Talk:IUPAC nomenclature of organic chemistry

message: "By suffix, it is meant that the parent functional group should have a suffix, unlike halogen substituents. "
Could the person, who added the entry elaborate a little more on what is a 'parent functional group', 'a substituent' etc.?  — Preceding unsigned comment added by 156.17.236.5 (talk) 19:55, 4 November 2011 (UTC)
thread_title:  What does this sentence mean? 

message: Under Basic Principles, it is currently stated under instruction 6.1. that the numbering is done according to which order (right to left or vice versa):
:"Has the lowest locant (or sum of locants) for the suffix functional group. Locants are the numbers on the carbons to which the substituent is directly attached."
Later, in the example of 18-bromo-12-butyl-11-chloro-4,8-diethyl-5-hydroxy-15-methoxytricos-6,13-dien-19-yne-3,9-dione, it is stated in instruction 2.2. that:
:"The numbering of the molecule is based on the ketone groups. When numbering from left to right, the ketone groups get numbered 3 and 9. When numbering from right to left, the ketone groups get numbered 15 and 21. 3 is less than 15, therefore, the numbering is done left to right, and the ketones are numbered 3 & 9. The lesser number is always used, not the sum of the constituents numbers."
To me this seems contradictory. Could someone please clarify and/or correct? 88.195.173.125 (talk) 21:07, 14 March 2011 (UTC)
replies: text: "The lowest set of locants is defined as the set that, when compared term by term with other locant sets, each cited in order of increasing value, has the lowest term at the first point of difference."
i.e. line up all the numbers in ascending order, compare the lowest numbers of the two possible names, second lowest numbers, etc. until there's a difference. The set of numbers with the lower number at this first point of difference is correct. Labmuffin (talk) 05:48, 26 October 2018 (UTC)
thread_title:  Numbering, by sum or smallest number? 

message: In my opinion there is a little error in the text about Amides. It is stating that Amides are always terminal so there would not be a need for a prefix for them. But looking for example at http://en.wikipedia.org/wiki/Carbamoyl_phosphate you can see that in this case the Amide group is used as a prefix and not as a suffix because of the phosphate group. I do not know why phosphate does take precedence in this case but due to that exception in nomenclature I would recommend changing the statement in the entry about Amides implementing the prefix "Carbamoyl-". 
Furthermore I guess that the article does not state that the basic form of an Amin is Ammonia(NH3). If you for example have Triethylamine you would have N(CH2,CH3)3. So the three H-atoms of N would be substituted with Ethyl groups!  —Preceding unsigned comment added by Xc!te (talk • contribs) 18:02, 30 December 2008 (UTC)
thread_title:  Amides 

message: Some text books say that it does. Is there a rule stating this?
:There is a rule, and it states the opposite! Chemical names are common nouns, and should only be capitalized at the beginning of a sentence (or in a title in U.S. English). Physchim62 (talk) 08:17, 12 October 2006 (UTC)
replies: text: Just to add - The names are capitalized in German but that is because all nouns are capitalized in German.130.225.245.182 20:35, 13 November 2006 (UTC)
thread_title:  Does the first letter of the name have to be capitalized?

message: I know halogens need to be on the list.  I just don't know where.  I've looked through two chemistry books and the IUPAC website, but still can't get a straight answer.
Plz fiz thx!!!1
Halogens do indeed belong on the precedence chart.  They take the lowest precedence just above Alkanes (and alkanes don't change the suffix at all.)  It should also be noted that Alkyne and Alkenes are missing from the precendence chart as well.  They should fall in between Amines and Ethers.  This is of course for numbering purposes and for which functional group takes priority for changing the last name and then which gets numbered with the lowest number on the parent chain.
Halogens are no longer considered as functional groups but as side chains, because they are in the form of the prefix in an IUPAC naming.  —Preceding unsigned comment added by 110.172.31.52 (talk) 12:58, 30 October 2010 (UTC)
thread_title:  Halogens missing from functional group precedence chart 

