Alcohols, Phenols, and Thiols Nanoplasmonic Research Group Organic Chemistry Chapter 7 Part I

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 K a, Smaller pK a, and weaker (more stable) conjugate base Weaker Acid –Equilibrium toward left, Smaller K a, Lager pK a, and Stronger (less stable) conjugate base Why should we care so much about pK a ? Acid-base reactions comprises a major set of reactions in organic chemistry!!!

We can determine magnitude of equilibrium from known pK a 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, sp 2, sp 3 ) 6. Resonance

Then, you can easily understand section 7.6!!!