guy
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Help turning chloroform to formate.
I tried adding NaOH(aq) to chloroform. Reaction is too slow. I tried an alcoholic solution and the reaction is very vigorous but turned orange along
with a strange smell.
I didnt know exactly how to test for the formate, but I tried Fehling's solution and got nothng.
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The_Davster
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I tried this a couple years back. Just chloroform in a NaOH solution, a month later after sitting it had dissolved. Evaporation yieldied a pure
white powder.
But I suppose if you want something relativly quick, reflux would be your best bet.
I would avoid extraneous solvents, I have a feeling protic solvents like ethanol would react causing unintended side products.
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garage chemist
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3 mol of NaCl are going to be produced per mol of formate. Evaporation will therefore not yield a pure powder.
Anyway, a phase transfer catalyst will most likely help. Get triethylamine and react it with benzyl chloride.
Why are you trying to turn chloroform into formate in the first place? Cant you buy formic acid? Its a cheap chemical, and unrestricted.
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guy
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Just for fun and experimentation.
So I have 10% quaternary ammonium solution. Should I use a stoichiometric amount? Because I tested that using a few mLs of that solution, and the
reaction was still kinda slow after one day too.
Also, should formate reduce copper salts? I need to test for formate somehow.
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woelen
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Formate probably reduces copper (II) to copper (I), but only at high pH. I don't expect any reduction at low pH. At such conditions, copper (II)
cannot go to copper (I), it must go all the way to copper metal and formic acid is not that strong a reductor.
A compound, which definitely is reduced by formic acid is dichromate, and the color of the solution goes from orange to green or dark purple. A little
heating helps speed up the reaction.
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Nerro
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Could a drop of washing up liquid serve as a phase transfer catalyst? It seems like the logical thing to use for a home chemist but perhaps there is
some real problem with the perfumes or other "contaminations" that make it useless. I remember that when I was making soap out of vegetable oil and
NaOH soln a drop of washing up liquid sped up the reaction greatly.
#261501 +(11351)- [X]
the \"bishop\" came to our church today
he was a fucken impostor
never once moved diagonally
courtesy of bash
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The_Davster
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I had meant pure in terms of colour, but thanks GC, I knew I was forgetting something. I do not recall purifing it, I never used the formate
produced.
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guy
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So I will try adding quaternary ammonium salt as a phase transfer catalyst.
What I am planning to do is to evaporate and get the salts (sodium chloride and sodium formate), and then react that with EtOH and sulfuric acid to
get ethyl formate.
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Sauron
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You are trying to prepare normal alkyl formate esters like methyl formate, ethyl formate etc from chloroform and alcoholic NaOH?
Those esters are extremely volatile, and you are probably losing them to evaporation as fast as they are being made.
Chloroform in many or most places is now restricted, I can't buy it where I am without a special government permit probably not forthcoming. So I must
make it. Having done so I am not interested in using it to make esters I can easily buy or prepare in a more conventional way.
Orthoformates are more interesting and those can only be had AFAIK from chloroform and Na metal in anhydrous methyl or ethyl alcohol. But again why
waste precious chloroform AND precious sodium on ortho-esters you can buy unrestricted?
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guy
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So is it even possible to get the ester by distillation? I want to make formamide from the ester.
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garage chemist
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Yes it is possible to get the ester by distillation, but using chloroform to make formate salts is nonsense. You are destroying a valuable chemical
(chloroform) to make a cheap and much easier obtained one (formic acid).
Buy formic acid and make the ester from this (make ethyl formate, methyl formate is extremely volatile and you need to take special measurements in
order to condense it).
Remember that formic acid is a strong enough acid to catalyze its own esterification, and that you must not add any mineral acid, otherwise most of it
will decompose into carbon monoxide.
I have done the reaction of ethyl formate with ammonia solution myself long ago. Contrary to the slow reaction of ethyl acetate with ammonia solution,
the reaction of ammonia with formate esters is fast and strongly exothermic. Add the ethyl formate to the ammonia under cooling and good stirring in
order to avoid evaporating the ammonia and ester by the heat generated.
Formamide can not be distilled at ordinary pressure (decomposes into CO and ammonia). You can only distill out the ethanol and water at ordinary
pressure.
If you want the formamide for preparing HCN by thermal dehydration, you need a tube furnace and suitable catalyst. The decomposition into CO and
ammonia instead is a competing side reaction which is the main reaction if no suitable catalyst is used.
Ammonia will also strongly destabilize HCN and rapidly cause its polymerisation, making an acid wash of the HCN obtained necessary.
[Edited on 24-5-2007 by garage chemist]
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guy
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Thanks for the info GC. Im just using a teeny bit of chloroform to make formate salts...just to experiment.
