Talk:Conformational isomerism

Changed Intro

I changed / shortened the introduction. My first basic problem was the previous intro was unbalanced & didn't cite sources. I intend to put some more references in here soon. I guess the intro should stay short, cause the two main pages (Alkane Stereochemistry & Cyclohexane conformations) where it points to do a lot of explaining (and citing), also when it comes to relative stabilities in those cases. Hope this is ok to some people reading this, I still intend to improve it. --WijzeWillem (talk) 15:17, 12 May 2008 (UTC)

Crams Rule

Anybody know anything about Cram's Rule? it's very important in determining major and minor products of various substitution mechanisms but my knowledge of it is flawed. Also some coverage of the finer points of conformer naming would be good. I know antiperiplanar is coincident with the simpler anti configuration. Snarfevs 04:20, 10 Jun 2005 (UTC)

Conformers

This page is used as a redirect for conformers but doesn't explain what is meant by that term85.210.50.176 22:46, 22 July 2007 (UTC)

Its short for conformational isomers. Richard001 05:39, 19 August 2007 (UTC)

Conformational analysis

Why does conformational analysis redirect here? The article doesn't even have the word "analysis", much less talk about what the term means! I get the idea that this page is all about conformers, but that's not what I'm looking for, which is, what constitutes "conformational analysis". 67.159.76.48 (talk) 15:15, 15 October 2009 (UTC)

Three conformers for butane

Two equienergetic gauche (they are distinct non superposable structures)and one anti. The png to the right of page also needs to be corrected and have the intension to do that also.Cleanthis (talk) 16:48, 14 July 2010 (UTC)

Peer review and responses during the educational assignment in Fall 2013

The introduction section is appropriately detailed and seems accessible to the general public. I thought it was good that you clarified that two conformational isomers can be exchanged without breaking a bond, whereas configurationally isomerism requires bond breakage to interconvert. It seems pretty obvious to us, but if you put in some arrows in the first figure to show how the bonds are rotated to go in-between gauche and anti, that might clarify the topic a bit. I like your figure of the free energy vs. dihedral angle, but it might be helpful to have Newman projections on each peak/trough to make more obvious what each energy corresponds to which conformation and maybe have units for the free energy to show the energies of the interactions. Also, under the topic “Types of conformational isomerism”, I thought maybe you could list the energies associated with specific eclipsing and gauche interactions to give an idea of which kinds of interactions are more energetically disfavorable.

I thought that the section for Protein rotamaer libraries was a bit too distantly related and long to be a sub-section; maybe it could be its own Wikipedia article. If not taken out, I think there should be a figure added to it to break up the big block of text. Also, the two final figures are in the protein rotamer section, but they should be formatted to be under the conformation-dependent reactions section.

Under the heading “Isolation or observation of the conformational isomers”, maybe the terms “protein folding” and “aliphatic” could be linked to their respective Wikipedia site. The figure of electrostatic and steric repulsion of eclipsed ethane should be made bigger and bolder, as it is pretty hard to see. Under “Conformation-dependent reactions” and in the associated figure, make sure you italicize the t or tert in t-Bu. Also, it might be helpful to show the 6-membered ring interactions that explain why the axial t-Bu group so unstable. You could also make a reference to the Wikipedia page for A-values in explaining why t-Bu is a conformational lock.

I think that the third-to-last figure could be eliminated because the final figure sums up the idea well enough. For the first figure, I do not think it is necessary to have two depictions of gauche, rather it would be more beneficial to show an eclipsing interaction of Me/Me and H/Me. The overall presentation is good, some of the figures should be made larger, bolder, and moved around to be next to the section that they are relevant to. (Yvonnedep (talk) 22:44, 1 November 2013 (UTC))

Content Is the introductory section accessible for non-experts? Yes. The introductory section is easy to be understood by the non-experts. Group 16 also added the concept of conformational analysis to the introduction to make people easier to understand the study of energy between different conformers. Several examples have also been shown in the introductory part to show the difference between conformational isomerism and configuration isomerism. Do the contents of each section justify its length? Yes. Group 16 has combined the two sections ‘Isolation or observation of the conformational isomers’ and ‘Techniques for study of conformational isomerism’ on the original page into one section. More information was given in the new section. And they also added a new section ‘Factors contributing to free energy of conformers’, which is very important part for conformational isomerism, to the new page. Are all the important terms/concepts linked to their respective Wikipedia pages for further reference? Yes. On the new page, they have already linked the terms and concepts to the Wikipedia pages. Are the highlighted examples appropriate? I think Group 16 may need to highlight the important concepts in the sections except for the introductory section. Is the content duplicative of any other content already on Wikipedia? No. Although some concepts on this page are also shown on page ‘Isomer’, but this page is mainly about conformational isomers; and they give more information about this topic.

