Chapter 11-12 Organic Chemistry: Hydrocarbons - PowerPoint PPT Presentation

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Chapter 11-12 Organic Chemistry: Hydrocarbons

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Chapter 11-12 Organic Chemistry: Hydrocarbons Suggested Problems: Chapter 11: 5,10, 18, 20, 22, 28-48 even Chapter 12: 3,4,5,6,8a,c, 20,21,39,52,53,73 – PowerPoint PPT presentation

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Title: Chapter 11-12 Organic Chemistry: Hydrocarbons


1
Chapter 11-12 Organic Chemistry Hydrocarbons
  • Suggested Problems
  • Chapter 11 5,10, 18, 20, 22, 28-48 even
  • Chapter 12
  • 3,4,5,6,8a,c, 20,21,39,52,53,73

2
Organic Chemistry
  • Organic chemistry is the study of the compounds
    containing carbon
  • Although inorganic cyanides and carbonates are
    generally excluded from this list

3
Organic Chemistry
  • The term organic says nothing about the source
    or purity of a compound
  • While many compounds found in living organisms
    are organic, most organic compounds do not come
    from living sources
  • Most organic compounds are synthetic, but
    ultimately come from petroleum

4
Structural Formulas
  • In organic and biochemistry it is much more
    useful to think of molecules in terms of
    structural formulas, rather than molecular
    formulas

5
Example
  • Butane is the stuff in lighters, and has a
    molecular formula C4H10

a full structural formula
a condensed structural formula
6
Bonding and Carbon
  • Carbon always has four covalent bonds

7
Functional Groups
  • It is helpful to think of organic molecules as
    having two distinct parts
  • A carbon backbone that is relatively inert
  • One (or more) functional group(s)
  • A functional group is a set of atoms bonded
    together in a specific way
  • Functional groups largely define the chemical and
    physical properties of the compound

8
Summary of the Functional Groups
Alkane C-C single bond Aldehyde Terminal carbonyl (CO), RCHO
Alkene CC double bond Ketone Carbonyl (CO), R2CO
Alkyne CC triple bond Carboxylic Acid Carboxyl group, RCO2H
Aromatic Benzene ring Ester Carboxylic acid alcohol, RCO2R
Alcohol Hydroxyl group, ROH Amide Carboxylic acid amine, RCONR2
Ether Oxygen bridge, ROR Amine Nitrogen, R3N
9
Hydrocarbon Functional Groups
  • Hydrocarbons contain only hydrogen and carbon
  • The hydrocarbon functional groups include
  • Alkanes
  • Alkenes
  • Alkynes
  • Aromatics

10
Alkanes
  • Alkanes are the simplest functional group
  • An older name for alkanes is parafins
  • The functional group is the C-C single bond
  • Methane and ethane are examples of alkanes

CH3CH3
CH4
ethane
methane
11
Alkane Models
a space-filling model of ethane
a ball-and stick model of ethane
12
Single Bonds
  • There is free rotation around carbon-carbon
    single bonds
  • For example both of these structures represent
    the same compound (butane)

13
The Normal Alkanes
CH4 methane
CH3CH3 ethane
CH3CH2CH3 propane
CH3CH2CH2CH3 butane
CH3CH2CH2CH2CH3 pentane
14
The Normal Alkanes
CH3(CH2)4CH3 hexane
CH3(CH2)5CH3 heptane
CH3(CH2)6CH3 octane
CH3(CH2)7CH3 nonane
CH3(CH2)8CH3 decane
15
Alkyl Groups
  • A carbon chain stuck onto a larger molecule is
    called an alkyl group
  • R is the symbol for a generic alkyl group
  • Think of the R group as the (relatively
    uninteresting) carbon backbone

16
Some Alkyl Groups
CH3 methyl
CH3CH2 ethyl
CH3CH2CH2 propyl
CH3CHCH3 isopropyl
17
Isomerism
  • Isomerism is one reason there are so many organic
    compounds
  • Isomers are different compounds that have the
    same molecular formula

18
Example
  • Draw 2 structural isomers of C4H10

19
Alkane Nomenclature Rules
  • Name the longest chain as the parent alkane
  • Find and Name alkyl substituents
  • Indicate the number of identical substituents
  • di2 tri3 tetra4 penta5
  • Number the parent chaine to give the lowest
    possible numbers to each substituent to indicate
    its position on the parent chain
  • Alphabetize the substituents by name Prefixes
    di, tri, tetra, however the prefixes iso and
    cyclo are considered when alphabatizing

