Lec-42-Exam4-Review

Lec-42-Exam4-Review - Lecture 42 Exam Review Concepts to...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 42 – Exam Review – Concepts to Remember – Organic Chemistry; Chapters 12 and 16. Prof. Wong So how do we make a double bond? To form a double bond, we must remove a proton and an anion Br OH ++ Br + O H H I + + I + O H H Elimination Reactions We should need a VERY strong base!!! Surprisingly, OH is sufficient
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Substitution vs. Elimination Substitution : Lewis base attacks the C-X bond directly. Cl + OH OH + Cl Cl + H + O H H + Cl One set of starting materials can produce both products!!! Substitution and elimination are competing reactions. Elimination : Lewis base attacks the proton on a carbon adjacent to the C-X bond. Summary of Reaction Mechanisms Substitution & Elimination : • Alkyl halide starting material acts as a Lewis acid • Lewis base leads to either: Substitution new bond to C is formed with loss of halide Elimination Lewis acid is deprononated to form a carbocation loss of halide anion leads to a double bond Addition : •C=C π bond acts as a Lewis base • Lewis acid is HBr, Br 2 , other Lewis acids. Addition-Elimination : • Acid chloride acts as a Lewis acid • Lewis base attacks sp 2 C, breaks π bond, forms sp 3 C π bond reforms with elimination of the chloride
Background image of page 2
Question: In substitution, why doesn’t X attack H–B? A: Formal charge B: Product base strength C: Reactant acid-base strength D: A & B E: B & C F: A,B,C D: Product base strength and formal charge NH 2 product is a very strong base!!! Cl would gain a +1 formal charge Eliminating HCl forms CH 3 , a very strong base!!! Reactants should have little effect H is a good Lewis acid Cl is not a particularly strong base H N H H Cl C H H H Summary of Synthetic Routes X X Alkynes X X Alkenes X X Alkanes X Amides X Esters X X Carboxylic acids X Amines X Ketones X Aldehydes X Ethers X Alcohols X X Alkyl Halides Elimination Addition Addition- Elimination Substitution Oxidation
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Substitution : What functional groups can we make? X :B + B + :X alcohols and ethers amines Br + N + HBr N H halides Br + I + I Br Br + O + HBr O H Br O + Br + O carbon-carbon bonds Substitution : What functional groups can we make?
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This test prep was uploaded on 03/31/2008 for the course CHEM 131 taught by Professor Wong during the Spring '08 term at SUNY Stony Brook.

Page1 / 17

Lec-42-Exam4-Review - Lecture 42 Exam Review Concepts to...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online