Amides
Page 1: Introduction to Amides
Amides: A class of compounds where the hydroxyl group of carboxylic acids is replaced by a nitrogen group from primary or secondary amines.
Example: Tylenol (acetaminophen) is an amide that reduces fever and pain, though it has minimal anti-inflammatory effects.
Page 2: Preparation of Amides
Amides are derived from carboxylic acids.
Formation involves replacing the hydroxyl group (-OH) of a carboxylic acid with a nitrogen group from a primary or secondary amine.
Page 3: Process of Amidation
Amidation Reaction: The synthesis of amides occurs through a reaction called amidation or condensation.
Chemical Reaction: A carboxylic acid reacts with ammonia or a primary/secondary amine under heat, resulting in the formation of an amide and the release of water.
Page 4: Learning Check 1
Task: Predict the products of a specific amidation reaction (details not provided).
Page 5: Solution 1
Task Resolution: Predict the products of amidation (specifics not provided).
Page 6: Naming Amides
Amides are named by modifying the name of the corresponding carboxylic acid:
Drop "oic acid" (IUPAC) or "ic acid" (common) from the name.
Add the suffix "amide".
Page 7: Alkyl Groups in Amides
When alkyl groups are attached to the nitrogen atom in an amide:
They are indicated with the prefix N- followed by the alkyl name.
Page 8: IUPAC Naming Steps
Example Task: Given an amide structure, determine the IUPAC name.
Steps to Name:
Replace "oic acid" in the carboxylic acid name with "amide".
For alkyl substituents on nitrogen, use the prefix N-.
Page 9: Continued Naming Guidance
Further steps to name amides include indicating each substituent on the nitrogen with the N- prefix and the corresponding alkyl name.
Page 10: Learning Check 2
Task: Identify the IUPAC and common names for given amides A and B (specifics not provided).
Page 11: Solution 2
Example Names:
A: ethanamide (IUPAC), acetamide (common).
B: N-ethylpropanamide (IUPAC), N-ethylpropionamide (common).
Page 12: Physical Properties of Amides
Amides largely lack the basic properties of amines.
At room temperature:
Only methanamide is liquid; others are solids.
Melting Points:
Primary amides have the highest due to maximized hydrogen bonding.
Secondary amides have lower melting points than primary.
Tertiary amides cannot form hydrogen bonds and have the lowest melting points.
Page 13: Melting Points Overview
Selected Amides and Melting Points:
Primary (Propanamide): 80 °C
Secondary (N-Methylethanamide): 28 °C
Tertiary (N,N-Dimethylmethanamide): -61 °C.
Page 14: Hydrogen Bonding in Primary Amides
Primary amides can form hydrogen bonds:
With other amides.
With water, leading to solubility in water if they have < 5 carbons.
Page 15: Hydrogen Bonding in Secondary Amides
Secondary amides have lower melting points due to fewer hydrogen bonds compared to primary amides.
They remain soluble in water when < 5 carbons are present.
Page 16: Hydrogen Bonding in Tertiary Amides
Tertiary amides have the lowest melting points because they form the least hydrogen bonds.
They can only engage in one hydrogen bond.
Page 17: Chemistry Link to Health: Urea
Urea: The simplest natural amide, product of protein metabolism.
It is excreted in urine; failure to excrete can lead to uremia, a toxic buildup in the body.
Page 18: Chemistry Link to Health: Aspirin Substitutes
Aspirin substitutes like phenacetin and acetaminophen are amides that reduce fever and pain, with minimal anti-inflammatory properties.
Page 19: Chemistry Link to Health: Barbiturates
Barbiturates: Cyclic amides derived from barbituric acid.
They act as sedatives in low doses and induce sleep in higher doses but are habit-forming.
Examples include phenobarbital (Luminal) and pentobarbital (Nembutal).