Figures Are the figures original and of high quality? Yes. Group 16 has added four new pictures to the new pages. Are the figures informative and add to the text? Yes. Are the Chemdraw structures chemically accurate, aligned, and easy to read? Yes.

References Are the references complete (≥ 8)? Yes. Group 16 has added 8 new references on the new web page. Are the references inclusive of non-journal sources? Yes.

Overall Presentation The original Wikipedia page has already covered most information about conformational isomerism. So it’s a difficult for Group 16 to edit it. Group 16 has added more content, figures and references to make it easier to understand and also more comprehensive. Here are some advices to improve the new page. 1. Add some more examples for the ‘Factors contributing to free energy of conformers’ section. For example, talk about which factor is more important in different molecules. 2. Highlight all the important concepts on the new page. 3. Conformation is also very important for the selectivity of chemical reactions. Maybe adding some more examples about the in the ‘Conformation-dependent reactions’ section will help readers better understand the importance of conformational isomerism. 4. Allylic system may be also a good example for conformational isomerism. Some conformation about allylic system may be added in the ‘Types of conformational isomerism’ section. — Preceding unsigned comment added by Ybs.Umich (talk • contribs) 04:06, 4 November 2013 (UTC)

ChemLibrarian (talk) 02:50, 5 November 2013 (UTC)

1. You added nice images but all of them are in thumbnail. For some places it's good but for some paragraphs, you probably want to enlarge the picture and place them at the center of the page so that people can read them without clicking on them and the whole page can flow better too. See this page Wikipedia:Picture tutorial for how to place the image at different places and adjust the size.

2. When you refer to images in the text, it's better to refer to their captions than their location because the location may change from browser to browser. I know images like the "Boltzmann distribution % of lowest energy conformation..." not added by you, but it would be nice to refer them in the text so that people know what they are about. For this particular image, it would be the best to identify the source and cite it since people may want to see the original data and it's ethical to give credits to whoever collected the data.

3. You may not have time to do so now, but I think the sections of this article could use some organization. The current sections seem a little wordy and could be further grouped.

Additional Comments

UMChemProfessor (talk) 20:15, 5 November 2013 (UTC) It seems as though you've added to the site but did not do much improvement to the current content. As a result, it feels disjointed. Feel free to edit/revise/delete current content as appropriate to make a single narrative that flows. I agree with most of the peer reviewer comments as well as ChemLibrarian. Please take their advice into consideration.

Mr.Holmium (talk) 03:06, 11 November 2013 (UTC)

We have incorporated almost all the suggestions you gave (thanks!), except for some minor details which can be ignored without affecting the flow of the information. For example, the free energy diagram has no unit or ΔG values because they are provided in the text and because it avoids convolution in the figure. Also, some suggestions were not taken literally but prompted new ideas for improvement. For example, figure 1 was replaced to show the rotation about a single bond (with the arrow, as suggested) because it complements the introduction better. We did not add the two eclipsed interactions Me/Me and H/Me; rather, both eclipsed and staggered conformations were incorporated to show that rotation would alternate between the two.

The structure of the article was reorganized a little to reflect the categories/hierarchy of information. Also, one old section was rewritten and one was deleted. We could not find sources relating to the Boltzmann distribution of conformers (only a reference merely alluding it, but there are research papers that uses it and we want to avoid citing sources that are hard to access) and the old version does not cite any sources. The "protein rotamers library" section was deleted because the amount of details and scope merit its own separate article like those cited in "types of conformational isomerism".

Proposed merge of Alkane stereochemistry into Conformational isomerism

The alkane stereochemistry article only covers the conformational aspect, which is already covered in conformational isomerism. The topic of stereochemistry involves other aspects as well, and these are already also covered in their own separate articles. DMacks (talk) 17:48, 6 December 2020 (UTC)

Support, just for the record as no-one else seems to care very much! Mike Turnbull (talk) 11:34, 5 March 2021 (UTC)

• Support per nom. Mdewman6 (talk) 08:32, 9 July 2021 (UTC)
• Support. This article could have included alkane enantiomerism of the chiral branched alkanes, but doesn't yet as noted. If chiral alkanes need a home in the future, they would fit nicely as a section in chirality (chemistry) or asymmetric carbon. –MadeOfAtoms (talk) 08:19, 11 August 2021 (UTC)

