Organic Chemistry

IntroductionFunctional GroupsAlkanesAlkenesAlkynesAlcoholsAcids, Esters and

Amides

Introduction

Organic chemistry is the study of carbon-containing compoundsespecially compounds containing C-C

bonds The field of organic chemistry is very important

for a wide variety of reasons.A huge number of carbon-containing

compounds are known. More than 16 million known compounds About 90% of new compounds made each

year contain carbon

Introduction

Most of the advances in the pharmaceutical industry are based on a knowledge of organic chemistry.Many drugs are organic compounds

Life as we know it is based on organic chemistry.Most biologically important compounds

contain carbon: DNA, RNA proteins carbohydrates

Introduction

Learning organic chemistry requires you to integrate and apply many of the concepts you’ve learned in general chemistry:

Electron configurationValence bond theory Lewis structuresResonance structuresHybrid orbitalsMolecular geometry

Acid/base reactionsOxidation/reductionKineticsEquilibriumThermodynamicsStoichiometry

Introduction

Some familiar organic compounds:

H

C

C C O

H

H

H

O

H

H

H

H

H

C

C C O

H

H

H

O

H

H

H C C

H H

H

H H

H

C

H

C C O

H

H

H

O

H

H

H C C

H H

H

H H

C C HH C C C H

H

H

O H

H

methane

acetyleneacetone

propane

Introduction

Some familiar organic compounds:

H C C O H

H

H

H H

H

C C

H

H H

H C C O

H

H

H

H

H

H C C O

H

H

H

O

C

O C

O

OH

CH3

O

Acetic acid

Ethyl alcohol

“ether”

aspirin

Introduction

Most organic compounds have a “skeleton” that is composed of C-C bonds.

The C-C bonds may be single bonds, double bonds, or triple bonds.

The “skeleton” of an organic compound has H’s attached to it.other “heteroatoms” like O, halogens or N

may be present as well

Introduction

The number of bonds formed by C in an organic compound is determined by the electron configuration of C.

Carbon has four valence electrons:1s22s22p2

Introduction

Carbon generally forms 4 equivalent bonds.

The formation of four equivalent bonds is best explained using the concept of hybrid orbitals.

Introduction

The structure of an organic compound can be predicted by drawing a Lewis structure:

H O H

H C C C H

H H

acetone

Introduction

In organic molecules, we generally describe the geometry around each carbon atom.

Geometry is predicted using:VSEPRhybrid orbitals

Introduction

When C forms four single bonds:sp3 hybrid orbitals are involved

tetrahedral geometry

When C forms a double bond:sp2 hybrid orbitals are used

trigonal planar geometry

When C forms a triple bond:sp hybrid orbitals are used

linear geometry

C CH

H

H

H

H C C H

Introduction

Example: Identify the electron domain geometry and hybrid orbitals used by each atom (except hydrogen) in the following compound.

C CH C C O H

OH

H

Introduction

Organic compounds contain not only C-C bonds but also C-H bonds.

C-C and C-H bonds tend to be non-polar because there is a small difference in electronegativites

Most (but not all) organic compounds are relatively non-polar

generally not very soluble in water

Hydrocarbons

The simplest organic compounds are the hydrocarbons:organic compounds that contain only

carbon and hydrogen

four general types:alkanesalkenesalkynesaromatic hydrocarbons

Hydrocarbons

Alkanes:hydrocarbons that contain only single

bonds

Examples:Methane CH4

ethane H H

H – C – C – H

H H

Hydrocarbons

Alkenes:hydrocarbons that contain a C = C double

bond

H2C = CH2 (ethylene)

Alkynes:hydrocarbons that contain a C C triple

bondH – C C – H (acetylene)

Hydrocarbons

Aromatic hydrocarbons:contain a planar ring structure in which

the carbon atoms are connected by a combination of both s and p bonds

H

C

C - H

C - H

H - C H - C C

H

benzene

Introduction

Organic compounds that are soluble in polar solvents such as water generally have a polar functional group present in the molecule.An atom or group of atoms that influences

the way the molecule functions, reacts or behaves.

an atom or group of atoms in a molecule that undergoes predictable chemical reactions

the center of reactivity in an organic molecule

Introduction

Functional groups that contain O or N atoms often lead to a polar organic moleculelarge difference in electronegativity

C vs. OC vs. N

Examples of familiar polar organic compounds:glucoseacetic acidVitamin C

amino acids

Functional groups contain C-O bonds

Functional groups contain C-O and C-N bonds

Functional Groups

Since functional groups are responsible for the many of the chemical and physical properties of organic compounds, we often classify and study organic compounds by the type of functional group present.

