Comments on: Ranking The Bulkiness Of Substituents On Cyclohexanes: “A-Values” https://www.masterorganicchemistry.com/2014/07/01/substituted-cyclohexanes-a-values/ Thu, 07 May 2026 14:06:24 +0000 hourly 1 https://wordpress.org/?v=6.9.4 By: Umang Singh https://www.masterorganicchemistry.com/2014/07/01/substituted-cyclohexanes-a-values/#comment-605794 Fri, 24 Sep 2021 10:19:23 +0000 https://www.masterorganicchemistry.com/?p=8375#comment-605794 Thanks for your response and I am also not getting any relevant information for this, by the way thanks for helping, can i get your contact information, if yes my e-mail is attached.

]]> By: James Ashenhurst https://www.masterorganicchemistry.com/2014/07/01/substituted-cyclohexanes-a-values/#comment-605764 Thu, 23 Sep 2021 21:41:36 +0000 https://www.masterorganicchemistry.com/?p=8375#comment-605764 In reply to Umang Singh.

Winstein defined it in 1955 as the free-energy preference of a substituent for the equatorial position. It was defined in this paper. I’m not sure use of the letter A refers to any physical property however. (I don’t have access to this paper otherwise I’d try to give you more information).
https://pubs.acs.org/doi/abs/10.1021/ja01626a037?journalCode=jacsat&quickLinkVolume=77&quickLinkPage=5562&selectedTab=citation&volume=77

]]> By: Umang Singh https://www.masterorganicchemistry.com/2014/07/01/substituted-cyclohexanes-a-values/#comment-605743 Thu, 23 Sep 2021 05:49:13 +0000 https://www.masterorganicchemistry.com/?p=8375#comment-605743 Thank you for the nice explanation,
I want to ask what does ‘A’ means in A-value, why is it called A-value?

]]> By: James Ashenhurst https://www.masterorganicchemistry.com/2014/07/01/substituted-cyclohexanes-a-values/#comment-581237 Tue, 16 Jun 2020 03:55:33 +0000 https://www.masterorganicchemistry.com/?p=8375#comment-581237 In reply to Mia Lehavi.

Isopropyl: 2.15 , propyl is similar to ethyl, around 1.75

]]> By: Mia Lehavi https://www.masterorganicchemistry.com/2014/07/01/substituted-cyclohexanes-a-values/#comment-581233 Mon, 15 Jun 2020 23:06:25 +0000 https://www.masterorganicchemistry.com/?p=8375#comment-581233 Hello,
This is a great explanation, thank you! How would you compare the A-values between isopropyl and propyl? Thanks so much!

]]> By: James Ashenhurst https://www.masterorganicchemistry.com/2014/07/01/substituted-cyclohexanes-a-values/#comment-580665 Sat, 30 May 2020 02:14:56 +0000 https://www.masterorganicchemistry.com/?p=8375#comment-580665 In reply to Rimsha Mujahid.

These come from experimental measurement. At some point in the near future I’ll include references.

]]> By: James Ashenhurst https://www.masterorganicchemistry.com/2014/07/01/substituted-cyclohexanes-a-values/#comment-580664 Sat, 30 May 2020 02:14:19 +0000 https://www.masterorganicchemistry.com/?p=8375#comment-580664 In reply to Jake.

Fixed. Thanks for the heads-up

]]> By: James Ashenhurst https://www.masterorganicchemistry.com/2014/07/01/substituted-cyclohexanes-a-values/#comment-580663 Sat, 30 May 2020 02:14:10 +0000 https://www.masterorganicchemistry.com/?p=8375#comment-580663 In reply to kc.

Fixed – thank you so much.

]]> By: kc https://www.masterorganicchemistry.com/2014/07/01/substituted-cyclohexanes-a-values/#comment-580584 Wed, 27 May 2020 15:31:21 +0000 https://www.masterorganicchemistry.com/?p=8375#comment-580584 Just FYI in the tert-butyl images, the second with the group in the axial position shows isopropyl instead of tert-butyl. Great explanation!

]]> By: Jake https://www.masterorganicchemistry.com/2014/07/01/substituted-cyclohexanes-a-values/#comment-580344 Tue, 19 May 2020 20:20:57 +0000 https://www.masterorganicchemistry.com/?p=8375#comment-580344 For the figure of tert-butyl under number 6. why did the methyl group over the cyclohexane become just an H?

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