Elimination and Addition

Question 1

Elimination Rx definition

Answer 1

-LG sub leaves, C=C forms with no addition

Question 2

E1 description

Answer 2

• alkyl halide, halogen is good LG
• after carbocation formed, nucleophile pulls off LP e-
• LP leftover attracted to carbo cation > C=C forms
• usu weak base

Question 3

E2 description

Answer 3

• 1 concerted step
• base attacks proton adjacent to substrate carbon
• kicks off LG and acid formation
• very strong base is required

Question 4

what does regioselective mean? what rule governs it?

Answer 4

• C=C double bond has preferred location
• Zaitse’vs rule: alkene with more sub comming off double bond is more stable
• trans > cis

Question 5

Requirements for Nuc addition:

Answer 5

• electrophile with double or triple bond
• USU carbonyl, also nitrile, alkene, alkyne
• usu alcohol attack aldehyde or ketone to form hemiacetal or hemiketal

Question 6

Hemiacetal vs hemiketal

Answer 6

hemiacetal: - OR, OH, R, H
hemiketal: - OR, OH, R, R

Question 7

Can a secondary alcohol be further oxidized?

Answer 7

Not enough hydrogens to be oxidized into COOH

• only primary alcohol can be > COOH with strong oxidizing agent
• PCC = weak oxidizing agent

Question 8

Elim/Addition Rx: pi and sigma bonds

Answer 8

Elimination: increase pi, reduce sigma ponds

Addition: reduce pi, increase sigma bonds