After the sad event of termination of Loong's account, his nomenclature questions cannot be searched easily anymore. Therefore, I've decided to section his 263 answers (as far as I've been able to find) based on the topic they deal with. I'll be adding answers for each section and they will be listed in the main question.

  1. General Principles, Rules and Conventions (2013 P-1)
  2. Parent Hydrides (2013 P-2)
  3. Characteristic (Functional) and Substituent Groups (2013 P-3)
  4. Rules for Name Construction (2013 P-4)
  5. Selecting Preferred IUPAC Names and Constructing Names of Organic Compounds (2013 P-5)
  6. Applications to Specific Classes of Compounds (2013 P-6)
  7. Radicals, Ions, and Related Species (2013 P-7)
  8. Specification of Configuration and Conformation (2013 P-9)
  9. Parent Structures for Natural Products and Related Compounds (2013 P-10)
  10. Miscellaneous
  • $\begingroup$ Not to be a bother, but is there a short discreet explanation for why that account was terminated? A link would be fine. $\endgroup$
    – Ed V
    Commented May 16, 2021 at 14:16
  • 1
    $\begingroup$ @EdV chemistry.meta.stackexchange.com/questions/4846/… $\endgroup$ Commented May 16, 2021 at 14:17
  • $\begingroup$ Thanks for the link! I tend to be clueless about this kind of thing. And thanks for the WIP! $\endgroup$
    – Ed V
    Commented May 16, 2021 at 14:26
  • 2
    $\begingroup$ For various reasons, I'd think that sorting them by the section of the Blue Book referred to, or the specific rule, is more useful. Firstly, that often gets closer to the crux of the question than just which molecule it is being applied to; and secondly, that makes identifying duplicates and related questions much easier. However, I'm not sure that a post on Stack Exchange is a good way to do that. Some kind of database, or at least a spreadsheet, would likely work better. $\endgroup$ Commented May 16, 2021 at 18:19
  • $\begingroup$ @orthocresol, i'm planning to do it in the same manner as math.meta.stackexchange.com/questions/5020/…, I see the reasoning in sorting by sections, and will do so.. thanks for the suggestion. $\endgroup$ Commented May 17, 2021 at 7:21
  • $\begingroup$ @EdV chemistry.meta.stackexchange.com/questions/4879/… $\endgroup$ Commented May 17, 2021 at 7:26
  • 1
    $\begingroup$ data.stackexchange.com/chemistry/query/edit/1409393 Posting this for reference to referred database for now.. $\endgroup$ Commented May 17, 2021 at 16:28
  • 4
    $\begingroup$ Woah @SafdarFaisal you’re doing a noble job. I am new to CH SE and I don’t know who Loong is but seeing the quality of his answers, I know why people are sad on his account termination. I saw the link you posted above, in reply to Ed V’s comment. Very sad about the new moderator policy. $\endgroup$
    – WhySee
    Commented May 22, 2021 at 13:01

10 Answers 10


General Principles, Rules and Conventions (2013 P-1)

Citation of locants (2013 P-14.3)

  1. Disubstituted cyclic alcohols - looking for IUPAC rule
  2. Where to put the number in organic nomenclature?
  3. What is the proper name for the but-1-ene's isomer methylpropene?
  4. Butanone or butan-2-one?
  5. Naming tetrahalogenated benzene
  6. Why is this molecule named 1,1-chloroiodoethane, rather than 1-chloro-1-iodoethane?
  7. Naming of halogen group in ethane
  8. How do I name this compound
  9. IUPAC nomenclature: Priority of alkene vs alcohol functional groups
  10. How to designate the position of an amine substituent in an alkyl-chain?
  11. What does this number indicate in the name of this organic molecule?
  12. Do 2-hexyne and hexa-2-yne mean exactly the same thing?
  13. Double Bond or Aldehyde priority?
  14. Amine Nomenclature – When to use "N"
  15. How to name the tautomers of hexane-2,4-dione correctly according to IUPAC rules?
  16. IUPAC nomenclature: putting the number before or in the middle of the name
  17. Nomenclature of a cyclohexyl ether and locant position enumeration
  18. IUPAC nomenclature: "Smallest sum of locants"?
  19. IUPAC nomenclature of cycloalkadienes with substituents and alkenes on the same carbons

