Functional Groups - Organic Chemistry Notes at Examville.com

8/9/2019 Functional Groups - Organic Chemistry Notes at Examville.com

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Organic Chemistry

Introduction

Functional Groups

AlkanesAlkenes

Alkynes

AlcoholsAcids, Esters and

Amides



Introduction

Organic chemistry is the study of carbon-

containing compounds

especially 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 configuration

Valence bond theory

Lewis structures

Resonance structuresHybrid orbitals

Molecular geometry

Acid/base reactions

Oxidation/reduction

Kinetics

EquilibriumThermodynamics

Stoichiometry



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

H O

C C HH C C C H

H

H

O H

H

methane

acetylene

acetone

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

OOH

CH3

O

Acetic acid

Ethyl alcohol

³ether´

aspirin



Introduction

Most organic compounds have a ³skeleton´

that is composed of C-C bonds.

The C-C bonds may be single bonds,

double bonds, or triple bonds.

The ³skeleton´ of an organic compound has

H¶s attached to it.

other ³heteroatoms´ like O, halogens or Nmay 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:

VSEPR

hybrid 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-Cbonds 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 thehydrocarbons:

organic compounds that contain only

carbon and hydrogen

four general types:

alkanes

alkenes

alkynes

aromatic 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

bond

H ± C C ± H (acetylene)



Hydrocarbons

Aromatic hydrocarbons:contain a planar ring structure in which

the carbon atoms are connected by a

combination of both W and T bonds

HH

CC

CC -- HH

CC -- HHHH -- CC

HH -- CC

CC

HH

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 atomsoften lead to a polar organic molecule

large difference in electronegativity

C vs. O

C vs. N

Examples of familiar polar organic

compounds:

glucose

acetic acid

Vitamin C

amino acids

Functional groupscontain 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 physicalproperties of organic compounds, we oftenclassify and study organic compounds by

the type of functional group present.

On your exam, you will be responsible for recognizing and naming the variouscommon functional groups that are found inorganic compounds:



Functional Groups

FunctionalGroup

p of Co poun a pl

C C al n H2C CH2

C C al n HC CH

C H alco ol CH3OH

C O C et er CH3CH2OCH2CH3

C a ine CH3NHCH3



Functional Groups

FunctionalGroup

Type of Compound Example

O

C ± H aldehyde

O

CH3C ± H

O

C ± C ± C ketone

O

CH3 ± C ± CH3



Functional Groups

FunctionalGroup


O

C ± O ± HCarboxylic

acid

O

CH3C ± O ± H

O

C ± O ± C ester

O

CH3C ± O ± CH2CH3



Functional Groups

FunctionalGroup


O

C ± N ± amide

O

CH3C ± N ± CH3

H



Functional Groups

Example: Name the functional groups that arepresent in the following compounds:

CH3CH2OHO

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

OO



Hydrocarbons

Alkanes are often called saturatedhydrocarbons

they contain the largest possible number

of hydrogen atoms per carbon atom.

Alkenes, alkynes, and aromatic

hydrocarbons are called unsaturated

hydrocarbons

they contain less hydrogen than an alkane

having the same number of carbon atoms

H H H H



Alkanes

Organic compounds can be represented inmany 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

HH

HH

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:

Con enseorm la Name

CH4 methane

CH3CH3 ethane

CH3CH2CH3 propane

CH3CH2CH2CH3 butane

CH3CH2CH2CH2CH3 pentane

You

mu

st know these!!! You

mu

st know these!!!



Alkanes

Some of the simplest alkanes:

CondensedFormula Name

CH3CH2CH2CH2CH2CH3 hexane

CH3CH2CH2CH2CH2CH2CH3 heptane

CH3CH2CH2CH2CH2CH2CH2CH3 octane

CH3CH2CH2CH2CH2CH2CH2CH2CH3 nonane

CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 decane

You must know these!!! You must know these!!!



