Talk:Chirality (chemistry)

message: Using the "CORN" method for amino acids, is the picture in the left hand really an L-amino acid, and is the picture in the right hand, really a D-amino acid?? BillChia (talk) 13:23, 24 February 2010 (UTC)
replies: text: It does have a C2 axis, just like hydrogen peroxide. See http://www.chemspider.com/Chemical-Structure.49724.html or https://www.chemtube3d.com/symhoohc2/, for example. The point group of all these molecules is C2. --Ben (talk) 21:11, 15 July 2020 (UTC)
thread_title:  Are the Pictures correct? 

message: No mention of what explanations are being hypthesised for the right-handedness of biology. Two I know of are
# it just turned out that way
# the weak nuclear force makes one way more low energy that the other
Pmurray bigpond.com 06:03, 12 September 2005 (UTC)
thread_title:  Why 

message: Would it make sense to merge material from Enantiomer? --Tabor 18:22, 18 October 2005 (UTC)
replies: text: I think so, I will add the proposed merge template to both pages. --Aaronsharpe 11:12, 22 June 2007 (UTC)

text: If you merge enantiomer into this article, you should merge diastereomer and atropisomerism, as these are all examples of chirality in chemistry.  One cannot discuss diastereomers without first discussing enantiomers anyway.  You could actually merge enantiomer and diastereomer into the stereochemistry article instead, which IMO would make more sense. There is no reason to only merge enantiomer into chirality, as there are many other forms of chirality in chemistry. Endtothemeans (talk) 03:34, 8 June 2008 (UTC)

text: This would work.  There is no need for an explanation of enantiomers in an article on chirality in chemistry...they can just be linked.  Endtothemeans (talk) 02:04, 21 June 2008 (UTC)
thread_title:  Merge? 

message: Alterations and restructuring are needed to properly represent use and meaning of the word chirality. Please join the multi-disciplinary discussion on Talk:Chirality. --Cigno 22:15, 15 November 2005 (UTC)
thread_title:  General issues 

message: Surely the word is asymmetry, not dissymmetry. I was also taught that the correct terms were <B>laevorotatory</B> and dextrorotatory.
21:01, 19 December 2005 (UTC)
thread_title:  Wrong word? 

message: Content of optical isomerism has been moved to chirality (chemistry), and optical isomer is now the redirect. The result is that many links to this article are now disabled. Please consider fixing the links or better revert the process as chirality (chemistry) is not an elegant name for an article.   V8rik 21:54, 6 April 2006 (UTC)
thread_title:  poorly executed content move 

message: Is it possible to have this property using isotopes?  Suppose in the Alanine molecule the H3C methyl group is replaced with Deuterium instead of hydrogen, does this create an optical isomer? —The preceding unsigned comment was added by 12.10.127.58 (talk • contribs) .
:In a glycine molecule where the methylene group is CHD instead of CH2, that carbon is a chiral center, and the molecule has two possible enantiomers. DMacks 20:36, 1 June 2006 (UTC)
thread_title:  Isotopes 

message: The article says:
:[...] the D/L system remains in common use in certain areas of biochemistry, such as amino acid and carbohydrate chemistry, because it is convenient to have the same chiral label for all of the commonly-occurring structures of a given type of structure in higher organisms. In the D/L system, they are all L;
They are not all L; there are lots of D's. Or do I misunderstand the sentence? There's for example D-Glyceraldehyde 3-phosphate at a prominent position in glycolysis. AxelBoldt 23:57, 22 September 2006 (UTC)
replies: text: I think this is probably a very poor attempt at pointing out that in the living, human body; the chiral ratio of amino acids is actively shifted to make L-amino acids dominant (90% L, 10% D); and conversely D-monosaccharides are dominant. Only the L-forms of amino acids are active in humans, only the D-forms of monosaccharides are active in humans, so the body keeps that gradient there. After you die, the ratio naturally switches back to 50:50.--KX36 20:07, 3 February 2007 (UTC)
thread_title:  Not all L 

