Organic reactions

Question 1

how does overall charge change in a reaction

Answer 1

it doesn’t - it’s conserved

Question 2

what is a nucleophile

Answer 2

have high electron density and donate electrons in a reaction
- negative charge or lone pairs often

Question 3

what are electrophiles

Answer 3

have low electron density and accept electrons in a reaction
- positive charge or neutral, with empty orbitals like lewis acids

Question 4

where do reactions typically occur on a molecule

Answer 4

at the funcitonal groups

Question 5

what to look for to find reaction site

Answer 5

• atoms with formal charge or lone pairs of electrons
• electronegative atoms since they have polarized bonds and electron are unevenly shared -> sites of high/low electron density where bonds can break/form
• double bonds; the second pi bond is weak and can break, acting as a nucleophile or electrophile

Question 6

the most EN atom is the ___ nucleophile

Answer 6

worst

Question 7

the most EN is ___ electrophile

Answer 7

best

Question 8

Acid-base reaction mechanism

Answer 8

• the proton is exchanged between electrophile and nucleophile (usually reversible)
• new bond to H forms and a diff bond breaks

Question 9

Nucleophilic addition to a C=O bond

Answer 9

nucleophile adds to C=O -> new Nu-C forms at same time as C-O breaks
- carbon geometry changes sp

Question 10

nucleophilic substitution at C=O

Answer 10

new Nu-C forms then C-LG bond breaks in 2 steps

Question 11

how does reactivity affect stability

Answer 11

increasing reactivity decreases stability

Question 12

what influences reactivity

Answer 12

1. Electronegativity
2. Induction = when EN atoms pull electron density through space
3. electron delocalization = spreads out electron density to stabilize the molecule, creating multiple possible sites of reactivity on the molecule (resonance)
4. atom size (or polarizability -> hard or soft) = larger atom -> longer and weaker H-atom bond
5. Steric Hindrance = when a reaction is prevented/slowed by the presence of bulky groups around the reaction site that physically prevent the reaction

Question 13

Leaving Groups

Answer 13

takes electron from bond when detaching from molecules

Question 14

what makes a good leaving group

Answer 14

• has polarized bonds (EN or + charge_
• Stabilized when they leave (delocalized charge, large atoms, neutral)