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not_important
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Chloroform reacts with alkoxides to give orthoformic esters, often shorted to ortho esters
3 RONa + CHCl3 => CH(OR)3 + 3 NaCl
these rapidly hydrolise in aqueous acid. Orthoformic acid itself is not stable, giving water and formic acid. Given the relative acidity of alcohols
and water, you shouldn't have been able to make much of the alkoxide and thus little if any of the orthoester. Remember that strong base, alcohol,
and air, can give oxidation products.
If I was doing this, and starting from scratch, I'd do the haloform reaction with ethanol. Start with the full amount of bleach and slowly add
the alcohol so that as much of it as possible goes to CHCl3. After adding the calculated amount of alcohol and letting it sit a bit, add enough
ethanol make up about 10% of the total volume, and 2.1 moles of NaOH for each mole of chloroform that was made. Let it sit without ready access to
air, for some time - until the chloroform smell is gone. The extra ethanol should function just as a solvent, if you add it early you can get some
acetaldehyde and chlorination products beside chloroform.
CH3CH2OH + 4 NaOCl => NaCl + HCO2Na + 2 NaOH + CHCl3
CHCl3 + 4 NaOH => 3 NaCl + HCO2Na + 2 H2O
Filter, evaporate, mix with ethanol, add enough concentrated HCl to almost neutralise all the sodium formate. Simplest way to do this is to titrate
the reaction, add concentrated hydrochloric acid until the pH is 4 or a touch lower. Then fractionally distill the ethyl formate off at 54 C; methyl
format could be made using methanol, but with a boiling point of 32 C you need to use ice or a freezing mixture to condense it.
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Klute
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Apparently, orthoformate esters can be obtained in usefull amouts using CHCl3 and NaOH, with an appropriate inerte solvant; remember:
psyloxy
(Hive Addict)
07-01-04 02:18
No 516633
Did the Japanese do the impossible ?
Trimethylorthoformate from chloroform with NaOH/MeOH ? It just looks like. No NaOMe needed.
Am I the only one that is unable to see more than the first page of this patent ?
(www.espacenet.com doesn't work for me, I get all my patents from www.depatisnet.de)
Patent JP000058225036AA
PURPOSE: The reaction mixture resulting from a reaction between methanol or ethanol, a caustic alkali and chloroform is combined with a specific
solvent to effect almost quantitative extraction of the titled compound into the solvent.
CONSTITUTION: Methanol, or ethanol, a caustic alkali, preferably an alcoholic solution of sodium or potassium hydroxide, and chloroform are made to
react and the resultant reaction mixture is combined with a solvent which is selected from aliphatic or aromatic hydrocarbons, ethers or their
halogenated products, and is low in compatibility with water and capable of separating the product by distillation, in an amount of 1.0W1.5 times the
volume of the product. Then, they are vigorously stirred at 20W35°C and separated by standing to effect extraction of the objective orthoformate into
the organic solvent layer, while the alkali chloride goes in the aqueous layer. The above solvent can be added at the reaction stage except carbon
tetrachloride.
--psyloxy--
(jumping a few posts on tosylations)
yei
(Stranger)
08-17-04 15:21
No 525886
I guess it would stand to reason
It would make sense that ROH + CHCl3 + [OH-] would produce orthoformates, to me at least--chloroform + hydroxide produces dichlorocarbene, which could
insert into the alcoholic -OH group and produce CHCl2OR. However, when this happens, another HCl can become eliminated, forming another carbene, and
inserting again to produce CHCl(OR)2.
The process would repeat a third and last time to yield CH(OR)3, trialkyl orthoformate. As long as the formed carbenes reacted with alcohol better
than with the water formed by neutralization of base by the eliminated HCl, it would work.
I guess this is a similar process to how diazomethane inserts itself into hydroxyls. The cool thing is that it doesn't need such a strong base, and
there is no competition between substitution and elimination reactions, since both have the same outcome!
--------------------------------------------------------------------------------
It's good to bee back! Don't trust your computer!!
A quat. PTC could be usefull here, sending OH- in the organic phase, without causing to much presence of water. It could be worth a try, very simple
materials, and very usefull product.
Azeotropic removal of the formed water with a large excess of chloroform and toluene as aromatic hydrocarbon solvant at ~50°c could be a good idea.
"reflux" until no more water forms, then distill solvants and possibly product under vacuum, that would be nice if it works.
What would be a easy and effective way of testing for orthoformates?
And if I remember correctly, decent concentration of alcoholic alkoxides can be obtained from anhydrous alkali and alcohols with CaO to deplace the
equilibrium; filtering the milky solution and adding choroform (in exces, or titrating the formed alkoxide) could give
a usefull orthoformate solution, no?
Any thoughts or experiences?
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