Sciencemadness Discussion Board - The short questions thread (1)

The short questions thread (1)

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Panache - 11-12-2008 at 17:55

what is the most likely culprit for tubidity in my sodium methoxide solution. I am making the methoxide by adding sodium metal to methanol, the methanol was dried over potassium carbonate, its density coming in at 0.78g/l, the sodium was patted to absorb excesss mineral oil then rinsed in methanol then added to fresh methanol. My only guess is that some paraffin was not effectively removed and this is forming a verry finely divided suspension, to test this i allowed a hunk of sodium to half dissolve before adding it to fresh methanol. All glassware was dry however what would the visual result be of using less than optiomally dry glassware i imagine one could not distinguish between a methoxide/hydroxide solution in methanol and a methoxide solution in methanol.

Fleaker - 11-12-2008 at 17:59

A shot from the ship here, but I think it is probably carbonate from minuscule amounts of CO2 reacting with the alkoxide.
Whenever I make methoxide solutions (especially the more concentrated it gets) I always notice this turbidity too whenever it is exposed to air. On one occasion, I made up a methoxide solution in MeOH and did it under argon and it was clear. Convinced me!

Panache - 11-12-2008 at 21:09

Quote:

Originally posted by Fleaker
A shot from the ship here, but I think it is probably carbonate from minuscule amounts of CO2 reacting with the alkoxide.
Whenever I make methoxide solutions (especially the more concentrated it gets) I always notice this turbidity too whenever it is exposed to air. On one occasion, I made up a methoxide solution in MeOH and did it under argon and it was clear. Convinced me!

Voila!, under argon tis also clear for me, thanking you!

raiden - 11-12-2008 at 22:47

Further to my vacuum questions, are there any good ways to improvise a cold trap? Just gave my medical pump a run and was boiling water at room temp with a change of oil

Panache - 12-12-2008 at 02:37

Quote:

Originally posted by raiden
Further to my vacuum questions, are there any good ways to improvise a cold trap? Just gave my medical pump a run and was boiling water at room temp with a change of oil

Man i have ben hanging out to give this tip. I use an ice-cream maker for my benchtop vac-pump cold trap. its probably the best thing i've ever improvised. It sits at -45. I turn it on at the start of the week and off at the end of the week, it has a basin of 1.5l in size which perfectly fits a 1L schott bottle and about 10mm of space around it to fill with methylated spirits as the cold bit. I simply have a bubbler head on the bottle. It's important to have any bleed valve (that bleeds to atmosphere) you might have between the cold trap and the pump, otherwise you consume all your cooling capacity cooling down the bleed air.
Of course it has it limitations being only at -45 but it beats the hell out of dry-ice or liq N2 for convenience. Its an italian thing but sold throughtout australia, i got mine second hand for like $30 because the stiring mechanism was broken, but given i wasn't making ice cream iit really didn't matter. Apparently this model always breaks stirrers so you should find one easily. The brand name is Nimox.

Aubrey - 14-12-2008 at 07:44

Ethylamine Synthesis?

I've searched fo a synth for this, wikipedia is a little lacking, would be interested to know how people here make it
thanks in advance

Klute - 14-12-2008 at 09:29

I don't thin k many people make it themselves, this is the kind of chemical that is much easier to purchase than to make...

Best options seems to me as been ethylation of protected ammonia, forming either the benzaldimine, or the phtalimide.. Ethylating acetamide or formamide with EtX, KOH and a PTC might be another good option, hydrolyzing the amide and distilling the ethylamine solution out.. There was a thread on diethylamine synthesis where I gave a few references on the subject, check it out: diethylamine synthesis.
I think there are some vapor methods using ethanol, ammonia and some catalyst, although you would surely obtain a mixture or mono-di and perhaps triethylamines.

DJF90 - 14-12-2008 at 10:23

How about an Sn2 reaction between ammonia in an appropriate solvent and an ethyl halide. A large excess of NH3 should be used to prevent multiple N-subtitutions (forming di and tri ethyamines, and quaternary ammonium salt).

Klute - 14-12-2008 at 10:49

No, unfortunaly this reaction cannot be used in a preparative way, there will always be various poly-alkylation products... Well, as far as I know.

I would rather concentrate on reactions producing only the primary amine, as seperating them will not be easy.

12AX7 - 14-12-2008 at 17:47

Phthalimide process.

Phthalic acid or anhydride + ammonia --> phthalimide (or buy phthalimide itself)
Phthalimide + base (pKa ~ 9) + electrophile (e.g. bromoethane) --> N-ethyl phthalimide
Hydrolyze alkyl phthalimide with dilute H2SO4. Freebase monoalkyl amine, purify etc.

Tim

Formula409 - 15-12-2008 at 14:58

Does anyone have any information regarding extracting PTCs from shampoos etc?

Formula409.

kclo4 - 15-12-2008 at 15:03

What PTCs are even in Shampoos?

Formula409 - 15-12-2008 at 15:12

Quote:

Originally posted by kclo4
What PTCs are even in Shampoos?

I do not know. I have read several forum posts which mention extracting them from shampoos and conditioners with no citations

Hmm. Will try and post links, however, with most things when you're looking for it you can never find it.

Formula409.

[Edited on 15-12-2008 by Formula409]

12AX7 - 16-12-2008 at 16:47

My shampoo lists ammonium laureth/lauryl sulfate, polymethacrylamidopropyltrimonium chloride and other chemicals that sound rich with alkyl chains. Detergents, especially antibacterials, often contain quaternary amines, though usually much larger than your average PTC, things like (12 to 18)-alkyl phenylethylmethylammonium.

Tim

not_important - 16-12-2008 at 17:03

Quote:

Originally posted by Aubrey
Ethylamine Synthesis?

Might consider the Hofmann rearrangement of propionamide.

Having said that, I've used the reaction of ethanol with ammonia over hot Ni-Cu to get a mix of all three ethyl amines and fractionated them. Wintertime in an unheated area and it's just separating three compounds that have boiling points about 40 C apart.

kclo4 - 16-12-2008 at 17:32

Quote:

Originally posted by Aubrey
Ethylamine Synthesis?

