i have been trying to find a synthesis for this compound but i have had no luck
i have even stooped low enough to check the "drug" forums and still no synthesis (no insults inteneded)
is there a chemical synthesis website?
you know one that you could type in the compound and get a procedure?Sauron - 29-9-2008 at 10:51
Try the ACS Journals search engine "Advanced Search"
Try forum library.
Try the Merck Index.
You could start with p-phenylenediamine, diazotize one amino group, and replace the diazo group with Cl
[Edited on 30-9-2008 by Sauron]Klute - 29-9-2008 at 12:03
[Edited on 29-9-2008 by Klute]pip - 29-9-2008 at 16:35
i was researching this very thing can this be adapted?
i "borrowed" it from another post here
Chlorination of Aniline
I've tried two ways, one by bubbling Cl2 through a solution of aniline in DCM (dried with P2O5) though this only resulted in immediate masses of
resinous crap. This method was from journal literature (Am. Chem. J.) I lost the original article. Though I substituted chloroform with DCM, the
original text follows:
"The trichloraniline used in this preparation was made by the excellent method of Victor Meyer and Sudborough' as follows : One hundred grams of
freshly distilled aniline were dissolved in one kilogram of chloroform, which had been washed to free it from alcohol, and thoroughly dried. The
vessel containing this solution was immersed in a bath of ice and water, and dry chlorine passed through the cold liquid, until it was saturated,
which occupied from twelve to fifteen hours. It is advisable to introduce the chlorine through a wide tube, as there is danger that a narrow one will
be stopped up by precipitated trichloraniline chloride. The precipitate formed by the action of the chlorine was freed from chloroform by means of a
filter-pump, dried and washed with water, which removed all the compounds of aniline except the trichloraniline. The yield was good, as 117 grams of
trichloraniline were obtained instead of 211 grams, that is 55.4 per cent, of the theoretical amount."
I have no intention of trying that again, toxic rainbow coloured resinous crap is hard to clean. I never dried the red MERK aniline, and the Cl2
derived from TCCA/HCl was dried through a flask of CaCl2. I suspect a small amount of water present is the reason for the dramatic failure.
I'm aware of US2675409 which first converts the aniline to its hydrochloride via reaction with anhydrous HCl before the chlorination. Though again
stringent exclusion of water is a must.
For a second try I used H2O2/HCl/AcOH, this seemed to have promise though is a hot reaction and good cooling is needed. Into a well cooled solution of
5.5g aniline in 60ml AcOH and 100ml 32% HCl was added small portions of 50% H2O2. The solution turned yellow to green to blue, after taking it out of
the freezer on warming an exotherm resulted which precipitated an olive drab coloured substance. This is too simple for the product to be
trichloroaniline, but what is it likely to be? This green compound is also seen in the resinous crap from the previous reaction of aniline + Cl2.
So I ask if anyone has experience chlorinating aniline through convenient means? Also if anyone has information on physical properties onf
mono/di/trichloroaniline? especially colour. Also If anyone knows what the reaction of aniline with AcOH/NaOCl yields?
I hate aniline very much.Sauron - 29-9-2008 at 19:54
Klute:
I looked in Org Syn first off but there were no entries on prep of p-chloroaniline. There were a number of preps using it as starting material.
I directed the thread author to the forum library. Specifically he would be well advised to try Fundamentals of Dye Chemistry as well as Preparation
of Organic Intermediates.
The ACS search engine is also a good bet. Google is a last resort.not_important - 29-9-2008 at 22:08
which is related to the one I remember, treatment of acetanilid in acetic acid (plus a few drops of acetic anhydride) with measured amounts of bromine
or chlorine. This give o/p ratios in the range of 75% to 85% para, and the isomers are fairly simple to separate through crystallisation.smuv - 29-9-2008 at 22:20
If this is for a homework problem or something...and wont actually be done....
Starting from acetanilide, chlorinate with Cl2 and AlCl3, deprotect with NaOH in H2O.
Alternatively you could start from chlorobenzene, nitrate it, and reduce to amine. You could make the argument that the p isomer would be the major
product.