20
Example
21
Example
22
Example
  • 3,5-diethyl-2,2,3-trimethyldecane

23
Halogens
  • Name halogens as stick-on groups
  • F fluoro
  • Cl chloro
  • Br bromo
  • I iodo

24
Example
Substituents are placed into the name in
alphabetical order disregarding the prefix needed
to identify the number of substituents
25
Example
  • 1,3,5-tribromo-2,4,6-trichloro-2-isopropylhexane

26
Cycloalkanes
  • Carbon chains can close on themselves to give
    cyclic structures
  • Add the prefix cyclo to indicate a cyclic
    structure

cycloalkanes are sometimes drawn as geometric
shapes
cyclobutane
27
Example
28
Alkenes
  • The functional group in an alkene is the CC
    double bond
  • An older name for alkenes is olefins
  • Ethene (or ethylene) is an example of an alkene

CH2 CH2
ethene common name ethylene
29
Alkene Models
a space-filling model of ethene
a ball-and stick model of ethene
30
Alkene Nomenclature
  • Name the longest chain as the parent
  • Add suffix -ene
  • Give double bond lowest number
  • Name and number substituents
  • Rules for alkanes are followed except for the
    double bond has to have the lowest number and you
    must tell where this is in the name if there are
    multiple places possible

31
Example
32
Example
  • 2,3-dimethyl-2-hexene

33
Alkenes Bonding
  • There is NO free rotation around carbon-carbon
    double bonds

34
Cis-Trans Isomerism
  • Since there is no rotation around the double
    bond, a special type of isomerism is possible for
    alkenes
  • Cis-Trans isomerism is possible ONLY when neither
    alkene carbon (i.e. the two carbons making the
    double bond) has two identical substitutents

35
Cis and Trans Isomers
cis-2-butene Hs on same side
trans-2-butene Hs on opposite sides
36
Example
  • Which compound exhibits cis-trans isomerism?

37
Example
  • trans-4-methyl-2-pentene

38
Reactions of Alkenes
  • Alkenes undergo addition reactions
  • This reaction always costs the double bond

39
Addition of Hydrogen Hydrogenation
  • This is the addition of hydrogen to an alkene
  • The product is an alkane
  • This reaction requires a Pt catalyst

40
Examples
41
Unsaturation
  • A saturated compound has the maximum possible
    amount of hydrogens per carbon atom
  • Since alkenes react with hydrogen, they are
    called unsaturated

42
Fats
  • Vegetable oils have double bonds
  • These oils are unsaturated
  • Addition of hydrogen to unsaturated fats gives
    hydrogenated vegetable oils

43
Alkynes
  • The functional group in an alkyne is the CC
    triple bond
  • Ethyne (or acetylene) is an example of an alkyne

H-C C-H
ethyne common name acetylene
44
Alkyne Models
a space-filling model of ethyne
a ball-and stick model of ethyne
45
Alkyne Nomenclature
  • Name the longest chain as the parent
  • Add suffix -yne
  • Give triple bond lowest number
  • Name and number substituents
  • Rules for alkanes are followed except for the
    triple bond has to have the lowest number and you
    must tell where this is in the name if there are
    multiple places possible

46
Example
47
Example
  • 4,4-dimethyl-2-pentyne

48
Aromatic Compounds
  • The functional group of aromatic compounds is the
    benzene ring
  • Benzene is the archetype aromatic compound

a space-filling model of benzene
benzene
49
Benzene Where are the Double Bonds?
  • Benzene appears to have alternating double and
    single bonds, but this is NOT the case
  • There are two identical structures for benzene
  • The actual benzene molecule is a hybrid of these

50
Benzene Where are the Double Bonds?
  • Because the double bonds are delocalized
    equally over all six carbons, benzene is often
    drawn with a circle

51
Naming Aromatic Compounds
  • Name benzene as the parent and then name the
    substituents

52
Examples
53
Ortho, Meta and Para Isomers
  • ortho 1,2 meta 1,3 para 1,4

54
Example
Trinitrotoluene OK Really ?
55
Benzene as an Alkyl Group
  • Benzene as a stick-on group is called a phenyl
    group

When polymerized styrene will make a rigid
plastic used in the production of plastic
cutlery, license plate frames and CD Jewel cases.
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