I've searched for a synth for this, wikipedia is a little lacking, would be interested to know how people here make it
thanks in advance

I'm not sure, This is how I would attempt to make it. I beleive Acetaldehyde + Ammonia might form a complex similiar to that of hexamine, which is formed from Formaldehyde and Ammonia.
You could then react that compound with some hydrochloric acid as they do hexamine in the methylamine synthesis. Look around on the Rhodium Archive, It has some information on making Methylamine.

If this reaction worked, it would allow using aqueous reagents, making it easier to produce mostly Ethlyamine, instead of the other amines that can form as well.
Ammonia and Ethanol seem like it would be nice, if you could regulate it to form mostly Ethylamine however.

Hoffman degradation would probably be the best if you could find the appropriate amide, which might be tricky, however acetaldehyde might be a bit tricky to get also.

Axt - 16-12-2008 at 23:17

Quote:

Originally posted by Aubrey
Ethylamine Synthesis?

Theres over 800 articles on scifnder reporting its preparation or at least as a product of a reaction. 145 reactions are given of which 100 are attached, they seem mainly by way of hydrogenation of acetonitrile.

There was only one reporting an ethyl analogue of hexamine and then no preparation, and was only a Jap patent.

Attachment: ethylamine product reactions.pdf (250kB)
This file has been downloaded 1999 times

Rosco Bodine - 17-12-2008 at 01:05

Nitroethane could possibly be reduced to ethylamine.
Al amalgam or Al isopropoxide would probably do it.

Metaldehyde and ammonium nitrate would possibly react
giving a nitrate salt which could then be basified to
free the volatile amine. This is not something I have ever seen described
but there is an analogous reaction for methylamine.

These reactions could be hazardous, but manageable.

You would have to distill out the free amine and
absorb it in water.

[Edited on 17-12-2008 by Rosco Bodine]

Klute - 17-12-2008 at 09:54

I'm sure to many nitroethane is more preciosu than ethylamine

I think the idea of oxidizing ethylamine to nitroethane popped up a few times!

I'm very impressed by the fact that Not_important succeded with vapor phase method, it would seem it is a very usefull procedure as diethylamine and triethylamine are also valuable reagents. I had just assumed seperating ethylamine and diethylamine would be very tricky..

How did you prepare your catalyst Not_important?

brew - 18-12-2008 at 13:50

question regarding spongy copper being used as electrodes, well this is what an article has implied. I have somewhat sorted this out.

[Edited on 19-12-2008 by brew]

[Edited on 19-12-2008 by brew]

solo - 20-12-2008 at 04:43

What would o-Phenylenediamine be called if it had a methylamine attached at both sites instead of the amine......solo

[Edited on 20-12-2008 by solo]

sparkgap - 20-12-2008 at 05:13

That would conceivably be N,N'-dimethyl-o-phenylenediamine, or better yet, 1,2-bis(methylamino)benzene.

sparky (^_^)

solo - 20-12-2008 at 05:37

......follow up question regarding amines

if this is true,

o-Phenylenediamine condenses with ketones and aldehydes to give rise to Schiff bases.

.......source,

http://en.wikipedia.org/wiki/O-Phenylenediamine

....then can this also be true?

N,N'-dimethyl-o-phenylenediamine condenses with ketones and aldehydes to give rise to Schiff bases.

Industrial Chemistry Question

kalacrow - 20-12-2008 at 15:16

Re: The Sodium-mercury amalgam created by electrolysis of a saturated NaCl solution - applicable to Li ?

Very facile process, and although you do need to distill off the mercury at the end to get the pure sodium out, it does work. It was originally used to make NaOH, but instead of adding water at the end, you can just remove the mercury.

I was wondering, I was looking at the LiCl/KOH electro process and I wondered if anything analogous to the sodium process could be done here? I am guessing I would have found something already if so... but I do know that Li/Hg forms an amalgam when mixed, and so the stopping block would be the solvent, electrochemical problems.

That is to say, is there a solvent that would free the Li ions, allow for electro amalgamation at a mercury cathode, and release Cl gas as a byproduct, meanwhile amalgamating the Li ions into the mercury, or is that just wishful thinking?

For that matter, what about KCl?

Pointing me at an Electro chem reference that resolves this would be a fine answer, as well!

Thanks

not_important - 20-12-2008 at 22:55

Lithium amalgam is less reactive towards water than sodium amalgam, you should be able produce low concentrations of Li without much trouble. Or at least much trouble from a technical standpoint, as Li-6 concentrates in the mercury the process is used to produce lithium enriched in Li-6 for tritium production, and thus falls into the arena of nuclear weapons technology.

here's a little on making Li-Hg amalgam and extracting Li metal from it.

Attachment: 80971.pdf (551kB)
This file has been downloaded 1231 times

Panache - 21-12-2008 at 16:29

Quote:

Originally posted by Rosco Bodine
Nitroethane could possibly be reduced to ethylamine.
Al amalgam or Al isopropoxide would probably do it.

Metaldehyde and ammonium nitrate would possibly react
giving a nitrate salt which could then be basified to
free the volatile amine. This is not something I have ever seen described
but there is an analogous reaction for methylamine.

These reactions could be hazardous, but manageable.

You would have to distill out the free amine and
absorb it in water.

[Edited on 17-12-2008 by Rosco Bodine]

Thats how i made it, i remember now. I used the nitrobenzene reduction reactions conditions using Sn/HCl in Vogel Vol 3 but using nitroethane, the ethylamine distills off from the horrendous reaction matrix at the end quite well. The aqueous solution can then be acidified and the Ethylamine.HCl crystallised and purified via recrystalisation, then basified using a minimum volume of caustic solution and distilling up a condenser running ~5C water then further up a NaOh pellet tower condensing the very pure ethylamine finally with ~-10 coolant or better still a dry ice condenser. If i recall correctly it was some >95% pure via gc. It took a couple of days but at the time was better than waiting for Sigma/Aldrich to ship via the slow boat (3months). Stores fine in the freezer at -20 with a good ground glass stopper, some silicon grease and an argon blanket. I only made ~50g this way so scaling it is anyones bet but i think the Sn reaction would be like NYE if it got too big.

