Reactivity

Question 1

electrophiles

Answer 1

electron accepting
partial positive charge

electrophiles act like lewis acids -> want to take more electrons

Question 2

nucleophiles

Answer 2

electron donors
negative/ partial negative charge

nucleophiles act like lewis bases -> want to donate electrons

Question 3

reactivity of carbonyls

Answer 3

low --> high
amide
carboxylic acid
ester
ketone
aldehyde
anhydride
acyl halide

high reactivity = less stable

Question 4

what is more reactive, ester or amide?

Answer 4

ester because is electron withdrawing which creates partial charges and decreases electron density

amides are electron donating and will increase electron density

Question 5

electron donating atoms

Answer 5

decrease reactivity and increase electron density around carbonyl carbons

when you donate electrons you are increasing amount of electrons in the near vicinity, spreading them out

Question 6

electron withdrawing atoms

Answer 6

increase reactivity and decrease electron density around carbonyl carbons

they have more electrons so can react more and also will hold electrons close, so decrease electron density around other places like carbonyl carbon

Question 7

leaving groups

Answer 7

weak bases

weaker the base, better the leaving group

I-, Cl-, Br-, H2O

Question 8

inductive effect

Answer 8

polarization of bonds due to electron withdrawing or electron donating

as moves further from central atom, inductive effect gets weaker
more electronegative atoms draw electrons towards themselves, creating larger dipole (-) and creating larger inductive effect

donated through sigma bonds

Question 9

Which halogens are good leaving groups and why?

Answer 9

Cl < Br < I

the larger the atom, the greater surface area, so the larger distance a negative charge can be spread and stabilized

Question 10

What determines nucleophilic ability?

Answer 10

1. solvent: want a polar protic solvent
2. charge: want charge to be negative
3. sterics: bulkier nucleophiles are hindered/slower
4. the more electronegative, the less nucleophilic

Question 11

What direction of reactivity do molecules follow? high to low or low to high

Answer 11

molecules want to move from state of high reactivity (low stability –> low reactivity (high stability)

Question 12

What increases nucleophilicity?

Answer 12

being closer to the left side of the periodic table because those elements have electrons that they want to donate. Also when something has a larger negative charge, stronger nucleophile

Question 13

azide

Answer 13

N3-

powerful nucleophile which can readily add to available electrophiles

Question 14

Is water a good nucleophile

Answer 14

water is a weak nucleophile until it loses a proton and becomes OH- then it becomes a really good nucleophile