Numbering (2013 P-14.4)

  1. Naming substituted bicyclo compounds
  2. What should be the name of the given compound?
  3. 1,6-dimethylcyclohexene and 2,3-dimethylcyclohexene
  4. IUPAC nomenclature of organic compound
  5. Numbering starts from the side that has more locants or from the side that has a more preferable group?
  6. Why is this named 3-phenyl-2-butanol instead of 2-phenyl-3-butanol?
  7. Does the priority go for the longer substituent, the closer one, or one which contains a pi-bond in naming Alkenes and Alkynes?
  8. What should be the IUPAC name of this compound?
  9. Nomenclature priority of prefixes consisting of identical letters but containing different locants
  10. Numbering in IUPAC name of a trisubstituted cyclohexane
  11. IUPAC Nomenclature of the organic compound(See Picture)
  12. Why is a double bond given priority over substituents during IUPAC nomenclature?
  13. Why is 3-chloro-5-(1-methylethenyl)cyclopenta-1,3-dien-1-ol named so?
  14. Naming a hexasubstituted benzene ring
  15. If both double and triple bonds are at the terminals,so prefreference would be given to?
  16. Assigning locants when both unsaturation and substituents are present in a hydrocarbon
  17. What will be the IUPAC name of this organic compound and why?
  18. Naming a hydrocarbon chain with multiple substituents equidistant from both terminals
  19. Location of double bond in 1,3-dimethylcyclohexene
  20. Formal nomenclature for fulvene
  21. Priority in naming organic compound
  22. What is the order of nomenclature priority among an alkyl side group, a double bond, and a triple bond?
  23. What does IUPAC mean by these rules?
  24. What is the numbering of substituted benzene derivatives according to IUPAC nomenclature?
  25. Nomenclature of an alkyne with bromo and hydroxy substituents
  26. Why do these two IUPAC naming examples not begin numbering the chain closest to the alkyne?
  27. Order of priority for including functional groups in the parent chain compared to order of priority for numbering the parent chain
  28. What should be the name of this substituted cyclopentane?
  29. Nomenclature alkyl halides
  30. Naming rules and acidity of Cl2CHCH2COOH
  31. 1,6-dimethylcyclohexene and 2,3-dimethylcyclohexene
  32. Nearest branch numbering
  33. Nomenclature Precedence Order for Unsaturation and Hydrocarbon Chain
  34. Stereochemistry: R and S notation
  35. 4-Bromo, 2,4-di-methylhexane and 3-Bromo, 3,5-di-methylhexane are the same thing?
  36. What is has a higher priority in naming organic compounds, alkyl groups or halides?
  37. Doubts about IUPAC nomenclature of 4-ethyl-1-fluoro-2-nitrobenzene

Alphanumerical order (2013 P-14.5)

  1. Shouldn't this compound be called 2-methyl-5-(1,2-dimethylpropyl)nonane?
  2. IUPAC naming of 1,2-disubstituted cyclohexane derivative
  3. IUPAC naming molecules?
  4. Why is this cycloalkane name giving the lower number to methyls over ethyl?
  5. Naming compound containing a ring (cycloalkane) side chain?
  6. Alphabetical order in nomenclature
  7. Is chloronitrobenzene and nitrochlorobenzene same?
  8. Order of citation of alkyl and halide prefixes in IUPAC names
  9. Nomenclature of alkoxy and halo groups
  10. Nomenclature of an organic compound
  11. Nomenclature of organic compounds containing complex side chains

Indicated and 'Added Indicated Hydrogen' (2013 P-14.7)