message: Don't both the methyl groups have to go on the carbon 2? Shouldn't it be dimethyl propane? This just says, take a propane molecule and stick two methyl groups on it...
If you choose carbon 1 or 3 then you lengthen the longest chain. Thus you must stick them both on carbon 2.
Appreciate this may be obviously flawed, I have just started chemistry at school.
Richard
I'm reasonably certain you are correct.  It's also called neopentane. Evand 03:13, 15 September 2005 (UTC)
replies: text: *I just checked the 3rd Edition Blue Book (1971) and it says (page 6) "The following names are retained [my italics] for unsubstituted hydrocarbons only... Neopentane". So it was not exactly "preferred". Pointillist (talk) 01:24, 26 March 2008 (UTC)
replies: text: *The 1993 Recommendations also use the phrase "retained in these IUPAC recommendations for naming organic compounds". In other words, these are the recommended names for such compounds. Physchim62 (talk) 13:48, 26 March 2008 (UTC)
replies: text: Point taken - dimethylpropane isn't listed in the online version. I had in mind that "preferred" had a special meaning in IUPAC... oh well. Pointillist (talk) 00:46, 28 March 2008 (UTC)
replies: text: Actually so did I—think that the Blue Book used "preferred" with some special meaning—until I checked my sources! Nevertheless, I don't think there's any harm done in using the term on WP. Chemical nomenclature is complicated, and we all make mistakes from time to time! Physchim62 (talk) 16:42, 28 March 2008 (UTC)

text: Actually, neopentane is a trivial (common) name. Dimethylpropane is correct.ManishEarthTalk • Stalk 03:48, 7 March 2009 (UTC)
thread_title: Why is it 2,2 dimethyl-propane?

message: where do they fit in the nomenclature?
*The nomenclature of sugars is separate from that of other organic compounds: the detailed recommendations can be found here. Physchim62 (talk) 18:42, 19 February 2006 (UTC)
thread_title:  sugars 

message: Could you not argue that (CF3)NH3+ is trifluoromethylammonium, as well as (CH3)NF3+? How would you distingiush them? Would you have to say the (CF3)NH3+ is trifluoromethyltrihydridoammonium?
:(CF3)NH3+ would be trifluoromethylammonium. (CH3)NF3+ could be uniquely named N,N,N-trifluoromethylammonium, whith the N denoting substitution on the nitrogen, rather then on the carbon (Not to be confused with the lower case n used to denote straight chain alkanes). This systematic name may not be correct by the current IUPAC naming method however.
::Parentheses can help here, as in (N,N,N-trifluoro)methylammonium vs. (trifluoromethyl)ammonium.  Same disclaimer as the previous editor, my knowledge of these obscure details is a bit hazy. Walkerma 05:48, 3 October 2006 (UTC)
replies: text: IUPAC doesn't give unique names, and has never pretended to! The two possibilities suggested by Walkerma seem pretty unambiguous to me: however the first species does't seem to exist, which simplifies naming matters considerably: I would not be confused by the name even in the absence of parentheses. Physchim62 (talk) 14:34, 5 October 2006 (UTC)
thread_title:  Is CH<sub>3</sub>F<sub>3</sub>N<sup>+</sup> trifluoromethylammonium? 

message: There seems to be a page for registry numbers, but none for CA nomenclature or for chemical nomenclature in general. 
Since there seems to be difficulty getting even one of these finished, shouldwe consider combining them?  i must first admit that though I'm very willing to set up pages, I am not quite so responsible about filling them in,especially here, where I would constantly have to check everything. I was a chem librarian once, but that was years ago. DGG 04:16, 30 September 2006 (UTC)
replies: text: I think CAS naming is less important than it used to be, but probably still worth an article.  I would be against putting it here, though, just because having two similar-but-different systems described on the same page may confuse the reader.  Also, there are thousands of college or A-level students struggling their way through IUPAC names coming here for help on their homeworks, whereas CAS naming is only used by a much more limited group of people. Walkerma 15:26, 30 September 2006 (UTC)
replies: text: Possibly the language used may be a UK/US difference?  But agreed, it isn't as important as when you had to learn it by heart in order to effectively search Chemical Abstracts. I see we already have a chemical nomenclature category, and it isnt high on my priority list either. DGG 05:02, 1 October 2006 (UTC)
replies: text: It is very difficult to write good articles on these subjects. CAS names are interesting because they are supposedly unique (that's the idea, anyway) whereas IUPAC ditched the goal of uniqueness to keep the system simpler. This story should be told somewhere on Wikipedia, but I'm never quite sure where. Physchim62 (talk) 14:37, 5 October 2006 (UTC)
replies: text: perhaps the article on chemical nomenclature, , then the specifics on a page for each.  DGG 18:49, 5 October 2006 (UTC)
thread_title: IUPAC vs CAS

