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Why 2,3 dimethyl indole more stable than 2ethyl indole?

Or

What's problem in synthesis of 2ethyl indole?

Answer:-

2,3 di methyl indole is more stable than 2 ethyl indole because of highly substituted double bond due to thermodynamic stabilization

Why pyrrole is easly converted to by mineral acid into polymer while 2methyl pyrrole forms dimer only and tetra metyl pyrrole doesn't dimerize ?

Because 1) methyl groups decrease positive charge ,so became poor E⁺

2) steric hinder of methyl group.

Discuss the useful of pyridine in :-

1)acetylation of phenol with acetic anhydride?

answer:-

1- py. Is good leaving group because it's big size

2- py. Is strong base attracting by HCl

3- activated carbonyl group increased by increasing electrophilicity of carbon atom.

2)nitration of furan by acetyl nitrate?

1-Because furan has lower energy of resonance led to higher activation energy of protonation

2- py. abstract acetic ion from furan.

Comment on the basic nature of exo and endo nitrogen in hetero cyclic gramine[3(N,N di methyl amino) methyl indole ] ?

Answer:-

Exo (N) is more basic than endo (N) because :-

1-have two electron donating group(Me₂)

2-don't enter in resonance

3- from sp³ hybridization

Predict the product which obtained by nitration using HNO₃&H₂SO₄ mixture over the following heterocycles , and giving your reasons?

1- pyridine -N- oxide

Reasone:-

On C-4 because of stabilization by resonance

2- pyridine

on C-3 because the attractive power of N atom where electron densit is higher than other

3-isoquinonline

On C-5 and C-8 Because of stabilization by resonance without removal aromaticity of py. ring

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ملا حظات :-
py= pyridine
qu=quinoline
iso qu=iso quinoline
Why in quinoline E⁺ attached to bezene ring not pyridine ring?
because:- acid make protonation to py. ring that make it inactive to attract negative charge
why in quinoline E⁺enter in C-5 and C-8?
because of :- stabilization of c5 and c8 without distribution of aromaticity of benzene
what's the difference between py. and qu.?
because qu. make reaction addition on C-N bond in the absence of benzene that make stabilization to py.
why Nu^- in qu. occurs in c2 and c4?
because of attractive power on N atom by:
1)inductive effect
2)mesomeric effect
why Nu^- in iso qu. occurs in c1 not c3 ?
because it takes palce in c1 without destroying of aromaticity but in c3 destroy aromaticity

above
convert indole to tryptophane?
tryptophane
gramine
mannich reaction
leimgrauber reaction

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