Download Organic Chemistry Chapter 1

Organic Chemistry
Chapter 7
Part I
Alcohols, Phenols, and Thiols
Nanoplasmonic Research Group
Nomenclature of Alcohols
• In the IUPAC system, the hydroxyl group
in alcohols is indicated by the ending -ol
• In common names, the separate word alcohol
is placed after the name of the alkyl group
• Please refer to a few examples on page 208
• Methyl (C has 3 H’s), Primary (1°) (C has two
H’s, one R), secondary (2°) (C has one H, two
R’s), tertiary (3°) (C has no H, 3 R’s),
Nomenclature of Phenols
• Phenols are usually named as derivatives
of the parent compounds
• BUT, when hydroxyl group co-exists with
carboxylic acid, aldehyde, or ketone
functionalities which have priority over
hydroxyl group, it is named as a substituent
• Please refer to a few examples on page 210
Acidity of Organic Molecules
Revisited!!!
• Bronsted-Lowry Acid/Base (proton
transfer)
• Acid-donates a proton
• Base-accepts a proton
• Lewis Acid/Base (electron transfer)
• Acid-accepts an electron pair to form a
bond (must have empty or easily vacated
orbital, or polar bond to a hydrogen
• Base-donates an electron pair to form a
bond (must have lone pairs to donate)
• Lewis acids is an “electrophile”, so it
seeks electrons
• Lewis base is a “nucleophile”, so it seeks
a nucleus
Acidity Strength (I)
• Ability to donate H+: The stronger the
acid, the better able to donate a proton
Acidity Strength (II)
• Stronger Acid
– Equilibrium toward right, Larger Ka, Smaller pKa,
and weaker (more stable) conjugate base
• Weaker Acid
– Equilibrium toward left, Smaller Ka, Lager pKa,
and Stronger (less stable) conjugate base
• Why should we care so much about pKa?
Acid-base reactions comprises a major
set of reactions in organic chemistry!!!
We can determine magnitude of
equilibrium from known pKa values!!
Using Structure to Predict
Acidity/Basicity
• Strong acid
– Relatively unstable acid
– Relatively stable conjugate base
• Weak acid
– Relatively stable acid
– Relatively unstable conjugate base
• 6 factors to be considered
– Charge, Electronegativity, Size, Induction,
Hybridization, Resonance!!!!
1. Charged vs. Noncharged Species
2. Electronegativity of the atom attached
to H (same row)
3. Size of attached atom (same column)
4. Inductive electron withdrawal
- The more EN, the more acidic & The closer, the
more acidic -
5. Hybridization (sp, sp2, sp3)
6. Resonance
Then, you can easily
understand section 7.6!!!