CHAPTER 8 INTRODUCTION TO ORGANIC CHEMISTRY

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CHAPTER 8INTRODUCTION TO ORGANIC CHEMISTRY

• BASIC CHEMISTRY
• CHM 138

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ORGANIC CHEMISTRY

• Organic chemistry
• The branch of chemistry that deals with carbons
  compounds.
• Organic derived from living organisms
• Study of compounds extracted from living
  organisms and their natural products.
• Examples sugar, starch, urea, waxes,
  carbohydrates, fats and etc
• Human are composed of organic molecules
  proteins in skin, lipid in cell membranes,
  glycogen in livers and the DNA in the nuclei of
  cells.

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• Chemistry of carbon
• - Two stable isotops (13C and 12C)
• - electron configuration 1s2 2s2 2p2
• - four valence electrons
• - can form more compounds than any other
  element
• - able to form single, double and triple
  carbon-carbon bonds, and to link up with each
  other in chains and ring structures

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HOMOLOGUE SERIES AND FUNCTIONAL GROUPS

• Functional group
• A group of atoms that is largely responsible for
  the chemical behavior of the parent molecule.
• Functional groups
• - hydrocarbons
• - alcohols
• - aldehydes
• - ketones
• - carboxylic acids
• - alkyl halides

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HYDROCARBONS

• Made up of only hydrogen and carbon

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ALKANES

• General formula
• CnH2n2, where n 1, 2, .
• Only single covalent bonds are present
• Known as saturated hydrocarbons because contain
  the maximum number of hydrogen atoms that can
  bond with the number of carbon atoms present.
• Can be assumed to be sp3-hydridized

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Structures of the first four alkanes
8
The melting and boiling points of the
straight-chain isomers of the first 10 alkanes
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Homologous Series 

1. Definition A series of compounds in which each
   member differs from the next by a specific number
   and kind of atoms.
2. Alkanes Differ only at number of (CH2)
3. Series of compounds that has the same functional
   group.

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INITIAL NAMES OF THE HOMOLOGOUS SERIES
Number of carbon atoms, n Name
1 Meth
2 Eth
3 Prop
4 But
5 Pent
6 Hex
7 Hept
8 Oct
9 Non
10 Dec
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NAMING ALKANES

• Alkyl groups are used to name organic compounds.

• The general formula of an alkyl group is CnH2n1.

• The letter R is often used in formulas to
  represent any of the possible alkyl groups.

• R CnH2n1 (any alkyl group)
• R CH3 methyl group
• R CH3CH2 ethyl group

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IUPAC RULES International Union of Pure and
Applied Chemistry
RULE 1. Select the longest continuous chain of
carbon atoms as the parent compound.

• Consider all alkyl groups attached to it as
  branch chains or substituents that have replaced
  hydrogen atoms of the parent hydrocarbon. If two
  chains of equal length are found, use the chain
  that has the larger number of substituents
  attached to it.
• The alkanes name consists of the parent
  compounds name prefixed by the names of the
  alkyl groups attached to it.

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This structure has 2 chains.
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This is a methyl group.
It is a branch chain and can be considered to
have replaced a hydrogen on the parent compound.
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1
2
4
5
6
3
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IUPAC RULES
RULE 2. Number the carbon atoms in the parent
carbon chain starting from the end closest to the
first carbon atom that has an alkyl group
substituted for a hydrogen atom.

• If the first subsitutent from each end is on the
  same-numbered carbon, go to the next substituent
  to determine which end of the the chain to start
  numbering.

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If the chain is numbered left to right, the
isopropyl group is on carbon 5.
isopropyl group
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If the chain is numbered right to left, the
isopropyl group is on carbon 4.
Use right to left numbering so that the isopropyl
group is on the lowest numbered carbon.
4-isopropyloctane
isopropyl group
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IUPAC RULES

• RULE 3. Name each alkyl group and designate its
  position on the parent carbon chain by a number
  (e.g., 2-methyl means group attached to C-2).

