CrossxD
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Friedel-Craft
Hi guys I need to learn the deepest depths of Friedel-Craft's reactions how can I make these molecules just by FC
and can you tell me or give me some papers about stability of made carbocations and when they create and when not?? thanks 
CxD
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theAngryLittleBunny
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You need to know that there are 2 different ones, friedel craft alkylations for alkylated aromatics, and friedel cradt acylation for ketones. The
first one uses an alkyl halide an aromatic compound, the second one an acid halide and an aromatuc compound.
Acid halides are carboxylic acids which hava a halogen instead of the OH group. For instance, acetyl chloride CH3COCl is the acid chloride of acetic
acid CH3CO2H. But for them to react you need a lewis acid as a catalyst, that's something like AlCl3, or FeCl3, whee the central atom is really
positivly charged. The positivly charged Al or Fe ion the takes the negativly charged Cl- atom from the acid chloride making AlCl4- and a positivly
charged acetyl ion. That attacks the electron rich aromatic ring replacing a hydrogen. The H+ ion the combines with the AlCl4- to make AlCl3 and HCl.
The alkylation is basically the same, but you only keed a catalytic amount of AlCl3, unlike with the acylation, because there the AlCl3 attaches to
the negativly charged O of the ketone and doesn't participate in the reaction anymore, which is bad, because you need a stocheometric amount of AlCl3.
But the alkylation is bad, becazse the attached alkyl groups make the ring even more positivly charged, wihich means it is then even more attractive
for alkylation and you end up with ring which have multible alkyl groups, so it's a really shitty and uncontrollable reaction. With that information
I'am sure you can figure out how there compounds you show there were made.
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CrossxD
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and how about stability of carbocations in example d) i have conjugated double bond does it effect reaction? and in example a) does it matter when I
have 2 chlorines in 1 molecule?
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theAngryLittleBunny
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Quote: Originally posted by CrossxD  | | and how about stability of carbocations in example d) i have conjugated double bond does it effect reaction? and in example a) does it matter when I
have 2 chlorines in 1 molecule? |
Double bonds shouldn't really effect the reaction, the compound that is used for that is allyl chloride or allyl bromide, and it's pretty stabile. And
in example a, you just have an aromatic acyl halude which reacts with itself, in this case it is 3-phenyl propioyl chloride.
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CrossxD
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thx and when there will be hydrogen/alkyl shift? all I found was how it heppens, but I dontknow when it happens XD 
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theAngryLittleBunny
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| Quote: Originally posted by CrossxD | | thx and when there will be hydrogen/alkyl shift? all I found was how it heppens, but I dontknow when it happens XD |
I honestly don't really know what you mean with that, sorry .-.
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CrossxD
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the mechanism goes through carbocations
https://chem.libretexts.org/@api/deki/files/37003/image175.p...
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Dr.Bob
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| Quote: Originally posted by CrossxD | | thx and when there will be hydrogen/alkyl shift? all I found was how it heppens, but I dontknow when it happens XD |
For the allyl case, the allyl usually stays at the terminal position, at least in textbooks.
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Texium
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25-1-2018 at 06:21 |
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