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 20 Beaker Bank points

Chemical Bingo: Alkanes

R

R

R

R

isopropyl sec-butyl

tert-butyl isobutyl

decane nonane

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 C5H12

Any isomer of C6H14

Any isomer of C7H16

Alkyl Halides

• The halogen is treated as a substituent on an alkane chain

• The halo-substituent is considered of equal rank with an alkyl substituent in the numbering of the parent chain

• In the case where each would have the same position number, the substituent that comes first in the alphabet takes the lower number!

3

Naming Alkyl Halides

• Follow the same system as with alkanes

• Give the name and carbon number for the halide just like a side branch!

C - C - F C - C - C C-C-C-C-C

Cl C-Br 1-fluoroethane

2-chloropropane

1-bromo-2-ethylbutane

1 2 3

4 5

6

Naming Practice: Haloalkanes

F Cl

F

Cl

IBr

Cl

Br

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 1

2

3 4

5

6

ALKENES AND ALKYNES

Alkenes and Alkynes • Alkanes are saturated hydrocarbons

• Simply put, a saturated hydrocarbon has no double bonds between the carbon atoms

• Therefore, there is a maximum number of hydrogens present

• Like the alkanes, the alkenes and alkynes form another homologous hydrocarbon series

• Alkenes form one double covalent bond between two C atoms

• Alkynes form one triple covalent bond between two C atoms • Alkenes and alkynes are unsaturated hydrocarbons

• This means more hydrogen atoms can be added

• General formula for alkenes:

CnH2n • General formula for alkynes:

CnH2n-2

Saturated vs Unsaturated

Naming Alkenes and Alkynes

• IUPAC nomenclature rules for alkenes and alkynes are similar to alkanes

• Name the parent compound

• Find the longest chain containing the double or triple bond and name the parent compound by adding the suffix –ene or –yne to the name of the main chain

• Number the carbon atoms in the parent chain, beginning at the end nearest the double or triple bond

• If the multiple bond is an equal distance from both ends, begin numbering at the end nearer the first branch point

9

Naming Alkenes and Alkynes

•Assign numbers and names to the branching substituents, and list the substituents alphabetically

•Use commas to separate numbers, and hyphens to separate words from numbers

•Indicate the position of the multiple-bond carbon •The number indicates which carbon the multiple bond is AFTER

•Do not use a # if there is only one possible location

•If more than one multiple bond is present, identify the position of each multiple bond and use the appropriate ending diene, triene, tetraene, and so forth

•Assemble the name as previously discussed

10

Example

11

H H H

C=C–C–C–H

H H H H

C4H8

CH2CHCH2CH3

H H H H

H–C–C=C–C–H

H H

C4H8

CH3CHCHCH3

1-butene (not 3) 2-butene

Structural Formula

Chemical formula

Condensed

Structural formula

Another Example

C=C–C–C

C C

C6H12

CH2C(CH3)CH(CH3)CH3

Structural Formula

(w/o the H)

Chemical formula

Condensed

Structural formula

2,3-dimethyl-1-butene

Assigning Priority • Alkenes and alkynes are considered to have equal

priority

• In a molecule with BOTH a double and a triple bond, whichever is closer to the end of the chain determines the direction of the numbering

• In the case where each would have the same position number, the double bond takes the lower number

• In the name, “-ene” comes before “-yne” because of alphabetization

13

Multiple Double/Triple Bonds

Learning Check

Write the IUPAC name for each of the following unsaturated compounds:

A. CH3CH2CCCH3

CH3

B. CH3C=CHCH3 C.

CH3

Properties of Alkenes and Alkynes • Like the alkanes, alkenes and alkynes are:

• Non-polar

• Insoluble in water

• Soluble in non-polar organic solvents

• Less dense in water

• Flammable

• Non-toxic

• Unlike the alkanes: • Alkenes and alkynes are chemically reactive at the multiple bond

• Alkenes display cis-trans isomerism when each double-bond carbon atom has different substituents

WAIT…WHAT IS CIS-TRANS ISOMERISM?

