Transcript Aldehid dan Keton

Aldehid dan Keton
• Pyridoxal phosphate (PLP) is common
coenzyme
• Hydrocortisone is steroid hormone
secreted by adrenal glands
• Penicillin G : an antibiotic
Carbonyl Compounds
Nomenclature of Aldehydes
Naming Aldehydes and Ketones
Nomenclature of Ketones
Naming Aldehydes and Ketones
Some common names accepted by IUPAC
Boiling Points
• More polar, so higher boiling point than
comparable alkane or ether.
• Cannot H-bond to each other, so lower
boiling point than comparable alcohol.
Carbonyl Structure
• Carbon is sp2 hybridized.
• C=O bond is shorter, stronger, and
more polar than C=C bond in alkenes.
Preparation of Aldehydes and Ketones
• Aldehydes from oxidation of primary alcohols using
pyridinium chlorochromate (PCC)
• Aldehydes from reduction of carboxylic esters using
diisobutylaluminum hydride (DIBAH)
Aldehydes and ketones react with nucleophiles to form
addition products: nucleophile addition reactions
Tetrahedral
intermediate
Acid catalyst
All carboxylic acid derivatives react by the same general
mechanism
The tetrahedral intermediate eliminates the weakest base
Nucleophilic Addition Reactions of Aldehydes and Ketones
Nucleophilic Addition of H2O: Hydration
Aldehydes and ketones react reversibly with water to give
1,1-diols, or geminal (gem) diols
• Equilibrium favors carbonyl compound for steric
reasons with the exception of formaldehyde
Formation of a New Carbon–Carbon
Bond Using Grignard Reagents
Reduction by Hydride Ion
Aldehydes and ketones react with a primary amine to
form an imine
This is a nucleophilic addition–elimination reaction
The pH of the reaction must be controlled
Aldehydes and ketones react with secondary amines to
form enamines
Water adds to an aldehyde or ketone to form a hydrate
Addition of an Alcohol to an Aldehyde
or a Ketone
Addition of Sulfur Nucleophiles
Oxidation
of Aldehydes
Tollens Test
O
R C H + 2
2
+
Ag(NH3)2
+
Ag(NH3)2
_
+
3 OH
_
+
3 OH
O
H2O
O
H2O
2 Ag + R C O
silver mirror
_
2 Ag + R C O
_
+
4 NH3 + 2 H2O
The reactivity of carbonyl compounds resides in the
polarity of the carbonyl group in a nucleophilic acyl
substitution reaction
The a-Hydrogen is Acidic
the anion is stabilized by resonance
Keto–Enol Tautomerism
The enol tautomer can be stabilized by intramolecular
hydrogen bonding
One molecule of a carbonyl compound acts as a
nucleophile and the other carbonyl compound acts as an
electrophile
Ketones are less susceptible than aldehydes to attack
by nucleophiles
An aldol addition product loses water to form an aldol
condensation product
The Mixed Aldol Addition