Dry Box techniques.

Panache - 21-12-2008 at 16:41

So i'm new to this dry box game. Been doing some reading on it and using it i'm slowly getting the hang of it, as usual practice is about 200 times more valuable than theory. There are however some simple things which no-one ever seems to give advice on. At the moment there are two questions i have.
Firstly what is standard protocol for how long you leave the box after you open it to put something into it before it's considered 'dry' again. I am running argon in the box.
Secondly if i want to filter something that is in the freezer very cold and the crystalls i want to keep dry by the time i get it from the freezer to the dry box water has condensed a little on the vessel, then waiting for this to 'dry' in the dry box means the solution comes to temperature and the crystals re-dissolve a little. So its lose-lose, ha! Any tricks?
Maybe i need a freezer room with a dry box within it!!!

sparkgap - 22-12-2008 at 06:50

Quote:

...then can this also be true?

N,N'-dimethyl-o-phenylenediamine condenses with ketones and aldehydes to give rise to Schiff bases.

Best to try, I think, to be sure. Offhand, your diamine seems rather too hindered for me; if it reacts, the enamine ( >C=C-N<

and not the imine (>C=N-) will form.

sparky (~_~)

Klute - 22-12-2008 at 08:37

Panache, put your schlenk/flask in a sealed bag or similar with a dessicant inside before putting it in the freezer, then open the bag justbefore inserting the schlenk into the port, leave it under vacuum a while, and open it up.

I'm not familar enough with glove boxes to give you a detailed procedure. Are you talking of a true glove box, or a home built dry box? With a dry box, a few hours with CaCl2, eventually followed by an hour or two with KOH or even P2O5 should give you very dry atmospher, more than suitable for most needs.

Using a glove box, you will need to let is turn overnight to be sure you have minimum oxygen and humidity, we usually have the glow boxes continually on, even if we don't use them for more than a week, no need of ruining the catalysts for a little argon and the electricity for the vacum pump. Obviously this might not be an option for an occasional, personal use!

Intergalactic_Captain - 22-12-2008 at 15:04

Anyone familiar with the Letts Nitrile Synthesis? Ar-COOH + KSCN -> ArCN +CO2 + KSH
http://en.wikipedia.org/wiki/Letts_nitrile_synthesis
Can't seem to find a mechanism, wondering if it would work with indole-3-carboxylic acid.

solo - 22-12-2008 at 15:51

Letts Nitrile Synthesis

E. A. Letts, Ber. 5, 669 (1872).

Formation of nitriles by heating aromatic carboxylic acids with metal thiocyanates:

G. Krüss, Ber. 17, 1766 (1884); E. E. Reid, Am. Chem. J. 43, 162 (1910); G. D. van Epps, E. E. Reid, J. Am. Chem. Soc. 38, 2120 (1916); D. T. Mowry, Chem. Rev. 42, 264 (1948); F. Klages, Lehrbuch der organischen Chemie I (Berlin, 1959)

brew - 22-12-2008 at 17:25

Does anyone know about the reaction conditions for the formation of Ethylenediamine via - and only via - electrolyses. Apparently Glysine as a copper salt is used and is converted to Ethylendiamine, and also 4-aminobenzoic acid-also as a copper salt is converted to benzidine. The information I have found for this is far from clear, other than the copper salts of these reagants were used. NO other details, I have looked pretty hard and assuming that it is something very unpracticle or just plain bullshit. If it isn't then I'd be interested in exploring perhaps the use of copper acetate with someother reagant containing a carboxy group. ie, AA"S Any help would be appreciated

not_important - 23-12-2008 at 01:55

Sounds like a variation of the Kolbe electrolytic dimerization :
2 RCO2(-1) => R-R + 2CO2
this reaction generally doesn't work well with carboxylic acids that have electron releasing groups alpha to the CO2, alpha amino acids being one such. This indeed could be a case of a low yield reaction, references to it seem to date from the later 19th and early 20th century - http://tinyurl.com/85ybbs mentions it about half way down the right hand column - when there was a lot of examples of reactions giving a mishmash of stuff being described as making some particular compound.

The mixed reaction has been suggested a number of times with no success reported, although SFAIK without the use of copper salts.

Intergalactic_Captain - 23-12-2008 at 07:59

solo - Thanks, but I've already followed out all those refs (except the german book) and found nothing of particular use. None of them speculate a mechanism.

Anyone know if Carolina Biological Supply sells to individuals? Failing that, any larger chemical suppliers that do?

Formula409 - 23-12-2008 at 22:37

Aluminum Triiiodide preparation

1 mol Al turnings (or foil or powder all work well, powder is the quickest closely followed by foil then turnings a distant third) is combind with 1.5mol (note the excess of Al) of Iodine in 1000mL of cyclohexane (exchange solvent as needed but not diethyl ether!). This mix is stirred under reflux until the red colour has turned to a grey (about 1.5hrs with powder, 2-3 with foil, 4+ with turnngs). At this point the heat is turned off and the AlI3 in solvent allowed to cool to room tempeature with stirring.

Would Toluene be a suitable substitute in this reaction? What does "AlI3 in solvent" mean? The AlI3 is dissolved? How would it be claimed, surely they don't expect one to evaporate off 1L of solvent!

Formula409.

brew - 24-12-2008 at 01:28

Thankyou not_important, yes I see what you mean by the amine and its lone pair and its possible effect towards the partially positive charged carboxyl carbon. This would inhibits its cleavage I'd imagine. I need to think through this stuff rather than just be looking for reactions and yields. It may be interesting to explore the effects of various pH values - Iso point ect- with such a reaction, and perhaps the effects of copper. Ive read somewhere about glycine complexing with copper, and it may be worth exploring.

