Organic Chemistry

1
Organic Chemistry

• The chemistry of carbon compounds.
• Carbon has the ability to form long chains.
• Without this property, large biomolecules such as
  proteins, lipids, carbohydrates, and nucleic
  acids could not form.

2
Structure of Carbon Compounds

• There are three hybridization states and
  geometries found in organic compounds
• sp3 Tetrahedral
• sp2 Trigonal planar
• sp Linear

3
Hydrocarbons

• Four basic types
• Alkanes
• Alkenes
• Alkynes
• Aromatic hydrocarbons

4
Alkanes

• Only single bonds.
• Saturated hydrocarbons.
• Saturated with hydrogens.

5
Formulas

• Lewis structures of alkanes look like this.
• Also called structural formulas.
• Often not convenient, though

6
Formulas

• so more often condensed formulas are used.

7
Properties of Alkanes

• Only van der Waals force London force.
• Boiling point increases with length of chain.

8
Structure of Alkanes

• Carbons in alkanes sp3 hybrids.
• Tetrahedral geometry.
• 109.5 bond angles.

9
Structure of Alkanes

• Only ?-bonds in alkanes
• Free rotation about CC bonds.

10
Isomers

• Have same molecular formulas, but atoms are
  bonded in different order.

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Organic Nomenclature

• Three parts to a compound name
• Base Tells how many carbons are in the longest
  continuous chain.

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Organic Nomenclature

• Three parts to a compound name
• Base Tells how many carbons are in the longest
  continuous chain.
• Suffix Tells what type of compound it is.

13
Organic Nomenclature

• Three parts to a compound name
• Base Tells how many carbons are in the longest
  continuous chain.
• Suffix Tells what type of compound it is.
• Prefix Tells what groups are attached to chain.

14
To Name a Compound

• Find the longest chain in the molecule.
• Number the chain from the end nearest the first
  substituent encountered.
• List the substituents as a prefix along with the
  number(s) of the carbon(s) to which they are
  attached.

15
To Name a Compound

• If there is more than one type of substituent in
  the molecule, list them alphabetically.When
  carbon chains stick out of a main chain, you add
  yl to the name.

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Example

• Name the following

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Cycloalkanes

• Carbon can also form ringed structures.
• Five- and six-membered rings are most stable.
• Can take on conformation in which angles are very
  close to tetrahedral angle.
• Smaller rings are quite strained.

18
Reactions of Alkanes

• Rather unreactive due to presence of only CC and
  CH ?-bonds.
• Therefore, great nonpolar solvents.

19
Alkenes

• Contain at least one carboncarbon double bond.
• Unsaturated.
• Have fewer than maximum number of hydrogens.

20
Structure of Alkenes

• Unlike alkanes, alkenes cannot rotate freely
  about the double bond.
• Side-to-side overlap makes this impossible
  without breaking ?-bond.

21
Structure of Alkenes

• This creates geometric isomers, which differ
  from each other in the spatial arrangement of
  groups about the double bond.

22
Properties of Alkenes

• Structure also affects physical properties of
  alkenes.

23
Nomenclature of Alkenes

• Chain numbered so double bond gets smallest
  possible number.
• cis- alkenes have carbons in chain on same side
  of molecule.
• trans- alkenes have carbons in chain on opposite
  side of molecule.

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Nomenclature

• Examples

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Reactions of Alkenes

• Addition Reactions
• Two atoms (e.g., bromine) add across the double
  bond.
• One ?-bond and one ?-bond are replaced by two
  ?-bonds therefore, ?H is negative.

26
Alkynes

• Contain at least one carboncarbon triple bond.
• Carbons in triple bond sp-hybridized and have
  linear geometry.
• Also unsaturated.

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Nomenclature of Alkynes
4-methyl-2-pentyne

• Analogous to naming of alkenes.
• Suffix is -yne rather than ene.

