Talk:Enantiomer

Poorly written

The introductory explanation is confusing, using several virtually synonymous terms without explaining how they are different. 'Although' is logically absurd.

GND FDL

I've taken out the following from the article:

"The above comes from my Organic Chemistry class notes (exceptionally well taught by Dr. Richard Jagger aka Jag) and as such are copyright by me (Tres) and now licensed under the GNU FDL."

While this may well be true, it's not standard practice to put such credits on Wikipedia articles, since they all contain the copyright of many authors, all automatically licensed under the GFDL as soon as they are placed here. As far as crediting your lecturer goes, perhaps leaving this note here is good enough.

Also, I'm afraid one of the external links is dead, so I've taken it out - for future reference, it was:

• http://www.chemistry.mcmaster.ca/berti/3f03/special_stereochemistry.pdf

Oh, and the article makes very little sense to me, but that's cos I'm not a chemist! :D - IMSoP 13:23, 28 Jun 2004 (UTC) The introductory explanation is confusing, using several virtually synonymous terms without explaining how they are different. 'Although' is logically absurd.

Opening Sentence

The opening sentence has twice been changed to say something that is incorrect. Currently (I've just corrected it) it says In chemistry two stereoisomers are said to be enantiomers if one can be superimposed on the mirror image of the other. This is correct. It does not say that an enantiomer can be superimposed on its own mirror image. It says that one enantiomer can be imposed on the mirror image of the other enantiomer, which is true. Changing the "can" to "cannot" makes it false. Josh Cherry 04:23, 11 July 2005 (UTC) The introductory explanation is confusing, using several virtually synonymous terms without explaining how they are different. 'Although' is logically absurd.

Opening Sentence

I changed the words can to cannot, and superimposed to superposed. Superimposed just means laying one thing on top of the other, you can do this with anything. Superposed means laying one thing on top of the other and have all parts coincide; you cannot do this with enantiomers.

The sentence you created is incorrect. One entantiomer can be superposed on the mirror image of the other. Josh Cherry 23:34, 12 July 2005 (UTC)

The first sentence was changed to read In chemistry two stereoisomers are said to be enantiomers if one cannot be superposed on its mirror image. This is false. D-glucose and D-galactose are stereoisomers, and neither can be superposed on its own mirror image, but they are not enantiomers (they are diastereomers). So I've reverted the changes. What I've reverted to may be confusing, but it is correct and what was there was incorrect. Josh Cherry 12:15, 13 July 2005 (UTC)

There was another problem with the opening sentence. The condition was insufficient. yes, yes, I understand that when the opening sentence said "stereoisomers" it ment something that didn't HAVE mirror symmetry, but the average Joe doesn't KNOW that... so, the letter "T" can be superposed on its mirror image, it IT an enantiomer? No. Enantiomers must be DIFFERENT and mirror images of each other. Other than that, I tried to re-word so that the use of "can" was OBVIOUSLY correct. By moving it down to the bottom of the opening paragraph, there has been time for some explanation. Rick Boatright 00:16, 14 July 2005 (UTC)

Still confusing

Changed it to make it a little less confusing. The way it was worded before it was basically saying the enantiomer can be superposed on the mirror image of its mirror image, which is confusing.

I don't suppose someone would translate this into english for the non-chemist? I still have absolutely NO idea what an enantiomer is. 206.169.45.183 —Preceding comment was added at 19:06, 25 October 2007 (UTC)

As a non-chemist, do you understand at least what is meant in the lead that they are [weird-word things] that are nonsuperimposable complete mirror images of each other, much as one's left and right hands are "the same" but opposite.? That's exactly what they are if one ignores the context of chemical structures. If you're not a chemist you probably don't care about the specific weird-word means, but if you wanted to know, you could follow its link. DMacks 19:27, 25 October 2007 (UTC)

Still confusing. The introductory explanation is confusing, using several virtually synonymous terms without explaining how they are different. 'Although' is logically absurd. — Preceding unsigned comment added by 2.97.119.211 (talk) 15:21, 14 March 2020 (UTC)

Merge?

Would it make sense to merge this with Chirality (chemistry)? --Tabor 18:22, 18 October 2005 (UTC)

• in my view Optical isomerism and Chirality (chemistry) should merge into a general article or introductionary text with the wider implications, the enantiomer article should stay as it is with the more technical information, nomenclature etc V8rik 22:28, 18 October 2005 (UTC)

Well, I think we should merge with Optical isomerism. The content of these articles are the same. Poppypetty 05:45, 5 December 2005 (UTC)

I vote for merging with Chirality. OR, tell me what the difference is between the two?

~ender 2014-03-08 8:45:AM MST — Preceding unsigned comment added by 75.167.36.29 (talk)

• Support merge because Chirality (chemistry) and chiral refer to the same phenomena as enantiomerism and Enantiomer; they are near synonyms except for precise usage differences. The articles contain mostly identical information, organized and worded differently only because of independent development. [Re Optical isomerism comments above: presently redirects to Enantiomer.] –MadeOfAtoms (talk) 06:54, 4 August 2021 (UTC)
• This discussion is 16 years old. Please make a formal proposal, with proper tagging to get current input. DMacks (talk) 15:29, 4 August 2021 (UTC)
• The customary process for merging is described at WP:MERGE. –MadeOfAtoms (talk) 08:48, 6 August 2021 (UTC)

Importance?

