Review ketone aldehyde : : Nucleophilic addition : - C=O very polar O + - C=O very polar Nucleophilic addition - O C : + H-Nu H Nu O C H Nu + H-OH H-OR H-NH2 + -

Nucleophilic addition C O-H R O-H C O R .. H C = O R .. H+ C = O R .. + H+ H H+ hydrate or diol C O R .. H C R O-H O-R + H+ + H-OH O .. H R .. O H N H .. C = O R .. + H-OR hemi-ketal C R O - H N - H2 + H+ C R N H + H2O + H-NH2 Schiffs base

Addition of alcohol H C O CH3 H3C H C O H3C H+ + CH3OH H OCH3 ketone hemi- ketal unstable aldehyde + alcohol = hemi- acetal unstable

Nucleophilic substitution .. .. hemi - acetal condensation reaction H3C H OH O - CH2 - CH3 O - CH2 - CH3 H .. .. H+ C H3C H OH O - CH2 - CH3 H+ .. OH - CH3 - CH2 .. .. + H2O hemi - acetal C H3C H O - CH2 - CH3 + H+ aldehyde alcohol + alcohol acetal + condensation reaction hemi-acetal + alcohol acetal + H2O

acetal propanal + 2 equivalents ethanol stable hemi- ketal 2-butanone + 1 equivalent methanol unstable

.. .. + cyclohexan one ethane diol .. .. ketal hemi-ketal H+ H + H2O

Carboxylic acids [O] [O] 1o alcohol aldehyde carboxylic acid methanol methanal methanoic acid H-bond acceptor - very high b.p. H-bond donor - + 2 H-bonds / molecule

Carboxylic acids Nomenclature 1. Carboxyl group (COOH) always C1 2. Family name is longest C chain with COOH 3. Suffix is “-oic acid” 4. Carbonyl groups (C=O) called “oxo” Hydroxy groups (OH) called “hydroxy”

Carboxylic acids 2-ethyl butan oic acid 2-ethyl 4-hydroxy 2-ethyl- CH3 – CH2 – CH – C CH2 – CH3 O OH 4 3 2 1 2-ethyl butan oic acid O CH3 – CH2 – CH – CH2 – CH – CO2H OH CH2 – CH3 2-ethyl 4-hydroxy 6 5 4 3 2 1 2-ethyl- 4-hydroxy hexan oic acid 2-ethyl- 4-oxo hexan oic acid add [O]

Carboxylic Acids Chemical properties = = OH C=O + Bronsted acid H+ donor HA H+ + A- H+ + weak acids, small dissociation Ka = [A-] [H+] Ka  1 x 10-5 pH  2.5 for 1M [HA]

Carboxylic Acids H+ + H+ + - resonance structure anion stabilized

Carboxylic Acids - acidity also affects solubility soluble short chain acids H-bonding long chain acids insoluble benzoic acid LDF - add a strong base (OH-) soluble ion-dipole

Reactions Acid-base reactions: + NaOH octanoic acid insoluble sodium octanoate + water soluble

Reactions Reduction: 5-oxo hexanoic acid 1,5- hexanediol 5-hydroxy LiAlH4 6 5 4 3 2 1 5-oxo hexanoic acid 1,5- hexanediol H2/ Pt NaBH4 5-hydroxy hexanoic acid