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Magpie
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[*] posted on 10-2-2006 at 09:44


GC I was afraid you were going to say that. But I am sort of committed to the steam distillation of both as I have already converted the aniline hydrochloride to aniline. Next time I will try the other method.

You are right about the massive precipitation of SnO2 - it was quite dramatic. When I took the clear honey-colored aniline hydrochloride brew off the steam bath (which worked beautifully BTW) there was this sudden and massive precipitation of white salt as it cooled. :o

I will be making the phenol next. This will be the termination of my planned synthetic route:

Rooto + Detrol + carp bait preservative + fishing lead + Red Devil Lye + Muriatic acid ---> benzene ---> nitrobenzene ----> aniline ----> phenol :D




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[*] posted on 13-2-2006 at 17:19


My aniline synthesis went OK but the yield was not very good, i.e, about 50%. I have a feeling that all those precipitated Sn hydroxides somehow interfered with the steam distillation.

One of the qualitative tests for aniline was to mix a few drops with 5 mL water then add 0.5g bleaching powder. This gave an immediate and strong purple color. Does anyone know what the purple product is and the reaction that occurs? I was wondering if this might be a chloroaniline.

I also wanted to point out that my aniline did not have much of an odor. Of course I really did not stick my snoot in it as it is highly toxic. But with a lineage of benzene and an amine I expected a strong, aromatic fishy smell.

Today I made phenol with the 6.4 mL of aniline and 5.5g NaNO2 that I had made. I will post results on a phenol thread.

[Edited on 14-2-2006 by Magpie]




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[*] posted on 13-2-2006 at 20:49


I decided to try to simplify the route from benzene to Aniline as much as possible. The aim was to do it easy, fast and use as little glassware as possible. I set out by generally using the procedure for nitrobenzene and aniline outlined in Vogel, but skipping the tedious washing and distilling of the C6H5NO2 and not spending time making sure all the previous residues were removed from the glassware before moving to the next step.

70ml HNO3, 68% and a stir bar were placed in a single neck 1000ml flat bottom flask, resting in an ice cube slush. Next 80ml H2SO4 ~95% was added in several portions over a few minutes. A thermometer was placed just into the liquid and when the mix fell to ~20º, 60ml C6H6 was then added drop wise but fast, over the course of 10 to 15 minutes generally keeping the temperature at least below 40º.
After the addition was complete, the ice bath was replaced with a water bath at 60º and a condenser was affixed for reflux. This setup was maintained for 20 minutes.
The contents were then dumped into 700ml cold water with a little ice. After resting for several minutes the contents were transferred to a separatory funnel and the lower layer was run off and discarded. 100ml cold H2O was added, shaken and the lower layer was run off and then repeated once again. The result was 61ml of wet nitrobenzene, certainly some residual nitrating acid and most likely some di-nitrobenzene, although none was seen to crystallize out upon standing.
19ml of wet crude C6H5NO2 was run out of the separatory funnel leaving 42ml remaining which is what I needed for the reduction using iron and HCL.
http://img149.imageshack.us/img149/7494/unusednb1ee.jpg

The 1000ml flat bottom used above was rinsed two times with water and into it was placed 80ml DI-H2O, 60gm 200 mesh iron powder and 5ml 34% HCL. http://img149.imageshack.us/img149/6089/iron8eo.jpg
The thermometer was placed back in loosely and while holding the flask in my hands I began the reaction by running 3 or 4ml of nitrobenzene from the funnel into the flask. Upon swirling the contents a temperature spike was noted but it never reached the intended 80º so I placed the flask on a hotplate until it was nearing ~80º. I then removed it and swirled by hand again. C6H5NO2 was added in ~4ml portions usually when the temperature had fallen below 80º which would then immediately cause a temperature rise.
http://img108.imageshack.us/img108/9657/reduction7bo.jpg
As noted in Vogel it was sometimes necessary to alternate the flask between a cool water bath and a hot plate to keep the temperature between 80º and 90º. After all the nitrobenzene had been added the flask was left on the hotplate and a condenser was affixed while maintaining a gentle reflux and continued for 20 minutes. It was then removed from the hotplate and cooled as fast as the glass would allow. After reaching room temperature, 10 grams of potassium carbonate was added slowly. The flask was then returned to the hotplate and setup for steam distillation.
On the flask was placed an angle adapter with a thermometer port that was fitted with a glass tube where the thermometer would be. A length of hose connected the tube to another flask with boiling water and a few boiling stones.
http://img108.imageshack.us/img108/5822/steamdistil0wo.jpg
A condenser and collecting flask was attached and the distillation begun. A turbid distillate begun to collect after a while and was continued until it ran clear. This process took roughly 30 minutes. A total of 250 ml was collected and then the crude wet aniline was then placed into the separatory funnel with 50 grams sodium chloride and shaken to dissolve the salt.
http://img108.imageshack.us/img108/1953/saltout3sd.jpg
Two layers politely formed and the lower run off and discarded.
http://img149.imageshack.us/img149/862/crudeaniline9pl.jpg