Klute - 24-12-2008 at 02:53

Formula, there has been a post on that exact subject not logn ago, try using the search engine. Basicly, yes AlI3 is dissolved in the solvent (and yes, they could expect you to evaporat 1L of solvent, it is not uncommon, but they don't here: you directly use the AlI3 in solution). There were some questiosn about toluene being able to disproportioante in presence of AlI3, even though it might not be a problem, better use something like hexane.

Read the related thread.

transformer - 24-12-2008 at 04:39

Does anyone know good solvent system (and maybe an aproximate Rf value) with regards to performing a tlc on phenylacetone?

DJF90 - 24-12-2008 at 06:00

@ Formula409: If aluminium powder and iodine powder is mixed as a small pile on a heat proof surface, then direct combination of the elements can bt achieved by adding a drop of water. The reaction is quite vigorous, and gives off alot of iodine vapour, but a cold surface abouve the reaction mixture should cause the iodine vapor to solidify, allowing you to recover some of this loss. Iodine is easy to powder using a pestle and mortar (or some inprovised aparatus) - Aluminium should be used as a powder, but it should still work if you cut Al foil into very small pieces.

My own question: I am currently learning about wagner meerwein rearrangements and am happy in general with the course of things. One thing however does not make sense. If we take for example neopentyl bromide and force it to react under Sn1 conditions, then there is a 1,2-methyl shift. I am happy with this.

However the mechanism I have is not particularly revealing, and I cannot quite see how the cyclic transition state is formed (And where is the positive charge in this transition state? Is it delocalised? I dont understand this.) Can anyone help?

Merry christmas everyone

[Edited on 24-12-2008 by DJF90]

Picric-A - 25-12-2008 at 00:42

This is probably a very simple organic question for some.
Starting from TerePhthalic acid, Benzene-1,4-dicarboxylic acid, Would it be possible to nitrate the acid group comming of the fourth carbon?
If so would i be able to simply nitrate it and hope it goes to the fourth group?
My apologies if this is elementary, my knowledge on reaction mechanisms is very poor.

kclo4 - 25-12-2008 at 18:47

Can the amines on amino acids be oxidized by Potassium Permanganate or Oxone (KHSO5) to nitro groups?
Also, does having the nitro group make it harder to decarboxylate or easier? The NO2 is very electronegative but I'm not to sure if that is even going to make much of a difference. I think it would make it easier to decarboxylate, but I haven't found any information on it, or on chloroacetic acids which i think would act similarly

If it is possible, seems like it would be easy to turn some of the smaller amino acids into Nitroacetic acid, and Nitropropionic acid. Might be kind of useful

powers gonna go out soon

sparkgap - 25-12-2008 at 19:55

kclo4:

With regards to oxidizing glycine, do take a look at this. I assume something similar might happen to larger amino acids.

Picric-A:

If you mean nitrating the benzene ring, you might have to resort to very harsh conditions to succeed because the two carboxyl groups will withdraw electrons from the benzene ring and make it less susceptible to electrophilic attack.

If you mean attaching a nitro group to the carboxyl group... I don't think you can, and I can't seem to find successful examples of such.

sparky (~_~)

texaspete - 25-12-2008 at 23:04

Question: Can Bakelite be made by the home chemist?

I've found various threads mentioning that bakelite can be made form formaldehyde and phenol, but no threads describing the process. Wiki says says it requires high heat and pressure...

not_important - 25-12-2008 at 23:54

Yes, if you are not out for a practical grade but just want to play with the process.

Mixing solutions of formaldehyde and phenol, with a molecular ratio of about 1.5:1, and adding a solution of NaOH to give a pH around 10, then warming to 60 to 70 C will give a prepolymer. Care must be taken to prevent thermal runaway of the reaction, else it will go too far.

This stage gives a still liquid if syrupy product. It would be mixed with wood flour (fine sawdust) and then heated to 120 to 130 C to complete the reaction to a thermoset plastic. The pressure was generally used to form or mold the plastic as it was reacting to set, just making small lumps wouldn't require that. Large amounts tend to overheat in their interior, cracking the piece, so slow heating and applied pressure would be needed for them.

A few old references. They state that pressure on the order of "50 to 100 lbs/sq-in" give a solid product rather than one containing bubbles or even being sponge-like. You can also use a bit lower ratio of formaldehyde to phenol, say 1.1:1, and then add a strong solution of HMTA to the resin to given enough additional formaldehyde to bring the ration up to 1.6:1 or higher. The HMTA decomposing on heating but stable enough at room temperature that more fluid resins can be prepared for use as coatings and such.

http://books.google.com/books?id=Vn1BAAAAIAAJ&pg=PA585&a...

http://books.google.com/books?id=X7OEAAAAIAAJ&pg=PA211&a...

[Edited on 26-12-2008 by not_important]

Picric-A - 26-12-2008 at 13:17

I was hoping to replace the -OH group with an -NO2 group, not add it on.
I dont see this working either to be honest.
Would it be possible to nitrate Benzoic acid and if so, what percentage of the Nitro group will go to the fourth carbon?
My aim is 4-nitrobenzoic acid by the way

thanks,

[Edited on 26-12-2008 by Picric-A]

dann2 - 26-12-2008 at 15:03

May be of some use:

A Bakelite + KClOx propellent.

Making the resol is relatively easy but if you want to make this king of propellent on a regular basis you need some sort of Vacuum pump
+ chamber and heater (inside the vacuum chamber). It is however possible to make a sstisfactory resol without a vacuum system but the resol takes a lot
longer to cure.
Note Phenol and Formaldehyde are poisonous and this procecure should be carried out in the open. Once the initial reaction is over and the syrupy
stage is reached then the stuff is relatively harmless (apart from flammability).

