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Topic: Benzyl Alcohol  (Read 5591 times)

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Offline lrisNil

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Benzyl Alcohol
« on: February 20, 2015, 12:52:25 AM »
Is Benzyl Alcohol (Benzene ring with CH2OH attached) a meta director? OR is it a ortho/para director?

I know the O deactivates (suggests meta) and alkyl groups activate (suggests ortho/para) but this group has both so I became confused!
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Offline Dan

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Re: Benzyl Alcohol
« Reply #1 on: February 20, 2015, 08:52:22 AM »
Apparently it is electronically neutral, i.e. the effects you mention cancel out.

Hammett constants: σm = σp = 0.00; source: Hansch Chem Rev 1991, 91, 165-195 Link

So expect nasty mixtures...
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Offline lrisNil

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Re: Benzyl Alcohol
« Reply #2 on: February 21, 2015, 07:19:05 PM »
Thanks Dan! C:
Iris Lin

Offline orgopete

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Re: Benzyl Alcohol
« Reply #3 on: February 22, 2015, 08:57:25 AM »
I thought this was an interesting question, although I cannot provide a definitive answer. I thought Friedel-Crafts reaction on the alcohol might be problematic (I did encounter a Russian ref to its nitration though). I thought I recalled a problem asking for the products of nitration of benzyl acetate and it was an o/p-director. I tried to confirm this, but I cannot determine the ratio of products from this reaction. It seems to be cited for the preparation of the para-nitro product.

The nitration of benzyl chloride would seem as though it may have a similar profile of an electron withdrawing chloride to counter electron donation. Again, I was unable to determine the ratio of products, but references seem as though this is used to prepare the para isomer(?).

Now, I want to take one step back and refer to the nitration of toluene. Although it is an o/p-director, the ratio of o,m, & p-isomers is ~63:3:34. Benzaldehyde gives a ~19:72:9 ratio.

I appreciate the opinion of Dan on this question and it may well be instructive, but I also think it may still be mainly an o/p-director. What might be as interesting would be the kinetics of any Friedel-Crafts reaction. Is or are they activators, deactivators, or neutral?
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Offline lrisNil

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Re: Benzyl Alcohol
« Reply #4 on: February 23, 2015, 07:01:26 PM »
Thank you orgopete, I've decided to not use this group when trying to solve a synthesis problem, but it probably is o/p according to my googling (some say o/p, few say meta)   :P
Iris Lin

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