message: There is an implication that all enantiomers are optically active - which is rubbish. Also the term is asymmetric, not dissymmetric - Look up most major textbooks it will use that term
Arguably the R & S nomenclature is the most important so surely that should be placed ahead of the d/l and D/L paragraphs - although I am saying this as a chemist rather than as a biologist
Stui 194.72.70.114 13:02, 4 October 2006 (UTC)
thread_title: Some dodgy stuff in here

message: The rule where if a tetrahedrally-bonded C has 4 different substituents, then it is chiral applies to any tetrahedrally-bonded element, although C is the most common example. This is according to my university textbook. Mike.lifeguard 00:07, 6 November 2006 (UTC)
replies: text: It's true. The article here notes that C is a simple example, and it's the  case most wikipedia readers will likely encounter or be likely to recognize or are here to learn about. But actually, it's not even limited to atoms that have 4 bonds, and it's not even limited to atom-centered things at all...see BINAP for example. DMacks 16:43, 6 November 2006 (UTC)
thread_title:  Rule surrounding C 

message: I changed the content of the article because it was just plain wrong!
It said that after putting the lowest priority group at the back, if the remaining constituents were counterclockwise it was D config. If clockwise L config.
This is wrong!!
If a chiral molecule has a counter-clockwise configuration it is L (corresponding to S in Organic Chemistry)
If a chiral molecule has a clockwise configuration it is D (corresponding to R in Organic Chemistry)
Just letting everyone know I fixed that. —The preceding unsigned comment was added by MikeMurko (talk • contribs).
I'm affraid it was right the first time and I changed it back. You can check this one yourself. Find yourself a picture of for example D-Alanine, turn the hydrogen away from the viewer and the order COOH R NH2 is counterclockwise! —The preceding unsigned comment was added by 62.253.240.3 (talk) 
Looking at the (claimed to be) L-(S)-alanine image on the alanine page, R is the methyl group, H is in the back, and I see (COOH)-(R)-(NH2) running counter-clockwise. This also seems to agree with the L-(S) stereochemical assignments on the glyceraldehyde page per the description of the origin of the L/R nomenclature (NH2 instead of OH, methyl instead of methylcarbinol). DMacks 02:13, 3 May 2007 (UTC)
thread_title:  D-L Chirality Notation Error 

message: suggest adding "counterclockwise as viewed against the direction of propagation" or something similar regarding polarization rotation under the History section, in addition to that in the optical activity naming convention section.
Angelafit 06:07, 3 December 2006 (UTC)
thread_title:  counter clockwise w. r. to... 

message: A para in the article says:
:By contrast, the operation of superimposition is trivial for a non-chiral mirror image (e.g., the letter "A"). Because letters such as "A" are not three-dimensional, though, no chiral letters exist to demonstrate the contrary.
Doesn't "L" 'demonstrate the contrary'? (i.e., it's chiral.) If that's not what the para is about, it needs fuller explanation.  -R. S. Shaw 18:37, 11 March 2007 (UTC)
thread_title:  Letter example - huh? 

message: One or more anonymous users (get a user account!) feel that this article should use superposition and not superimposition to explain chirality. I know that McMurry, March etc. use superimposable but what the heck is the difference between the two!. Is is one of those flammable / inflammable thingies that non-native English speakers always mess up or a UK vs US English difference? Any ideas? V8rik 17:53, 6 November 2007 (UTC)
replies: text: Yes, I'm in favor of "superimposition" both in my mind and because we can support it with McMurry, Wade, Streitwieser/Heathcock/Kosower, and Morrison & Boyd. I'd actually never noticed the "IM" word-root similarity:) DMacks 17:48, 7 November 2007 (UTC)

text: Just for the heck of it, here's the Google Books Popularity Contest result: enantiomer superposed, 61 hits; enantiomer superimposed, 322 hits. In my opinion, both are equally valid. I don't know if it is due to regional differences or if it is random, though. --Itub (talk) 09:59, 30 June 2008 (UTC)
replies: text:  It's not likely that the non-technical audience will appreciate, or even understand the distinction. Please continue to clarify and simplify (within reason). Kortoso (talk) 23:08, 13 December 2013 (UTC)
thread_title:  [[Superposition]] vs [[Superimposition]] 

