Aromaticity and Benzene Reactions

Question 1

Criteria for aromaticity

Answer 1

must be cyclic
must be fully conjugated
must be planar
must obey huckels rule (4n+2)

Question 1

What steps are involved in creating Frost Circles?

Answer 1

Draw a circle, draw the molecule with the vertex pointed down, draw a horizontal line where the circle and ring meet, and fill with the appropriate amount of pi electrons

Question 2

Aromaticity and lone pairs

Answer 2

lone pairs can exist in either hybridized or unhybridized p-orbitals; that may or may not contribute to aromaticity

Question 3

Aromaticity and polycyclic molecules

Answer 3

Not all double bonds participate in aromaticity; look for the largest closed loop

Question 4

Criteria for anti-aromaticity

Answer 4

obey all other rules for aromaticity, however, these do not obey huckels rule

Question 5

Criteria for non-aromatics

Answer 5

does not obey one or more rules for aromaticity

Question 6

Acidity and Basicity of aromatics

Answer 6

if deprotonation of the ring results in gaining/retaining aromaticity then the molecule is likely acidic; the more stable the conjugate base, the more acidic the molecule; via delocalization

Question 7

pKa

Answer 7

dissociation constant of an acid; -log(Ka); the more negative the value, the more acidic the compound

Question 8

Electron density

Answer 8

can be donated or withdrawn from a ring via induction and resonance

Question 9

What to consider with inductive effects

Answer 9

electronegativity, polarizability, charges

Question 10

polarizable alkyl groups

Answer 10

donate electron density (CH3)

Question 11

Atoms with a positive charge

Answer 11

are electron withdrawing

Question 12

what to consider with resonance

Answer 12

lone pairs and p-bonds

Question 13

Neutral atoms on aromatic molecules

Answer 13

have opposing effects; resonance predominates over induction

Question 14

Halogens on aromatic molecules

Answer 14

induction predominates over resonance

Question 15

EDG =

Answer 15

Activators; O/P

Question 16

EWG =

Answer 16

Deactivators; M

Question 17

General steps to aromatic substitution

Answer 17

addition of an electrophile to benzene followed by a deprotonation to restore aromaticity

Question 18

Halogenation

Answer 18

Cl2, AlCl3 or Br2, FeBr3

Question 19

Nitration

Answer 19

HNO3, H2SO4

Question 20

Sulfonation

Answer 20

Fuming H2SO4; can be reversed using diluted H2SO4 and heat

Question 21

Friedel-Crafts acylation

Answer 21

CLOR, AlCl3: R must be a carbon

Question 22

Friedel-Crafts alkylation

Answer 22

RCL, AlCL3; R(Alkyl); SN2; Consider carbocation rearrangements

Question 23

Clemmensen Reduction (reduction of aldehydes and ketones)

Answer 23

Acidic; Zn(Hg), HCl, Heat

Question 24

Wolff-Kishner Reductions (reduction of aldehydes and ketones)

Answer 24

Basic; NH2NH2, NaOH, Heat

Question 25

RXN rate; EDG

Answer 25

better nuc; Fast

Question 26

RXN rate; EWG

Answer 26

Weak nuc; Slow

Question 27

Strongly Activating

Answer 27

NH2, NHR, NR2, OH

Question 28

Moderately activating

Answer 28

RO or NHCOR

Question 29

Weakly activating

Answer 29

alkyl groups, or benzene

Question 30

weakly deactivating

Answer 30

Halogens; Exception (O/P not M)

Question 31

Moderately deactivating

Answer 31

SO3H, CN, aldehydes, esters, carboxylic acids, ketones

Question 32

Strongly deactivating

Answer 32

N(+)R3, NO2, CCl3, CF

Question 33

Benzylic Oxidation

Answer 33

RQ: benzylic carbon ->Carboxylic acid KMnO4 or Na2Cr2O7, or H+ and H2O

Question 34

Nitro Reduction (NO2->NH2)

Answer 34

H2,Pd/C