Recall Way Back When…

• Draw the Lewis Dot structures and predict the shapes of the following molecules:

•Methane

•Ethylene (C2H4)

•Acetylene (C2H2)

•What carbon families are these molecules a apart of?

Answers

• As predicted by the VSEPR theory discussed earlier: • Methane (an alkane) is tetrahedral (sp3 hybridization)

• Ethylene (an alkene) is planar (sp2 hybridization) Acetylene (an alkyne) is linear (sp hybridization)

Molecule Rotation • In alkanes, there is free rotation around the single bond • In alkenes, there is NO rotation around the double bond

• The double bond is “fixed”

• As a consequence, a new kind of structural isomerism is possible • Called stereoisomerism

• More specifically, this type of stereoisomerism is called cis-trans isomerism

Stereoisomerism • To see this new kind of isomerism, look at the following butene

compounds:

• The two 2-butenes are called cis-trans isomers • They have the same formula and connections between atoms, but

different structures

Cis- and Trans- Isomerism • A cis-isomer contains substituents on the same side of the

double bond

• A trans-isomer contains substituents on opposite side of the double bond

• Cis-trans isomerism occurs in an alkene whenever each double-bond carbon is bonded to two different substituent groups

• If one of the double-bond carbons is attached to two identical groups, cis-trans isomerism is not possible as shown below

TIME FOR PRACTICE!

AROMATIC COMPOUNDS

Benzene Structure • Benzene as 6 electrons shared equally among the 6 C atoms

• Resonant bonding

It is also represented as a hexagon with a circle drawn inside

Benzene, C6H6, is one of the most important industrial chemicals

Benzene is regarded as a highly carcinogenic substance

• Use and disposal of benzene are regulated

• Compounds containing benzene rings are not necessarily toxic

Aromatic Compounds

• At the time of its discovery, many compounds containing benzene had fragrant odors

• So, the family of benzene compounds became known as aromatic compounds

Common Aromatic Compounds

Naming Aromatic Compounds

• Aromatic compounds are named • with benzene as the parent chain

• with one side group named in front of benzene

Methylbenzene Chlorobenzene

ClCH3

Naming Aromatic Compounds

Several base names…

benzene toluene phenol

aniline benzaldehyde benzoic acid

Abbreviations Used with Di-Substitution

1,2 difluoro benzene Ortho difluoro benzene o – difluoro benzene

1,3 dichloro benzene Meta dichloro benzene m – dichloro benzene

1,4 dibromo benzene Para dichloro benzene p – dichloro benzene

Toluene

• For methylbenzene, the common name, toluene, may be used

Xylene

• For isomers of dimethylbenzene, the common name, xylene may be used

Naming Aromatic Compounds with Three Substituents

• Use numbers for giving the positions:

1,3,5-Trichlorobenzene 2,6-Dibromo-4-chlorotoluene

4-Bromo-2-chlorotoluene

Cl

Cl

CH3

Br

CH3

Br

Cl

Cl Br

Cl

1 1

Learning Check

Select the correct name(s) for each of the following compounds.

A. chlorocyclohexane

B. chlorobenzene

C. 1-chlorobenzene

A. 1,2-dimethylbenzene

B. 1,3-dimethylbenzene

C. m-xylene

CH3

CH3

Cl

Solution

B. chlorobenzene

B. 1,3-dimethylbenzene or

C. m-xylene

CH3

CH3

Cl

Learning Check

Draw the condensed structural formulas for each of the following.

1. 1,3-dichlorobenzene

2. o-chlorotoluene

Solution

One possible way to draw each…

1. 1,3-dichlorobenzene

2. o-chlorotoluene

Cl

Cl

CH3

Cl

Benzene as a Substituent…

• If you have the aromatic ring as an attachment, it is named phenyl

Try one…

• What would this name be?