Although honestly if it IS just a homework problem this should be in beginnings.
[Edited on 9-30-2008 by smuv]Sauron - 29-9-2008 at 22:44
Merck Index does the trick.
Prepn of m-, o- and p- isomers: Sidgwick, Rubie, J. Chem. Soc. 119, 1013 (1921). Manufacture of m- and p- isomers by catalytic hydrogenation of
chloronitrobenzene: Pray, Trager, U.S. pat. 2,791,613 (1957 to Columbia-Southern Chem.); by reduction of chloronitrobenzene with NaHS: Latourette et
al., U.S. pat. 2,894,035 (1959 to Food Machinery and Chem.). Properties of o- isomer: Dreisbach, Martin, Ind. Eng. Chem. 41, 2875 (1949). Toxicity
data: H. F. Smyth et al., Am. Ind. Hyg. Assoc. J. 23, 95 (1962).
The patents are easy to get via www.freepatentsonline. You need to register (just an email address and password).
I will fetch the J Chem Soc paper for you.
Chloroanilines are rather more toxic than aniline, but the worst is the ortho isomer.not_important - 29-9-2008 at 22:48
I'd though of the nitrating chlorobenzene, but hadn't found the refs; thanks Sauron.
A no registration alternative to freepatentsonline is
Freepatentsonline registration is nothing to be afraid of. They do not ask for name, address, tel, credit card.
All they ask for is an email address which can be an anonymous one (Hotmail, Hushmail) and a password of your own devising.
There's no hassle and no fee.
This prep was not hard to find. Merck Index, whether hard copy or on CD, is one of the very first hald a dozen places to look. You really ought to
learn how to search the lit. if you want to live up to the handle "organicchemistrystudent".
Forget Wiki, Google, and the drug forums. Learn Beilstein instead. There is a vast body of chemical literature that you can download for free and have
at your fingertips on HDD or DVD or CD. VAST.
[Edited on 30-9-2008 by Sauron]
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Sauron - 30-9-2008 at 03:11
The J Chem Soc paper is of partial help only, as what is still needed is a decent procedure for mononitration of chlorobenzene.
The following paper looks highly on point:
Effect of Process Conditions on Formation of Isomers in Nitration of Chlorobenzene
Harold Bieber, W. Fred Schurig
Ind. Eng. Chem.; 1957; 49(5); 832-837. DOI: 10.1021/ie50569a026
The possibility of monochlorination of aniline or acetanilide ought to be investigated as this would be a one step prep rather than a multi-step one.
PATR turned out to be useless, merely referring to Beilstein
While we await the endowment from References of the 1957 I&EC paper on optimizing yield of p-nitrochlorobenzene, here is a 1923 paper from same
journal detailing both nitration of chlorobenzene and reduction of the products, as well as seperation of the isomeric chloroanilines.
The mixed acids were normal conc reagents. The product was 70% para and 30% ortho. About 50% of the total product could be seperated out as very pure
p-isomer after cooling. The remaining mixture was about 1:1 p/o and was reduced as such, with Fe filings and hydrochloric acid. The isomeric
chloroanilines were then seperated by various means described. The crop of nearly pure p-nitrochlorobenzene isolated prior to reducing the oil, was
also reduced and produced a very high grade of p-chloroaniline.
Attached below.
[Edited on 30-9-2008 by Sauron]
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Sauron - 30-9-2008 at 03:52
not_important, that JOC article (attached below in full text, your link was only first page) is interesting, it showed that TCCA in CCl4 reacts with
aniline under mild conditions, but the yield is low, and the authors did not bother to isolate products, they were content to strip CCl4 off and
analyze the mix with GC. That is just a tease from a preparative point of view. It is worthwhile to note that dinitro isomers were not detected, the
ration of p to o-isomer was high and the only other component unreacted aniline. So maybe a vacuum distillation would suffice to seperate this mix. I
have not looked at the bp's.
