1.1-1.5 Introduction

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1.1-1.5 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

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Introduction

• Some familiar organic compounds

Acetic acid
ether
aspirin
Ethyl alcohol
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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

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Introduction

• Functional groups that contain O or N atoms often
  lead to a polar organic molecule

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Functional Groups

• Example Name the functional groups that are
  present in the following compounds
• CH3CH2OH
• O
• H2C CHCOH
• CH3CH2NCH3
• CH3

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Functional Groups

• Example Name the functional group(s) that is
  (are) present in the following compounds
• H2C CH2
• H2C CH2
• CH3NHCH2CH2OCH3

O
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Hydrocarbons

• The simplest organic compounds are the
  hydrocarbons
• organic compounds that contain only carbon and
  hydrogen
• four general types
• alkanes
• alkenes
• alkynes
• aromatic hydrocarbons

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Hydrocarbons

• Alkanes
• hydrocarbons that contain only single bonds
• Examples
• Methane CH4
• ethane H H
• H C C H
• H H

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Bonding Characterstics of Carbon

• 4 valence electrons means carbon can (and does!)
  form 4 bonds
• These bonds can be to
• 4 other atoms
• 3 other atoms
• 2 other atoms

Linear
Tetrahedral
Trigonal planar
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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)

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Hydrocarbons

• Aromatic hydrocarbons
• contain a planar ring structure in which the
  carbon atoms are connected by delocalized
  electrons

H C
C - H
H - C
benzene
C - H
H - C
C H
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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 hydrocarbons
• they contain less hydrogen than an alkane having
  the same number of carbon atoms

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Alkanes

• Organic compounds can be represented in many
  different ways
• molecular formula C4H10 (butane)
• Lewis structure
• Condensed structural formula
• CH3CH2CH2CH3
• Line angle drawings

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Alkanes

• Some of the simplest alkanes

You must know these!!!
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Alkanes

• Some of the simplest alkanes

You must know these!!!
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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

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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
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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

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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
CH2
H2C
cyclopropane
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• Fig. 12.11 For a series of
  alkanes or cycloalkanes, melting point increases
  as carbon chain length increases.

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Saturated Hydrocarbons contd

• Fig. 12.4
• Models of (a) pentane, (b) isopentane, and (c)
  neopentane.

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Saturated Hydrocarbons contd

• Fig. 12.3
• Molecular structures of (a) methane, (b) ethane,
  and (c) propane, the three simplest alkanes.

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Alkanes

• Examples of cycloalkanes

CH2
CH2
H2C
cyclopentane
CH2
H2C
cyclohexane
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Naming 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

1
2
CH3 - CH - CH3 CH2 - CH2 - CH2 - CH3
Base name hexane
3
4
5
6
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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 that have taken
  the place of a hydrogen atom on the main chain

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A substituent
2
CH3 - CH - CH3 CH2 - CH2 - CH2 - CH3
3
4
5
6
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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 is called an alkyl group
• Name alkyl groups by dropping the ane ending of
  the parent alkane and adding yl

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Alkanes

• Alkane Nomenclature
• Common alkyl groups (substituents)
• CH3 methyl
• CH3CH2 ethyl
• CH3CH2CH2 propyl
• CH3CH2CH2CH2 butyl

Know these!
1
2
CH3 - CH - CH3 CH2 - CH2 - CH2 - CH3
2-methylhexane
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4
5
6
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Alkanes

• Alkane Nomenclature
• Halogen atoms are another common class of
  substituents.
• Name halogen substituents as halo
• Cl chloro
• Br bromo
• I iodo

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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.
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Alkanes

• Example Name the following compounds
• CH3CH2CHCH2CH3
• CH3
• CH2CH2CH3
• CH3CHCHCH3
• CH3

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Alkanes

• Example Name the following compounds
• CH3CH2CHCH3
• CH2CH2Br
• CH2CH2CH3
• CH3CHCHCH3
• Cl

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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
  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

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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

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Alkenes

• Alkenes
• unsaturated hydrocarbons that contain a CC
  double bond
• Alkene Nomenclature
• Names of alkenes are based on the longest
  continuous chain of carbon atoms that contains
  the double bond.

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Saturated Hydrocarbons contd
CAG 12.1
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Alkenes

• Alkene Nomenclature
• Find 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

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Alkenes

• Alkene Nomenclature
• Indicate the location of the double bond using a
  prefix number
• designate 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.

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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

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Alkenes

• Alkene Nomenclature
• Cis 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

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Alkene
CH3 CH3 C C H H
CH3 H C C H CH3
trans-2-butene

• cis-2-butene

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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
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Alkene

• Example Name the following alkenes
• CH3CH2 H
• C C
• H H
• CH3CH2 H
• C C
• CH3CHCH2 CH2CH3
• CH3

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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

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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

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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

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Alkynes

• Example Name the following compounds
• CH3CH2C CCHCH3
• CH2CH3
• CH2CH2C CH
• Cl

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Alkynes

• Example Draw the following alkynes.
• 4-chloro-2-pentyne
• 3-propyl-1-hexyne