Comments on: HOMO and LUMO In the Diels Alder Reaction

By: Eugenio Mauricio

Eugenio Mauricio — Sat, 13 Sep 2025 18:27:50 +0000

Maior site de Quimica organica que ja encontrei!

By: pobha

pobha — Mon, 03 Feb 2025 20:42:17 +0000

Found this gem after a long search! Thanks a ton for these detailed and meaningful articles.

By: James Ashenhurst

James Ashenhurst — Fri, 22 Nov 2024 03:33:53 +0000

In reply to Krishna Pokharel. Where does it show that? It should not.

By: Krishna Pokharel

Krishna Pokharel — Thu, 21 Nov 2024 03:06:29 +0000

Lumo of ethylene and homo of butadiene are antarafacial but homo of ethylene and lumo of butadiene are suprafacial, why?

By: James Ashenhurst

James Ashenhurst — Thu, 06 Jul 2023 01:06:22 +0000

In reply to Dimitris. Hi Dimitris - I am very glad you found the article helpful! Best wishes with your studies! James

By: Dimitris

Dimitris — Wed, 05 Jul 2023 23:02:14 +0000

When I study for exams, I tend to detour from what I actually have to study and instead I dig in the things that don’t make enough sense to me, until they do. I was studying pericyclic reactions and HOMO/LUMO concept was a bit blurry, despite being able to predict the right answers. Then I landed on this article. Couldn’t be more thankful for the deeper understanding of the concept, thank you very much sir.

By: Nilesh Kumar

Nilesh Kumar — Sun, 31 Jul 2022 09:15:50 +0000

Hi James, thanks for this wonderful piece, wouldn’t have been more organized and to point if this article went unread. Thanks and only thanks. More power to you.

By: James Ashenhurst

James Ashenhurst — Fri, 30 Apr 2021 16:21:11 +0000

In reply to Vaibhav Raj. Great, glad you found it useful Vaibhav.

By: Vaibhav Raj

Vaibhav Raj — Fri, 30 Apr 2021 06:59:41 +0000

I couldn’t possibly thank you more. This is a wonderful article and helped me immensely in the understanding of pericyclic reactions.

By: Gabriel

Gabriel — Sat, 31 Mar 2018 10:25:17 +0000

Hi James, your posts have helped me a lot over my undergrad studies in organic chemistry! I have several questions: if we’re going to use the Woodward-Hoffman rules, how do we apply it for a 4+4 cycloaddition? I’m struggling to identify how (in a 4+4 of 2 butadiene molecules) one is either a suprafacial or anarafacial if i draw out one butadiene homo and one butadiene lumo!

Also, in your closing statements, the 14+2 example is very well used in my slides and a lot of texts, it how did they know it was antarafacial? I saw a diagram from Fleming’s book, and many other resources that just showed empty p orbitals linking antarafacially.