message: Can an organic compound have more than 20 carbon atoms ? If so, the table would need to be extended. MP   (talk) 07:26, 14 October 2006 (UTC)
replies: text: An organic compound can indeed have more than 20 carbons (or more than 1000) and I have added the system for naming carbon-chains up to 100 carbons. You won't need those names very often though. I know the table doesn't look very nice but I don't know how to make it look better. I hope some one will fix that.130.225.245.182 20:48, 13 November 2006 (UTC)
replies: text: The page here is about all IUPAC nomenclature. We don't need and shouldn't try to have full details about every specific class here--many of them already have their own pages that go into fuller detail. The alkane section already begins with "Main article: Alkanes", taking one to a pages explains the chain-length rules in more detail, and from there further linking to IUPAC numerical multiplier for the more complete and gory details. So I replaced your "more but still not all lengths" table here with a link to that comprehensive list. DMacks 20:56, 13 November 2006 (UTC)
thread_title:  Regarding the table in the Alkanes section 

message: I didn't see any mention of acid chlorides or acid anhydrides as carboxylic acid derivatives.  Inclusion would be helpful.71.215.136.243 21:35, 10 June 2007 (UTC)
thread_title: Acyl Chlorides

message: I've removed the following comment from the article: (The structure shown in the image at the left is incorrect.)  Indeed, the image :Image:Iupac-amine.png is inconsistent with the text that states "the substituent groups are ordered alphabetically". -- Ed (Edgar181) 16:11, 22 January 2008 (UTC)
replies: text: A corrected image was provided by Fvasconcellos (Project Wikipedia:Graphic_Lab/Images_to_improve#Vectoring_images_for_IUPAC_nomenclature). --Ondrejsv (talk) 18:13, 22 January 2008 (UTC)
replies: text: Fantastic.  Shouldn't all the .svg images be added in place of the .pngs, then? -- Ed (Edgar181) 18:53, 22 January 2008 (UTC)

text: I've gone ahead and replaced them all with the new .svg files.  -- Ed (Edgar181) 19:43, 22 January 2008 (UTC)
replies: text: Yes, they should. Thanks, Ed. --Ondrejsv (talk) 14:28, 23 January 2008 (UTC)
thread_title:  Error in image 

message: * I propose that all the prefix/suffix organic chemistry pages be merged to this page. Most of the information covered by these articles, does or should belong here. Also I see little reason for these articles to be expanded much more than their current state. - Jkasd (talk) 18:12, 28 March 2008 (UTC)
thread_title:  Merger proposal 

message: I added a table of the overview of most functional groups. Please add the remaining groups.
Thanks,  Manish<I>Earth</I>Talk 10:42, 6 August 2008 (UTC)
thread_title: Table added

message: Folks, I think that the American Chemical Society Committee on Nomenclature should have a link to its website posted at the External Links of this entr.  It seems to make sense that a question of nomenclature might be answerable here, as it is at IUPAC.  What do you think?
MarkBenvenuto (talk) 23:25, 20 February 2010 (UTC)
thread_title:  Adding ACS Link 

message: Under the header 'Order of precedence of groups' the last sentence is 
'The N position indicator for amines and amides comes before "1", e.g. CH3CH(CH3)CH2NH(CH3) is N,2-dimethylpropanamine.' I think the correct name for CH3CH(CH3)CH2NH(CH3) would be N,2-dimethylpropan-1-amine as CH3C(CH3)(NCH3)CH3 would be N,2-dimethylpropan-2-amine. In other words, I think there are two different positional isomers and therefore the locant for the amine group is needed. Please change the article if I am right, or enlighten me if I am wrong. Nirmos (talk) 14:57, 2 May 2010 (UTC)
thread_title:  Possible error 

message: I'm not feeling well with the "information" in the C. A. article itself. This article reads: Citric acid is one example; it is named 2-hydroxypropane- 1,2,3-tricarboxylic acid, rather than 3-carboxy, 3-hydroxypentanedioic acid.. I agree by 100%. But why has the variant with ...-pentanedioic acid been put up as the one and only "IUPAC name" in the article, and the naming ending on "...-tricarboxylic acid" is listed as alternate (?!?) name? The latter *IS* the one and only recommended IUPAC name and that's that. -andy 77.7.12.96 (talk) 04:50, 3 December 2010 (UTC)
thread_title:  [[Citric acid]] vs. article of substance 

message: I'm about to believe Courtland was right about us "barely scratching the surface". For instance, cf. polycyclic aromatic hydrocarbons like Benzo[a]pyrene, Benzo[j]fluoranthene. Why those letters in brackets? [a], [h], [j]. Where's the reason? Well, the Benzo[a]pyrene article explains it perfectly, but here (which should be the main location to look for) this is not covered at all. Wagonloads still to go: this article is perforated like a Swiss cheese. -andy 77.191.218.219 (talk) 04:06, 9 September 2011 (UTC)
thread_title:  Nomenclature of polycyclic aromatic hydrocarbons ENTIRELY missing? 

