Chapter_03 Prop Fisicas y Nomenclatura

Chapter 3

An Introduction to Organic Compounds: Nomenclature, Physical Properties, and

Representation of Structure

Essential Organic ChemistryPaula Yurkanis Bruice

William Setzer, Bernhard Vogler, Mary Setzer

University of Alabama - Huntsville

Physical Properties of Organic Compounds

Recall intermolecular forces:• Ion–ion interactions

• Sodium chloride

• Ammonium tetrafluoroborate

NH4 BF4

Na Cl


Recall intermolecular forces: Hydrogen bonding

The dotted bond is a hydrogen bond.Strong hydrogen hydrogen bond is limited tomolecules having a hydrogen atomattached to an O, N, or F O, N, or F atom


Recall intermolecular forces:• Dipole–dipole interactions


Recall intermolecular forces:• London dispersion London dispersion forces (van der Waals van der Waals interactions)

• These are instantaneous induced-dipole interactions

• Important interactions between nonpolar compounds

• Hydrocarbons (C, H)

Temporary dipoles and induced dipoles in nonpolar molecules


• Melting and boiling points Melting and boiling points increase with increasing

molecular weight molecular weight within a homologous series.

Compound Formula MW (g/mol)

mp (ºC) bp (ºC)

Methane CH4 16 –182 –164

Pentane CH3(CH2)3CH3 72 –130 36

Decane CH3(CH2)8CH3 142 –30 174

Pentadecane CH3(CH2)13CH3 212 10 271

Eicosane CH3(CH2)18CH3 282 37 343

Alkanes• Boiling points decrease with chain branching.

Compound bp (oC)

mp (oC)

CH3

CH3

CH3 CH3

CH3

CH3 CH3

CH3 CH3

CH3

octane

4-methylheptane

2,2,4-trimethylpentane

57

121

107

127

118

99

• SolubilitySolubility – “Like dissolves like” “Like dissolves like” • Examples: Alkanes are nonpolar, hydrophobichydrophobic

Alcohols are polar. hydrophillic hydrophillic

SolubilitySolubility

hydrophobichydrophobic


CH3

CH3

Compound MW bp (oC)

H2O solubility

86.18 69 insoluble

ClCl 98.96 83 0.8%

CH3

CH3

O

O

86.09 88 20%

hexane

1,2-dichloroethane

2,3-butanedione


CH3

OO

CH3

HOOH

H2NNH2

CH3

NN

CH3

H

H

Compound MW bp (oC)

H2O solubility

90.12 83

90.12 230

88.15 158

88.15 119

dimethoxyethane

1,4-butanediol

putrescine

N,N'-dimethylethylenediamine

Alkanes

Saturated hydrocarbons (Aliphatic) • Hydrocarbons – Contain only C and H atoms.• Saturated – Only single bonds. • Aliphatic – “Fat” like. • Can be acyclic (no rings) or cyclic

(cycloalkanes).

AlkanesMethane, CH4

Ethane, CH3CH3

H

CH H

H

AlkanesMethane, CH4

Ethane, CH3CH3

H

CH H

H

H

CH C

H

H

H

H

AlkanesPropane, CH3CH2CH3

Butane, CH3CH2CH2CH3

H

CH C

H

H

C

H

H

H

H

AlkanesPropane, CH3CH2CH3

Butane, CH3CH2CH2CH3

H

CH C

H

H

C

H

H

H

H

H

CH C

H

H

C

H

H

C

H

H

H

H

Alkanes

Pentane, CH3CH2CH2CH2CH3

Hexane, CH3CH2CH2CH2CH2CH3

Heptane, CH3CH2CH2CH2CH2CH2CH3

Octane, CH3CH2CH2CH2CH2CH2CH2CH3

Nonane, CH3CH2CH2CH2CH2CH2CH2CH2CH3

Decane, CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3

IsomerismConsider C4H10

These structures are constitutional isomers

H

CH C

H

H

C

H

H

C

H

H

H

HC C

C

C

H

H

H HH

H

H HH H

Normal Butane Isobutane

IsomerismConsider C4H10

These structures are:

Constitutional or Chain Isomers

H

CH C

H

H

C

H

H

C

H

H

H

HC C

C

C

H

H

H HH

H

H HH H

Normal Butane Isobutane

IsomerismIsomerism – The phenomenon whereby

certain chemical compounds have structures that are different although the compounds possess the same elemental composition.

Isomers – Two or more chemical substances having the same elementary composition and molecular weight but differing in structure.