Support, I am glad that you are doing this kind of work. It is confusing to readers when we have articles on heavily overlapping topics. It is also worthwhile to create redirects of related quasi-synonyms to minimize this effect.--Smokefoot (talk) 14:13, 25 August 2021 (UTC)

Comment: you can see from the previous section that this article was the topic assigned in some course. That fact often guarantees that the article will be wordy, US-oriented, and often quite mediocre. So be prepared to slash and burn.--Smokefoot (talk) 14:19, 25 August 2021 (UTC)

Oppose on the grounds that Alkane stereochemistry seems to be a subtopic of stereochemistry; conformational isomerism is a subtopic within stereochemistry, but there are many topics that are the subject of stereochemistry that are not about isomerism. Klbrain (talk) 12:20, 16 January 2022 (UTC)

Reply: I don't follow your reasoning: why would it matter that these are both subtopics of stereochemistry, which also has many other subtopics? My concern with the present contents of alkane stereochemistry is that it is mostly a wordy discussion of some of that material that is already present in conformational isomerism. I have no objection to alkane stereochemistry on its own but it would need new material unique to that article; that mostly consists of the rather slim subject of chiral branched alkanes like 3-Methylhexane. As far as I know there's not yet enough to say about those to devote an article, but someone could always write it in the future if warranted. Does that seem reasonable? –MadeOfAtoms (talk) 05:02, 19 January 2022 (UTC)

MadeOfAtoms correctly clarifies that the problem is the current content of the articles, not their names. And it's also a good point that "alkane stereochemistry" as a topic seems like a difficult niche for specific content. DMacks (talk) 09:15, 19 January 2022 (UTC)

Another relevant factor that supports merging is that conformation is a Gold book term[1] relating to the topic being discussed in these two articles, whereas there is no term equivalent to "alkane stereochemistry" in the way it is used in that article. Readers would be more likely to search for "conformation..." than "alkane..." when seeking an article like this. Mike Turnbull (talk) 09:52, 19 January 2022 (UTC)

Withdrawing opposition, given the arguments about content rather than title. So, perhaps merge the content as indicated in the proposal, then the decision about the direction of the redirect can made separately. Klbrain (talk) 09:40, 20 January 2022 (UTC)

  Y Merger complete. Klbrain (talk) 07:05, 1 August 2022 (UTC)

Never heard of "conformational isomerism"

I am an organic chemist for 45 years, and this is the first time I have ever seen or heard of "conformational isomerism". Conformers are NOT a type of "isomer". Isomers are all interconvertible via breaking and making bonds. For constitutional, aka structural, isomers these bonds originate from or terminate to different atoms. For stereoisomers, they are of the same atom. Conformers, on the other hand, have IDENTICAL bonding. Isomers are also all potentially isolable, discrete molecules. You can not isolate the staggered form of n-butane, as it would immediately equilibrate with the eclipsed form.

Conformers are simply different energy states of the exact same molecule, generated by torsional angle changes.

Would you count all of the quantum allowed vibrational states of water as "isomers" of water? Of course you wouldn't.

• • • This entire article should be taken down. It will thoroughly confuse students.Retired angler2924 (talk) 19:23, 8 April 2023 (UTC)

I moved the above content to the bottom of the page and gave the remark a header.

I agree that the title is awful. But once lots of content has been written, it is nearly impossible to remove an article from Wikipedia for good and for bad reasons. So the article needs to be renamed.--Smokefoot (talk) 13:41, 9 April 2023 (UTC)

I also hate the title but this is complex. For example see here: https://www.sydney.edu.au/science/chemistry/~george/isomers.html

as well as

https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Basic_Principles_of_Organic_Chemistry_(Roberts_and_Caserio)/05%3A_Stereoisomerism_of_Organic_Molecules/5.03%3A_Conformational_Isomers

and this article:

https://www.nature.com/articles/s41557-018-0043-6

The more I look, the more I see this term being used by folks teaching organic chemistry as well as it being used in the literature.

Now personally, I don’t think of this as isomerism either, and prefer “conformer distribution” or “conformational flexibility.” These also get used in the primary literature. See here for example: https://pubmed.ncbi.nlm.nih.gov/8808740/. Anyway I would hesitate to change the title given that the term does have currency. Qflib, aka KeeYou Flib (talk) 15:53, 9 April 2023 (UTC)