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RULE 4. When the same alkyl-group branch chain
appears more than once, indicate this repetition
by a prefix (di-, tri-, tetra- and so forth)
written in front of the alkyl group name (e.g.
dimethyl indicates two methyl groups). The
numbers indicating the alkyl-group positions are
separated by a command and followed by a hyphen
and are placed in front of thename (e.g.,
2,3-dimethyl).
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• RULE 5. When several different alkyl groups are
  attached to the parent compound, list them in
  alphabetical order (e.g. ethyl before methyl in
  3-ethyl-4-methyloctane). Prefixes are not
  included in alphabetical ordering (ethyl comes
  before dimethyl).

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1
2
4
5
3
6
7
8
3
4
25

• Alkanes can have many different types of
  substituents.
• For example

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CYCLIC HYDROCARBONS

• A hydrocarbon that contains carbon atoms joined
  to form a ring.
• Cycloalkanes all carbons of the ring are
  saturated

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NOMENCLATURE OF CYCLOALKANES

• Similar to that alkanes. For examples

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ISOMERISATION

• Structural isomers
• Molecules that have the same molecular formula,
  but different structure

Three isomers of pentane (C5H12)
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STRUCTURE ISOMERS FOR ALKANES
NAME MOLECULAR FORMULA TOTAL OF ISOMERS
Methane CH4 1
Ethane C2H6 1
Propane C3H8 1
Butane C4H10 2
Pentane C5H12 3
Hexane C6H14 5
Heptane C7H16 9
Octane C8H18 18
Nonane C9H20 35
Decane C10H22 75
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ALKENES

• Also called olefins
• Contain at least one carbon-carbon double bond
  (CC)
• General formula, CnH2n (n2,3,)
• Classified as unsaturated hydrocarbons (compound
  with double or triple carbon-carbon bonds that
  enable them to add hydrogen atoms.
• sp2-hybridized
• For example
• C2H4 - ethylene

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ALKYNES

• Alkynes contain at least carbon-carbon triple
  bond.
• General formula CnH2n-2, where n 2, 3,.
• Alkyne nomenclature
• Used suffix yne
• Same as alkene nomenclature

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NamingAlkenes and Alkynes
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IUPAC RULES

• RULE 1. Select the longest continuous carbon
  chain that contains a double or triple bond.

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• RULE 2. Name this compound as you would an
  alkane, but change ane to ene for an alkene and
  to yne for an alkyne.

This is the longest continuous chain. Select it
as the parent compound.
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• RULE 2. Name this compound as you would an
  alkane, but change ane to ene for an alkene and
  to yne for an alkyne.

This chain contains a triple bond. Name the
parent compound octyne.
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RULE 3. Number the carbon chain of the parent
compound starting with the end nearer to the
double or triple bond. Use the smaller of the
two numbers on the double- or triple-bonded
carbon to indicate the position of the double or
triple bond. Place this number in front of the
alkene or alkyne name.
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IUPAC RULES
This end of the chain is closest to the double
bond. Begin numbering here.
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IUPAC RULES
The name of the parent compound is 1-octene.
4
3
2
1
5
6
7
8
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IUPAC RULES
The name of the parent compound is 1-octyne.
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RULE 4. Branched chains and other groups are
treated as in naming alkanes. Name the
substituent group, and designate its position on
the parent chain with a number.
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IUPAC RULES
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IUPAC RULES
44

• must specify whether the molecule is cis or
  trans (geometric isomer)

• cis two particular atoms (or groups of atoms)
  are adjacent to each other
• trans the two atoms (or groups of atoms) are
  across from each other

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CYCLOALKENES

• Contains CC in the ring

• Nomenclature of cycloalkenes
• Similar to that alkenes
• Carbons atoms in the double bond are designated
  C1 and C2

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AROMATIC HYDROCARBONS

• Contain one or more benzene rings

Benzene Kekulé Structure
6 carbons in a ring
3 double bonds
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The structure of benzene can be represented in
two abbreviated ways.
The corner of each hexagon represents a carbon
and a hydrogen atom.
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Naming Aromatic Compounds
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• A substituted benzene is derived by replacing one
  or more of benzenes hydrogen atoms with an atom
  or group of atoms.
• A monosubstituted benzene has the formula C6H5G
  where G is the group that replaces a hydrogen
  atom.
• All hydrogens in benzene are equivalent.
• It does not matter which hydrogen is replaced by
  G.