message: I notice that all of the instances of "D" and "L" are wrapped in  tags. If they're supposed to be in smallcaps, we should use  instead: small-caps. I didn't convert over myself because I'm not certain this is what the small tags were intended to accomplish. Bryan Derksen (talk) 05:38, 23 November 2007 (UTC)
replies: text: The D and L in this context are indeed intended to be small caps.  is heck of a lot easier to type than a longer, er "span" of text. DMacks (talk) 16:34, 24 November 2007 (UTC)
replies: text: There is now a  template that produces .  (One of the very few "good" templates in Wikipedia: among other qualities, it does make editing easier, it can be immediately and completely learned from a single example, and does not generate more visible text than the template call itself.) --Jorge Stolfi (talk) 22:29, 1 February 2020 (UTC)
thread_title:  D/L typesetting

message: Ibuprofen is another example of a chiral molecule. One entantiomer has pain relieving effects while the other is inactive. Also, if I remember correctly, the body can convert the inactive form to the active form, which extends the duration of the pain relieving effect of the drug.
KingHanneman (talk) 04:12, 1 February 2008 (UTC)
replies: text: Yup. See the "Stereochemistry" section of the Ibuprofen article for more info. DMacks (talk) 10:21, 3 February 2008 (UTC)
thread_title:  Ibuprofen 

message: From the article:
:"The origin of this homochirality in biology is the subject of much debate. Most scientists believe that Earth life's choice of chirality was purely random, and that if carbon-based life forms exist elsewhere in the universe, their chemistry could theoretically have opposite chirality."
I was under the impression that the weak interaction is often suspected as having a role in the origin of homochirality, based partially on indicative experiments involving crystal growth like those of Compton and Pagni (sorry, I don't have a cite off the top of my head).  I realize that it's still very speculative to believe this with regards to amino acids in particular, but I wonder whether it's significant enough to comment on in the article? (chemistry isn't my area, so I cannot say)
Even if the hypothesis involving the weak interaction isn't significant enough to include here, the assertion that "most scientists" believe the origin of Earth-bound life's homochirality to be purely random seems misleading.  There are certainly plenty who believe it could be the result of natural physical laws.  -- 98.26.182.245 (talk) 22:45, 13 October 2008 (UTC)
thread_title:  Comment on the origin of homochirality 

message: Amputated hands represent a pair of enantiomers.  But while still attached to the body, and ignoring our blemishes and the "enantioselective" placement of organs, the hands are not chiral since we are Cs-symmetric. So the analogy to hands is flawed.  We are however prochiral. Am I missing something?--Smokefoot (talk) 16:16, 20 December 2008 (UTC)
replies: text:  It is not unreasonable to use an analogy when describing a technical topic. Perhaps the word "example" leads readers to assume that hands are actually chiral. Kortoso (talk) 23:11, 13 December 2013 (UTC)
thread_title: Are hands really chiral?

message: The term chirality is derived from the Greek word for hand, χειρ-(/cheir/). I'm know this is improper IPA (which is what one uses inside phonological brackets "/ /"), so I'm guessing that the original editor was simply putting the standard romanization in parentheses. Therefore, I've edited out the brackets. 99.141.180.36 (talk) 02:02, 10 June 2009 (UTC)
replies: text: In Modern Greek it's /çir/, not "cheir". There may have been a point in time when the χ was pronounced /x/ while the ειρ was still pronounced /ěːr/ or /ějr/ — I don't think we really know which change occurred first. I doubt that scholars pronounced the χ like a hard k, it's just that the k sound is the usual way to pronounce words that had a χ in Greek, like "Christ" or "architecture", or the word "scholar" itself. The only exception I can think of in English is the word "cherub", which normally should be pronounced "kerub". Eric Kvaalen (talk) 12:33, 11 May 2021 (UTC)
thread_title:  Greek IPA /cheir/ 

message: I've seen both, is there any difference?  Is it worth mentioning?  —Preceding unsigned comment added by 173.250.142.56 (talk) 01:45, 1 February 2011 (UTC)
thread_title: "chiral center" vs. "chirality center"

