Talk:Cyclohexane conformation

Untitled

The most stable position of a cyclohexane would be the "chair-position". But if the cyclohexane has 2 or more t-butyl groups off the 1 and 4 position then the boat position is the best due to the avoidance of steric interference.

Remember: more stable means less potential energy (it won't blow up on you)!

Conformational Discussion

This page needs some editing in relation to conformational changes. What is there is very crude, and there is no reference to the calculation used to get the energy values of the various conformations. It's nice to see the use of the IUPAC definition of the half chair (four coplanar atoms).

Hansonrstolaf (talk) 00:14, 7 March 2011 (UTC)

Merge of ring flip

no: Ring inversion does not occur in cyclohexanes only. Although the way the ring flip is written now it's not obvious. --Cubbi 02:37, 4 June 2007 (UTC)

Keep::See above comment. Fuzzform 00:38, 26 October 2007 (UTC)

• merge tag removed V8rik 17:48, 2 December 2007 (UTC)

A-values

I can't seem to find any discussion of A-values on wiki! This seems like the obvious place for it, sicne they're always calcuated for cyclohexane, but possibly merits its own page - any thoughts?? Seansheep (talk) 09:22, 14 March 2008 (UTC)

Naming of conformations, Nelson paper

I was quite shocked to see the conformations listed here. There was "envelope" listed as a major conformation, but with no explanation of what it was. I think it's someone's misinterpretation of this, the most common conformation for cyclopentanes, so I simply removed it. I suppose that a half-chair cyclohexane looks quite similar to that. Also, there was mixed use of "twist-boat" (which is what I have always heard and used) and "twist" (which I was unfamiliar with). I am recommending that we follow the recommendations of the Nelson paper I've cited in the lede section, and use twist-boat throughout, so I made the appropriate changes. Is this reasonable? Did I miss something? Walkerma (talk) 18:48, 8 August 2011 (UTC)

nice paper! It's certainly a good idea to use it. I keep telling myself to some day put together a Cremer-Pople conformation space plot for this page, where all those conformations map to points on a sphere and make for awesome big-picture presentation. --Cubbi (talk) 19:35, 8 August 2011 (UTC)

Yes, I was thinking that the page needs some nice graphics, but I'm lousy at such things! Walkerma (talk) 20:45, 8 August 2011 (UTC)

Disubstituted section so much nonsense

Will anyone object if I replaced this citation-less, near indecipherable morass with a short, referenced, scholarly paragraph? Notes to defend this diagnosis to follow. Le Prof Leprof 7272 (talk) 18:24, 30 May 2014 (UTC)

With apologies to the author of the second legible paragraph: though you did not provide references, yours is apt, but unfortunately set among three hopeless paragraphs. To whit:

• Citation-less: Speaks for itself. Not one, as of this date. And two citation-needed tags are dated January 2008. Le Prof Leprof 7272 (talk) 18:25, 30 May 2014 (UTC)
• Near indecipherable: three examples.

(1) Opening paragraph, which uses "formation" instead of conformation, makes no mention of the required reference plane to define cis and trans, etc. And "upper side" and "dubbed"?

(2) Bullets near end, which contain a list of molecules with purported conformational preferences, introducing abbreviations and shorthands not appearing anywhere else in the article (e-Br, a-Br, -ve), and describing a justification of the conformation in quotes, whose content is—to put it as kindly as I might—unacceptable with regard to any standard of chemical communication. [ To whom is the author speaking, when he or she writes, yes, with quotation marks as appearing, "also intra-H-bond" and "1,3 diaxial interaction(-ve in e-Br) more than dipolar repulsion: (and yes, with closing colon instead of quotation mark)? ]

(3) Setting aside for the moment the non-verifiability of the clear research claims of paragraphs 2-4, consider only ''the cart-before-the-horse third paragraph, which has the thermodynamics being the result of the conformation, rather than the actual, correct causal relationship. (!) Le Prof Leprof 7272 (talk) 19:15, 30 May 2014 (UTC)

• Morass: Forget the fact that the section as a whole closes with a further undecipherable, dis-attached phrase ("while present in equtorial form in polar solvents 'dipoles reinforce'"). Morass, a noun, is defined as a complicated or confused situation, is used with the intention to invoke the literal meaning (a bog, wherein one is easily lost). Its synonyms of muddle, tangle, jumble, clutter all clearly apply. The second paragraph excepted—is there a word for a quagmire with a single bit of solid ground?—this section is a verbal morass unfit for Wikipedia. If it were a 6th form exam question briefly answered, I would mark it 1 in 4 or 1 in 5 for content quality (i.e., fail it, at the pre-bacc level). Le Prof Leprof 7272 (talk) 19:17, 30 May 2014 (UTC)

Bottom line, this is a posted article, not someone's classroom scratch pad or Wikipedia sandbox. Information here is intended to be reliable, and verifiable. Content that is unverifiable—or worse, gibberish or nonsense—must be removed. Repeating the opening question, Will anyone object if I replaced this [section] ... with a short, referenced, scholarly paragraph? There is no way that I or anyone else can reliably, sentence by sentence, turn this into sourced prose, without introducing further errors or discrepancies (brought on by assumptions either of the meaning of the original editors intention, or of the relationship between the source's meaning to the bit of text to which it might be attached). No, such a mess as this cannot be cleaned up and forensically referenced. Not to mention the unconscionable waste of time (see opportunity cost). The opportunity for getting this composition correct was long ago missed by the authors that added material here, with their sources/books opened beside them to place and page. Le Prof Leprof 7272 (talk) 19:20, 30 May 2014 (UTC)

