Transcript Chem 341 Review for Finals Key Reactions Mechanisms

Chem 341 Review for Finals
Structure Determination
• NMR
–Chemical shifts, splitting patterns,
integrations
• IR
–ROH, C=O
• Formula => # of Rings + Pi-Bonds
Chem 341 Review for Finals
Structure and Bonding
• s- Bonds & p-Bonds
• Resonance Structures
• Aromaticity
–Heterocycles
• Pyramidal Amines & Flat Amides
• Cyclohexane
Chem 341 Review for Finals
Physical Properties
Boiling Points and Water Solubility
• Hydrocarbons
– weak forces, van der Waals Attraction
• Ethers, Ketones, Esters, Halides
–medium strength attraction: dipoles
• Alcohols, Acids, Amides
– strong attraction: hydrogen bonds
Chem 341 Review for Finals
Isomers
• Structural Isomers
• Stereoisomers
–Enantiomers (Chirality; R/S nomenclature)
–Diastereomers (meso isomers)
• epimers and anomers
• tautomers: ketones and enols
Chem 341 Review for Finals
Classes of Compounds
• Synthetic Polymers
– Polyesters, Polyamides,
– Radical Polymerization of alkenes
• Lipids and Detergents
–Fats, Waxes, Soaps, Detergents, miceles,
Phospholipid bi-layers
• Carbohydrates
– hexose, pentose, furanose, pyranose, aldose, ketose,
di- and polysaccharides, anomeric center
Chem 341 Review for Finals
Classes of Compounds
• Amino Acids
– acidic, basic, neutral
– isoelectric point
– peptides and proteins
• Nucleotides and Nucleic Acids
– purine and pyrimidine bases
– ribose and deoxyribose
– phosphate links between sugars
– hydrogen bonding of base pairs
Chem 341 Review for Finals
Acidity
• pKa and pH relationships
–Alcohols - phenols - carboxylic acids
–Alkyl amines - aryl amines
• Amino Acids
–Isoelectric point
Chem 341 Review for Finals
Reaction Types
• Reaction Energy Diagrams
• Additions to Alkenes
–H2, HBr, Br2
• Electrophilic Aromatic Substitution
(ortho/para vs meta directing groups)
- Nitration, bromination, alkylation,
sulfonation, alkylation, acylation
Chem 341 Review for Finals
Reaction Types
• Reaction Energy Diagrams
• Additions to Alkenes
– H2, HBr, Br2
• Reactions of Organic Halides
- Sn1, Sn2, E2
- Carbocation stabilities
Chem 341 Review for Finals
Reaction Types
• Reactions of Alcohols
–Dehydration, conversion to alkyl halides
–Oxidation of alcohols to aldehydes or acids
–Concept of oxidizing and reducing agents
• Ether Synthesis
• Epoxide ring opening
Chem 341 Review for Finals
Reaction Types
• RMgBr (Grignard Reagents)
–Preparation from alkyl halides
–Reactions with aldehydes, ketones, and esters
• Nucleophilic Addition to Ketones
– Irreversible additions: LiAlH4 RMgBr
– Reversible additions: alcohols => hemiacetal & acetal
– Addition-Elimination: amines => imines
Chem 341 Review for Finals
Reaction Types
• Reactions involving Enol Intermediates
– Exchange of ketone a-hydrogens with D2O
– Aldol condensation: addition of enolate anion
to an aldehyde carbonyl carbon
• Carboxylic acid derivatives
– Relative reactivity:
Acid halides > Anhydrides > Esters > Amides >
– Synthesis and Hydrolysis of Esters and Amides
– Reactions of Esters with RMgBr and LiAlH4
Chem 341 Review for Finals
Reaction Types
• Reactions of Amines
• Carbohydrates
– Reactions interconverting aldehydes and cyclic
hemiacetals, the anomeric center
Chem 341 Review for Finals
Key Reactions Mechanisms
• Electrophilic Addition to Alkenes
– HBr Addition to 1-hexene
• SN2 Reaction
–amine reaction with 1° halide
• SN1 Reaction
–water reaction with 3° halide
Chem 341 Review for Finals
Key Reactions Mechanisms
• E2 Elimination
–base reaction with a 2° halide to give
alkene
• Electrophilic Aromatic Substitution
– nitration of benzene
• Hemiacetal Formation
–Acid catalyzed reaction of alcohols with
aldehydes to give hemiacetal (sugars)
Chem 341 Review for Finals
Key Reactions Mechanisms
• Nucleophilic addition to Carbonyl Groups
–Base catalyzed hydrolysis of esters
• Acid Catalyzed Esterification
–Synthesis of esters from acids and alcohols
• Aldol Condensation
– enolate anion addition to carbonyl carbon