Method
Add 20g of Phenol and 0.5ml of 40% NaOH solution to 40ml of 37% aqueous Formaldehyde solution (Formalin). Bring to the boil and boil untill the liquid
becomes noticably thicker (typically in the order of 10 minutes). If you stop too soon it will take forever to cure the resin, if you wait too long it will beocme too
viscous to mix with the oxidizer (like toffee) or even become fully cured in whatever vessel you were boiling it in. You might be able to salvage it with alcohol.
The resol is removed from the heat and 108g of KClO4 or 125g KClO3 is stirred in. The resultant is poured or pressed into a mold/casing. Try your utmost
to get rid of bubbles at this stage. The grain is cured by placing
it in an oven at around 50C or so for about 12-24 hours. The temperature is slowly increased untill the resin sets rock hard at a final temperature of 120C or so.

If you increase the temperature too quick big bubbles will form in the grain.. The first cool part is mostly to allow excess water to evaporate., the actual curing
takes place at the higher temperatures. A resol that has been dried in a vacuum can be cured somewhat faster.
Never tried the above myself BTW.
Dann2

kclo4 - 26-12-2008 at 15:04

sparkgap, thanks for the link but it seems to be oxidizing it further then I want.

I was thinking more so of turning glycine into nitroacetic acid. It seems that amines can be turned into NO2 easily with KMnO4 or Oxone and acetone (or just Oxone if it is an aryl amine) but I think the carboxylic group might interfere with that reaction.

Also, is something like Nitroacetic acid/nitroacetate easier to decarboxylate compared to acetic acid/acetate?

Picric-A - 26-12-2008 at 16:28

KClO4, why not make Nitroacetic acid from nitromethane (if nitroacetic acid is your desired product)
It seems very easy, http://orgprepdaily.wordpress.com/2008/03/10/nitroacetic-aci...

kclo4 - 26-12-2008 at 16:49

Not in need of nitroacetic acid, just want to know if the NH2 on amino acids can be turned into NO2 for some other experiments I'd like to try eventually

sparkgap - 26-12-2008 at 18:02

Quote:

Originally posted by Picric-A
Would it be possible to nitrate Benzoic acid and if so, what percentage of the Nitro group will go to the fourth carbon?
My aim is 4-nitrobenzoic acid by the way

After nitrating benzoic acid under harsh conditions, you'll get mostly the meta-isomer, and only a touch of the ortho and para isomers. That is because the carboxyl group is an electron-withdrawing, meta-directing group.

If it is the para isomer you wish, just oxidize para-nitrotoluene.

Quote:

Originally posted by kclo4
sparkgap, thanks for the link but it seems to be oxidizing it further then I want.

I know, that's why I gave the link to the paper.

I did find a JOC reference that claims to be able to turn amino acids to alpha-nitro acids... the catch is that you need hypofluorite in acetonitrile.

Quote:

Originally posted by kclo4
Also, is something like Nitroacetic acid/nitroacetate easier to decarboxylate compared to acetic acid/acetate?

It should. A nitro group attached to the alpha carbon of the acid has the same effect as the non-carboxyl carbonyl in acetoacetic acid.

sparky (~_~)

not_important - 26-12-2008 at 18:43

Quote:

Originally posted by Picric-A
...
Would it be possible to nitrate Benzoic acid and if so, what percentage of the Nitro group will go to the fourth carbon?
...

Very little, nitration of benzoic acid is used to make 3-nitro aand 3,5-dinitro benzoic acid; it needs concentrated acids aand forcing conditions.

Best to mono-nitrate toluene, isolate the p-nitrotoluene, and oxidise that to the benzoic acid.

But if you insist on starting from PABA, see

http://www.orgsyn.org/orgsyn/orgsyn/prep?prep=cv6p0803

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv3p0334

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv5p0845

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv5p0367

Note that while the oxidation with KMnO4 can give excellent yields, it only work well if at all with tertiary amines R3C-NH2

kclo4 - 26-12-2008 at 19:02

Quote:

Originally posted by sparkgap

I did find a JOC reference that claims to be able to turn amino acids to alpha-nitro acids... the catch is that you need hypofluorite in acetonitrile.

sparky (~_~)

*sigh*
haha but thank you

I'll look around some more, that was helpful

sonogashira - 29-12-2008 at 06:50

Quote:

Originally posted by Picric-AMy aim is 4-nitrobenzoic acid by the way

Here is a nice method for you Mr Picric Acid starting with PABA and oxidizing with DMDO which may be generated in-situ from oxone and acetone. 95% isolated yield too! You may need to look up some other papers for preparation of DMDO solution but references are given within.

Attachment: Oxidation of Aromatic Amines with DMDO.pdf (919kB)
This file has been downloaded 861 times

sonogashira - 29-12-2008 at 07:08

And here is another very interesting paper for you Mr Picric Acid.

I go back to Taiwan in the new year for national service so maybe i won't be able to visit so much for a while. All the very best to you all for the new year and keep doing interesting Chemistry! I have learned very much here and also with my studies. And now I have many interesting books too!!! I finally realized that Nicodem was right, reading books is better than asking many questions! Thank you for all your help over past years and pray for me that China sends more pandas and no bombs

Attachment: A Mild Oxidation of Aromatic Amines with Oxone.pdf (114kB)
This file has been downloaded 10434 times

sparkgap - 29-12-2008 at 08:12

I will merely hasten to add that you should be very cautious in the handling of DMDO... it still is a peroxide of acetone after all.

(edit: Alright, I will have to ask something after all. I am far away from my Merck Index, so could someone be so kind as to post the whole Merck Index entry for the antihyperlipidemic acipimox? I am especially looking for synthesis-related references.)

sparky (~_~)

[Edited on 30-12-2008 by sparkgap]

crazyboy - 30-12-2008 at 21:00

Any idea how to synthesize tetramethylammonium nitrate? I don't really have much info other then its name.

not_important - 30-12-2008 at 21:27

React tetramethylammonium chloride/bromide/iodide with AgNO3 in solution, filter off the silver halide ppt.

sparkgap - 30-12-2008 at 21:32

Surely as straightforward as tetramethylammonium hydroxide and nitric acid, right?

