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#91
Organic Chemistry / Re: Alkene mechanism of ether ...
Last post by uma - November 05, 2025, 04:50:26 AM
step by step.

Protonation of the alkene (electrophilic addition)
• In H₂SO₄/MeOH, the alkene π bond is the nucleophile and grabs H⁺.
• Proton adds in the Markovnikov direction to give the more stable carbocation (a cyclobutyl-carbinyl cation).

Fast ring expansion (carbocation rearrangement)
• A C–C bond from the adjacent cyclobutane migrates (1,2-shift) to the positively charged carbon.
• This converts the strained 4-membered ring into a 5-membered ring and places the positive charge on the new cyclopentyl carbon.
• Driving force: relief of cyclobutane ring strain and formation of a more stabilized carbocation (the classic cyclobutyl-carbinyl ⇌ cyclopentyl rearrangement).

Nucleophilic attack by methanol
• MeOH (the solvent, present in large excess and far more nucleophilic here than HSO₄⁻) attacks the planar carbocation to form a C–O bond.
• The oxygen bears a positive charge in this "oxonium" intermediate.

Deprotonation (regeneration of the acid catalyst)
• Another MeOH molecule acts as a base and removes the extra proton from oxygen.
• This neutralizes the oxonium, giving the ether product and regenerating H⁺ (acid-catalyzed addition overall).
Mechanism of carbocation rearragement .jpg
Net reaction: "hydro-alkoxylation" of the alkene by MeOH under acid catalysis to give a methyl dicyclopentyl ether.
• The key feature is the carbocation rearrangement (ring expansion) that occurs before nucleophilic capture; without it you'd retain a 4-membered ring, but the system preferentially expands to a 5-membered ring because it is both less strained and better at stabilizing the cation.
• Stereochemistry: attack occurs on a planar carbocation, so if a stereocenter were formed it would come from either face; here the final product (a monosubstituted cyclopentane) is not stereogenic.
#92
Organic Chemistry / Alkene mechanism of ether form...
Last post by amimi - November 05, 2025, 02:31:53 AM
Hello! I would appreciate some help with these questions, thank you so much!! Ring expansion and carbocation rearrangement .png
#93
Organic Chemistry / Re: Ranking bases from weakest...
Last post by uma - October 29, 2025, 08:37:03 AM
Hi Sorry for late reply
Just saw this post.
Order is D B A C
First Go with Atom
O is more EN than N so it is less basic than N .It means D is least basic as O is holding its LP tightly.
Then B because it has so many EN atoms (3 Cl)  on it.
C is most basic because O is EDG here and making ring electron rich so deloaclization of LPs of N atom rons is less.
#94
Organic Chemistry / Ranking bases from weakest to ...
Last post by amimi - October 21, 2025, 01:42:32 PM
Hi! I wanted to be sure of my reasoning for this question. I thought B would be the weakest base, since it is most stabilized due to the presence of resonance, induction, and the negative charge being on N. However, structure B has resonance, in addition to the negative being on the more electronegative oxygen.  Ranking of bases in organic molecules from strongest to weakest.png
#95
Organic Chemistry / Re: Conformations of alkanes
Last post by uma - October 08, 2025, 12:29:50 PM
First one is 3-Methyhexane and second one is 2Conformations of  3-Methyhexaneand ,3-dimethylpentane.png,3-dimethylpentane .
#96
Organic Chemistry / Re: Functional groups and mole...
Last post by uma - October 08, 2025, 12:18:29 PM
a is correct
in b alkene is not present.Aromatic ring and alkene are entirely different groups with different chemical nature.
Rest is ok.
#97
Organic Chemistry / Conformations of alkanes
Last post by amimi - October 08, 2025, 12:36:02 AM
I wanted to get some help in terms of the orientation of drawing the newman projection, and I need clarification about right vs. left side!
Thank youIMG_0333.pdf
#98
Organic Chemistry / Functional groups and molecula...
Last post by amimi - October 08, 2025, 12:34:50 AM
I was hoping to get some help regarding this homework problem.  Problem Set 1 - DUE10.08.pdf
#99
YBTC chemistry for young children / Re: 14.2 Quiz - Acid Strength
Last post by Aditi - August 09, 2025, 10:26:00 PM
thank you :)
#100
YBTC chemistry for young children / Re: Kw of water and effect of ...
Last post by Aditi - August 09, 2025, 10:22:12 PM
ohhh okay then it will be d
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