nucleophilic aromatic subs experiment #2

Flashcard maker : Lily Taylor
How would you make a benzene ring susceptible to nucleophilic attack?
-By adding a deactivating functional group electron withdrawing
How did the reaction of 3,4-dichloronitrobenzene with sodium methoxide take place in this experiment?
-A resonance stabilized anionic intermediate known as the Meisenheimer complex
Why did the reaction of 3,4-dichloronitrobenzene with sodium methoxide not undergo by either SN-1 or SN-2 processes?
-SN2: Can’t take place because attack from rear is impossible because the ring blocks the path of any nucelophile
-SN1: Can’t occur because ionization would produce an unstable carbocation
What is the name for the anionic intermediate formed during a nucleophilic aromatic substitution reaction?
-Meisenheimer complex
When two different compounds have the same melting point, how can they be distinguished from one another?
The answer is to take a mixed melting point. Say for example that an unknown is either A or B, both of which have a mp of 110°. If one were to mix the unknown with first A and then B, and take a mp of each mixture, only one of them would maintain the mp of 110°C. Since different molecules do not fit into eacother’s crystal lattices in exactly the same way, the presence of even a small amount of unknown in a sample of A will lower the mp of A unless of course the unknown is A.
What is the chemical equation for the formation of 1,2-dimethoxynitrobenzene illustrated by this experiment?
3,4-dichloronitrobenzene + methoxide →1,2-dimethoxynitrobenzene
Which Intermediate is stabilized more effectively by nitro group?
carbocation intermediate
Nucleophile:
methoxide ion:H3CO-
3,4-dichloronitrobenzene: which Cl is favored for substitution, meta or para?
para
Resonance-stabilized carbanion intermediate stabilized by
strong e- withdrawing groups, -NO2
Replace good LG
with strong nucleophile
3,4-dichloronitrobenzene + methoxide →
1,2-dimethoxynitrobenzene
what kind of substitution?
Nucleophilic Aromatic Substitution
aromatic substituted benzene ring behaves as a?
-nucleophile

-normally it behaves as a electrophile

benzene survives treatment with?
strong nucleophiles
the presence of a nitro group will?
stabilize the negative charge through resonance
when it comes to kick of the leaving group, only the reaction that have the leaving group in _______, will occur at decent rate
-orto, para position
if benzene has an electron-donating group attached to it
no reaction will also be observed
To obtain an appropriate mixture of methanol and water for recrystallizing a sample you should do the following…
1. Dissolve your sample in a minimum amount of hot methanol.
2. Add water to the hot solution to decrease the solubility.
3. Once your solution becomes cloudy, enough methanol should be added to just bring the product back into solution
Be careful when handling sodium methoxide and methanol.
-Sodium methoxide is corrosive and toxic.
– Methanol is flammable and toxic.
IN BOTH ELECTROPHILIC AND NUCELPHILIC SUBSTITUTION, the electrical charge is distributed to the positions that are
ortho and para to the carbon at which the electrophile or nuclephile reacts.
because the -NO2 group is ____ to one chlorine and ____ to the other, the effects that NO2 group exerts on the reactivity of the two chlorine atoms are ____
-meta
-para
-not equal.
benzene ring behaves as an?
-nucleophile
-normally will act as electrophile

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