(edit: cripes, n_i gave the better one...

)

sparky (~_~)

[Edited on 31-12-2008 by sparkgap]

Klute - 4-1-2009 at 06:52

Or react ammonia or (mono-, di-, tri-)methylamines with excess methyl nitrate?

SelfInflicted - 4-1-2009 at 12:15

Today I wanted to make zinc chloride.

I dissolved some Zn metal, from zinc carbon batteries, and a scored copper penny in HCl from the hardware store sold as muriatic acid.
I put this on the hotplate to speed the reaction.
I was left with an oily solution that appears reddish brown with some black particles floating about.

What could cause this to appear reddish brown?

kclo4 - 4-1-2009 at 20:39

I believe Muriatic acid often contains some iron compounds in it.
Also, you didn't do this in a metal pot or can, and you did take out the copper left behind from the penny, correct?
I am going to guess it is probably an Iron or Copper impurity but is hard to tell until you give us a bit more detail.

By the way, You won't be able to produce dry (anhydrous) zinc chloride. ZnCl2 is a Lewis acid and you will either get a hydrate or an oxychloride.

SelfInflicted - 5-1-2009 at 17:54

kclo4, thanks for the reply.

I am sure the muriatic acid I am using has some iron contamination. I would not think enough to have this as dark as it is. I am thinking the zinc was not that pure and possibly the zinc in the penny is not as pure as most claims I have seen. Could be small copper particles also.

I tried another route.

This time I added zinc oxide in the HCl untill it would not react any more. This reation was exothermic.

I decanted the solution and left the un-reacted/undissolved zinc oxide behind.

I heated the solution to boiling and monitored the temperature at 133C there was not enough depth to accuratly measure with my PI thermometer. At this point the solution was clear but slightly yellow, as is the muriatic acid.

I let this cool. It was not a reddish brown as the previous attempt. So I thought I would push this further to see what color I would get. I got a salt forming at 203C (IR therm) and dry at 227C. Its very slightly gray/brown, i would say dingy.

So this must be Zinc oxychloride with some iron and other contanimants ?

It is hydroscopic and feels greasy and then oily.

I have tried to search the net for zinc oxychloride and can not find much about its properties. Any hints ?

I would also like to find out at what point does the zinc chloride convert to oxychloride and how.

I guess thats not such a short question thread.

kclo4 - 5-1-2009 at 19:55

Upon drying it, did it let off HCl fumes?
You either have Zinc oxychloride, or hydrated Zinc Chloride. At 227*C you probably have the oxychloride, but if absolutely no HCl fumes were let off, maybe not.

Zinc chloride just converts to Hydrogen chloride and Zinc oxychlorides by hydrolysis. aluminum chloride, a much stronger Lewis acid, can be simply heated with water and precipitate out aluminum hydroxide and produce hydrochloric acid (always thought this might be an interesting way to produce hydrogen, since you are only using up water and aluminum while recycling HCl)

I found this interesting when reading about since chloride, How the heck does it work?

"Concentrated aqueous solutions of zinc chloride have the interesting property of dissolving starch, silk and cellulose, so that solutions cannot be filtered through standard filter papers." - http://www.experiencefestival.com/a/Zinc_chloride/id/1952449

I can't find much on Zinc oxychlorides.. but I didn't look very hard.. perhaps there is a better name for them?
I think its chemical formula is Zn(OH)Cl, but I could be wrong.

UnintentionalChaos - 6-1-2009 at 10:50

My question is about cyanuric acid.

I've read in several places that it crystallizes from water as the dihydrate, but does anyone know how stable this hydrate is? For example, will storing over H2SO4 in a dessicator leave the anhydrous product, or will it not lose any water? I've been meaning to do some experiments, but the stoichiometry will go out the window if I don't know if it's hydrated or not. Thanks.

jhullaert - 7-1-2009 at 06:58

Hi

I have a small problem and I thought this was the best place to ask it.

I want to know the pKa value of caffeine.
When I searched on google I found every value starting from -1.14 to 50.

First I have to know if caffeine is an acid. I've read that a 1% solution has a pH of 6.9 so it has to be a weak acid if it's correct. Maybe they found this value using a digital pH-meter that gave a slightly wrong measurement.

If it's an acid then it's probably the methylated amine group (between the two carbonyls that loses a proton. The charge is divided between the methylated amine and the 2 carbonylgroups. Is this correct?

thanks

Jor - 7-1-2009 at 10:27

No. The nitrogen between the carbonyls has formed 3 bounds, none with a plain hydrogen (no N-H). You are right a compoud with a nitrogen between two carbonyls can act as an acid, like in the case of phthalimide. But a N-H bond is required, and this nitrogen is methylated.

All other nitrogen can be protonated as far as I know, but it doesn't seem to be very likely that that occurs to any great extent, looking at the structure, especially not with something like water (strong acids like HCl should do the job though).

There are 10 hydrogens in caffeine, of wich 9 are in the methyl-groups. The final hydrogen is bonded to the carbon on the 5-ring, and this is the only possible candidate. Normally C-H bonds will not break up giving a proton and carboanion, because of the great stability of a C-H bond and the high instability of a carboanion.
However, this carbon is bonded to 2 nitrogen's, of wich one is a double bonded. Both these nitrogen's are electron withdrawing and pull the electrons of the carbon towards the nitrogen. This has as a result that the electrons of the C-H bond are pulled more closely to the carbon, and therefore making the C-H bond more loose/weaker. Therefore I think it would be likely that caffeine is SLIGHTLY acidic. However please note that at pH 6,9 the H3O+ concentration is still EXTREMELY low.

I'm n ot sure if I'm right here, it's just my hypothesis. Can anyone tell me if this is true?

turd - 7-1-2009 at 11:56

http://en.wikipedia.org/wiki/Caffeine#cite_note-0
The pKa values of -0.12->1.22 are for the *protonated* form. That means the protonated form is a rather strong acid and therefore the non-protonated form is a weak *base*.