  1. Chromene and cumarin nomenclature

Length of chain to be numbered (2013 P-

  1. Is this chemical name wrong? 2-bromobutane vs 1-bromobutane

Substitution rules for Type 2a retained names

  1. Nomenclature of benzene derivatives with two functional groups

Multiplicative name formation (2013 P-

  1. IUPAC nomenclature for tricarboxylic acids
  2. How to arrive at the preferred IUPAC name for 1,2-diphenylethane?

Full stops in nomenclature (2013 P-16.2.2)

  1. What is the rule for the punctuation marks for a bicyclo compound?

Elision of vowels (2013 P-16.7)

  1. When naming alcohols based on alkanes, when do you keep the "e" at the end of the alkane's name?
  2. How do I name a molecule with a compound substituent?

Superscript Arabic numbers for locants (2013 P-16.9)

  1. Organic nomenclature of substituted diamines
  2. What does the prime symbol mean in organic nomenclature (e.g 2')?
  • 7
    $\begingroup$ You don't need to use [title](link) syntax for Stack Exchange questions, just put the bare link, the title will be shown automatically (and will be updated if the question title is edited, which some of these titles really do need). The caveat is that you must put a link to the question, not the answer, which I suggest anyway because answers only make sense in context of the question. I edited the first few ones. $\endgroup$ Commented May 17, 2021 at 13:43
  • 1
    $\begingroup$ I changed the classification criteria as per @orthocresol's suggestion. I believe that the first one might be broken down further into smaller sections, but I don't think I have the valor to accomplish that today. Afterall it's WIP. $\endgroup$ Commented May 18, 2021 at 12:14

Parent Structures for Natural Products and Related Compounds (2013 P-10)

  1. Confusion about Ethinyl estradiol IUPAC name

Numbering Parent Structures (2013 P-102.2)

  1. Convention for numbering of carbons

Monosaccharide Derivatives (2013 P-102.5.6)

  1. How would I name O-methylations on sugars while retaining the sugar’s common name?

Naming Esters of sugars with phosphoric Acid (2013 P-

  1. Why is the nomenclature glucose 6-phosphate, not 6-phosphateglucose?

Applications to Specific Classes of Compounds (2013 P-6)

Primary amines (2013 P-62.2.1)

  1. What is the preferred IUPAC name of o-toluidine?
  2. Can there be two IUPAC names of a compound?

Secondary and Tertiary amines (2013 P-62.2.2)

  1. Dipropylamine vs n-dipropylamine
  2. How to select the parent chain in mechlorethamine?
  3. Nomenclature of a tertiary amine

General nomenclature of imines (2013 P-62.3)

  1. IUPAC names of imines

Substitutive Nomenclature (2013 P-63.1)

  1. Naming a molecule with both alcohol and aldehyde functional groups
  2. How to name molecules with a hydroxyl group in a side chain?
  3. How to name this benzene alcohol?

Nomenclature of Sulfur, Selenium and Tellurium Analogues of hydroxy compounds (P-63.1.5)

  1. Thiol prefixes for nomenclature

Substitutive Nomenclature in $\ce{R'-O-}$ groups (2013 P-

  1. Ether nomenclature: Oxygens on alkyls and alkyls on alkyls

Nomenclature of Ketones (2013 P-64.2)

  1. Space in naming Acetophenone
  2. Nomenclature of a cyclic ketone
  3. Carbon with two double bonds and oxygen name

Retained names only for general nomenclature in carboxylic acids (2013 P-

  1. Cinnamaldehyde -> trans-3-phenylprop-2-enal

Nomenclature of polycarboxylic acids (2013 P-65.1.2)

  1. IUPAC Nomenclature of a dioic acid

Substitutive nomenclature for sulfonic, sulfinic etc. acids (2013 P-65.3.2)

  1. IUPAC nomenclature benzene ring and functional group

Nomenclature of Acid Halides (2013 P-65.5.1)

  1. Naming compounds with multiple -COX functional groups

Esters cited as prefixes (2013 P-65.6.3)

  1. How to name the following compound?
  2. Naming a keto ester
  3. Naming of bicyclo[2.2.1]hept-5-ene-1,4,5,6-tetramethyl-3-bromo-2-ethyl carboxylate

General nomenclature of esters (2013 P-65.6.1)

  1. Nomenclature of ester with cyclic substituents
  2. What is the proper description/name of this amide/ester structure?
  3. What is the name of this ester?

