Title: Chapter 11-12 Organic Chemistry: Hydrocarbons
1Chapter 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
2Organic Chemistry
- Organic chemistry is the study of the compounds
containing carbon - Although inorganic cyanides and carbonates are
generally excluded from this list
3Organic 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
4Structural Formulas
- In organic and biochemistry it is much more
useful to think of molecules in terms of
structural formulas, rather than molecular
formulas
5Example
- Butane is the stuff in lighters, and has a
molecular formula C4H10
a full structural formula
a condensed structural formula
6Bonding and Carbon
- Carbon always has four covalent bonds
7Functional 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
8Summary 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
9Hydrocarbon Functional Groups
- Hydrocarbons contain only hydrogen and carbon
- The hydrocarbon functional groups include
- Alkanes
- Alkenes
- Alkynes
- Aromatics
10Alkanes
- 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
11Alkane Models
a space-filling model of ethane
a ball-and stick model of ethane
12Single Bonds
- There is free rotation around carbon-carbon
single bonds - For example both of these structures represent
the same compound (butane)
13The Normal Alkanes
CH4 methane
CH3CH3 ethane
CH3CH2CH3 propane
CH3CH2CH2CH3 butane
CH3CH2CH2CH2CH3 pentane
14The Normal Alkanes
CH3(CH2)4CH3 hexane
CH3(CH2)5CH3 heptane
CH3(CH2)6CH3 octane
CH3(CH2)7CH3 nonane
CH3(CH2)8CH3 decane
15Alkyl 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
16Some Alkyl Groups
CH3 methyl
CH3CH2 ethyl
CH3CH2CH2 propyl
CH3CHCH3 isopropyl
17Isomerism
- Isomerism is one reason there are so many organic
compounds - Isomers are different compounds that have the
same molecular formula
18Example
- Draw 2 structural isomers of C4H10
19Alkane 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
20Example
21Example
22Example
- 3,5-diethyl-2,2,3-trimethyldecane
23Halogens
- Name halogens as stick-on groups
- F fluoro
- Cl chloro
- Br bromo
- I iodo
24Example
Substituents are placed into the name in
alphabetical order disregarding the prefix needed
to identify the number of substituents
25Example
- 1,3,5-tribromo-2,4,6-trichloro-2-isopropylhexane
26Cycloalkanes
- 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
27Example
28Alkenes
- 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
29Alkene Models
a space-filling model of ethene
a ball-and stick model of ethene
30Alkene 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
31Example
32Example
33Alkenes Bonding
- There is NO free rotation around carbon-carbon
double bonds
34Cis-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
35Cis and Trans Isomers
cis-2-butene Hs on same side
trans-2-butene Hs on opposite sides
36Example
- Which compound exhibits cis-trans isomerism?
37Example
38Reactions of Alkenes
- Alkenes undergo addition reactions
- This reaction always costs the double bond
39Addition of Hydrogen Hydrogenation
- This is the addition of hydrogen to an alkene
- The product is an alkane
- This reaction requires a Pt catalyst
40Examples
41Unsaturation
- A saturated compound has the maximum possible
amount of hydrogens per carbon atom - Since alkenes react with hydrogen, they are
called unsaturated
42Fats
- Vegetable oils have double bonds
- These oils are unsaturated
- Addition of hydrogen to unsaturated fats gives
hydrogenated vegetable oils
43Alkynes
- 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
44Alkyne Models
a space-filling model of ethyne
a ball-and stick model of ethyne
45Alkyne 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
46Example
47Example
48Aromatic Compounds
- The functional group of aromatic compounds is the
benzene ring - Benzene is the archetype aromatic compound
a space-filling model of benzene
benzene
49Benzene 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
50Benzene Where are the Double Bonds?
- Because the double bonds are delocalized
equally over all six carbons, benzene is often
drawn with a circle
51Naming Aromatic Compounds
- Name benzene as the parent and then name the
substituents
52Examples
53Ortho, Meta and Para Isomers
- ortho 1,2 meta 1,3 para 1,4
54Example
Trinitrotoluene OK Really ?
55Benzene 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.