message: I found in the the first two paragraphs of the introduction part of the article an incorrect wording :-"non-superposable mirror image".So I corrected it to "non-superimposable".Superposable has a totally different meaning in physics and  mathematics.Please check article on Superposition Principle for verification.  — Preceding unsigned comment added by Ichgab (talk • contribs) 07:35, 11 June 2011 (UTC)
replies: text: I have undone this change per the WP:RS noted in the #Superposition vs Superimposition discussion earlier on this talk-page. As a chemistry article, IUPAC is more authoritative than physics/math technical meanings in their fields (and your change was not supported by that cite given in the article). I have added a heading...because this was filed under '"chiral center" vs. "chirality center"', it's no wonder nobody else noticed or bothered to respond at the time to your separate issue. I have added an additional IUPAC ref that specifically defines "Superposition" as it is used in chemistry to help clarify its meaning in this field. It's definitely different than the superposition principle, so I have removed the link to that target. DMacks (talk) 13:53, 22 January 2012 (UTC)
replies: text:  Is there another way to describe this without resorting to technical terms that require their own definitions? Kortoso (talk) 23:13, 13 December 2013 (UTC)
thread_title:  Superposition vs Superimposition again 

message: Should the chirality of phosphorus (as in sarin) be included? Whoop whoop pull up Bitching Betty | Averted crashes 21:45, 3 August 2011 (UTC)
replies: text: The article should definitely note the general idea that a lone-pair can be considered a substituent (or at least consume a geometric position like one), and therefore give a stereocenter. The "Chirality of amines" section is a start, but it focuses on the transient nature due to rapid inversion, not the fact that each single state is chiral. Probably best to put the idea of chirality for molecules like RR'RN and RR'RP and RR'SO in the "Stereogenic centers" section (including how to name them R/S, etc.). Then separately can have some commentary on the fact that some chiral molecules can invert under standard conditions (pulling together the conformational-changes from "Stereogenic centers" and the amine-inversion idea). There was a discussion on the science ref-desk within the past month or two about barriers to inversion of P and N centers, I think with some links to other WP articles and/or literature sources. DMacks (talk) 02:45, 4 August 2011 (UTC)
thread_title:  Chirality of phosphorus 

message: It states that " it is labeled R (for Rectus, Latin for right), if it decreases in counterclockwise direction, it is S (for Sinister, Latin for left)." That is incorrect. rectus means straight (such as rectus abdominis), right in latin is dexter. Where does the R come from then?  — Preceding unsigned comment added by 86.135.11.19 (talk) 14:59, 15 January 2012 (UTC)
replies: text: In English, "right" can mean "correct", but it can also refer to the side opposite "left". In Latin, "rectus" seems to refer to the former, "dexter" the latter, though "right" is a 100% acceptable translation of both words—the problem is that "right" has multiple meanings. Is this as simple as a very old conflation of terms? Or is "rectus" really an additional word for the side opposite left in Latin (even though "dexter" has that covered)? 70.172.214.70 (talk) 04:58, 23 June 2013 (UTC)
replies: text: * I also spotted this ... imperfection. R must come from Rectus, there is no doubt about it. This looks wrong to some of us, because there's apparently a pair of right and wrong and another pair of right and left. I am not a linguist but this must be related to the fact that most of the population is right-handed. Right side is the good side, while left side is the bad side. Right in English has several meanings, in Latin sinister has that property. It could help perfectionists to change the translation to something which includes correct. Waydot (talk) 09:53, 12 December 2013 (UTC)
thread_title:  Naming conventions 

message: Do all sugars have chirality? Or is it only for monosaccharides? 173.17.169.171 (talk) 08:28, 6 March 2012 (UTC)
replies: text: Dihydroxyacetone is a three-carbon sugar that is not chiral. In principle you could have other ketoses that would not be chiral if there are an odd number of carbon atoms and the ketone group is on the central atom. In that case there would be chiral forms but alwo "meso" forms that would not be chiral. But as far as I know, ketoses always have the ketone group on the carbon next to the end. Eric Kvaalen (talk) 12:33, 11 May 2021 (UTC)
replies: text: 3-Pentulose and 3-hexulose are known. DMacks (talk) 13:47, 11 May 2021 (UTC)
replies: text: And 3-heptulose and 4-heptulose and 5-nonulose. Several stereoisomers of 3-pentulose, 4-heptulose, and 5-nonulose are meso compounds. DMacks (talk) 03:47, 12 May 2021 (UTC)