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Monosubstituted Benzenes
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Some monosubstituted benzenes are named by adding
the name of the substituent group as a prefix to
the word benzene.

• The name is written as one word.

nitrobenzene
ethylbenzene
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• Certain monosubstituted benzenes have special
  names.

• These are parent names for further substituted
  compounds.

phenol
toluene
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benzoic acid
aniline
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• C6H5 is the phenyl group.
• It is used to name compounds that cannot be
  easily named as benzene derivatives.

diphenylmethane
4-phenyl-2-pentene
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Disubstituted Benzenes
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• Three isomers are possible when two substituents
  replace hydrogen in a benzene molecule.

• The prefixes ortho-, meta- and para- (o-, m- and
  p-) are used to name these disubstituted benzenes.

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ortho-dichlorobenzene(1,2-dichlorobenzene)mp
17.2oC, bp 180.4oC
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meta-dichlorobenzene(1,3-dichlorobenzene)mp
24.82oC, bp 172oC
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para-dichlorobenzene(1,4-dichlorobenzene)mp
53.1, bp 174.4oC
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When one substituent corresponds to a
monosubstituted benzene with a special name, the
monosubstituted compound becomes the parent name
for the disubstituted compound.
m-nitrophenol
phenol
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When one substituent corresponds to a
monosubstituted benzene with a special name, the
monosubstituted compound becomes the parent name
for the disubstituted compound.
m-nitrotoluene
toluene
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Tri- and Polysubstituted Benzenes
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• When a benzene ring has three or more
  substituents, the carbon atoms in the ring are
  numbered.

• Numbering starts at one of the substituent
  groups.
• The numbering direction can be clockwise or
  counterclockwise.
• Numbering must be in the direction that gives the
  substituent groups the lowest numbers.

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clockwise numbering
6
1
5
4
2
3
1,4,6-trichlorobenzene
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counterclockwise numbering
chlorine substituents have lower numbers
2
1
3
4
6
5
1,2,4-trichlorobenzene
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• When a compound is named as a derivative of the
  special parent compound, the substituent of the
  parent compound is considered to be C-1 of the
  ring.

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1
6
2
3
5
2,4,6-trinitrotoluene(TNT)
4
toluene
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ALCOHOLS

• Alcohols Organic compounds containing hydroxyl
  (-OH) functional groups.

• Phenols Compounds with hydroxyl group bonded
  directly to an aromatic (benzene) ring.

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CLASSIFICATION

• According to the type of carbinol carbon atom (C
  bonded to the OH group).

• Classes
• i) Primary alcohol
• - -OH group attached to a primary carbon
  atom
• ii) Secondary alcohol
• - -OH group attached to a secondary
  carbon atom
• iii) Tertiary alcohol
• - -OH group attached to a tertiary
  carbon atom

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• TYPE STRUCTURE
  EXAMPLES
• Primary (1)
• Secondary (2)
• Tertiary (3)

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Polyhydroxy Alcohols

• Alcohols that contain more than one OH group
  attached to different carbons are called
  polyhydroxy alcohols.
• Monohydroxy one OH group per molecule.
• Dihydroxy two OH groups per molecule.
• Trihydroxy three OH groups per molecule.

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Naming Alcohols
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IUPAC RULES

1. Select the longest continuous chain of carbon
   atoms containing the hydroxyl group.
2. Number the carbon atoms in this chain so that the
   one bonded to the OH group has the lowest
   possible number.
3. Form the parent alcohol name by replacing the
   final e of the corresponding alkane name by ol.
   When isomers are possible, locate the position
   of the OH by placing the number (hyphenated) of
   the carbon atom to which the OH is bonded
   immediately before the parent alcohol name.
4. Name each alkyl branch chain (or other group) and
   designate its position by number.