Compare decent source to section content

Compare the definition of cis and trans in paragraph 1 of this article's "Disubstituted cyclohexanes" section, as of today's date:

• "Substituents found on cyclohexane adopt cis and trans formations... Cis formation means that both substituents are found on the upper side of the 2 substituent placements on the carbon, while trans would mean that they were on opposing sides."

to the definition contained in a reliable source:

• cis, trans: Descriptors which show the relationship between two ligands [atoms, group] attached to separate atoms that are... contained in a ring. The two ligands [atoms, group] are said to be located cis to each other if they lie on the same side of a [reference] plane. If they are on opposite sides, their relative position is described as trans. The appropriate reference plane… [f]or a ring (the ring being in a conformation, real or assumed, without re-entrant angles at the two substituted atoms) it is the mean plane of the ring(s). … If there are more than two entities attached to the ring the use of cis and trans requires the definition of a reference substituent…"

See http://www.chem.qmul.ac.uk/iupac/stereo/BC.html#26. Le Prof Leprof 7272 (talk) 20:05, 30 May 2014 (UTC)

Forced conformations

The section "Forced conformations" was added by "Uncle Al", a well-known physics crackpot, and the links in the section go to his own homepage. I don't know much about this topic so I cannot comment on the accuracy of the information he added. But he inserted some long-lived | nonsense into the page on the equivalence principle, so I think it's likely that his edits here were similarly bogus. Amaurea (talk) 13:31, 29 September 2016 (UTC)

I couldn't find chiralane in SciFinder, Scopus, or Science Direct, and the main published ref I can find is indeed by Uncle Al:

• Schwartz, Alan M.; Petitjean, Michel (2008). "[6.6]Chiralane: A Remarkably Symmetric Chiral Molecule". Symmetry: Culture and Science. 19 (4): 307–316.

Two other refs use cite it for purposes of using its coordinates in collections of special/pathological-case molecules, but do not seem to have critical commentary on the molecule itself. I don't know about the physics/crackpot aspects of the author, which probably wouldn't be relevant anyway if there were WP:SECONDARY refs or publications by others or in higher-impact journals. But I can't find those sorts of refs, so I removed that bit of content for now. If we wanted to keep it, we should at least cite the published report rather than "citing" via links to external gifs. DMacks (talk) 14:54, 29 September 2016 (UTC)

Intro -- show the boat and chair conformation in an easy-to-compare way

It would be most helpful to show both boat and chair conformations at the beginning. There is a beautiful picture of the chair conformation, but we need a similar one of the boat conformation. Can anyone supply it? CharlesHBennett (talk) 13:13, 22 November 2016 (UTC)

Yes, even with long-ago academic qualifications in organic chemistry and in biology, I can't picture each of the conformations described. Even just a clearer key to accompany File:Cyclohexane universe.png, naming each numbered conformation would be an improvement. — OwenBlacker (talk) 16:38, 15 May 2017 (UTC)

"Interconversions between conformations" Image

Only some of the 5 numbers 1,2,3,4,5 are mentioned in Wikipedia text. Please mention all five. And explain E=Energy unless already explained.

91.155.24.127 (talk) 09:48, 21 September 2017 (UTC)

Major revision

I removed all dispute tags, and I generally dumbed down the article to keep it (fairly) factual and uncomplicated. If others think that my revision was too drastic, then revert my work.--Smokefoot (talk) 01:33, 20 November 2019 (UTC)

The article mentioned the plausible "The polarity of substituent can influences their axial vs equatorial preferences. cis-Cyclohexane-1,3-diol prefers diaxial conformation, which allows formation of intramolecular hydrogen bond." But doi:10.1016/S0277-5387(02)00934-8 indicates that cis-Cyclohexane-1,3-diol crystallizes as the diequatorial conformer. So at minimum, the situation is complex.--Smokefoot (talk) 13:17, 20 November 2019 (UTC)

doi:10.1039/P29930001061 discusses the 1,3-diol in various solvents: "Values for ΔG° range from 0.1 kcal mol^–1 in CCl₄ to 2.7 kcal mol^–1 in aqueous solution in favour of the conformation in which both hydroxy groups are equatorial." So intramolecular H-bonding (and solvent effects on it) do seem to have an effect on relative conformational stability. But not enough to overcome the ordinary equatorial preference. I tweaked your DOI format to make it a hyperlink. DMacks (talk) 06:42, 21 November 2019 (UTC)

@DMacks: Thank you! I was wondering about the Keq and I guess inevitable that H-bonding solvents are a big factor. There are many other things about the article that would be worth expanding or explaining. It would be nicely illustrative to show low T and RT H NMR spectra for C6H12. --Smokefoot (talk) 15:30, 21 November 2019 (UTC)

And doi:10.1021/jo051049w addresses trans-1,2-dihalocyclohexane stability in solution and gas-phase for the different halogens, and different solvents for difluoro in particular. DMacks (talk) 05:59, 22 November 2019 (UTC)

Wiki Education assignment: Honors Organic Chemistry I

This article was the subject of a Wiki Education Foundation-supported course assignment, between 22 August 2022 and 2 December 2022. Further details are available on the course page. Student editor(s): Leslieblakney75, Kcat3, Bluelucero (article contribs).

— Assignment last updated by Kcat3 (talk) 00:25, 17 November 2022 (UTC)