text:  Thanks. I wonder, do those ketoses exist naturally? I mean, I suppose you could make any ketose you wanted synthetically. By the way, I learn'd recently that there were many unsuccessful attempts to synthesize sucrose (from glucose and fructose) before it was finally achieved in 1953. I wonder whether the problem was to cause the condensation, or to get the right isomer. Eric Kvaalen (talk) 08:04, 15 May 2021 (UTC)
thread_title:  Chiral sugars?  

message: Dear Editors,
The article currently states the following in the RS section of the Naming conventions:
:If the center is oriented so that the lowest-priority of the four is pointed away from a viewer, the viewer will then see two possibilities: If the priority of the remaining three substituents increases in clockwise direction, it is labeled R (for Rectus, Latin for right), if it increases in counterclockwise direction, it is S (for Sinister, Latin for left).
This disagrees with the standard definition (see, e.g., Voet and Voet). 
A suggested correction follows:
:If the center is oriented so that the lowest-priority of the four is pointed away from a viewer, the viewer will then see two possibilities: If the priority of the remaining three substituents decreases in a clockwise direction, it is labeled R (for Rectus, Latin for right), if it decreases in a counterclockwise direction, it is S (for Sinister, Latin for left).
Thank you
Mewalloffice (talk) 19:10, 17 April 2012 (UTC)
thread_title:  Error in RS section of Naming conventions 

message: User:Rifleman 82 disagrees with my edit, but I do not understand why there should be pictures of both Δ and Λ conformationsisomers. Indeed, if it should, then which design is preferable? Incnis Mrsi (talk) 15:13, 7 March 2013 (UTC)
replies: text: "Stereoisomers" not "conformations". But anyway, the whole point of this article is to discuss and illustrate the idea of chirality, and especially the differences among stereoisomers. Only having a picture of one possibility and then saying "and there's another" does not help anyone who does not already understand the key aspect of the difference or to illustrate the quick definition of the "other" symbol. But I also think :File:Énantiomères octaèdriques.jpg might be too oversimplified, since it doesn't help if you don't really understand the molecules being represented. Maybe the [Fe(ox)3]3– 3D-balls images from Complex (chemistry)#Optical isomerism would be better here? DMacks (talk) 15:28, 7 March 2013 (UTC)

text: I do not object against any picture but JPEG, and any changes but destruction of typography fixes and wikification already made by me. Incnis Mrsi (talk) 15:56, 7 March 2013 (UTC)
replies: text: We have indeed been moving away from JPEG to PNG or SVG images, but JPEG images should not be removed unless an equally good replacement is available. --Rifleman 82 (talk) 16:10, 7 March 2013 (UTC)
replies: text: And agree with this statement too. A JPEG is better than nothing and better than an image that doesn't illustrate the appropriate/relevant content. File format is *not* the most important aspect of an article. DMacks (talk) 16:29, 7 March 2013 (UTC)
thread_title:  Δ and Λ complexes 

message: I'm curious as to if there are chemicals with different melting points, or such, when flipped.  I mean it doesn't seem like there would be according to simple valance electron theory, but then again, He3/He4 are very different beasts when isolated (spin-related cause).
I'm curious as to if some trios of atoms have a preferred relative orientation.  Think of particle physics and the layout of the brain where globally it seems they're reflections but locally they might not be.  They turn out to only be good approximations.71.196.246.113 (talk) 19:21, 9 March 2013 (UTC)
replies: text: In their pure forms and when not mixed with other chiral compounds, two enantiomers have the same melting point and such as each other because whatever their preferred relative orientation, it's a relative orientation. The mirror image would have the same relative orientation, just in the opposite direction. Diastereomers could be as different as any two unrelated compounds (except for same molecular weight) precisely because of different relative orientations. DMacks (talk) 20:55, 9 March 2013 (UTC)

