Chapter 15 Flashcards
Are reactions favored when products are aromatic?
Yes
When happens when X2 and FeX3 (X=halogen) reacts with a benzene molecule? Can also be AlCl3,FeCl3, or FeBr3.
X replaces a hydrogen. The location of the halogen is determined by ortho/para or meta directing groups
What happens when HNO3 and H2SO4 reacts with a benzene molecule? Can also be XNO2 and FeCL3 or AlCl3.
NO2 replaces a hydrogen. The location is determined by directing groups.
What happens when SO3 and H2SO4 reacts with a benzene molecule?
SO3H replaces a hydrogen. The location is determined by directing groups. Use concentrated/fuming sulfuric acid to sulfonate and use dilute sulfuric acid and steam to desulfonate
What happens when RX and AlCl3 (or FeCl3) reacts with a benzene ring?
R replaces a hydrogen, carbocation rearrangement possible with most stable product only. (iso-butyl will rearrange to test-butyl)
What happens when RCOCl or (CH3CO)2O and AlCl3 reacts with a benzene ring? (RCOCl is aldehyde with Cl replacing the H)
C(=O)R replaces a hydrogen
What is the general mechanism for Electrophilic substitution?
Benzene-H + EA -> Benzene-E + H-A. All the reactions in this chapter are electrophilic substitution.
What are electron-withdrawing groups?
Make the ring less nucleophilic and slow reactions. Function as Meta directors.
What are electron-donating groups?
Make the ring more nucleophilic and speed up reactions. Function as Ortho/Para directors
What are the common withdrawing/deactivating groups?
Nitro (NO2), Carbonyl (=O), Cyano (CN), CF3, Sulfonyl (SO3R), NR3
What are the common donating/activating groups?
Hydroxyl (OH), Alkoxy (OR), Amino (NH2), Alkyl (-R)
Which substituents are Ortho-Para directors?
Activating/Donating groups and halogens.
Which substituents are Meta-directors?
Withdrawing/Deactivating groups
Which dominates, Ortho/Para directors or Meta?
Ortho/Para
If a benzene ring has two O/P groups or two M groups, which one applies?
The most activating one
What happens when hot concentrated KMnO4 reacts with Ph-CH2-R?
->Ph-C=O,-OH
What happens when hot concentrated KMnO4 reacts with Ph-CH3?
->Ph-C=O,-OH
What happens when hot concentrated KMnO4 reacts with CH3-Ph-CH3?
->Ph-COOH,-COOH
Order these from most donating to most withdrawing:
((-RX3/-NO2/-N+R3))
((-NH2/-NR2/-OH/-O-))
((RC(=O)OR/-R(=O)R/-R(=O)OH/-RC≣N/-SO3H))
((-R))
((-X))
((-OR)
1) -NH2/-NR2/-OH/-O-
2) -OR
3) -R (including phenyls)
4) -X
5) -RC(=O)OR/-R(=O)R/-R(=O)H/-RC(=O)OH/-RC≣N/-SO3H
6) -RX3/-NO2/-N+R3
If you want to add an R group to a benzene and avoid rearrangements, how would you do it?
Friedel-Crafts acylation (RCOCl) followed by clemmensen reduction (Zn(Hg) and HCl)
How do bulky substituents affect substitution reactions?
They prevent interactions with adjacent carbons
How can you monobrominate a benzene ring with an amine group?
Convert the amine (NH2) to an amide (NHCOCH3) by FC acylation, then add acid to remove the protecting group. (back into NH2). Will be Ortho/Para
