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Non Life Sciences => Chemistry => Topic started by: 113zami on 19/06/2008 17:23:30

Title: carbocation stability, directing abilities, benzene acidity questions
Post by: 113zami on 19/06/2008 17:23:30
Can someone PLEASE help me with the following questions, these are not in my text book ( I have the 4th edition by L.G. Wade) and I searched online but didn't find any convincing ansewrs so I am really lost, PLEASE help, thanks alot

http://i274.photobucket.com/albums/jj243/113zami/orgodd0002.jpg
1) is this group meta or ortho/para directing, and if it's ortho/para directing, is it activating or deactivating.?
I think it should be meta due to the oxygens which are electron withdrawing, am I correct?

2)Between tertiary non allylic and primary allylic carbocation which one is more stable?I know allylic makes you more stable because of resonance but this is primary allylic vs. TERTIARY non allylic carbocation, not just a primary one, so I don't know which to choose??

3)Which substituents will make the benzene more acidic, halogens or meta directing deactivators? I think the halogones should make them more acidic since they're more electron withdrawing than any meta directing group, correct?
Title: carbocation stability, directing abilities, benzene acidity questions
Post by: 113zami on 22/06/2008 15:51:29
can someone PLEASE help me with these questions??, thanks
Title: carbocation stability, directing abilities, benzene acidity questions
Post by: Bored chemist on 22/06/2008 19:41:49
The photobucket image doesn't seem to relate to the question.
Title: carbocation stability, directing abilities, benzene acidity questions
Post by: 113zami on 24/06/2008 15:26:48
no, that group should be attached to the benzene ring, it's just not attached to the benzene in that image, you are getting a cyclic looking compound whith 2 oxygens in it, correct?
Title: carbocation stability, directing abilities, benzene acidity questions
Post by: Bored chemist on 24/06/2008 19:07:59
To what part is the benzene ring attached?
Title: carbocation stability, directing abilities, benzene acidity questions
Post by: 113zami on 26/06/2008 19:50:34
Quote from: Bored chemist on 24/06/2008 19:07:59
To what part is the benzene ring attached?

I have 2 structures, in the first structure the benzene is attached to the right hand CH2 group in the ring, in the 2nd structure the benzene is attched to the right hand CH3 group in the ring, so if you can shed some light on how this group in each of these 2 structures behaves that would be great
Title: carbocation stability, directing abilities, benzene acidity questions
Post by: Bored chemist on 26/06/2008 20:44:39
To be honest I'm not sure. If you put a simple alkyl group like methyl on a benzener ring you activate it. A hydroxy group has the same effect. I think that structure you have looks like the activating groups here.
http://en.wikipedia.org/wiki/Activating_group

I take your point about some oxygen containing things being deactivating, but they are generally oxygen with a double bond.
Nitro, ester etc are shown here.
http://en.wikipedia.org/wiki/Deactivating_groups

Sorry I can't be more help- it's a long time since I studied that sort of thing.
Title: carbocation stability, directing abilities, benzene acidity questions
Post by: 113zami on 27/06/2008 19:09:50
ok thank you very much for the help