IUPAC name for following alkane? (picture inside)

[nuvydeep]

 

What is the name of the alkane? I circled it in red. I am having trouble..

 

Thanks!!

[Horza2002]

Well you've got a five membered ring so you have cyclopentane. The substituents are isopropyl and ethyl (of which the isopropyl is higher prioritry).

 

So itl be 1-(S)-isopropyl - 3-(S)-ehtyl cyclopentante

[nuvydeep]

Thank you! I wasad kind of close..this may seem like a stupid question but what do the S represent?

[Penny]

Thank you! I wasad kind of close..this may seem like a stupid question but what do the S represent?

 

You need to basically indicate whether the groups are pointing out or into the page. Therefore, you need to use R (clockwise) or S (counterclockwise) to label the chiral centers.

[Horza2002]

Yep, the two groups are chiral centres and you need to indicate which is which. See Gold-Ingham rules for how to identify chiral centres if your unsure how to do it

[Guest Nerddoc]

Content deleted

Edited June 23, 2010 by Nerddoc

[multisnp]

Well you've got a five membered ring so you have cyclopentane. The substituents are isopropyl and ethyl (of which the isopropyl is higher prioritry).

 

 

So itl be 1-(S)-isopropyl - 3-(S)-ehtyl cyclopentante

 

Why have you chosen isopropyl as the highest priority? According to my textbook, substituents of arenes are prioritised alphabetically (lower first). Or am I missing something else?

[Horza2002]

Why have you chosen isopropyl as the highest priority? According to my textbook, substituents of arenes are prioritised alphabetically (lower first). Or am I missing something else?

 

You are right that for arenes you name them alphabetically. But this example is not an arene. An arene is a aromatic system with a delocalised pi system in it (like benzene). In this case you simpley have a 5-membered cycle so you order them accordinging to which has the highest priority.

 

P.S. Sorry for the VERY late reply

Edited July 17, 2010 by Horza2002

[multisnp]

Thanks. That was actually pretty quick.

[adianadiadi]

The correct IUPAC name is (1S,3S)-1-ethyl-3-(propan-2-yl)cyclopentane. You can get the details at IUPAC nomenclature exercises in organic chemistry at AdiChemAdi.