On your exam, you will be responsible for recognizing and naming the various common functional groups that are found in organic compounds:

Functional Groups

FunctionalGroup

Type ofCompound Example

C = C alkene H2C = CH2

C C alkyne HC CH

C – O – H alcohol CH3OH

C – O – C ether CH3CH2OCH2CH3

C – N amine CH3NHCH3

Functional Groups

FunctionalGroup

Type ofCompound Example

O

C – H aldehyde

O

CH3C – H

O

C – C – C ketone

O

CH3 – C – CH3

Functional Groups

FunctionalGroup

Type ofCompound Example

O

C – O – HCarboxylic

acid

O

CH3C – O – H

O

C – O – C ester

O

CH3C – O – CH2CH3

Functional Groups

FunctionalGroup

Type ofCompound Example

O

C – N – amide

O

CH3C – N – CH3

H

Functional Groups

Example: Name the functional groups that are present in the following compounds:

CH3CH2OH

O

H2C = CHCOH

CH3CH2NCH3

CH3

Functional Groups

Example: Name the functional group(s) that is (are) present in the following compounds:

H2C CH2

H2C CH2

CH3NHCH2CH2OCH3

O

Hydrocarbons

Alkanes are often called saturated hydrocarbons they contain the largest possible number

of hydrogen atoms per carbon atom.

Alkenes, alkynes, and aromatic hydrocarbons are called unsaturated hydrocarbonsthey contain less hydrogen than an alkane

having the same number of carbon atoms

Alkanes

Organic compounds can be represented in many different ways:molecular formula: C4H10 (butane)Lewis structure:

Condensed structural formula

CH3CH2CH2CH3

Line angle drawings

H

H C C C C H

H

H H H H

H H H

C C C C H

H H H H

HHHH

H

H C C C C H

H

H H H H

H H H

C C C C H

H H H H

HHHH

Alkanes

Some of the simplest alkanes:

CondensedFormula Name

CH4 methane

CH3CH3 ethane

CH3CH2CH3 propane

CH3CH2CH2CH3 butane

CH3CH2CH2CH2CH3 pentane

You must know these!!!

Alkanes

Some of the simplest alkanes:

CondensedFormula Name

CH3CH2CH2CH2CH2CH3 hexane

CH3CH2CH2CH2CH2CH2CH3 heptane

CH3CH2CH2CH2CH2CH2CH2CH3 octane

CH3CH2CH2CH2CH2CH2CH2CH2CH3 nonane

CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 decane

You must know these!!!

Alkanes

The previous alkanes are also called straight-chain hydrocarbons:all of the carbon atoms are joined in a

continuous chain

Alkanes containing 4 or more carbons can also form branched-chain hydrocarbons (branched hydrocarbons)some of the carbon atoms form a “branch”

or side-chain off of the main chain

Alkanes

An example of a straight chain hydrocarbon:

C5H12 CH3CH2CH2CH2CH3 pentane

Examples of a branched hydrocarbon:

C5H12 CH3CHCH2CH3 CH3

CH3 CH3CCH3

CH3

2-methylbutane

2,2-dimethylpropane

Alkanes

The three structures shown previously for C5H12 are structural isomers:compounds with the same molecular

formula but different bonding arrangements

Structural isomers generally have different properties:different melting pointsdifferent boiling pointsoften different chemical reactivity

Alkanes

Alkanes with three or more carbons can also form rings or cycles.

Cycloalkanes:Alkanes containing a ring structure that is

held together by C – C single bonds

Examples: CH2

CH2H2C

cyclopropane

Alkanes

Examples of cycloalkanes:

CH2

CH2

CH2H2C

H2C cyclopentane

H2C

H2C CH2

CH2

CH2

CH2

cyclohexane

Alkanes

Organic compounds can be named either using common names or IUPAC names.

You must be able to name alkanes, alkenes, alkynes, and alcohols with 10 or fewer carbons in the main chain using the IUPAC naming system.

