[toadesque]

When talking about Friedel-Crafts Akylations:

                                  AlCl3
aromatic ring + C=C-X    ---->    No Rxn

It would be this

aromatic ring bonded to C=C

why can this not happen?

[chuckycheeze]

When talking about Friedel-Crafts Akylations:

                                  AlCl3
aromatic ring + C=C-X    ---->    No Rxn

It would be this

aromatic ring bonded to C=C

why can this not happen?

first AlCl3 is used not in Friedel-Craft alkylation but in F-C acylation
                                                         R
second F-C acylation involved reactant X-C=O(acyl chloride)
so C=C as far as my concern shouldn't react.
I might be wrong though

[orgopete]

If we were to determine the acidity of substituted carbons, you would find the following order:
RC≡CH>R2C=CH2>RCH3

From this, we should think an sp carbon is more electron withdrawing than an sp² carbon which in turn is more electron withdrawing than an sp³ carbon. In a Friedel Crafts alkylation reaction, we require the intermediate to be a carbocation. From the information we just considered, rate the stability of the following carbocations?
RC≡C⁺, R2C=CH⁺, and RCH2⁺

The problem is not with the Lewis acid used, but the difficulty in forming the required sp²-carbocation intermediate.

[toadesque]

thanks