The salted out crude aniline was placed in a 250 ml round bottom set up for distillation. http://img149.imageshack.us/img149/9625/anilinedist21or.jpg
The heat was applied and after some time the temperature reached 100º and water began coming off which was collected in a beaker and discarded.
http://img108.imageshack.us/img108/8316/begindist9rx.jpg
Shortly after the temperature quickly rose to 180º whereupon the heat was shut off and the flask pulled from the mantle to cool. The adapter and condenser were removed and rinsed of the remaining water with acetone and forced to dryness with a hot air gun. The setup was reassembled and the heat turned on again.
http://img108.imageshack.us/img108/6728/anilinedist16ni.jpg

The distillation proceeded very smoothly with no trouble to just dryness where upon the flask was quickly removed from the mantle and the collecting flask was removed.

The result was 31.22 grams of a lovely golden aniline oil. I think the yield could have been better but I lost some with the first water coming over and subsequent glassware drying.
http://img108.imageshack.us/img108/2835/result10ky.jpg
http://img149.imageshack.us/img149/4193/result22ax.jpg

I too did not smell the fishy odor as was reported in vogel and other texts. There was a faint amine smell and other somewhat pleasing notes similar to nitrobenzene but different. I will run a sample on the FTIR and report the findings when I have more time.

[Edited on 14-2-2006 by ordenblitz]
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[*] posted on 14-2-2006 at 09:31


Ordenblitz your streamlining of the synthesis of aniline is outstanding. I would be embarassed to compare the hours I spent getting my aniline.

Could you please calculate your %yields for both nitrobenzene and aniline? I will sheepishly provide mine once my phenol is made.

[Edited on 14-2-2006 by Magpie]




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[*] posted on 19-10-2006 at 05:14


I followed the procedure in Vogel using granulated tin that I made myself using wire clippers. The tin obviously dissolves as the reaction procedes using magnetic stirring the whole time to keep the two immiscible layers in close contact. A few pointers:

*Making nitrobenzene, the reaction became dark and fuming so I stopped early. Be careful not to over heat this although I was lucky that there was a healthy amount of nitrobenzene at the end of the reaction though not as much as there would have been. I got the amount necessary for all the tin I had available to me which was the limiting reactant (111g). [The reaction lightens upon diluting with water as the nitric oxide goes back into solution].

*I did the reduction as in Vogel except I just streamlined it and used a little bit over to compensate. The nitrobenzene was a turbid opaque color but I added a 2ml test aliquot that I had left over to some CaCl2 and it does clear up on standing.

*Vogel says to pour the acid down the condenser. I have a Graham condenser and found this retarded. It's much better if you have a Claisen head and a pressure equalising addition funnel. You dont need to cool this reaction at all as long as you dont add the acid too fast. I also doubt what effect heating it on the water bath has but I did this 1/2 hr just because it said to.

*Steam distillation was actually just distillation of the water until the white scum (aniline) floating on the surface of the boiling mixture stopped coming over. You can play it by eye if you like. I think I added about 250mL additional water thoughout the boil although im not 100% to what extent this is actually necessary.

*The aniline is colorless. However traces of nitrobenzene in the sep funnel gave it a yellow tinge. The yield was 37.5ml aniline from 62g PhNO2 (I added 64g since it was emulsified). Didnt bother using ether either.

Im drying it over NaOH pellets now. I cant imagine it being anything other than very pure although its probably worth distilling it just in case.




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[*] posted on 15-11-2006 at 09:07


At my school chemistry lab I found an old (20-30 years) bottle of aniline. It was never opened before and is was tightly sealed. What suprised me is that the aniline is dark red and I have never heared before of dark red aniline. Is that possible?