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This is the longest continuous chain that
contains an hydroxy group.
Select this chain as the parent compound.
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4
3
2
1
This end of the chain is closest to the OH.
Begin numbering here.
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4
3
2
1
3-methyl-2-butanol
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This is the longest continuous chain that
contains an hydroxy group.
Select this chain as the parent compound.
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4
3
5
2
1
This end of the chain is closest to the OH.
Begin numbering here.
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4
3
5
3
2
1
2
3-methyl-2-pentanol
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EXAMPLE

• 1) Longest carbon chain 4 carbons
• 
  root name butanol
• 2) Position of OH group second carbon atom
• 
  2-butanol
• 3) Name of substituents 1-bromo
• 
  3-methyl
• 
  3-methyl
• COMPLETE IUPAC NAME 1-bromo-3,3-dimethyl-2-butan
  ol

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EXAMPLES OF POLYHYDROXY ALCOHOL
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Ethers

• An ether has the formula ROR.

• R and R can be the same or different groups.
• R and R can be saturated, unsaturated or
  aromatic.
• Saturated ethers have little chemical reactivity
  but are often used as solvents.

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• Alcohols and ethers are isomeric.

• They have the same molecular formula but
  different structural formulas.
• An alcohol and its isomeric ether have different
  chemical and physical properties.

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Naming Ethers
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Common Names

• Common names of ethers are formed from the names
  of the groups attached to the carbon atom in
  alphabetical order followed by the word ether.

CH3CH2CH2 O CH2CH3
propyl
ethyl
ether
ethyl propyl ether
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IUPAC RULES

• RO is an alkoxy group.
• Ethers are named as alkoxy derivatives of the
  longest carbon-carbon chain in the molecule

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IUPAC RULES

1. Select the longest carbon-carbon chain and label
   it with the name of the corresponding alkane.
2. Change the yl ending of the other hydrocarbon
   group to oxy to obtain the alkoxy group name.
3. Combine the names from steps 1 and 2, giving the
   alkoxy name first, to form the ether name.

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This is the longest carbon-carbon chain.
Label it with the name of the corresponding
alkane.
Change the name of the other hydrocarbon group to
oxy.
CH3CH2CH2 O CH2CH3
ethyl
propane
IUPAC name ethoxypropane Trivial name ethyl
propyl ether
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ALDEHYDES AND KETONES

• Functional group carbonyl group

• Aldehyde one hydrogen atom is bonded to the
  carbon in the carbonyl group.
• Ketone the carbon atom in the carbonyl group is
  bonded to two hydrocarbon groups.

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Naming Aldehydes
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The IUPAC names of aldehydes are obtained by
dropping the e and adding -al to the name of
the parent hydrocarbon.
butane
butanal
al
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• The parent hydrocarbon is the longest chain that
  carries the CHO group.

• This chain has 4 carbon atoms.

3
2
1
4
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• The parent hydrocarbon is the longest chain that
  carries the CHO group.

• This chain has 5 carbon atoms.

4
3
2
5
1
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4
3
2
5
3-methylpentanal
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• The common names of aldehydes are derived from
  the common names of the carboxylic acids.

• The ic acid or oic acid ending of the acid name
  is dropped and is replaced with the suffix
  aldehyde.

butyric acid
butyraldehyde
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Naming Ketones
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• The IUPAC name of a ketone is derived from the
  name of the alkane corresponding to the longest
  carbon chain that contains the ketone-carbonyl
  group.

• The parent name is formed by changing the e
  ending of the alkane to -one.

propane
propanone
one
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• If the carbon chain is longer than 4 carbons,
  its numbered so that the carbonyl carbon has the
  smallest number possible, and this number is
  prefixed to the name of the ketone.

