloride Chloroform Carbon tetrachloride All are liquids at room temperature Heavy Cl atoms increase LDF Polar C-Cl bonds – can have polar molecules

32 Textbook Resource Chemistry: An Intro to General, Organic and Biological Chemistry by Timberlake (Green/Tan Book) Sections already covered Currently Section 11.2 (Haloalkanes) Can be used as an outside reference

33 Naming Practice: Haloalkanes 5-chloro-2-fluorohexane 2-chloro-5-fluorohexane 2-chloro-4-fluoro-2,3-dimethylpentane 2-bromo-3-ethyl-4-iodopentane 2-bromo-4-chloro-3-isopropylpentane Two equal numbering options? Number based on alpha order

34 ? Radical Halogenation: Predict the Product + Cl 2 → OR 1-chloropropane 2-chloropropane + Br 2 → OR 1-bromo-2-methylbutane 2-bromo-2-methylbutane Remember that any H on the alkane can be replaced by a halogen OR 3-chloropropane? + HCl ? ?

35 Radical Halogenation: Predict the Product + Br 2 → OR 1-bromo-2-methylbutane 2-bromo-3- methylbutane 1-bromo-3- methylbutane 1-bromo-2- methylbutane 2-bromo-2-methylbutane

36 Structural Isomers What are the possible structural isomers of C 3 H 7 Br? 1-bromopropane 2-bromopropane What are the possible structural isomers of C 4 H 9 Cl? 1-chlorobutane 2-chlorobutane 2-chloro-2-methylpropane 1-chloro-2-methylpropane

37 Structural Isomer Practice On piece of your own paper, draw AND name ALL of the isomers with the following formulas: Formulas # isomers Some of your drawings may look different, but they are only different structures (isomers) if they also have different names C4H9IC4H9I C 3 H 6 Cl 2 C 5 H 11 Br C 4 H 8 Cl To be honest, there may be more…this is what I found, so try and prove me wrong! Extra Credit to anyone who can find more structures…

38 Structural Isomers: C 4 H 9 I 1-iodobutane 2-iodo-2-methylbutane 2-iodobutane 1-iodo-2-methylbutane I I I I

39 Structural Isomers: C 3 H 6 Cl 2 1,1-dichloropropane 1,3-dichloropropane 1,2-dichloropropane 2,2-dichloropropane

40 Structural Isomers: C 5 H 11 Br 1-bromopentane 2-bromopentane 1-bromo-3-methylpentane 3-bromopentane

41 Structural Isomers: C 5 H 11 Br 1-bromo-2-methylbutane 2-bromo-3-methylbutane 1-bromo-2,2-dimethylbutane 2-bromo-2-methylbutane

42 Structural Isomers: C 4 H 8 Cl 2 1,1-dichlorobutane 1,2-dichlorobutane 1,3-dichlorobutane 1,4-dichlorobutane

43 Structural Isomers: C 4 H 8 Cl 2 2,2-dichlorobutane 1,1-dichlorobutane 2,3-dichlorobutane 1,2-dichloro-2-methylpropane 1,3-dichloro-2-methylpropane

44 Halogenation Reaction Byproduct Technically, any halogenation reaction will also produce HX as a byproduct (HCl, HBr, etc.) However, we are not concerned with this byproduct and thus ignore it CH 4 + X 2 → CH 3 X + HX where X = any halogen


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