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[*] posted on 15-11-2006 at 09:40


Aniline can be anything from just yellowish to intense orange or reddish. It all depends on how much oxidation products it contains. Mind that the oxidation products of aniline are the polyanilines which are a black dye (worth a fortune in the old days, but just an annoyance nowadays). You can purify it if you think it is worth the fuss (by vacuum distillation or steam distillation followed by drying).
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[*] posted on 15-11-2006 at 14:00


I have an old bottle of analytical grade aniline and it is dark red as well. The aniline is perfectly fine, the red stuff is just an impurity of oxidised aniline which is strongly colored.
A simple distillation again yields nearly colorless pure aniline- it says so on the bottle.


The reduction of nitrobenzene with metals is an antiquated method of aniline synthesis. There are much more convenient methods available both for industry and lab that don't make such a mess upon basification with all the metal hydroxides.
I am especially thinking of catalytic transfer hydrogenation (CTH) using formate salts or straight formic acid as the hydrogen donor. Any common metal hydrogenation catalyst such as raney nickel, palladium or platinum on activated charcoal or similar carriers can be used.
Look here to see how truly easy, versatile and high- yielding this method is:
http://www.designer-drugs.com/pte/12.162.180.114/dcd/chemist...

I am in the process of getting some palladium. When I have it, I plan on preparing some Pd/C catalyst and doing such a hydrogenation with a formate salt and an aromatic nitro compound (probably a nitrotoluene isomer, as I already have enough unsubstituted aniline). Maybe I'm going to document it here how it went.



[Edited on 15-11-2006 by garage chemist]




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[*] posted on 16-11-2006 at 06:17


At http://en.wikipedia.org/wiki/Aniline I have read that potassium permanganate in neutral solution oxidises aniline to nitrobenzene. Has aniline to perform that reaction be dissolved in water in its pure form or in the form of its salts?


[Edited on 16-11-2006 by Zinc]




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[*] posted on 16-11-2006 at 23:34


While on the topic of aniline- what could one do with aniline HCl to produce a desired substance??:
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[*] posted on 17-11-2006 at 00:58


Aniline can be used to make azodyes. p-DiMe-phenyl-azobenzene gives brightly yellow colored crystals whereas p-OH-phenyl-azobenzene is orange colored.

Sulfanilamide is also made from aniline.
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[*] posted on 17-11-2006 at 12:23


Aniline can also be used to make mauve (not sure if this is an azo-dye or not), you also need p,o-toluidine.
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[*] posted on 18-1-2007 at 11:19


I know that aniline reacts with acids to form salts. I am planning to react aniline with HNO3 (60%) to make aniline ntrate. Is the HNO3 enoguh concentrated to perform the reaction?

Also does anyone know some properties of aniline nitrate?




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[*] posted on 18-1-2007 at 22:19


Some comments:

Nitrobenzene is now regarded as a serious carcinogen suspect.

Aniline is a serious hepatotoxin.

You should be working in a fume hood.

You should be using goggles and gloves.

Get yourself Vogel's 3rd ed. and/or the Org.Syn. procedures for the aniline reduction.

Once you have aniline, purified by distillation, and want to take it to the next step, you have a lot of technique to learn before attempting diazotization.

Temperature control is paramount.

You need starch-iodide paper.

Diazotization is a highly versatile reaction, which benzene derivative are you trying to make?
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[*] posted on 18-1-2007 at 22:41


Quote:
Originally posted by Zinc
I know that aniline reacts with acids to form salts. I am planning to react aniline with HNO3 (60%) to make aniline ntrate. Is the HNO3 enoguh concentrated to perform the reaction?

Also does anyone know some properties of aniline nitrate?


More than enough. Aniline and nitric acid tends to give oxidation products, nitration of the ring, and hair pulling. Treat the nitric acid with a small amount of urea just before reacting with the aniline, the urea removes traces of nitrous acid and NOx.

A better route is through the reaction of aniline hydrochloride with ammonium nitrate in a water-alcohol solution (or water solution followed by addition of some alcohol) followed by filtering to remove the ammonium chloride. Alternative is to use sodium nitrate in water solution.

Aniline nitrate is very soluble in water and alcohol.


These might be of interest:

http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/1908/30/i09/...

http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?_handler_=H...

http://pubs.acs.org/cgi-bin/abstract.cgi/jpchax/1932/36/i10/...
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[*] posted on 18-1-2007 at 23:06


It's rather the long way round the course to make phenol this way, the short toute is sulphonation then fusion with alkali then liberation of the phenol from the phenoxide salt.