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Reactions of Alkynes

• Undergo many of the same reactions alkenes do.
• As with alkenes, impetus for reaction is
  replacement of ?-bonds with ?-bonds.

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Aromatic Hydrocarbons

• Cyclic hydrocarbons.
• p-Orbital on each atom.
• Molecule is planar.
• Odd number of electron pairs in ?-system.

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Aromatic Nomenclature

• Many aromatic hydrocarbons are known by their
  common names.

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Reactions of Aromatic Compounds

• Unlike in alkenes and alkynes, ?-electrons do not
  sit between two atoms.
• Electrons are delocalized this stabilizes
  aromatic compounds.

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Structure of Aromatic Compounds

• Two substituents on a benzene ring could have
  three possible relationships
• ortho- On adjacent carbons.
• meta- One carbon between them.
• para- On opposite sides of ring.

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Functional Groups

• Term used to refer to parts of organic molecules
  where reactions tend to occur.

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Halogens

• Put the number position and add the halogen
  (fluro, chloro, iodo, bromo)
• Example

35
Alcohols

• General structure
• Alcohols have a hydroxyl group
• Naming simple alcohols
• Methane
• Methanol
• Ethane
• Ethanol

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Alcohols

• Propane
• 1-Propanol
• 2 Propanol

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Phenols

• General Structure
• They have a hydroxyl group attached to a benzene
  ring
• There are three positions on the phenol

ortho
ortho
meta
meta
para
38
Phenols

• Metamethyl Phenol

• Orthomethyl phenol

• Paramethyl Phenol

39
Ethers

• General Structure ?
• They are bonded by having two carbon groups
  bonded to an oxygen
• The shorter of the two chains becomes the first
  part of the name with the -ane suffix changed to
  -oxy, and the longer alkane chain become the
  suffix of the name of the ether.
• Naming some simple ethers
• Methane
• Methoxymethane (Dimethyl ether)

40
Ethers

• Ethane
• Ethoxyethane (diethyl ether)
• Ethane and Methane
• Methoxyethane (Ethyl methyl ether)

41
Amines

• General Structure
• Amines are nitrogens bonded with one, two or
  three carbons.

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Amines

• Ethane
• Ethylamine
• Diethylamine
• Triethylamine

43
Amines

• Ethyl methyl amine
• Diethyl methyl amine

44
Ketones

• General structure
• Ketones have a double bond O bonded to C and two
  other carbon groups

45
Ketones

• 2 - butanone
• 2 - pentanone
• 3 - hexanone

46
Aldehydes

• General structure
• Aldehyde groups have a double bonded O with a
  hydrogen
• -ane becomes anal-ene becomes enal-yne become
  ynal
• Carbon 1 is always starting at the carbon double
  bonded to O

47
Aldehydes

• Pentane
• Pentanal
• 3 Pentenal
• 3 - Pentynal

48
Carboxylic Acids

• General structure
• Add the ending oic acid to the prefix
• ane ? anoic acid
• ene ? enoic acid
• yne ? ynoic acid
• Carbon 1 is anchored at the double bond O

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Carboxylic acid

• Three single bond carbons ? Propane
• Propane ? Propanoic Acid
• One carbon ? Methane
• Methane ? Methanoic Acid

50
Carboxylic Acid

• 2-propenoic acid
• 3-butynoic acid

51
Esters
This is just a regularbranched yl group
This is where you have to add an oate ending
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Esters
propanoate
methyl
Methyl propanoate
53
Esters
propanoate
ethyl
Ethyl propanoate
54
Esters
pentanoate
Propyl
Propyl pentanoate
55
Practice
56
Chirality

• Carbons with four different groups attached to
  them are handed, or chiral.
• Optical isomers or stereoisomers
• If one stereoisomer is right-handed, its
  enantiomer is left-handed.

57
Chirality
S-ibuprofen

• Many pharmaceuticals are chiral.
• Often only one enantiomer is clinically active.