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4
3
2
1
5
6
3-hexanone
102

• The common names of ketones are derived by naming
  the alkyl or aryl groups attached to the carbonyl
  carbon followed by the word ketone.

ethyl
propyl
ethyl propyl ketone
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ALKYL HALIDES

• General formula CnH2n1X where n 1,2, and X
  (halogen)
• Functional group halogen, -X (X F, Cl, Br, I)
• Naming alkyl halides
• - same as nomenclature of alkanes

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AMINES

• Amines are organic compounds and functional
  groups that contain a basic nitrogen atom with a
  lone pair

• Functional group

• Classification of amines

Primary amine Secondary amine Tertiary amine
                                                                                            
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• Primary (1o) amine one hydrogen of ammonia is
  replaced by an alkyl or aryl group
• Secondary (2o) amine two hydrogens of ammonia is
  replaced by an alkyl or aryl group
• Tertiary (3o) amine three hydrogens of ammonia
  is replaced by an alkyl or aryl group
• Quaternary (4o) amine an ion in which nitrogen
  is bonded to four alkyl or aryl groups and bears
  a positive charge

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NAMING AMINES

• Common names
• - formed from the names of the alkyl groups
  bonded to nitrogen, followed by the suffix
  amine.
• - the prefixes di-, tri-, and tetra- are used to
  decribe two, three or four identical substituents.

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NAMING AMINES

• IUPAC names
• - similar to that alcohols.
• - the longest continuous chain of carbon atoms
  determine the root name.
• - the e in alkane name is changed to amine,
  and a number shows the position of the amino
  group along the chain.
• - other substituents on the carbon chain are
  given numbers, and the prefix N- is used for each
  substituent on nitrogen.

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CARBOXYLIC ACIDS

• Functional group carboxyl group, -COOH

• The carboxyl group can also be written as

or
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• Open-chain carboxylic acids form a homologous
  series.

• The carbonyl group ( ) is always at
  the beginning of a carbon chain.

• The carbonyl carbon atom is always designated as
  C-1.

3
2
1
110

• The IUPAC name of a carboxylic acid is derived
  from the name of the alkane corresponding to the
  longest carbon chain that contains the carboxyl
  group.

• The parent name is formed by changing the e
  ending of the alkane to oic acid.

methanone
oic acid
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Examples of carboxylic acid
112

• Organic acids are usually known by common names.
• These names usually refer to a natural source of
  the acid.

ethanoic acid
methanoic acid
IUPAC name
IUPAC name
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CARBOXYLIC ACID DERIVATIVES
Group replacing the OH group of RCOOH Class of compound General formula Example
-X (halogen) Acyl halide
-OR Ester
-NH2 Amide
Acid anhydride
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Esters
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An ester is an organic compound derived from a
carboxylic acid and an alcohol.
carbonyl group
OR bonded to a carbonyl carbon.
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Esterification is the reaction of an acid and an
alcohol to form an ester.
acetic acid(ethanoic acid)
ethyl alcohol(ethanol)
ethyl acetate(ethyl ethanoate)
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IUPAC NAME

• According to the IUPAC system the alcohol part of
  the ester (R?) is named first.

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IUPAC NAME

• This is followed by the name of the acid where
  the ic ending of the acid has been changed to
  ate.

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IUPAC NAME

• According to the IUPAC system the alcohol part of
  the ester (R?) is named first.
• This is followed by the name of the acid where
  the ic ending of the acid has been changed to
  ate.

ethyl ethanoate
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• COMMON NAME
• The alcohol part is named first (derived from the
  common names of alcohol).
• The common names of esters are derived by adding
  ate to the name of the acid.

acetate
acetic acid ?
ethyl
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• COMMON NAME
• The alcohol part is named first (derived from the
  common names of alcohol).
• The common names of esters are derived by adding
  ate to the name of the acid.

ethyl acetate
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Amide

• Amide a composite of a carboxylic acid and
  ammonia or an amine.
• Classification of amide
• i) primary amide RCONH2 (two H atoms bonded to
  N atom)
• ii) secondary amide RCONHR (one H atoms
• bonded to N atom)
• iii) tertiary amide RCONRR (no H atoms bonded
  to N atom)

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NAMING AMIDE

• IUPAC name
• i) primary amide
• - first name the corresponding acid. Drop the
  ic acid or oic acid, and add the suffix amide.

ammonia
ethanoic acid
ethanamide
IUPAC name
acetic acid
acetamide
Common name
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NAMING AMIDE

• IUPAC name
• i) secondary and tertiary amide
• - treat the alkyl groups on nitrogen as
  substituents, and specify their position by the
  prefix N-.