text: I do not think that something like this is possible under typical circumstances because both electromagnetic and nuclear force are P-invariant. Though, it is perfectly possible under the same external influence which is not P-invariant. I can easily imagine two chiral isomers which have different properties if irradiated by the same circularly-polarized light. Or, say, under superposed electric and magnetic fields which are not perpendicular – parities of E and H fields are positive and negative respectively. Incnis Mrsi (talk) 21:09, 9 March 2013 (UTC)
replies: text: Yes, I was thinking of the magnetic and spin properties.  A neat (and lethal) thing is that H2 has biologically different effects than the H1 that is in most water molecules.  For microbes, it slows them down to about half speed (twice as much energy needed to move the same number of hydrogen atoms?) but for animals... does a lot more than just slow us.  Another thing that seems odd at first sight is that helium actually becomes toxic at high enough depths.  I think it was related to neuron connections? I actually doubt too many if any molecules will have detectable differences in melting points but I'm willing to bet that muons or something will react differently.  μ+SR and μ-SR (Muon/Mu Meson/Mu-Electron bombardment) is an interesting technology.  Not everything can be done at places like the CERN LHC.  We need smaller-hadron colliders, too!  ;)  Too bad there's no practical way to do Muon-chemistry in electronics.  I could see a lot of potential applications.  71.196.246.113 (talk) 19:45, 10 March 2013 (UTC)

text: *Deuterium is toxic because it has different chemistry, it's C-H bonds are slightly stronger than those of normal hydrogen and enzymes have a very hard time dealing with that (see Heavy water. I think helium toxicity (HPNS) is caused by it building up in the tissues to such a point that it becomes disruptive (similar to Nitrogen narcosis).Project Osprey (talk) 20:18, 10 March 2013 (UTC)
thread_title:  Chiral molecules with different properties? 

message: Tried to clean up the lede so it was clearer to the uninitiated. If the result is technically inaccurate, please help. Kortoso (talk) 23:16, 13 December 2013 (UTC)
thread_title:  Lede 

message: If the "rule" is supposed to be L amino and R sugar (in fact in many sources we see "all"), then what are the exceptions? Where do we encounter R aminos and L sugars? Archaea? Kortoso (talk) 23:24, 13 December 2013 (UTC)
thread_title:  "Most" amino acids are L 

message: An interesting discussion of how amino acids might have become (mostly?) homochiral. Also good examples of clear, simple language:
: http://www.nasa.gov/topics/solarsystem/features/life-turned-left.html Kortoso (talk) 23:33, 13 December 2013 (UTC)
thread_title:  How life turned left 

message: This article Chirality_(chemistry) has it that "all life on Earth being homochiral". Perhaps that phrase should be modified a bit then to mark what is actually homochiral in "all life"? Amino acids, proteins and sugar , yes. Higher level structures of DNA, perhaps not so much. I suspect one could modify it to either "all amino acids , proteins and sugars" or perhaps "all primary level chirality of molecules" or something to that effect, but I am not qualified to make the change right now. Star Lord  -   星王 (talk) 15:24, 28 March 2014 (UTC)
replies: text: Higher level structures are just a composite/effect, not an independent nature. The helicity (screw-thread direction) of the double-strand of each form of DNA always has the same handedness, or at least different stabilities and biochemical interactions when both directions are possible (see Nucleic acid double helix#Helix geometries). This higher-level handedness is due to the atomic chirality details. Same with other macromolecular details, such as the direction of a protein alpha-helix (see Alpha helix#Geometry and hydrogen bonding). DMacks (talk) 16:11, 28 March 2014 (UTC)
thread_title: All life needs to be modified

message: I've restored the disambiguation note that was recently removed by user Smokefoot on the grounds that it "seems obscure". That is, the note that says: "L-form" redirects here. For the bacterial strains, see L-form bacteria.
Just in case this is controversial, here are my reasons.
* It is plausible that a reader looking for information on L-form bacteria might type "L-form" into the URL. One of the functions of the redirect system is to facilitate that kind of shorthand.
* Wikipedia better meets its objectives if readers can serendipitously discover new information, as they can in a print encyclopaedia. Disambiguation notes are a good way to facilitate this.
* In my experience it is not common practise to remove disambiguation notes simply because the topic insufficiently well known.
(For the record, I have an account but choose not to use it. No need to reply to this parenthetical aside.)
14.2.35.204 (talk) 11:31, 18 March 2016 (UTC)
thread_title:  Restoration of disambiguation note 