message: The statement "If the alkyl group is not attached at the end of the chain, the bond position to the ester group is infixed before "-yl": CH3CH2CH(CH3)OOCCH2CH3 may be called but-2-yl propanoate or but-2-yl propionate." in the Esters section seems wrong. Although this usage is common, I could not find this naming method in the IUPAC Blue Book. It states that the nomenclature of the alkyl chain follows the guidelines for naming alkyl radicals: (Rule A-2. Saturated Branched-chain Compounds and Univalent Radicals
2.25 - Univalent branched radicals derived from alkanes are named by prefixing the designation of the side chains to the name of the unbranched alkyl radical possessing the longest possible chain starting from the carbon atom with the free valence, the said atom being numbered as 1.
I've added a "citation needed" tag - in case there are guidelines or recommendations that I've overlooked.  — Preceding unsigned comment added by Marko223 (talk • contribs) 11:06, 20 January 2012 (UTC)
thread_title:  Nomenclature of esters 

message: Should the "a" be added like in hexadiene (vs. hexdiene)?  — Preceding unsigned comment added by 217.94.43.184 (talk) 04:33, 13 April 2012 (UTC)
thread_title:  tricos-6,13-diene vs. tricosa-6,13-diene 

message: I've already fixed a few, but there are many more mistakes in the article. 1. Absolute stereochemistry is always convention. This is the IUPAC nomenclature page and we should be giving people what is convention. Relative stereochemistry is often used, but it's not convention. 2. Numbering short branches from short chains is often redundant (e.g. 2-methylpropane). That is not the IUPAC name for the compound. It is simply methylpropane. ★Ffgamera★ - My page! · Talk to me!· Contribs 10:09, 1 May 2013 (UTC)
thread_title:  Multiple mistakes in convention 

message: e.g. 'bis-'--عبد المؤمن (talk) 12:29, 9 April 2014 (UTC)
thread_title:  Missing info 

message: When improving this article, it must be considered that the 2013 version of the IUPAC's “blue book” contains important mistakes in section P-45.5.1. This is relevant even to write a basic description of the nomenclature because this section is necessary to name even some simple acyclic compounds. It describes a criterion used to select what the book calls “parent senior structure”. This corresponds roughly to the concept of parent chain/main chain. A correction has been published online . Mario Castelán Castro (talk) 19:08, 23 August 2016 (UTC)
thread_title:  An important erratum to consider when improving this article 

message: "In order of precedence" leaves it unclear whether the order given is in *increasing* or in *decreasing* precedence. I.e. is the highest-precedence item the one at the top of the list, or the highest-numbered item? Bernd Jendrissek (talk) 18:46, 26 February 2018 (UTC)
replies: text: I have changed the language in that section to specify. Mehmuffin (talk) 17:15, 10 June 2019 (UTC)
thread_title:  Ambiguity of precedence 

message: In the table on precedence, the formula for imides is shown as "–CON=C<". What is the less than sign doing here? Why is the nitrogen shown as double bonded to the carbon? I can't tell if this is a method for writing condensed symbols that I haven't seen before (and doesn't appear to be documented anywhere) or if it's just an error. The article for imide uses "(-CO)_2N-", which seems alright to me (although a little rough, but I don't think there's any fixing the roughness of this completely since it has three R's on it), should this be changed to that? Mehmuffin (talk) 15:22, 10 June 2019 (UTC)
thread_title:  Imide formula in precedence table 

message: Pls review it 202.142.79.252 (talk) 17:34, 27 February 2022 (UTC)
thread_title:  Priority order for isopropyl,secbutyl,terbutyl in prefix 

message: "Identification of the side-chains. Side chains are the carbon chains that are not in the parent chain, but are branched off from it. (ZGSKS)"
What does ZGSKS mean? When I Googled it, nothing useful came up. 2603:8080:4E02:3942:E073:A66E:DFBA:42BC (talk) 01:04, 29 June 2023 (UTC)
replies: text: That indeed does look weird, one of two edits by User:103.178.128.71, all of which were problematic. I removed it. DMacks (talk) 04:35, 29 June 2023 (UTC)
thread_title:  ZGSKS