[Edited on 30-9-2008 by Sauron]
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Sauron - 30-9-2008 at 22:15
As I remembered, the excellent book Fundamental Processes of Dye Chemistry (freely downloadable from forum library) has a section on derivatives of
chlorobenzene, pp 90-110, and the very first two entries are the mononitrochlorobenzenes and from them, the nitroanilines. Pages 90-93 encompass the
preparation and purification of these four compounds, and are attached below.
The nitration uses nitric acid d.1.52, fuming, and is less convenient therefore than the I&EC methods. Also few of us have a large centrifuge at
hand.
I would like to stress once again that I would much prefer to teach newcomers how to use the chemical literature, than to merely spoonfeed them
individual preparations like recipes from cookbooks. Until the student or hobbyust knows how to search the lit., they can't be regarded as a chemist
any more than a person who does not know how to use a law library can be regarded as a lawyer. Know how to tap it and you are empowered. This forum
provides three vital and valuable free resources: the library, USE IT. the References forum, USE IT. and the Search function, MASTER IT. Then you can
call yourself a chemist among chemists. Build your own chemistry library and READ IT.
As a final resource you can tap into the pool of knowledge of fellow forumites. But we are a little abrupt sometimes with those who appear to have not
attempted to help themselves first. I hope you can understand why.
Another useful and related book is The manufacture of intermediate products for dyes by John Cannell Cain. Available from Google books and
the Internet Archive:
With these scanned books it sometimes is useful to get them from multiple sources, as deficiencies in the scanning by one source generally don't occur
at the same locations as those from another source.
While these manufacturing books usually describe processes on a ... slightly larger scale than most board participants generally work with, they still
can provide useful information and occasionally do include smaller scale preparations. You'll likely not find detailed instructions for a particular
compound, you'll need enough background and experience to adapt the processes in the books and lab scale preparations for similar compounds (as from
OrgSyn) to your neededs.
[Edited on 1-10-2008 by not_important]Sauron - 1-10-2008 at 00:08
Org Syn in the earlier decadres tended to be larger prep scale, and in more recent decades has rather steadily downsized its procedures in keeping
with present vogue. Personally I like making hundreds of grams of something a lot more than hundreds of mgs.
I have not yet looked at the patents cited by Merck. Nor have I peeked in Ullmann or Kirk-Othmer. Frankly I think what we now have upthread plus the
one further I&EC paper I am awaiting, is entirely adequate. Here is a summary of what we know:
Ordinary mixed xonc acids are entirely adequate. Fuming nitric acid is not needed unless and until you want DNCB.
The o/p ratio is at least 1:2 (30%/70%) with details awaited for optimizing further in either direction by control of process conditions, still
using ordinary mixed acids. The key variables appear to be temperature and final concentration of spent H2SO4, based on abstract and first page of the
paper we are waiting for.
Even with the 70/30 "ordinary isomeric split, at least the bulk of the p-isomer can be recovered straightaway by cooling and filtering of the crystals
from the oil. If the p-nitochlorobenzene is the only target and economy is not a huge consideration then the further workup of the oil is unnecessary.
Details are given for such workup. Basically the two options are partial fractionation and crystallization, repeated until adequate seperation has
been obtained. Or, reduction of the oil, followed by seperation of the chloroanilines, Several reduction methods are at hand. The fastest and best is
hydrochloric acid and Fe filings. A necessary precondition is absence of chlorobenzene; if present due to incomplete nitration the PhCl should be
removed by fractionation up to 100 C.
The completely reduced chloroanilines are seperably by steam distillation. If reduction is incomplete the unreduced nitrochlorobenzenes are removed
from the chloroaniline sulfates, and these are then seperated by steam distillation and the isomers recovered by basification.
Chlorination of aniline with N-Chlorosuccinimide has been reported to give monochloroanilines in an ortho:para ratio of 2.4:1 and a 65% yield.
Solvent is benzene, time is less than 1 hour, conditions mild.
This chlorination proceeds via N-chloroaniline as intermediate.
While the desired p-chloroaniline is the minor product, this simple one-step-one-pot preparation is still a viable alternative to the nitration of
chlorobenzene and reduction of nitrochlorobenzenes.