Isomerism (Isomería)Isomerism – The phenomenon whereby

certain chemical compounds have structures that are different although the compounds possess the same elemental composition.

Isomers – Two or more chemical substances having the same elementary composition and molecular weight but differing in structure.

ISÓMEROS ISÓMEROS

AlkanesNames and Formulas of Alkyl Groups:

Formula Name Formula Name

CH3- methyl CH3CH2CH2CH2- butyl

CH3CH2- ethyl (CH3)2CHCH2- isobutyl

CH3CH2CH2- propyl CH3CH2CH(CH3)- sec-butyl

(CH3)2CH- isopropyl (CH3)3C- tert-butyl







Primary (1o) carbon







Secondary (2o) carbon







Tertiary (3o) carbon

IUPAC Rules for Naming Alkanes Select the longest continuous chain of carbon

atoms as the parent compound. Number the carbon atoms in the parent carbon

chain starting from the end closest to the first carbon atom that has an alkyl or other group.

Name the alkyl group and designate the position on the parent carbon chain by a number.

When the same alkyl group branch chain occurs more than once, indicate this repetition by a prefix (di-, tri-, tetra-, and so forth).

When several different alkyl groups are attached to the parent compound, list them in alphabetical order.

Examples

CH2 CH

CH3

CH3CH2CH3parent alkane

alkyl group

12345

3-methylpentane

Examples

CH2 CH

CH3

CH3CH2CH3parent alkane

alkyl group

12345

2-methylpentane

Examples

1 2 3 4CH3 CH CH CH3

CH3 CH3

2,3-dimethylbutane

CH3 CH2 C CH3

CH3

CH3

1234

2,2-dimethylbutane

Examples

CH3 CH CH2 CH CH CH CH3

CH3

CH3

CH3

CH3

1

2

3

4

567

2,3,4,6-tetramethylheptane

Examples

CH3 CH CH2 CH CH CH CH3

CH3

CH3

CH3

CH3

1

2

3

4

567

2,3,4,6-tetramethylheptane

Note: Number the chain so that the substituents get the lowest possible numbers.

Examples

CH3 CH CH2 CH2 CH3

CH2 CH312

3 4 5 6

3-methylhexane

Examples

Caution: Be careful to choose the longest chain as the parent alkane.

CH3 CH CH2 CH2 CH3

CH2 CH312

3 4 5 6

3-methylhexane

Examples

123456CH3 CH2 CH2 CH2 C CH CH CH3

CH3CH3

CH2 CH3

Cl

78

3-chloro-4-ethyl-2,4-dimethyloctane

Examples

Note: Substituents are listed in alphabetical order.

123456CH3 CH2 CH2 CH2 C CH CH CH3

CH3CH3

CH2 CH3

Cl

78

3-chloro-4-ethyl-2,4-dimethyloctane

Draw the Compounds 3-ethylpentane




CH3 CH2 CH2 CH2 CH3

1 2 3 4 5

CH2 CH3



1 2 3 4 5CH2 CH3CH3 CH2 CH

CH2 CH3



1 2 3 4 5CH2 CH3CH3 CH2 CH

CH2 CH3

CH3 CH2 CH2 CH2 CH3

CH3

CH3 CH3

1 2 3 4 5



1 2 3 4 5CH2 CH3CH3 CH2 CH

CH2 CH3

CH3 C

CH3

CH3

CH2 CH2 CH3

CH3

1 2 3 4 5

Cycloalkanes

H2C CH2

CH2=

CH3

CH2H2C CH2

CH2CH

H2C

CH3

=

Cycloalkanes

H2C CH2

CH2=

CH3

CH2H2C CH2

CH2CH

H2C

CH3

=

Cyclopropane

Methylcyclohexane

Lineal representationLineal representation

Cycloalkanes

(CH2)5CH3

CH2

H2C CHCH2

CH2CH2CH2CH2CH2CH3

Cycloalkanes

(CH2)5CH3

CH2

H2C CHCH2

CH2CH2CH2CH2CH2CH3

Lineal representationLineal representation 1-Cyclobutylhexane

Cycloalkanes

CH2H2C CH

CHCH2

H2C

CH2

CH3

CH3=

Cycloalkanes

1-Ethyl-2-methylcyclohexane

CH2H2C CH

CHCH2

H2C

CH2

CH3

CH3=

1

23

4

5

6

Name the Following Compounds

Name the Following Compounds

Methylcyclopropane 1,1-Dimethylcyclohexane

1,2-Dimethylcyclopentane 3-Cyclopropylpentane

Geometric Isomerism in Cycloalkanes Geometric isomers have the same molecular

formula and the same order of attachment but a different orientation in space that cannot be overcome by rotation around a bond.