Of course that aromatic H is probably quite easily nibbled off, making the whole thing amphoteric.

jhullaert - 8-1-2009 at 02:00

So the protonated form is with an hydrogen at the double bonded nitrogen atom of the 5 ring. is that correct?

thanks for helping me.

Jor how was your holiday? :cool:

Jor - 8-1-2009 at 05:37

I'm not sure wich N-atom is protonated, e.g. wich N-atom had the strongest basic properties. I do know that the hydrogen is at the C-atom in the 5-ring is the only hydrogen wich can be splitted of as a proton.

My holiday was great. Thailand. What a country! :cool:

Rotterdam is just a village compared to the chaos in Bangkok.
Only one thing made me a bit scared. My dad and sister wanted to buy some Thai vegetables at the airport as a present, and took it in their hand luggage. I told to do not, but they did. We had some problems with the customs. Gave me thrills, I know what happens when you smuggle something: Bangkwang aka Bangkok Hilton. Ofcourse I knew we did nothing wrong, but when you're there, it's not something nice.

And yours? :cool:

hector2000 - 8-1-2009 at 09:21

what is name of this componet?this componet is possible?if yes what is another name of it?

thx

turd - 8-1-2009 at 09:25

Quote:

Originally posted by hector2000
what is name of this componet?this componet is possible?if yes what is another name

acetophenone

Nicodem - 8-1-2009 at 09:26

That is the enolic form of acetophenone. Simple enols like this one are not stable compounds. They can only be prepared in completely neutral media and their shelf life is generally less then 30 minutes. In the slightest presence of acids or bases they immediately tautomerize to the corresponding ketone in matters of seconds.

jokull - 8-1-2009 at 09:36

Quote:

Originally posted by hector2000
what is name of this componet?this componet is possible?if yes what is another name of it?

thx

This is called 1-phenylethenol. It should be possible since it has a CAS number: 4383-15-7.

UnintentionalChaos - 8-1-2009 at 09:56

It's possible to trap that form by making the OH group an ether. Trimethylsilyl is fairly commonly seen, I believe. You'd need trimethylsilyl chloride and a strong base to generate the enolate.

[Edited on 1-8-09 by UnintentionalChaos]

noname01.bmp - 262kB

appetsbud - 8-1-2009 at 11:36

is silica gel classed as a molecular seive? and if so, what adsorbtion capability? if not, is it possible to use it as a substitute for 3A molecular seives? will it remove substances other than water from things?

thanks

Nicodem - 9-1-2009 at 00:40

No, neither silicagel or silica is a molecular sieve. Molecular sieves are zeolite-type materials. They are very cheap, almost as cheap as silica. Silicagel can absorb some water, but it does not do so as energetically as molecular sieves and it can therefore not be used for the same principle. Also, I never heard of silicagel being used in liquid phase, generally it is just used to maintain dry atmosphere in desiccators. As for it absorbing other things, it depends on what other thing is.

Quote:

Originally posted by UnintentionalChaos
My question is about cyanuric acid.

I've read in several places that it crystallizes from water as the dihydrate, but does anyone know how stable this hydrate is? For example, will storing over H2SO4 in a dessicator leave the anhydrous product, or will it not lose any water? I've been meaning to do some experiments, but the stoichiometry will go out the window if I don't know if it's hydrated or not. Thanks.

I think if you store it over H2SO4 it will not loose hydration water at room temperature, at least if it is a real crystal hydratation water. Hydrated cyanuric acid has the form of larger needles (it looks "crystalline", 1-2 mm needles, depending on how slowly they grew), while the anhydrous form is more fine (more powder-like). I have no idea at which temperature the hydrate starts loosing water.

[Edited on 9/1/2009 by Nicodem]

S.C. Wack - 9-1-2009 at 11:03

Quote:

Originally posted by Intergalactic_Captain
Anyone familiar with the Letts Nitrile Synthesis? Ar-COOH + KSCN -> ArCN +CO2 + KSH

Quote:

Originally posted by solo
E. E. Reid, Am. Chem. J. 43, 162 (1910); G. D. van Epps, E. E. Reid, J. Am. Chem. Soc. 38, 2120 (1916)

I posted the JACS article before in a relevant thread (acetonitrile), in a zip due to the attachment size limit at the time, and have reattached it there just now.

I did this because I've been reading some lately, because the American Chemical Journal has just become available at Google Books. Including the above citation from 1910, which jogged my memory:
http://books.google.com/books?id=AcsAAAAAYAAJ&pg=PA162

This is interesting because it shows that ferrocyanide and sulfur substitute for thiocyanate, at least with metal benzoates.

It is nice to finally be able to read that journal. Unfortunately only 1880-1910 volumes are available, and only a third of those. The Big State U. down the road has it in inaccessible offsite storage, like nearly all QD journals, in favor of barren expanses of carpet. Literally half the library is empty space. The local library just down the street, which used to enable me to find many thousands of journal references, put ALL of their journals in inaccessible offsite storage a couple years ago.

Picric-A - 9-1-2009 at 14:44

Hey, Does anybody know the percentage yield of 4-Nitrotoluene after a mono nitration?
thanks,

Reference Information

solo - 9-1-2009 at 14:46

STUDIES IN THE PREPARATION OF NITRILES. II. THE PREPARATION OF ALIPHATIC NITRILES.
G. D. van Epps, E. Emmet Reid
J. Am. Chem. Soc. 1916, 38 (10), pp 2120–2128

Attachment: STUDIES IN THE PREPARATION OF NITRILES. II. THE PREPARATION OF ALIPHATIC NITRILES.pdf (553kB)
This file has been downloaded 1222 times

not_important - 9-1-2009 at 17:40

Quote:

Originally posted by Picric-A
Hey, Does anybody know the percentage yield of 4-Nitrotoluene after a mono nitration?
thanks,

Under what conditions? Simple nitration with HNO3 gives roughly 60 o / 40 p, but I've read reports for different conditions ranging from 2.5:1 o/p to 1:4 o/p ratios.

