Nomenclature - IUPAC and Common Names

In summary, the conversation discusses the potential confusion in naming a compound with an isopropyl group using systematic nomenclature. While switching to a 1-methylethyl group would reverse the alphabetical priorities, it would also create ambiguity in the numbering of the carbons and the ordering of the name. The expert suggests that the prefix "iso" should be ignored in alphabetization, as aliases are common in chemistry.
  • #1
Qube
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What if we stuck with the IUPAC name and called the isopropyl group a 1-methylethyl group? That would definitely reverse the alphabetical priorities; because the substituents here on the hydrocarbon are on equivalent positions, we must give the lower number to the substituent that comes first in the alphabet.

But that's the rub! (No isopropyl alcohol pun!)

Isopropyl - "I" comes before "M" as in methyl.

But if we name the isopropyl group systematically,

Methylethyl comes after just methyl in the alphabet.

So could the name of this also be:

1,1-dimethyl-7-(1-methylethyl)bicyclo[3.2.0]heptane?
 
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  • #2
The numbers, in this case, are unambiguous.The largest ring is numbered lowest.
but you seem to be confusing two different things, the numbering of the carbons (atoms) and the ordering (alphabetical) of the name.
2-propyl is NOT systematically methylethyl.
It is 7,7-dimethyl-2-(2-propyl)bicyclo[3.2.0]hepatane, (imho).
But nobody will be confused by 7,7-dimethyl-2-(isopropyl)bicyclo[3.2.0]hepatane
but I think *might be* by 7,7-dimethyl-2-(methylethyl)bicyclo[3.2.0]hepatane (did you mean 2-methyl-2-ethyl?)
imho, iso, just like di, tri, etc. prefixes, should be ignored in alphabetization. (sec, tert, neo, ...)
Been years since I worried about this stuff. Truth is, few Chemists can be trusted to be 100%, so you got to be flexible when searching (that is, aliases abound). So, while you can worry about which is "the" right name, that won't stop anybody else from doing their own thing.
 

Related to Nomenclature - IUPAC and Common Names

What is the difference between IUPAC names and common names?

IUPAC names are systematic names given to chemical compounds according to a set of rules established by the International Union of Pure and Applied Chemistry (IUPAC). They are unique and unambiguous, allowing for easy identification of a compound's structure. Common names, on the other hand, are often based on the historical or traditional use of a compound and can vary widely depending on geographical location and language.

Why is it important to use IUPAC names instead of common names?

Using IUPAC names ensures consistency and accuracy in the naming of chemical compounds, especially in the scientific community. It also allows for easier communication and understanding among scientists and eliminates any confusion or ambiguity that may arise from the use of different common names for the same compound.

How are IUPAC names determined?

IUPAC names are determined by a set of systematic rules that take into account the molecular structure and functional groups present in a compound. The name is based on the longest carbon chain in the molecule, with numerical prefixes indicating the location of functional groups and substituents. If there are multiple functional groups, they are listed alphabetically in the name.

Can a compound have both an IUPAC name and a common name?

Yes, a compound can have both an IUPAC name and a common name. For example, the compound with the IUPAC name "1,2-ethanediol" is commonly known as "ethylene glycol". However, in scientific literature and communication, the IUPAC name is generally preferred.

Are there exceptions to the IUPAC naming rules?

Yes, there are exceptions to the IUPAC naming rules, especially for complex compounds. In such cases, a preferred or recommended name may be used instead of strictly following the rules. Additionally, some compounds may have common names that are widely accepted and used in scientific literature, even though they do not follow the IUPAC naming rules.

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