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Acyl halide / acid halides

• Naming acid halides
• - replacing the ic acid suffix of the acid name
  with yl and the halide name.

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Acid anhydride

• Naming acid anhydride
• - the word acid is changed to anhydride in both
  the common and the IUPAC name

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FUNCTIONAL GROUPS OF ORGANIC COMPOUNDS
130
POLYMERS

• A polymer is a high molar mass molecular
  compound made up of many repeating chemical units.

• Naturally occurring polymers
• Proteins
• Nucleic acids
• Cellulose
• Rubber

• Synthetic polymers
• Nylon
• Dacron
• Lucite

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• The simple repeating unit of a polymer is the
  monomer.

• Homopolymer is a polymer made up of only one
  type of monomer

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• Copolymer is a polymer made up of two or more
  monomers

Styrene-butadiene rubber
133
Formation of Polyethylene
ethylene monomer
nCH2CH2 ?
CH2 CH2CH2 CH2n CH2 CH2 CH2 CH3

• n the number of monomer units.
• n ranges from 2,500 to 25,000

134
SOME MONOMERS AND THEIR COMMON SYNTHETIC POLYMERS
135
USES AND IMPORTANCE OF ORGANIC COMPOUNDS

• NYLON

• Nylons are condensation copolymers formed by
  reacting equal parts of a diamine and a
  dicarboxylic acids, so that peptide bonds form at
  both ends of each monomer in a process analogous
  to polypeptides biopolymers.

• General reactions

Nylon
Diamines
Dicarboxylic acids
136
Basic concepts of nylon production

• The first approach
• combining molecules with an acid (COOH) group on
  each end are reacted with two chemicals that
  contain amine (NH2) groups on each end.
• Form nylon 6,6, made of hexamethylene diamine
  with six carbon atoms and acidipic acid, as well
  as six carbon atoms.
• The second approach
• a compound has an acid at one end and an amine
  at the other and is polymerized to form a chain
  with repeating units of (-NH-CH2n-CO-)x.
• Form nylon 6, made from a single six-carbon
  substance called caprolactam.

137
Uses and important of nylon

• Apparel Blouses, dresses, foundation garments,
  hosiery, lingerie, raincoats, ski apparel,
  windbreakers, swimwear, and cycle wear
• Home Furnishings Bedspreads, carpets, curtains,
  upholstery
• Industrial and Other Uses Tire cord, hoses,
  conveyer and seat belts, parachutes, racket
  strings, ropes and nets, sleeping bags,
  tarpaulins, tents, thread, monofilament fishing
  line, dental floss

138
AZO-DYES

• Azo compounds
• - compounds bearing the functional group
  R-NN-R',
• in which R and R' can be either aryl or
  alkyl.
• - NN group is called an azo group
• - HNNH is called diimide
• Aryl azo compounds have vivid colors, especially
• reds, oranges, and yellows

• Yellow azo dye

139
Uses and important of azo dye

• Methyl orange - used as acid-base indicators due
  to the different colors of their acid and salt
  forms
• Artists paints clays, yellow to red range
• Dye in food and textiles

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E102 Tartrazine                                       
E107 Yellow 2G                                                                
E110 Sunset Yellow                                         
E122 Azorubine                                       
EXAMPLES OF AZO DYES USED IN FOOD
141
E123 Amaranth                                       
E124 Ponceau 4R                                 
E129 Allura Red                              
E151 Brilliant Black                                                           
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FUEL

• Any material that is burned or altered to obtain
  energy and to heat or to move an object
• Its energy can be stored to be released only when
  needed, and that the release is controlled in
  such a way that the energy can be harnessed to
  produce work
• Examples Methane, petrol and oil.
• Application of energy released from fuels
• - cooking
• - powering weapons to combustion
• - generation of electricity
• Fuel oil generate heat or used in an engine for
  the generation of power