Stereo chemistry of enantiomers is of great importance nowadays. The Food and Drug Administration (FDA) of the United States of America recently recommended that drug molecules having stereocentres should be given to patients only in the active enantiomeric form and not as a racemic mixture.

The first sentence of this statement does not add any factual content to the article. The second is at best an oversimplification of the issue, and at worse incorrect. I replaced it with a description of the range of benefits offered by single-enantiomeric forms vs. racemic forms, as well a a link to the FDA statement regarding the issue. Bushing 11:55, 15 December 2005 (UTC)

Naming Conventions

I am not in this field, so I shall just ask a question about the following:

• (+)- vs. (−)-
• D- vs. L-
• (R)- vs. (S)-

The (+)- vs. (−)- convention is based on the substance's ability to rotate polarized light. The other two conventions are based on the actual geometry of each enantiomer.

I thought that D- and L- referred to dextrorotatory & levorotatory (or laevorotatory), which would make it refer to the ability of the compound to rotate polarized light, which would put it in the same class as + & - rather than with R- & S-. Whatever the case, could someone who knows about this topic add clarification as to where the D- & L- and R- & S- come from? I'm interested :-) Thanks. --Muchado 04:50, 7 February 2006 (UTC)

I'll put up a description of the distinction between R & S.(Cahn-Ingold Preolg rules) Got a question, though. Should it be it's own article or include in this one?--Luke Hayden {4th May 06}

There's a fairly extensive discussion of the different naming conventions on the Chirality (chemistry) page. DMacks 16:29, 4 May 2006 (UTC)

Light rotation and ligand priorty

Dextro in Dextrorotary means 'to the right' and refers to its optical rotation and describes the '+' symbol. Levo in Levorotary, of course, denotes rotation to the left and describes the '-' symbol.

The symbols 'R' and 'S' refer to the latin roots 'Regio' and 'Sinistere' also denoting left and right. This, however, describes the hierarchy of weight priority of the ligands on the molecule. —Preceding unsigned comment added by 75.144.199.145 (talk) 14:40, 3 September 2009 (UTC)

Top Right Picture

I'm currently studying A level Chemistry and I learnt that Enantiomers can only exist when a central carbon has 4 different groups attached to it. The image at the top-right of the page shows 2 Methyl groups attached to it, therefore they are superimposible onto each other and they are not optical isomers. Am I missing something or should I create a new image that correctly shows two optical isomers. —Preceding unsigned comment added by Sam Dangit (talk • contribs)

You are not noticing the implied "CH₂" in the semi-skeletal structure: the carbon has a methyl and an ethyl, not two methyl. That's consistent with the name "2-bromobutane" (two methyls would make it only a propane). DMacks (talk) 17:32, 27 September 2009 (UTC)

Are human hands chiral or amphichiral?

I am not in this field, and it may be that I misunderstand, but it sounds to me as if this article says that human hands are examples of chiral objects, but the article on chirality says that hands are NOT chiral. Is it worth anyone's time to verify this, or respond to me that I am wrong? Sallypursell (talk) 14:10, 9 July 2011 (UTC) — Preceding unsigned comment added by Sallypursell (talk • contribs) 14:08, 9 July 2011 (UTC)

I still dont know what R and S mean

or where to find it — Preceding unsigned comment added by 96.224.73.39 (talk) 19:52, 17 July 2011 (UTC)

+++So I looked up the reference at <http://www.chem.qmul.ac.uk/iupac/AminoAcid/AA3t5.html#AA35> and found this:

A more general system of stereochemical designation, which is especially convenient when there is no simple way of relating a compound to a defined standard, is the RS system of Cahn, Ingold & Prelog [13, 18]. In this system the ligands of a chiral atom are placed in an order of preference, based largely on atomic number. If the first three ligands appear clockwise in this order when viewed from the side remote from the least-preferred (fourth) ligand, the chiral centre is R; if anticlockwise, it is S. — Preceding unsigned comment added by 71.92.132.50 (talk) 09:11, 28 July 2016 (UTC)

ent-

I encountered these names:

• (-)-alpha-zingiberene ((5R)-5-[(1S)-1,5-dimethyl-4-hexenyl]-2-methyl-1,3-cyclohexadiene), PubChem CID#92776
• ent-zingiberene ((5S)-5-[(1R)-1,5-dimethyl-4-hexenyl]-2-methyl-1,3-cyclohexadiene or (+)-alpha-zingiberene), PubChem CID#11127403

I think that the ent- should be explained.

Simon de Danser (talk) 21:10, 12 September 2020 (UTC)

@SimonDeDanser: I added a note (with IUPAC cite). DMacks (talk) 21:44, 12 September 2020 (UTC)

Thanks. Simon de Danser (talk) 21:33, 21 September 2020 (UTC)

Wiki Education assignment: Honors Organic Chemistry I

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— Assignment last updated by 123pickles456 (talk) 01:08, 10 October 2022 (UTC)

Wiki Education assignment: CHEM 300

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Enantiopure redirects here, but article doesn't define it

The article should clearly define enantiopure, since "enantiopure" redirects here. Matt-bacon-bcm (talk) 04:43, 12 August 2023 (UTC)

 Done --Smokefoot (talk) 17:18, 12 August 2023 (UTC)