Organic Chem question

[fifi1314]

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Do you guys know is cycloctene an antiaromatic or aliphatic.

----Top score says it is a aliphatic, although it follows 4n pi electron(antiaromatic rule), due to it's stability, it is not planar, just like alkane.

---- Kaplan says it is a antiaromatic, cuz it follows 4n pi electron rule.

So which one is correct?

Any help will be appreciated. Thanks!

 

[Streetwolf]

Aren't they both right?

 

[fifi1314]

Hey Streetwolf:

Aliphatic:
organic compounds in which carbon atoms are joined together in straight or branched chains or in rings, that can be either saturated or unsaturated, but not aromatic.

Antiaromatic:
1. The molecule must have 4n π electrons where n is any integer.
2. The molecule must be cyclic.
3. The molecule must have a conjugated pi electron system.
4. The molecule must be planar.

Aromatic:
Huckel's --- 2n+2 conjugated, double bond and cyclic rule.

So, does that mean Antiaromatic is one of category within Aliphatic? I guess so huh, from the definition...

 

[Streetwolf]

Oh sorry I don't know why I was thinking of an octane ring with 4 double bonds.

It isn't anti-aromatic. It's the other one only.

 

[fifi1314]

Oh sorry I don't know why I was thinking of an octane ring with 4 double bonds.

It isn't anti-aromatic. It's the other one only.

Octene, not octane... Octene is 4 double bonds... so it's antiaromatic.. ?

 

[TheWiredNerv]

Cyclooctane is neither aromatic nor antiaromatic. Cyclooctene lacks a conjucated pi system as it has only one double bond. The true answer would be that it is an aliphatic compound.

 

[Streetwolf]

Octene, not octane... Octene is 4 double bonds... so it's antiaromatic.. ?

You misunderstand me. I at first thought of an 8 carbon ring with 4 double bonds which explains my original answer.

When I looked back at it I realized what I did. Cyclooctene is an 8 carbon ring with only one double bond. It is aliphatic and not anti-aromatic. It isn't aromatic either.

 

[Flipper405]

Just to clarify, cyclooctatetraene is also not antiaromatic because it is tub-shaped. The p system is not conjugated (which is really why a ring would have to be planar).