Comments on: Disubstituted Benzenes: The Strongest Electron-Donor “Wins”

By: James Ashenhurst

James Ashenhurst — Tue, 23 Sep 2025 16:15:41 +0000

In reply to Michael Fallentine. There is a source of carbon (CH3Cl) but I redrew the quiz to make it more clear. Thanks!

By: Michael Fallentine

Michael Fallentine — Mon, 22 Sep 2025 21:49:08 +0000

It appears the 7th flashcard has a carbon added in all answer choices in spite of no carbon source being provided in the reactants. Just a minor error that could be adjusted.

By: Bob

Bob — Tue, 15 Jul 2025 16:57:58 +0000

I saw in several comments and your Note 2 that in the case of two deactivating substituents, the less deactivating/more activating would “win.” I’m looking at 4-nitrobenzaldehyde and having trouble justifying it. Based on this, we would want to say that we add ortho to the nitro, meta to the aldehyde. However, I learned that EWGs that are meta directors don’t activate the meta positions, they deactivate the O/P positions. Wouldn’t this mean that the nitro group is more strongly deactivating the position ortho to it, and that the major product should result from addition to the position ortho to the aldehyde (the less deactivated position)? Following this path also avoids placing a positive charge next to the nitro group in the intermediate structure (assuming we use the 2-step mechanism). Is this just a special case where the rule doesn’t apply or am I missing something?

By: James Ashenhurst

James Ashenhurst — Thu, 27 Feb 2025 15:14:03 +0000

In reply to Himanshu garg. Possibly, but the effect is small. If you look at the rate of EAS for methylbenzene versus t-butylbenzene (24 vs 15.7 vs. 1 for benzene itself) there is not a huge difference in rate, which points to the hyperconjugation effect for methyl being of minor importance vs t butyl, if anything.

By: Himanshu garg

Himanshu garg — Thu, 27 Feb 2025 13:52:22 +0000

In case of tertbutyl grp attached to toluene at para position where electrophile goes to ortho position of methyl grp, do we not consider that ortho position is preferred due to hyperconjugation which methyl grp offer instead of steric hinderance by tert butyl?

By: Hassan Riyaznur alom

Hassan Riyaznur alom — Thu, 05 Sep 2024 18:17:31 +0000

Today was my reaction mechanisms exam. And thankfully I go through your article. Ohh I can’t express my happiness. Just thank you.

By: James Ashenhurst

James Ashenhurst — Tue, 16 Jan 2024 09:17:14 +0000

In reply to tej gandhi. Thank you. I am so glad you are finding it helpful! James

By: tej gandhi

tej gandhi — Sat, 13 Jan 2024 14:54:22 +0000

i cant describe how wonderful this site is. its helped me understand and fall in love with organic chemistry

By: lea

lea — Wed, 15 Nov 2023 14:31:21 +0000

Hello again! I’m unable to reply to my previous comment (regarding catechol). I’ve understood now that out of the four of the possible products there are only two different ones. Thank you!. I have one more question, if there is a CHO group attached to catechol at position C-3 relative to one of the OH groups, what would be the product formed in the reaction with excess aqueous bromine. According to the markscheme there would be 2 bromines each at position adjacent to the 2 OH groups, if possible could you explain why? (Apologies if my questions sounds confusing it’s much easier to draw the structure)

By: James Ashenhurst

James Ashenhurst — Wed, 15 Nov 2023 14:11:12 +0000

In reply to lea.

Try this exercise. Draw out catechol (ortho-dihydroxybenzene). Label the two hydroxyl groups A and B. Now draw 4 products.
#1: Bromine is ortho to A
#2: bromine is para to A
#3: bromine is ortho to B
#4: bromine is para to B.

Now compare the four. Are they four different products?