Talk:SN1 reaction

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
WikiProject Chemistry (Rated B-class, Mid-importance)
WikiProject iconThis article is within the scope of WikiProject Chemistry, a collaborative effort to improve the coverage of chemistry on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
B-Class article B  This article has been rated as B-Class on the project's quality scale.
 Mid  This article has been rated as Mid-importance on the project's importance scale.


I don't think that "step 3" (deprotonation step) is necessary for SN1. This implies that all SN1 should have a deprotonation step, which is not true. Absurdpoet 18:38, 7 July 2015 (UTC)

"Nuclophiclic attack": is that "nucleophilic attack"? The Anome 22:00 7 Jun 2003 (UTC)

Yep, typo. --Menchi 23:01 7 Jun 2003 (UTC)

Should SN1 and SN2 have some kind of link to each other? Or could they be combined? --Gregoe86 06:37, 27 November 2005 (UTC)

Thanks for pointing that out. I did a big rewrite of all these pages recently, but I failed to link them together properly. I have added a mention of SN2 in the intro, and all of the nucleophilic substitution pages now have "See also" links. As you can NOW see, there are not only separate SN1 and SN2 articles which contain a lot of specific details, we also have a combined nucleophilic substitution article which gives a broader picture. The latter article includes a comparison of SN1 vs SN2, and also it is intended to cover aromatic, acyl and non-carbon substitutions in a similar way once I or someone else finds time to write that. Thanks, Walkerma 05:35, 28 November 2005 (UTC)
You're welcome! I have an exam on all this stuff tomorrow, and have been using wiki for some different explanations than my textbook. Well written articles, all in all. ----Gregoe86 18:28, 28 November 2005 (UTC)


Just for the sake of completeness, I’ve started adding in mechanistic diagrams of nucleophilic substitution and elimination reactions that include electron movement. I’m attempting to do these diagrams to enhance the existing example mechanisms already written by Walkerma. Please let me know if I’ve missed something in them. Thanks. --AirMonk 20.23 9 Dec 2005 (UTC)

Thanks! There's a lot still to be done on this article, I appreciate your work, especially as some of my students may be reading this page ready for their exam next week! Don't hide your diagram as a thumbnail, though. Cheers, Walkerma 20:28, 9 December 2005 (UTC)


Is it just me or is the diagram incorrect, the overall reaction quotes the Tert-Butyl-Bromide correctly but in the first step is written incorrectly?

You're right, it looks like someone put isopropyl bromide (2-bromopropane) in there by mistake. I'll see if I can paste the right structure in. Walkerma 20:22, 4 February 2007 (UTC)
OK, if you reload the page it should look right now. Thanks for pointing that out! Walkerma 20:32, 4 February 2007 (UTC)

meaning of SN1[edit]

SN1 stands for substitution -nucleophilic-first order [not unimolecular,an older term] similarly,SN2 is substitution-nucleophilic-second order[not bimolecular] E1 and E2 are defined similarly in terms of order and not molecularity —Preceding unsigned comment added by (talk) 18:17, 7 October 2008 (UTC)

I don't think so. Recent books still call it unimolecular, and in fact molecularity is not the same as reaction order. See [1]. --Itub (talk) 20:31, 10 October 2008 (UTC)
Reread the article. It states First Order reaction kinetics, not reaction order: the rate of reaction depends on a single reactant concentration. SN2, the rate of reaction depends on both reactant concentrations. Three body reactions are rare and low probability of all three tree reactants coming together. (Before you mention Hydrogenation, reactions that require a substrate to occur include the substrate "concentration" as part of the constant in the equation of reaction.) See my note below re "textbook" SN1 reactions are actually non-existent. Shjacks45 (talk) 19:00, 21 September 2013 (UTC)

No mentioning about Arenes[edit]

In case of arenes, SN1 reaction is ruled out as the the phenyl cation is too unstable to carry SN1 reaction. (Hence haloarenes prefer SN2 reactions). However it is not mentioned in the topic here. It is very important. Exceptions should be mentioned. Valchemishnu Valchemishnu 12:58, 26 May 2011 (UTC) — Preceding unsigned comment added by Valchemishnu (talkcontribs)

Textbook SN1 reactions are actually incorrect[edit]

My Chemistry Professor at UCSB was disturbed by a textbook illustration "proving" SN1 hydrolysis of halide as a straight line graphed through a series of non-linear points (statistically inconclusive confidence level in the data). ("Thiry caliber pencil" in military terms; common for scientists to fudge research results to get published.) She had several students redo the results with newer lab equipment and published. However the SN1 rubbish is still peddled in undergrad textbooks. This implies that e.g. 2-BromoButane will racemize in a non-reactive polar solvent say NaBr in DMSO ith first order kinetics also but that is not the case. Kinetics are actually somewhere between SN1+ and SN2-. Admittedly this an easy simplification for high school or freshman Chemistry. Shjacks45 (talk) 19:35, 21 September 2013 (UTC)

Yeah because DMSO favors SN2 in that situation, of course you're going to get both situations. Secondary SN1 is a bit controversial, but this isn't data. — Preceding unsigned comment added by (talk) 15:59, 20 July 2016 (UTC)

Assessment comment[edit]

The comment(s) below were originally left at Talk:SN1 reaction/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

A very good article. The main suggestion I would make is to add an energy profile diagram for a reaction to show the transition states and intermediate states. Also explanation of the mechanics behind these states (e.g. what is the molecular arrangement during the first peak? Why is the carbocation more stable than these?) would help.

I also suggest adding some information on how this reaction mechanism might be used - what are some of the important reactions/applications for which this reaction is employed?

Finally, a 'substitution reactions' template (or something similar) might be handy to connect these reactions and concepts together. Richard001 00:34, 6 May 2007 (UTC)

Last edited at 00:34, 6 May 2007 (UTC). Substituted at 05:11, 30 April 2016 (UTC)

External links modified (January 2018)[edit]

Hello fellow Wikipedians,

I have just modified one external link on SN1 reaction. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

As of February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{sourcecheck}} (last update: 15 July 2018).

  • If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
  • If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 03:19, 24 January 2018 (UTC)