Alkanes

The previous alkanes are also calledstraight-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 ³branch´

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 points

different boiling points

often different chemical reactivity



Alkanes

Alkanes with three or more carbons can alsoform rings or cycles.

Cycloalkanes:

Alkanes containing a ring structure that isheld together by C ± C single bonds

Examples: CHCH22

CHCH22HH22CC

cyclopropanecyclopropane



Alkanes

Examples of cycloalkanes:

CHCH22

CHCH22

CHCH22HH22CC

HH22CC cyclopentanecyclopentane

HH22CC

HH22CC CHCH22

CHCH22

CHCH22

CHCH22

cyclohexanecyclohexane



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 writtenin a straight line

CH3 - CH - CH3

CH2 - CH2 - CH2 - CH3

1 2

34 5 6

Base name:Base name:

hexanehexane



Alkanes

Alkane Nomenclature:Number the carbon atoms in the longest

chain beginning with the end of the chain

closest to a substituent

groups attached to the main chain thathave taken the place of a hydrogen

atom on the main chain

CH3 - CH - CH3

CH2 - CH2 - CH2 - CH3

11 22

3344 55 66

A substituentA substituent



Alkanes

Alkane Nomenclature:Name and give the location of each

substituent group

A substituent group that is formed by

removing an H atom from an alkane iscalled an alkyl group:

Name alkyl groups by dropping the ³ane´

ending of the parent alkane and adding³yl´



Alkanes

Alkane Nomenclature:Common alkyl groups (substituents):

CH3 methyl

CH3CH2 ethylCH3CH2CH2 propyl

CH3CH2CH2CH2 butyl

22--methylhexanemethylhexaneCH3 - CH - CH3

CH2 - CH2 - CH2 - CH3

11 22

3344 55 66

KnowKnowthese!these!



Alkanes

Alkane Nomenclature:

Halogen atoms are another common class

of substituents.

Name halogen substituents as ³halo´:Cl chloro

Br bromo

I 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 samesubstituent is present (i.e. two methylgroups), use prefixes to indicate thenumber:Di = two Tri = three Tetra = four Penta = five

Know these.Know these.



Alkanes

Example: Name the following compounds:

CH3CH2CHCH2CH3

CH3

CH2CH2CH3

CH3CHCHCH3

CH3



Alkanes


CH3CH2CHCH3

CH2CH2Br

CH2CH2CH3

CH3CHCHCH3

Cl



Alkanes

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

To do so:

Identify the main chain and draw thecarbons in it

Identify 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 ³ane´ ending from thecorresponding alkane to ³ene´

butane butene

propane propene

octane octene



Alkenes

Alkene NomenclatureIndicate the location of the double bond

using a prefix number

designate the carbon atom that is part

of the double bond AND nearest to theend 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 isomer

trans 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 = Cdouble bond



Alkene

cis-2-butene

CHCH33 CHCH33

C = CC = C

HH HH

CHCH33 HH

C = CC = C

HH CHCH33

trans-2-butene



Alkene

For an alkene with the general formulaFor an alkene with the general formula

AA PP

C = CC = C

BB QQ

cis and trans isomers are possible only if cis and trans isomers are possible only if

A = B andA = B and

P = QP = Q



Alkene

Example: Name the following alkenes:

CH3CH2 H

C = C

H H

CH3CH2 H

C = C

CH3CHCH2 CH2CH3

CH3



Alkenes

Example: Draw the structures for the followingcompounds:

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 endingof the corresponding alkane from ³ane´ to

³yne´



Alkynes

Alkyne Nomenclature:Use a number to designate the position of

the triple bond

number from the end of the chain

closest to the triple bond just like with alkenes

Name substituents like you do with

alkanes and alkenes



Alkynes


CH3CH2C CCHCH3

CH2CH3

CH2CH2C CH

Cl



Alkynes

Example: Draw the following alkynes.

4-chloro-2-pentyne

3-propyl-1-hexyne



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Functional Groups - Organic Chemistry Notes at Examville.com

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