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organicchemstudent - 1-10-2008 at 11:20
thank-you for all the texts if i don't respond to anything in the next few days it's because i am reading through it all.
my paper is due soon. Thank-you.Sauron - 1-10-2008 at 15:18
The lowest pits of Hell are reserved for poltroons who come here and expect others to research their homework for them.
Sloth is a cardinal sin, kid.
I have half a dozeb more papers on aniline chlorination by various reagents but now that you have admitted what this is all about, I'm not going to
post them. At least not till after your paper is due.
[Edited on 2-10-2008 by Sauron]organicchemstudent - 1-10-2008 at 22:27
i know it is lazy but in my case please belive me it isn't so. Im in my first year college inorganic chem class and i have never had a highschool chem
class. i am catching up fast but this is a major part of my grade and i don't want to fail when i feel i only need a few more weeks cramming some good
books to be o.k.
you guys know how hard chemistry is as it is. i'm not whining but think about having to take college chem as your first class. i didn't know jack on
the periodic table.Sauron - 1-10-2008 at 23:22
Why is a paper on an organic preparation assigned to a student in a freshman general chemistry course? That's odd.
What I want you to understand is that the purpose of an assignment like this is to force you to learn how to search the literature, and by delegating
the assignment to others you have learned approximately nothing. Most likely (based on your own remarks) you won't comprehend much of what you are
reading, you haven't had basic organic chemistry. Unavoidably this will show through in your paper, I don't see how it could be otherwise.
Chemistry isn't hard once you get beyond the basics. It's fun, at least till you get to p-chem (physical chemistry) in your senior year. No one thinks
p-chem is fun. The freshman courses are as much for weeding out students without the aptitude as for actually conveying knowledge. You will start
learning real chemistry in sophomore and junior years. By my junior year I was auditing graduate courses.
You will need good math skills, I mean calculus, and German and/or Russian, particularly reading skills. Both languages if possible.
For your paper you now have three routes to your target compound
From chlorobenzene, nitration then reduction and seperation of isomers
From aniline, chlorination with N-chlorosuccinimide in warm benzene, and seperation of isomers
From p-nitroaniline, diazotization, then Sandmeyer reaction, gets you p-nitrochlorobenzene; reducing that gets you p-chloroanioine, no need for steam
distillation as no o-isomer present.
Good luck with your paper.
[Edited on 2-10-2008 by Sauron]organicchemstudent - 2-10-2008 at 08:13
Thanks i promise this is the only time i will be asking for help. Like I said I'm a quick learner but for some reason we are being tested on what we
remember from highschool chem. And like i said i didn't have chem in highschool.Klute - 2-10-2008 at 08:23
would it be possible to go via the acetanilide? I know I can be brominated with majorly para-isomers been formed, can't this be applied to chlorine
(maybe using a "smoother" equivalent like NCS or TCCA?)? O ris the o/p ratio too high?smuv - 2-10-2008 at 08:41
SYNTHETIC COMMUNICATIONS
Vol. 34, No. 12, pp. 2143–2152, 2004
acetanalide is para brominated with 98% selectivity by the dropwise addition of H2O2 to a solution of NH4Br in AcOH.
P.S. I proposed this above
[Edited on 10-2-2008 by smuv]Klute - 2-10-2008 at 08:52
oups my bad, I went through the thread quickly and must have over read your post..Sauron - 2-10-2008 at 10:09
Read this paper and weep. With acetanilid and chlorine all you get is trichlorinated product and tar.
TCCA in CCl4 is 90% selective for para monochlorination. As the isomers are readily seperated by steam distillation of their sulfates, this is not a
hassle. No peroxide, no catalyst, and aniline not acetanilide.
[Edited on 3-10-2008 by Sauron]
[Edited on 3-10-2008 by Sauron]
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smuv - 2-10-2008 at 10:24
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...."not_important - 2-10-2008 at 16:33
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.Sauron - 2-10-2008 at 23:22
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.smuv - 3-10-2008 at 06:47
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.
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).Sauron - 3-10-2008 at 08:09
ok not a problempip - 4-10-2008 at 09:18
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.Sauron - 4-10-2008 at 09:46
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.