Nomenclature of cyclic anhydrides (2013 P-65.7.7)

  1. IUPAC name, phthalic anhydride

Nomenclature of Lactams and Lactims (2013 P-66.1.5)

  1. IUPAC name of this compound

Nomenclature of aldehydes (2013 P-66.6.1)

  1. 1,1-diformyl propanal
  2. Is it wrong to call carbon dioxide "methanedial"?
  3. Aldehyde and ketone nomenclature when aldehyde/ketone group is bonded to an alkyl group
  4. When is the carbaldehyde suffix correct?
  5. IUPAC name of aldehyde with two functional groups

Nomenclature of anhydrides (2013 P-67.1)

  1. How would the "-COOCl" functional group be named?

Esters of mononuclear noncarbon oxoacids (2013 P-

  1. Naming compounds with an OX group

Heterocyclic Parent Hydrides containing Group 13 atoms (2013 P-68.1.1)

  1. What is this Boron Compound called?

Heterocyclic parent hydrides containing Group 15 atoms (2013 P-68.3.1)

  1. what's the name of this org. compound. RR'-C=NNH2

Heterocyclic Parent Hydrides containing Group 16 atoms (2013 P-68.4.1)

  1. What is the name of C(OOOH)₄?

Nomenclature of Characteristic Functional Groups and Substituents (2013 P-3)

  1. Naming alkenes with double bond branches

Nomenclature for multiple saturations (2013 P-

  1. Preferred IUPAC names for branched unsaturated hydrocarbons (polyenes)?
  2. Naming unsaturated hydrocarbons
  3. How is a side-group that contains a double bond named?
  4. Why are enynes named as -en-yne and not -yn-ene?

Nomenclature of von Baeyer Heterocycles (2013 P-

  1. Why should ether O be named as OXA in a bicyclo ring when it is a substituent?

Rules for Name Construction (2013 P-4)

Priority for citation as parent structure (1979 C-10.4, 2013 P-44)

  1. Is the precedence of functional groups used in IUPAC naming arbitrary?
  2. How do I use the priority list of substituent groups to decide the parent chain for this compound?
  3. When we name an organic compound ,if there is double bond and a functional group which is now a substituent who has priority?
  4. 3-methyl-4-oxobutanenitrile or 3-formylbutanenitrile?
  5. In Parent chain choosing should one consider longest chain or chain with more substituents?
  6. How do you name an alkene using IUPAC rules if the longest carbon chain in this alkene does not include the double bond?
  7. Selection of parent chain (IUPAC nomenclature)
  8. Chain with double bond or triple bond
  9. How to decide whether to pick 4-bromo-2-methoxyphenol or 4-bromo-6-methoxyphenol as the name for the compound?
  10. Why is 5-(aminomethyl)-3-ethylheptan-2-ol named so?
  11. How to name this hydrocarbon
  12. IUPAC name of a molecule with a cyanide group and a double bond
  13. Have I identified the IUPAC name of this ketone correctly?
  14. What is the senior parent chain in the following compound?
  15. Do we prefer the substituent or the longest chain in IUPAC nomenclature?
  16. What is IUPAC name of this compound?
  17. Does the name 4-nitrodiphenylmethane follow the IUPAC rules?
  18. IUPAC Naming of CH3C(p-ClC6H4)2CH(Br)CH3
  19. How to decide at which end to start the numbering of the parent chain when the options for locant sets are the same?
  20. Nomenclature of Halogen substituted Alcohol and longest chain
  21. IUPAC nomenclature for many multiple bonds in an organic compound molecule
  22. Nomenclature problem, when would ring be parent?
  23. Confusion in naming a carboxylic acid with a cyclohexyl group
  24. Need an explanation for how they got this compound name out of this structure
  25. Two possible chains - isopropyl or ethyl and methyl?
  26. Is preference given to long alkyl group or branched cycloalkane?
  27. How to identify the parent chain if two chains have the same number of skeletal atoms and the same number of double bonds?
  28. IUPAC naming for compounds containing carboxylic acid and anhydride together?
  29. Nomenclature of aryl halides
  30. IUPAC name for citric acid
  31. What is more important, to have the parent chain be the cycle or the chain that has an hydroxyl group
  32. How can I find the parent chains in these two compounds?
  33. Is the name of this chemical 3-oxopropanoic acid?
  34. Nomenclature of cycloalkane with substituent having the same number of carbons
  35. Nomenclature priorities with ethers, acyl groups and ketones
  36. What is the parent chain in a hydrocarbon with two different rings?
  37. What is the correct nomenclature for diphenyl methane?
  38. Nomenclature of a poly-nitrile
  39. How do you name an alkene using IUPAC rules if the longest carbon chain in this alkene does not include the double bond?
  40. Alkane nomenclature - choosing the parent chain - maximize or minimize substituents?
  41. Is the ring or the chain chosen as the parent structure in octan-2-ylbenzene?

