Nomenclature of Organic Compounds: Significance of -#-yl and E/Z Isomerism

In summary, the -#-yl nomenclature in organic compounds indicates the carbon on a subunit that attaches to the main compound. In the case of bicyclo subunits, the number before the -yl denotes the position of the attachment on the subunit, with the larger portion of the subunit being taken into consideration. In the example given, the -5-yl in bicyclo[2,1,0]pent-5-ylbicyclo[3,3,0]octane indicates that the attachment is on the fifth carbon of the cyclobutyl portion of the bicyclo[2,1,0]pentyl. The use of descriptors such as 'cyclobutyl' and '
  • #1
newyorkcity
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Hi all,

I have a question regarding the nomenclature of organic compounds. What is the significance of -5-yl in

bicyclo[2,1,0]pent-5-ylbicyclo[3,3,0]octane

? In general, what is the significance of the # in -#-yl in compounds?

Additionally, in (E)-1,2-diiodo-1methylcyclohexane, does the E indicate trans, whereas a Z would indicate cis? As in the two iodine atoms are on the first and second carbons, and they are both trans to each other (both axial)?

Thanks guys!
 
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  • #2
I think I figured this out. So I think the -#-yl (when used with bicyclo subunits) denotes the carbon on the subunit that attaches to the main compound.

In the case presented above, the bicyclo[2,1,0]pentyl is not attached via a bridgehead C but rather one C over, but since the 'cyclopropyl' side is attached to the bicyclo[3,3,0]octane, we need to first go around the larger 'cyclobutyl' portion of the bicyclo[2,1,0]pentyl, thus getting a -5-yl. Note that I am using 'cyclobutyl' and 'cyclopropyl' as rough descriptors of the portions of the bicyclo[2,1,0]pentyl I am trying to reference; I can't think of a better way to accomplish this without an image.

Similarly, if we had 5-methylbicyclo[3,3,0]oct-2-yl-4-methylnonane, this would indicate that there is a methyl on the bridgehead of methylbicyclo[3,3,0]oct-2-yl and the bond to the main nonane chain is on the second carbon (one over from the bridgehead carbon) of the methylbicyclo[3,3,0]oct-2-yl.

Can someone confirm this analysis?
 

What is the basic structure of an organic compound?

The basic structure of an organic compound consists of a carbon atom bonded to hydrogen atoms. Other elements like oxygen, nitrogen, and halogens may also be present in the structure.

What is the purpose of naming organic compounds?

The purpose of naming organic compounds is to have a systematic and standardized way of identifying and communicating the structure and properties of a compound. This helps in understanding and predicting the behavior and reactions of different compounds.

What does the #-yl suffix in an organic compound name indicate?

The #-yl suffix in an organic compound name indicates the presence of a carbon chain or group attached to the main carbon chain of the compound. This suffix is used to denote specific functional groups and their position in the molecule.

How do you name an organic compound with multiple #-yl groups?

To name an organic compound with multiple #-yl groups, you must first identify and name the longest continuous carbon chain in the molecule. Then, number the carbon atoms in the chain starting from the end closest to the first #-yl group. The second #-yl group is then named as a substituent and its position is indicated by the number of the carbon atom it is attached to in the main chain.

Are there any exceptions to the #-yl naming convention?

Yes, there are some exceptions to the #-yl naming convention. For example, the #-yl suffix is not used for certain functional groups like alcohols and carboxylic acids, which have their own specific suffixes (-ol and -oic acid, respectively). In addition, for some complex molecules, the numbering of carbon atoms may not follow the traditional rules, and a different naming system may be used.

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