Organic chemistry - Chapter 3: Introduction to reaction mechanisms - Nam Phan
A nucleophile: an electron-rich species that can
form a covalent bond by donating 2 electrons to a
positive center
• A nucleophile is any negative / neutral molecule
that has 1 unshared electron pair
• Substitution reaction: chemical reaction in which
1 atom / group replaces another atom / group in the
structure of a molecule
• In a nucleophilic substitution reaction, a
nucleophile attacks / bonds with the positive cent
form a covalent bond by donating 2 electrons to a
positive center
• A nucleophile is any negative / neutral molecule
that has 1 unshared electron pair
• Substitution reaction: chemical reaction in which
1 atom / group replaces another atom / group in the
structure of a molecule
• In a nucleophilic substitution reaction, a
nucleophile attacks / bonds with the positive cent
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- Chapter 3: INTRODUCTION TO REACTION MECHANISMS Reaction mechanism: the description of the step-by-step process by which reactants are changed / converted into products Nucleophilic substitution Nucleophilic addition Electrophilic substitution Electrophilic addition Elimination 2
- UNIMOLECULAR NUCLEOPHILIC SUBSTITUTION REACTION (SN 1) 6
- ELIMINATION REACTIONS In an elimination reaction: + Groups / atoms are eliminated from a reactant + A double bond is formed between the 2 carbons from which atoms are eliminated 8
- Weak base 12
- NUCLEOPHILIC ADDITION REACTIONS (AN) The carbonyl group is polar because the oxygen, being more electronegative, has greater share of double-bond electrons The partial positive carbon can be attacked by nucleophiles The addition of nucleophiles to the carbon atom of the carbonyl group in nucleophilic addition reactions 16
- Examples: Nucleophiles 18
- Reaction mechanism Rate-determining step An electrophile 20