Selection of preferred IUPAC Names (2013 P-45)

  1. Help with naming molecule
  2. Choosing Parent Chain, Complexity of Side Chains
  3. How to name alicyclic compound with hydroxymethyl substituent?
  4. What are the preferred IUPAC names of these two compounds?
  5. Selecting parent chain considering substituent (prefix) functional groups
  6. What is the rationale of the IUPAC name for DDT?
  7. IUPAC naming - choosing the main branch


Preferred name vs General name

  1. Nomenclature of unusual nitrogen functional group
  2. Ketone prefix organic chemistry nomenclature
  3. IUPAC nomenclature of aspartame
  4. When to use iso and sec while naming compounds in alkyl halides?
  5. Are ortho, meta and para used in IUPAC nomenclature?
  6. Is didehydrobenzene valid IUPAC nomenclature?
  7. Nomenclature of amoxicillin
  8. Confusion in the order of precedence: alkyl side-chain vs. dimethyl at different positions
  9. Acetic acid or ethanoic acid - trivial names vs systematic names and correct formula representation
  10. Systematic IUPAC names for beta-glucose and lactic acid
  11. Can we use prefixes like iso, neo, etc in IUPAC nomenclature of organic compounds?
  12. Are common names of substituents accepted by IUPAC?
  13. What are ketoximes?
  14. What is the priority of a phenyl group in a compound such as this?
  15. What do the numbers in the preferred IUPAC name for ascorbic acid mean?

Glossary of class names

  1. Can benzene ring be the part of a acyl group
  2. Is Alkanol an official part of chemical Nomenclature?

General Nomenclature

  1. Why is 2-(3-aminomethyl-2-hydroxypropyl) cyclohexan-1-one named so and not 2-(2-hydroxy-4-aminobutyl) cyclohexan-1-one?
  2. Why is polyethylene not called polymethylene?
  3. IUPAC-Naming of Dioxin
  4. Difference between 'Preferred IUPAC Name' and 'Systematic IUPAC Name'
  5. What is the correct nomenclature for Glucuronyl C5-epimerase?
  6. RCOH and RCHO Nomenclature
  7. What are the practices to naming organic chemicals by abbreviations?
  8. IUPAC nomenclature of coordination complexes
  9. IUPAC name of a salt made of both cationic and anionic complexes
  10. Semi-sandwich complex IUPAC name
  11. Nomenclature and chemical formulae for bridged dinuclear chromium complexes
  12. When are the prefixes bis, tris etc. used in nomenclature of complexs?
  13. What is the IUPAC name of [Co(NH3)5H2O]Cl3?
  14. Why do we write NH3?
  15. Why was Lawrencium's symbol changed?
  16. What do the prefixes meta, ortho, pyro mean in inorganic chemistry?
  17. IUPAC naming of double salt
  18. Nomenclature of compounds by the IUPAC
  19. Why is monohydrogen phosphate an incorrect name?
  20. Why is CaCl2 called calcium chloride?
  21. Name for analog of salt hydrate with non-water solvents?