But learning to diazotize is a nobel goal.
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[*] posted on 19-1-2007 at 07:10


Quote:
Originally posted by not_important
More than enough.


Should I dilute it?
If yes to what concentration?




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[*] posted on 19-1-2007 at 07:16


Diazotization is really simple if the important conditions are met, like enough acid, low enough temperature (best attained by putting ice in the reaction mix itself) and diazotization to an end point with KI/starch paper or the like.

I made iodobenzene and it worked marvellously. Upon addition of the KI solution to the diazonium salt solution, it turns deep red and nitrogen is being given off for several hours, making it look like if it was fermenting. The product seperates as a black very dense oil (the black color is due to oxidised aniline compounds, the iodobenzene becomes colorless upon distillation).




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[*] posted on 24-1-2007 at 09:06


Is aniline nitrate explosive (If it is I am not going to make it)?

[Edited on 24-1-2007 by Zinc]




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[*] posted on 25-3-2007 at 13:09


I usually don't post too much about my failures, but this one is really bothering me, so I'm seeking your comments:

I attempted to make aniline a few days ago using powdered iron (from United Nuclear), a little HCl, water, and nitrobenzene. I had made it before successfully using tin instead of iron. I wanted to use iron this time as it is cheaper, and just to try something new.

I used the method in Vogel's 3rd. Add 40 mL of water, 30g of iron, 2.5mL of conc HCl, and 21 mL of nitrobenzene. The nitrobenzene is added a little at a time to keep the exothermic reaction under control.

There wasn't much heat evolved. In fact I had to place the RBF in a hot water bath to get the temperature up to 80C. After all the nitrobenzene had been added I attached a reflux column and placed the RBF on a heating mantle. Occaisionally I would shake the flask for mixing. [I initially tried to use a mag stirrer but this failed due to the magnetic properties of the iron (duh).] Once the flask got hot enough I could see some bubbles forming and took this as H2 and as a very good sign. This became fairly active with much more bubbles and heat generation. I gave the flask a little cooling in a cold water bath when it looked like it might start to boil. I don't think I heated it much after the reaction subsided.

I added Na2CO3 to bring to basic pH (10) and then steam distilled. Following this I added the NaCl. This is when I knew I had a failure as no aniline floated to the top. Instead there was a reddish-orange layer at the bottom of the separatory funnel. I took this as unreacted nitrobenzene and terminated the procedure.

Your critique is sought, please. What do you think went wrong?




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[*] posted on 25-3-2007 at 14:17


Maybe you'd like to try using more heat to start with, and different addition strategy such as in Cumming or Cheronis:

60 ml of water and 120 g of iron powder are placed in the reduction pot, agitation being maintained during the addition. The pot is then heated to 90-95°, and 10 ml conc. hydrochloric acid (d 1.18) are poured in; 100 g nitrobenzene are then added, a few ml at a time. The temperature must be held at 100°, and this can be conveniently done by regulating the addition of the nitrobenzene. When all the latter has been added, the reduction is continued at about 100° until no smell of nitrobenzene remains, or until a sample dissslves completely in dilute hydrochloric acid.

If the agitation is not powerful enough to carry through this process, the following may be adopted: 100 g of nitrobenzene and 60 ml water and 10 ml of conc. hydrochloric acid (d 1.18) are heated in the pot up to 95°. 120 g iron powder are then added carefully, the temperature being maintained at about 100°. After all the iron has been added, the temperature is maintained at 100° by external heat, and agitation continued until all the nitrobenzene has been reduced.

Steam Distillation.--If direct steam can be led into the reduction pot, this process is simplified, for, by merely altering the condenser to the usual sloping position, the aniline can be distilled off. If direct steam cannot be led into the reduction pot, the contents, after the reduction is finished,, are poured into a large round-bottomed flask, and steam from a steam generator led into it, the products of vaporisation being condensed in the usual way.

Separation.--The condensate is poured into a separating funnel and allowed to stand until separation into two layers is complete. This may be assisted by applying heat or by adding salt. The aniline is then poured off, dried over solid NaOH and distilled.