1,2-Dimethylcyclopentane:

Geometric Isomerism in Cycloalkanes Geometric isomers have the same molecular

formula and the same order of attachment but a different orientation in space that cannot be overcome by rotation around a bond.

1,2-Dimethylcyclopentane:

H3C CH3

H3C CH3

H H

H3C H

H CH3

1,2-dimethylcyclopentane

cis-1,2-dimethylcyclopentane trans-1,2-dimethylcyclopentane

Geometric Isomerism in CycloalkanesName the following compounds:

C

CCH

H3CH

CH3H

H

H3C

H H

C CH3

CH3H3C

H H

H H

H

H H

H


C

CCH

H3CH

CH3H

H

H3C

H H

C CH3

CH3H3C

H H

H H

H

H H

H

trans-1,2-dimethylcyclopropane


C

CCH

H3CH

CH3H

H

H3C

H H

C CH3

CH3H3C

H H

H H

H

H H

H

trans-1,2-dimethylcyclopropane cis-1-tert-butyl-4-methylcyclohexane

Conformations of AlkanesEthane

• Staggered conformation

• Newman projection:

=

H

H H

H H

H

Staggered = 60o


• Eclipsed conformation


=

H

H H

H

HH

Eclipsed = 0o


• Eclipsed conformation


=

H

H H

H

HH

Eclipsed = 0o

~3 kcal/mole higher in energy than staggered conformation

Conformations of AlkanesButane

180o

120o

60o

0o

Erel 0 kcal/mol 3.4 kcal/mol 0.9 kcal/mol 6.1 kcal/mol

Conformations of AlkanesCyclohexane

• “Chair” conformation

H

H

HH

H

H

HH

H

H

HH



Equatorial hydrogens

H

H

HH

H

H

HH

H

H

HH



Axial hydrogens

H

H

HH

H

H

HH

H

H

HH


• “Boat” conformation

HH

H

H

H H

H

H H

H

HH



HH

H

H

H H

H

H H

H

HH Steric

interactions



HH

H

H

H H

H

H H

H

HH Eclipsing

Conformations of Cyclohexane

chair

halfchair

twistboat

boat

E

Conformations of Substituted Cyclohexanes

Monosubstituted Cyclohexanes• Methylcyclohexane

CH3

CH3



CH3

CH3

Equatorial methyl group Axial methyl group



CH3H

H

CH3

Steric interactions



CH3H

H

CH3

steric interactions



CH3H

H

CH3

steric interactions

more stable

Organic Functional GroupsClass

Functional Group

Example

Alkene C C

CH3

H3C CH2Limonene

Organic Functional Groups

Alkyne

ClassFunctional Group

Example

Norethindrone

C C

O

COH CCH3

H



Example

Alkyl HalideX = F, Cl, Br, I

R X

Cl

Cl

Cl

Cl

Cl

Cl

1,2,3,4,5,6-Hexachlorocyclohexane Lindane



Example

Alcohol R OH

CH3

H3C CH3

OH

2-Isopropyl-5-methylcyclohexanol Menthol


O

H3C CH3

(CH2)4CH3HO

H3C

9-Tetrahydrocannabinol

THC


Example

Ether R O R'



Example

Aldehyde

Cinnamaldehyde

O

CR H

CC

C

O

H

H

H



Example

Ketone

Jasmone

CH3

CH3

OO

CR R'



Example

Carboxylic Acid

Ibuprofen

O

CR OH

C

CH3

CH3

CH3

O

OH


EsterO

CR O

R'C

O

OCH3

OH


Example

Methyl salicylate



Example

Amine

Mescaline

NR

R'R"

NH2

OCH3

H3CO

H3CO



Example

Amide

Lysergic acid diethylamide LSD

O

CR N

R'

R" N

N

CN

CH2CH3

CH2CH3

CH3

H

O

Organic Functional Groups Paclitaxel (TAXOL, isolated from the Pacific yew tree, Taxus

brevifolia), is clinically useful in the treatment of ovarian cancer. Identify the functional groups in TAXOL.

OO

HOO

CH3 OHCH3

O O

CH3

H3C

CH5C6

O CCH3O

CN

CH5C6

OO C6H5

OHH

O

C

O

H3C



OO

HOO

CH3 OHCH3

O O

CH3

H3C

CH5C6

O CCH3O

CN

CH5C6

OO C6H5

OHH

O

C

O

H3C

Amide