Unsure of classification

I do not have access to the IUPAC Blue book and so questions that I am unsure of will be placed here. Someone who has access and can classify this may do so if they please.

  1. What is the meaning of parentheses in a condensed molecular formula?
  2. Is there a (carbon) heterocyclic compounds named from number three to infinity?
  3. Why do we insert a numeric multiplier after group positions when naming an isomer?

Parent Hydrides (2013 P-2)

Heterogenous parent hydrides excluding carbon and halogens (2013 P-21.2)

  1. What is the preferred IUPAC name of hexamethyldisilazane?

Retained Names of parent hydrocarbons (2013 P-22.1)

  1. What is the correct organic nomenclature of this substituted toluene?

Multiplicity of heteroatoms (2013 P-22.2.2)

  1. Chemical name : Melamine
  2. Why is 2-methyloxirane not named 1-methyloxirane?
  3. Numbering in phenolphthalein versus ascorbic acid
  4. Nomenclature of saturated aliphatic hetrocyclic amines with an alkyl group on the nitrogen

Naming and numbering tricyclic hydrocarbons (2013 P-23.2.5)

  1. Naming a 4 branched cyclic compound
  2. How to name tricyclo carbon compounds?

Naming polycylic alicyclic hydrocarbons (2013 P-

  1. Cubane systematic name

Nomenclature of spiro alicyclic compounds (2013 P-24.2)

  1. Naming of a dispiroalkane compound
  2. How to name an unsaturated spiro compound with many substituents?
  3. Nomenclature of spiro compounds

(2013 P-25.1.1)

  1. IUPAC systematic name of Carminic Acid
  2. Nomenclature of a fused tricyclic hydrocarbon
  3. Nomenclature of a fused tricyclic hydrocarbon
  4. Nomenclature of tetrahydropyran ring

Heteromonocyclic components fused to a benzene ring (2013 P-

  1. Numbering in chlordiazepoxide

Nomenclature of fused locants in polycyclic compounds (2013 P-

  1. What is the meaning of [2,1-c][1,4] in Pyrrolo[2,1-c][1,4]benzodiazepine?
  2. What does the "h" "k" and "(,6)" mean in Dibenzo(h,k)-4-oxatricyclo(,6)undec-8,10- diene-3, 5-dione

Nomenclature of ring assemblies (2013 P-28.2)

  1. Bibenzimidazole nomenclature: Indicated H and locants
  2. Nomenclature for two cyclohexane rings linked by a single bond
  3. What would this unsaturated cyclic compound be called?
  4. What is the preferred IUPAC name of 4-propionyl biphenyl?

Substituents in IUPAC nomenclature (2013 P-29)

  1. Imine as substituent nomenclature
  2. What is the nomenclature of this alkane?
  3. How should I name this branched alkyl substituent?

Selecting Preferred IUPAC Names and Constructing Names of Organic Compounds (2013 P-5)

Selection between a ring and a chain as parent hydride (2013 P-52.2.8)

  1. Why do we call a benzene ring attached to an hydroxyl functionality an alcohol and not a benzene?
  2. How is the numbering in phenylpropenes?
  3. IUPAC nomenclature of alicyclic compound with an equal number of cyclic and acyclic carbons

Retained prefixes that are no longer recommended (2013 P-57.1.4)

  1. IUPAC name of the tert-pentyl group
  2. Nomenclature of a branched alkane

General Methodology of naming derived hydrides (2013 P-58.2)

  1. Nomenclature of acid anhydride

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