Yield.-95% theoretical (70 g). bp 184°

--------

In a 500 ml round-bottom or Florence flask place 30 ml (35 g) of nitrobenzene, 5 g of Bentonite clay, 120 ml of water, and 20 ml of concentrated hydrochloric acid. Heat to boiling, remove the flame, and after a minute or so lift the cork which holds the condenser, and add all at once 36 g of iron powder. Replace the cork at once and allow the vigorous reaction to proceed for 2-3 minutes, then resume heating. Boil briskly for 2 hours. Cool the reaction mixture, and add 50 ml of water and 8-10 g of sodium carbonate. The carbonate is added gradually to avoid frothing. Set up a steam distillation apparatus, and steam-distill the reaction mixture until the distillate is perfectly clear. Saturate the distillate with 30 g of commercial sodium chloride, and extract with three 50-ml portions of ether. Dry the combined ethereal solutions with 6-8 g of sodium hydroxide pellets. If an aqueous solution forms on shaking, decant the ether solution into another dry flask and add a fresh amount of sodium hydroxide. Allow the ether to stand overnight. Pour one-half of the ether solution into a 125-ml distilling flask and distill off the ether from a water bath. After most of the ether has distilled, add the remaining portion, and continue the distillation until all the ether has been removed. Remove the water bath, wipe off the outside of the flask, and heat the flask with a small free flame. When the temperature of the vapor reaches 120°, disconnect the water in the condenser and allow the jacket to drain, thus converting it to an air condenser. The fraction which boils at 180-185° is collected in a tared flask or bottle. The yield is 20-23 g.

----------

I've found some old block tin things here and there with help from people who don't know the worth of scrap tin. Very easy to melt and the little pieces of tin that go flying everywhere upon adding molten tin to water are lots of fun.

Edit: It is interesting that neither Cumming above (whose experiments seem sometimes not based upon the experience of the authors and their students; but in this case probably is) nor Fieser (the eminently trustworthy but unscanned Experiments in Organic Chemistry 2nd ed.) basify before steam distillation.

[Edited on 25-3-2007 by S.C. Wack]
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[*] posted on 25-3-2007 at 16:06


Thank you S.C. Wack. It seems like insufficient temperature for a long enough time is likely the culprit based on your submittals.

I wanted to blame the iron powder, thinking that it was excessively oxidized. But I really don't think I can justify that. I've attached a picture of my iron. The colors seem accurate.

Yes, I've melted tin myself and dropped it into water to form a "mossy" tin with more surface area. It is indeed fun. I'm going to have to be on the lookout for cheap sources as you have done.

I don't like wasting my precious nitrobenzene in an effort to find out what I did wrong, so if I have enough tin will likely just use that for now. I really do want to find out what went wrong, at some point in my mad science career, however.

Fe powder.jpg - 56kB




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[*] posted on 25-3-2007 at 17:32


Just a random thought. If you had some time and tin on your hands, you could reduce it to dust by putting it in the freezer and leaving it there for a while, converting it into the alpha allotrope (gray tin) which should be incredibly easy to powder.

I get my tin from fishing sinkers at Walmart. It runs me roughly $6.86 US a pound, or the truly important figure $1.80/mol. Purity is unknown, but likely higher than 95%

[Edited on 3-25-07 by UnintentionalChaos]




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[*] posted on 25-3-2007 at 17:55


S.C. Wack says:

Quote:

Edit: It is interesting that neither Cumming above (whose experiments seem sometimes not based upon the experience of the authors and their students; but in this case probably is) nor Fieser (the eminently trustworthy but unscanned Experiments in Organic Chemistry 2nd ed.) basify before steam distillation



I noticed that too in the 1st procedure. I don't see how you could steam distill the aniline if it had not been basified to the free base. It would still be in the aniline HCl form, a salt.

The 2nd procedure uses sodium carbonate to basify.

I had Fieser & Fieser's text for my organic course in the 60's and liked their style. I have nver seen a copy of Experiments in Organic Chemistry. But as you say I would definitely trust Louis Fieser.




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[*] posted on 25-3-2007 at 23:58


Since HCl is only used to start up the reaction (FeCl3 can be used instead) and Fe is in large excess, the side products are only Fe hydroxides (very slightly basic buffer) and chlorides (only slightly acidic). Thus the post reaction medium is more or less neutral and the aniline can be steam distilled even without basifying. However, perhaps I'm wrong but I would expect aniline to somewhat complex with the dissolved Fe(III) ions, though this is probably of little importance where only little HCl is used and besides the complex is probably not particularly stabile anyway.



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