Alkanes

Alkane Nomenclature:Find the longest continuous chain of

carbon atoms and use the name of the chain for the base name of the compound:longest chain may not always be written

in a straight line

CH3 - CH - CH3

CH2 - CH2 - CH2 - CH3

1 2

34 5 6

Base name: hexane

Alkanes

Alkane Nomenclature:Number the carbon atoms in the longest

chain beginning with the end of the chain closest to a substituentgroups attached to the main chain that

have taken the place of a hydrogen atom on the main chain

CH3 - CH - CH3

CH2 - CH2 - CH2 - CH3

1 2

34 5 6

A substituent

Alkanes

Alkane Nomenclature:Name and give the location of each

substituent groupA substituent group that is formed by

removing an H atom from an alkane is called an alkyl group:

Name alkyl groups by dropping the “ane” ending of the parent alkane and adding “yl”

Alkanes

Alkane Nomenclature:Common alkyl groups (substituents):

CH3 methylCH3CH2ethylCH3CH2CH2 propylCH3CH2CH2CH2 butyl

2-methylhexaneCH3 - CH - CH3

CH2 - CH2 - CH2 - CH3

1 2

34 5 6

Know these!

Alkanes

Alkane Nomenclature:

Halogen atoms are another common class of substituents.Name halogen substituents as “halo”:

Cl chloroBr bromoI iodo

Alkanes

Alkane Nomenclature:When two or more substituents are

present, list them in alphabetical order: Butyl vs. ethyl vs. methyl vs. propyl

When more than one of the same substituent is present (i.e. two methyl groups), use prefixes to indicate the number: Di = two Tri = three Tetra = four Penta = five

Know these.

Alkanes

Example: Name the following compounds:

CH3CH2CHCH2CH3

CH3

CH2CH2CH3

CH3CHCHCH3

CH3

Alkanes

Example: Name the following compounds:

CH3CH2CHCH3

CH2CH2Br

CH2CH2CH3

CH3CHCHCH3

Cl

Alkanes

You must also be able to write the structure of an alkane when given the IUPAC name.

To do so:Identify the main chain and draw the

carbons in itIdentify the substituents (type and #) and

attach them to the appropriate carbon atoms on the main chain.

Add hydrogen atoms to the carbons to make a total of 4 bonds to each carbon

Alkanes

Example: Write the condensed structure for the following compounds:

3, 3-dimethylpentane

3-ethyl-2-methylhexane

2-methyl-4-propyloctane

1, 2-dichloro-3-methylheptane

Alkenes

Alkenes:unsaturated hydrocarbons that contain a

C=C double bond

Alkene Nomenclature:Names of alkenes are based on the

longest continuous chain of carbon atoms that contains the double bond.

Alkenes

Alkene NomenclatureFind the longest continuous carbon chain

containing the double bond.

Change the “ane” ending from the corresponding alkane to “ene” butane butene propane propene octane octene

Alkenes

Alkene NomenclatureIndicate the location of the double bond

using a prefix numberdesignate the carbon atom that is part

of the double bond AND nearest to the end of the chain

Name all other substituents in a manner similar to the alkanes.

Use a prefix to indicate the geometric isomer present, if necessary.

Alkenes

Alkene Nomenclature

Different geometric isomers are possible for many alkenes.Compounds that have the same molecular

formula and the same groups bonded to each other, but different spatial arrangements of the groups

cis isomertrans isomer

Alkenes

Alkene NomenclatureCis isomer:

two identical groups (on adjacent carbons) on the same side of the C = C double bond

Trans isomer:two identical groups (on adjacent

carbons) on opposite sides of the C = C double bond

Alkene

cis-2-butene

CH3 CH3

C = C

H H

CH3 H

C = C

H CH3

trans-2-butene

Alkene

For an alkene with the general formula

A P

C = C

B Q

cis and trans isomers are possible only if

A = B and

P = Q

Alkene

Example: Name the following alkenes:

CH3CH2 HC = C

H H

CH3CH2 HC = C

CH3CHCH2 CH2CH3

CH3

Alkenes

Example: Draw the structures for the following compounds:

2-chloro-3-methyl-2-butene

trans-3, 4-dimethyl-2-pentene

cis-6-methyl-3-heptene

Alkynes

Alkynes:unsaturated hydrocarbons that contain a

C C triple bond

Alkyne Nomenclature:Identify the longest continuous chain

containing the triple bond

To find the base name, change the ending of the corresponding alkane from “ane” to “yne”

Alkynes

Alkyne Nomenclature:Use a number to designate the position of

the triple bondnumber from the end of the chain

closest to the triple bondjust like with alkenes

Name substituents like you do with alkanes and alkenes

Alkynes

Example: Name the following compounds:

CH3CH2C CCHCH3

CH2CH3

CH2CH2C CH

Cl

Alkynes

Example: Draw the following alkynes.

4-chloro-2-pentyne

3-propyl-1-hexyne