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smuv
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| Quote: | | Read this paper and weep. |
Hehe, yes the tears are streaming. For a homework assignment, he would get the credit. If I were the teacher I would give him credit. For low level
organic chemistry classes the idea is to learn to think through problems and have a vague idea how to get from intermediates to products. These
classes are theoretical, not practical; teachers dont expect people to resort to literature searches to do their homework. In fact you can probably
get through a year of organic chemistry without ever doing a literature search.
This is why I prefaced my post with "If this is for a homework problem or something...and wont actually be done...."
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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not_important
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| Quote: | Originally posted by organicchemstudent
... Like I said I'm a quick learner but for some reason we are being tested on what we remember from highschool chem. ... |
When I went through university, I'd worry about seeking outside help if a professor gave such an assignment, it usually meant they were calibrating
where you were starting from so as to adjust their scoring of each student. Look brilliant in the first couple of weeks and face a year of tough
grading.
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Sauron
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smuv, your post contained a proposal for an experiment based on the assumption that the chlorination of acetanilide would be analogous to a
bromination you cited.
But I can cite just as much lit. and then some, that says that that is not so.
You can find both the p-monobromoaniline and the tribromoaniline in Vogel (and in Org Syn where Vogel copied the,)
You won't find the chlorinations in either.
The iodinations are there as well. No chlorinations.
Chlorination of aniline or acetanilide goes via N-chloro intermediate and on to ring chlorination. The paper I cited above demonstrates that
acetylation and diacetylation were ynadequate to prevent overchlorination.
Phenyl isocyanate succesfully chlorinates to hexachlorocyclohexane!
My point is that bromination and iodination are simply not analogous in the halogenation of aniline or acetaniide, by chlorine.
But some N-chloroimides and -amides are a lot milder and work as desired.
I don't know what decade you were at university, but when I was, an assignment like this would certainly require a trip to the university library.
Today some but not all can be done online, but in neither case would getting someone else to do the paper chase be deemed worthy scholarship. Only
professors get to do that - they reckon that's what grad students are for.
Sic gorgeamus a los subjectatus nunc.
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smuv
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Let's get this straight; I dont think and never did think that directly chlorinating acetanilide with AlCl3 and Cl2 would work But for a homework
assignment in first year organic chemistry that is full credit. I knew this kid was using this forum for a homework assignment and I gave him an
answer that would get the job done and make him go away, as well hopefully warning you guys to stop wasting time on a freeloader.
| Quote: |
My point is that bromination and iodination are simply not analogous in the halogenation of aniline or acetaniide, by chlorine.
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I agree.
About why I posted this reference; I speed read klute's post and interpreted it as asking IF the halogenation of acetanilide under mild conditions
gives predominantly para products and answered with a reference that showed it did.
About which decade I went to university, this decade, now, presently.
I go to a top tier school, and this is how things are. I think a major reason why is premeds; there are hundreds of them fulfilling their chem
requirements. If there are more future doctors in a chemistry class than future chemists, things get dumbed down.
I have been bitten in the ass in the past for not using procedures directly out of the book. For example I used NBS in water to make a bromohydrin
instead of bromine water and received no credit. With a hundred students they just don't have time to track down refrences. On top of that you can
receive credit for things that won't work with any selectivity (friedel crafts methylation of benzene to get toluene) and still receive full credit.
Now, In higher level classes this shit doesn't fly and things get more interesting (thank god).
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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Sauron
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ok not a problem
Sic gorgeamus a los subjectatus nunc.
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pip
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I agree that this kid is a free loader but I am seriously interested in a pratical synthesis for this compound. What is the most practical way of
doing this. I almost wasted time, effort, and money on the Starting from acetanilide, chlorinate with Cl2 and AlCl3, deprotect with NaOH in H2O
suggestion.
As allways I feel that even if the main poster doesn't deserve an answer people shouldn't put out fake or "on paper only" synthesis. It isn't fair to
people who are looking for this information honestly to be mislead.
Besides who wants to answer why someone a year in the future who dug up the post looking for help who's trying to do the synthesis and keeps failing.
Especially to have to say that is isn't even feasible and He/She wasted money buying chems of no use for what they are trying to do.
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Sauron
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I took the problem seriously and approached it as a chemist. There are three practical and straightforward methods, I described them above but am
willing to repeat myself. In order of number of steps required they are:
A. TCCA chlorination of aniline in CCl4, total about 28% yield, of which 25% is p-isomer. Steam distill the o-isomer off as sulfate, liberate the
non-steam-volatile p-isomer with base.
B. Nitrate chlorobenzene with ordinary conc mixed acids at or below room temperature. Reduce the mixture of 70% para and 30% ortho with Fe
filings/HCl aq, seperate the chloroanilines as above.
C. Diazotize p-nitroaniline and do a Sandmeyer. Reduce the nitro group with Fe/HCl. Advantage is no isomer mix.
Detailed lit. is posted above on A and B.
The choice is personal, unless dictated by which starting material you can obtain. B and C give higher yields. But A is simplest and shortest and TCCA
is cheap. CCl4 may be a problem to get.
Sic gorgeamus a los subjectatus nunc.
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