Answer…

• 4-phenyl octane

Learning Check

Draw and identify the organic family (functional group) for each of the following.

A.

B.

C.

D.

Solution

The functional groups are as follows…

A. alkene

B.

cycloalkane (alkane)

C.

alkyne

D.

aromatic

FUNCTIONAL GROUPS

Types of Organic Compounds Classified according to functional group

Alkane

Alkene

Alkyne

Haloalkane

Alcohol

Ether

Ketone

Aldehyde

Carboxylic acid

Amine

Amino acid

Amide

O

H

O

NH2

O

OH

O

H2NOH

O

OH

Cl

Br

NH2

C C

O

Problems: • Draw the following alkenes:

• 2-Butene

• methylpropene

• 4–Methyl–2-pentene

• 3,3-Dimethyl-1-butene

45

46

Can you name this compound?

3-ethyl-1-pentyne

Problems

47

Name this alkyne:

5,7-diethyl-3-methyl-4-decyne

C

C-C-C=C-C-C-C-C

C C C

C C

C

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…

Structural Isomers of C4H10

2-methylpropane

or

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 (C8H18). 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

C5H12

C6H14

C7H16

3

5

9

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

C4H9I

C3H6Cl2

C5H11Br

C4H8Cl2

4

4

8

9

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…

Structural Isomers: C4H9I

II

II

1-iodobutane

2-iodo-2-methylbutane

2-iodobutane

1-iodo-2-methylbutane

I

I I

I

Structural Isomers: C3H6Cl2 Cl

ClCl

Cl

ClClClCl

1,1-dichloropropane

1,3-dichloropropane

1,2-dichloropropane

2,2-dichloropropane

Structural Isomers: C5H11Br

BrBr

BrBr

1-bromopentane 2-bromopentane

1-bromo-3-methylpentane 3-bromopentane

Structural Isomers: C5H11Br

Br

Br

Br

Br

1-bromo-2-methylbutane 2-bromo-3-methylbutane

1-bromo-2,2-dimethylbutane 2-bromo-2-methylbutane

Structural Isomers: C4H8Cl2

Cl

ClCl

Cl

Cl

Cl

ClCl

1,1-dichlorobutane 1,2-dichlorobutane

1,3-dichlorobutane 1,4-dichlorobutane

Structural Isomers: C4H8Cl2

Cl Cl

Cl

Cl

Cl

Cl

ClCl

Cl

Cl

2,2-dichlorobutane

1,1-dichlorobutane

2,3-dichlorobutane

1,2-dichloro-2-methylpropane

1,3-dichloro-2-methylpropane

Structural Isomers: Pentane (C5H12)

pentane

2-methylbutane

2,2-dimethylpropane

Structural Isomers: Hexane (C6H14)

hexane

2-methylpentane

3-methylpentane

2,3-dimethylbutane

2,2-dimethylbutane

Structural Isomers: Heptane (C7H16)

heptane

2-methylhexane

3-methylhexane

2,2-dimethylpentane

2,3-dimethylpentane

Structural Isomers: Heptane (C7H16)

2,4-dimethylpentane

3,3-dimethylpentane

3-ethylpentane

2,2,3-trimethylbutane

Comparing Structural Isomers C5H12

(Same formula, different structure)

More branching → weaker London dispersion forces

36.0 pentane

27.9 2-methylbutane

9.5 2,2-dimethylpropane

Boiling point (°C) Name Structure

BP/MP of Linear alkanes > BP/MP of branched alkanes

Structural Isomers What are the possible structural isomers of C3H7Br?

BrBr

1-bromopropane 2-bromopropane

What are the possible structural isomers of C4H9Cl?

Cl

Cl

Cl

Cl

1-chlorobutane

2-chlorobutane

2-chloro-2-methylpropane

1-chloro-2-methylpropane