dennisfrancisblewettiii
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Determining theoretical yield of friedel-crafts reaction?
Say I have benzene and some other alkyl halide.
How do I determine the theoretical yield of the products I'm going to get?
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Reaction:benzene + 1-chloropropane -- AlCl3 --> n-propylbenzene + isopropylbenzene |
Here are the parameters:
Benzene (1 g, 12.5 mmol)
1-chloropentate (1 g, 12.5 mmol)
Product (1.2 g)
analyze with GLC (isopropylbenzene are = 113 mm^2; wf = 1.09)
n-prop area = 65; wf = 1.09
using thermo detector
Hints would be great, such as rhetorical questions.
update: still not sure what is going on but..
I re-read up on rate laws and rate constants. As I innately thought before from prior training years ago, I can't really do this without knowing the
rate constant? right?
I don't know the rate constant, and I don't believe I can derive it from what I already know.
[Edited on 23-9-2011 by Genecks]
[Edited on 23-9-2011 by Genecks]
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fledarmus
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You need a few rate constants here to find your expected product composition. You will need to calculate the concentrations of the primary and
secondary propyl cations (assuming that the hydride shift is much faster than the addition to benzene) and the rates of reaction for each of these
with benzene. There is also a steadily increasing concentration of alkylated benzene in your reaction, which is more reactive to Friedel-Crafts
reactions than benzene, and even with slow addition of your alkylating agent, may give you substantial quantities of multiply-alkylated products.
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dennisfrancisblewettiii
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I talked to a teaching assistant, and he told me to completely ignore the kinematics of it, because it was not relevant at time: Furthermore, I'm not
expected to understand the physical chemistry complexity I was considering at the moment.
Anyway, I was suppose to observe this as an issue of moles and considering the two reagents as equal limiting agents. I was supposed to do Moles of
Product A / grams of benzene... or something like that.
Thanks for the help, though, fledarmus.
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