message: The following resources and comments for editors was placed within the article, but it is more appropriate here.  -- Ed (Edgar181) 17:20, 16 May 2016 (UTC)
thread_title: Moved from article

message: I'm moving the following comment for editors which was placed in the "Methods and practices" section to here.  -- Ed (Edgar181) 17:23, 16 May 2016 (UTC)
thread_title:  Moved from article 

message: Achiral redirects to this article as a whole, e.g. from xylitol, but the only definition is an example embedded in a table under Definition. The latter is so terse and the language so technical that even I, as a BSc in Chemistry, have trouble following it.  Either achiral should have its own stub, or the definition of chiral needs to be clarified and include achiral, and redirects on achiral should link to the Definition section. 
* As so many compounds, especially biologically active compounds and drugs, are chiral, the article is likely to be read by those unfamiliar with current technical language and stereoisomer diagrams, and needs clarification.  WP is a general cyclodaedia, not an advanced chemistry dictionary. 
* I also tend to agree with the usage 'asymmetric'. 'Dissymetric' may be technically correct, but is controversial and unfamiliar to many. D Anthony Patriarche (talk) 23:27, 23 September 2017 (UTC)
replies: text:  I also agree.  This article as written is nothing but confusing, and then jargon.  So it is absolutely worthless.  Definitions are just flat-out wrong, starting with the "mirror image" statement.  Needs a complete re-write.  98.194.39.86 (talk) 13:32, 4 August 2018 (UTC)
thread_title:  Achiral/needs better definition 

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thread_title:  External links modified 

message: In the section "Stereogenic centers", I had written
:Many chiral molecules have point chirality, namely a single stereogenic center that coincides with an atom. This atom usually has four or more bonds to distinct atoms
It was changed to
:Many chiral molecules have point chirality, namely a single stereogenic center that coincides with an atom. This atom usually has four or more bonds to different groups
This passage is not precise anyway; it is a "usually" sort of claim. The point of saying "distinct atoms" was to exclude multiple bonds to the same atom, as in acetylene.  On the other hand, "different groups" is not precise either, because a carbon in a pyranose ring (say) is connected to only three groups (one of them divalent).I wish this paragraph could be made more precise, but I don't see how to do that without making it inaccessible to the general reader. Suggestions? --Jorge Stolfi (talk) 23:32, 1 February 2020 (UTC)
thread_title:  "Different groups" versus "Distinct atoms" 

message: The article now says
: While the presence of a stereogenic atom describes the great majority of chiral molecules, many variations and exceptions exist. For instance it is not necessary for the chiral substance to have a stereogenic atom. 
The definition of "stereogenic center" (whose article sorely needs cleanup, by the way) says that a stereogenic center need not be an atom. While the presence of a stereogenic atom is not necessary, a stereogenic center is, no? If so, this article should say so.... Or is the concept of "stereogenic center" a bogus one?  Achirality requires a reflection across a plane that leaves the molecule unchanged apart from a rotation.  If the rotation can be null, that plane is a (proper) "symmetry plane"; if it must be not null, the point where the axis cuts the plane is a (generalized) "symmetry center", and any plane through it has the same property.  Thus that plane or point can be considered the "source" (more appropriately, the "witness") of the achirality.  But chirality means only the absence of such a symmetry plane or center.  It does not make sense to say that the absence of such a thing is located in a particular place; does it?Moreover, in all the examples given next, some stereogenic atoms do seem to exist.  In FClBr-adamantane, for example, the carbon connected to F has three other bonds that are not equivalent, because each leads in two C-C steps to a carbon with a different substituent.  So the vertex carbons are all stereogenic atoms, no?All the best, --Jorge Stolfi (talk) 00:09, 2 February 2020 (UTC)
replies: text: Good point. I have rewritten that sentence and modified the next two. Eric Kvaalen (talk) 12:33, 11 May 2021 (UTC)
thread_title:  Stereogenic centers x stereogenic atoms