Comments for Master Organic Chemistry https://www.masterorganicchemistry.com/ Thu, 12 Sep 2024 21:49:36 +0000 hourly 1 https://wordpress.org/?v=6.6.2 Comment on Lewis Structures by Bismuth https://www.masterorganicchemistry.com/2010/08/14/from-gen-chem-to-org-chem-pt-7-lewis-structures/#comment-706593 Thu, 12 Sep 2024 21:49:36 +0000 http://masterorganicchemistry.wordpress.com/?p=736#comment-706593 the sense of humour used in these lessons and how fun they teach are what I love about this site

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Comment on Reagent Friday: Lithium Di-isopropyl Amide (LDA) by James Ashenhurst https://www.masterorganicchemistry.com/2011/08/05/reagent-friday-lithium-di-isopropyl-amide-lda/#comment-706568 Thu, 12 Sep 2024 17:21:30 +0000 https://www.masterorganicchemistry.com/?p=1891#comment-706568 In reply to Moses Alege.

LDA will not attach, but it may be strong enough to form an aryne. For example one could deprotonate C-H and elimination of the best leaving group (Cl) would give an aryne, which could then undergo attack by a nucleophile. When the nucleophile does attack, it will likely do so such that the negative charge is placed closer to the electron withdrawing fluoro groups.
See this artice on arynes – possibly helpful. https://www.masterorganicchemistry.com/2018/09/17/nucleophilic-aromatic-substitution-2-benzyne/

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Comment on Chiral Allenes And Chiral Axes by James Ashenhurst https://www.masterorganicchemistry.com/2015/01/13/chiral-allenes-and-chiral-axes/#comment-706565 Thu, 12 Sep 2024 17:19:27 +0000 https://www.masterorganicchemistry.com/?p=8674#comment-706565 In reply to karan.

For molecules with an axis of chirality, one looks along the chiral axis and numbers the substituents on the near carbon (1) or (2) according to the CIP rules. One then looks at the substituents on the far carbon and numbers them (3) or (4) according to the CIP rules. One then notes whether 1,2,3 goes clockwise (r) or counterclockwise (s). See this article (wikipedia) for an example:
https://en.wikipedia.org/wiki/Axial_chirality

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Comment on Reagent Friday: Lithium Di-isopropyl Amide (LDA) by Moses Alege https://www.masterorganicchemistry.com/2011/08/05/reagent-friday-lithium-di-isopropyl-amide-lda/#comment-706466 Thu, 12 Sep 2024 03:34:53 +0000 https://www.masterorganicchemistry.com/?p=1891#comment-706466 What will the attaching position of LDA for 1-chloro-3,4-difluorobenzene?

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Comment on Chiral Allenes And Chiral Axes by karan https://www.masterorganicchemistry.com/2015/01/13/chiral-allenes-and-chiral-axes/#comment-706171 Tue, 10 Sep 2024 03:58:50 +0000 https://www.masterorganicchemistry.com/?p=8674#comment-706171 can we assign R and S nomenclature for 3 cumulative diene between 4 carbon atoms. for eg C=C=C=C type systems.

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Comment on Disubstituted Benzenes: The Strongest Electron-Donor “Wins” by Hassan Riyaznur alom https://www.masterorganicchemistry.com/2018/03/19/eas-disubstituted-benzenes/#comment-705578 Thu, 05 Sep 2024 18:17:31 +0000 https://www.masterorganicchemistry.com/?p=11452#comment-705578 Today was my reaction mechanisms exam. And thankfully I go through your article. Ohh I can’t express my happiness. Just thank you.

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Comment on Rules For Aromaticity by James Ashenhurst https://www.masterorganicchemistry.com/2017/02/23/rules-for-aromaticity/#comment-705564 Thu, 05 Sep 2024 14:57:25 +0000 https://www.masterorganicchemistry.com/?p=10497#comment-705564 In reply to Chris.

Thanks for the question! Short answer is that the nitrogen in NADH is very poorly basic here because the lone pair on nitrogen is conjugated with the two adjacent pi bonds. Protonation of these types of functional groups (look up “enamines”) requires pretty strong acid (at least below pH 4). Even if it was protonated at physiological pH, protonation is very reversible, and it would represent a dead-end that just quickly equilibrates back into NADH.

Furthermore, if protonation were to occur, it would happen primarily on carbon, rather than on nitrogen. This is because the nitrogen lone pair donates a lot of electron density into the adjacent alkenes, and these carbons become quite basic (relatively speaking). Enamines protonate primarily on carbon.

There is no partial aromaticity in NADH. The ring in NADH is not aromatic, nor is it even partially aromatic. That’s because the carbon with two H’s attached has no orbital capable of pi-bonding with the adjacent atoms. In order for aromaticity to occur, there must be a continuous ring of atoms capable of pi-bonding. When NADH donates hydride (H-) this breaks one of the C-H bonds, and results in formation of a new C-N pi bond. This allows conjugation of pi bonds all around the ring, and formation of an aromatic ring provides the driving force for this reaction.

I hope this answers your question! James

I hope this answers your question

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Comment on Rules For Aromaticity by Chris https://www.masterorganicchemistry.com/2017/02/23/rules-for-aromaticity/#comment-705508 Thu, 05 Sep 2024 02:26:38 +0000 https://www.masterorganicchemistry.com/?p=10497#comment-705508 I found this page while looking for an answer to why the pyridine ring nitrogen of reduced nicotinamide adenine dinucleotide (NADH) does not become protonated at physiological pH to form NADH2.

I am wondering if the pyridine ring has any partial aromaticity?

And to what extent is that more or less important than steric and electron-withdrawing effects of the ring itself and the nearby ribose?

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Comment on Formation of Carboxylic Acids from Acyl Chlorides by James Ashenhurst https://www.masterorganicchemistry.com/reaction-guide/formation-of-carboxylic-acids-from-acyl-chlorides/#comment-705344 Tue, 03 Sep 2024 15:23:27 +0000 https://www.masterorganicchemistry.com/?page_id=6212#comment-705344 In reply to Thomas Evans.

Fixed – thank you for spotting the typo and letting me know. Please let me know of any other ones you see! James

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Comment on Formation of Carboxylic Acids from Acyl Chlorides by Thomas Evans https://www.masterorganicchemistry.com/reaction-guide/formation-of-carboxylic-acids-from-acyl-chlorides/#comment-705159 Mon, 02 Sep 2024 02:16:33 +0000 https://www.masterorganicchemistry.com/?page_id=6212#comment-705159 There is a typo in step two of the mechanism. Elimination is spelled with two “i”s by mistake as: “Eliimination.”

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