Magnesium

Squall - 9-1-2009 at 18:14

I am looking for a small quantity of scrap magnesium. I would appreciate any information on where to get some or if you have some to sell or give. Thanks

[Edited on 9-1-2009 by Squall]

Picric-A - 10-1-2009 at 02:27

I was thinking a simple nitration with HNO3/H2SO4, with reflux at 50degrees C.
Do you know what the conditions are to get the 1:4 o:p ratio? seems temting...

Squall- try marine stores, they may have old magnesium sacrificial anodes, other than that any scrap metal dealer may be able to help you,

Thanks,

not_important - 10-1-2009 at 03:33

Don't think you need to heat for nitrating toluene, and I'm puzzled at how you reflux that mix at 50 C .

A lot of the high ratio methods depended on using hardtogetium difficulttoobtainate, I don't remember real details. Vapour phase nitration over Zeolite H-beta at 120-140 C converts about half the toluene and 3/4 of the HNO3 to mono-nitrate with less than 1% loss to benzoic acid, ratio of p/o was around 2.6 to 2.8 to 1.

Picric-A - 10-1-2009 at 05:34

Your right, i was confusing toluene with benzene, sorry.
I am probably going to try a normal nitration folowed by seperating the 40% P from the O.
Vapour phase nitrations are beyond my ability.
Thanks.

hector2000 - 11-1-2009 at 01:33

this reaction is possible?

sparkgap - 11-1-2009 at 02:20

No, for one thing lead tetraacetate cannot magically convert an -OH group into a -CH3 group.

sparky (~_~)

turd - 11-1-2009 at 04:50

Quote:

Originally posted by sparkgap
No, for one thing lead tetraacetate cannot magically convert an -OH group into a -CH3 group.

No, not by magic: http://en.wikipedia.org/wiki/Dakin-West_reaction#General_ket...

sparkgap - 11-1-2009 at 05:39

And if you'll look at what turd posted, the extra carbon should have come from somewhere, acetic anhydride in the case of Dakin-West.

sparky (~_~)

turd - 11-1-2009 at 07:56

Or from Pb(OAc)2 in the "lead acetate process".

Quote http://en.wikipedia.org/wiki/Phenylacetone:

Quote:

For example, phenylacetic acid is distilled with lead acetate to yield phenylacetone.

So the question has some merit.

Maja - 11-1-2009 at 10:11

I have MEK/Water mix distilled from nail polish, what would be the best way to separate MEK from water ?

solo - 11-1-2009 at 13:58

.....try distilling it out since it goes at 80C .... or make an adduct and separate that way........solo

solo - 11-1-2009 at 14:08

I have recently tried reading the rotation of a sample using a polarimeter, I don't know the angle of rotation of (2S)-N-methyl-1-phenyl-propan-2-amine, because I don't know the concentration of the sample to use .....also I guess recemic (2S)-N-methyl-1-phenyl-propan-2-amine will have no rotation at all?...and so what is the l-isomer's rotation ?.... does anyone know where I might look to find this information .....solo

DJF90 - 11-1-2009 at 16:03

With angles of rotation, both isomers will rotate the same amount so long as the concentration is the same, but in opposite directions (one will be clockwise, the other is counterclockwise, but which isomer rotates in which direction is found experimentally. You are right in saying racemic mixtures have no rotation though. The wikipedia page below ought to help slightly: http://en.wikipedia.org/wiki/Specific_rotation . Where to find the specific rotation for this compound is beyond me, although I would hazard a guess and say the merck index, seeing as it has a vast quantity of data on different compounds. This page may also help: http://library.tedankara.k12.tr/carey/ch7-4.html

[Edited on 12-1-2009 by DJF90]

solo - 11-1-2009 at 16:47

.......`i just read my own question, `i can be so blind sometimes, hence if recemic is 0˚ rotation it would mean that the l,isomer has the same 18˚ that the d, isomer has but in the opposite direction ......what `i need to know what concentration of the material should be that i load into the vial that is used to read in the polarimeter........solo

497 - 11-1-2009 at 18:42

Will this work?

NaNO2 + Na2S2O7 -> N2O3 + Na2SO4

or..

4NaNO3 + 2Na2S2O7 -> 2N2O4 + O2 + 4Na2SO4

Specifically will it work by direct reaction of the reactants in the solid state?

hector2000 - 11-1-2009 at 23:41

how much is solubility of sodium phenylacetate in acetone and ETOH?

Nicodem - 12-1-2009 at 01:41

Quote:

Originally posted by solo
.......`i just read my own question, `i can be so blind sometimes, hence if recemic is 0˚ rotation it would mean that the l,isomer has the same 18˚ that the d, isomer has but in the opposite direction ......what `i need to know what concentration of the material should be that i load into the vial that is used to read in the polarimeter........solo

Literature values are always described as specific rotations, therefore it does not matter much what is the concentration of your sample, because you have to calculate the specific rotation anyway. Optical rotation is wavelength, solvent and temperature dependent, so you need to use these conditions as reported in the literature (in reality they are also concentration dependent due to molecular association, but this effect is usually minor).
http://en.wikipedia.org/wiki/Specific_rotation

aniline HCl solubilities

chemrox - 12-1-2009 at 14:24

I need an expanded list of solvents for aniline HCl..ie as many solvents as possible. Thanks, CRX

kclo4 - 12-1-2009 at 14:59

Quote:

Originally posted by 497
Will this work?

NaNO2 + Na2S2O7 -> N2O3 + Na2SO4

or..

4NaNO3 + 2Na2S2O7 -> 2N2O4 + O2 + 4Na2SO4

Specifically will it work by direct reaction of the reactants in the solid state?

If they were ground to a fine powder, and heated it would work. Of course, at standard pressures, they would form as the gases NO and NO2 which would then need to be condensed to form N2Ox.

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