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chemoleo
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Nitroalkane syntheses ?
I was wondering, not for the first time, which general methods are available for the production of simple nitro alkanes.
I can see two routes for this:
1) R3C-NH2 --> oxidise --> R3C-NO2.
2) R3C-Cl/Br/I + NO2- --> R3C-NO2 + Cl/Br/I-
where R is H or whatever.
I know that both reactions have been shown to work, but particularly in the latter case I failed to find references as to what conditions exactly need
to be employed.
For instance, tetranitromethane can be made by the reaction of iodopicrin I3CNO2 with AgNO2. What reaction conditions are supposed to be employed
there? I.e. iodopicrin is surely insoluble in water, so to facilitate the reaction with silver nitrite would be tricky. Equally, how about the
reaction of chloroform with AgNO2? The former is definitely not soluble, so how can one go about to get the reaction to work?
Alternatively, how about chlorination of ethylene to form 1,2 dichloroethane... and to react this with AgNO2.
I take it the reason why the Ag, rather than the Na/K nitrite is chosen is because the former is highly insoluble, thus shifting the equilibrium of
the reaction faster to the right.
As to reaction scheme 1) - the oxidation of amines - what are the generic conditions there? I.e. what if the starting compound was ethylenediamine
H2N-CH2CH2-NH2? It's a liquid, soluble in H2O and highly basic.
Any help on this would be appreciated.
[Edited on 21-11-2006 by chemoleo]
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UpNatom
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1. CH3CH(OH)COOH + HBr ------> CH3CH(Br)COOH + H2O
2. CH3CH(Br)COOH + NaNO2 ------> CH3CH2NO2 + NaBr + CO2
Although not really answering any of your questions chemoleo, this is a rather elegant specific nitroalkane synthesis don't you think? ( I'm
not sure if the first step has been proven in practice, but I see no reason for it not to work well.) I'm almost 100% certain I've seen the
second step reported to yield ~70%. It's essentially the same synthesis described in Vogel for NM but from a fantastically OTC starting point.
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solo
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Ref: Nitroalkenes
Gilbert found a general high yield synthesis of nitroalkanes from amines using m-chloroperbenzoic acid(m-CPBA) at elevated temperatures.
Ref.
J. Org. chem. 44, 659, 1973
Gilbert.,E. and W.T. Borden
as read in The Nitro Book in Organic Synthesis by Noboru Ono, Wiley-VCH 2001 pg.20
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solo
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Ref: Nitroalkenes
Rhodium has an unfinished page with many FAQ on the synthesis of nitroalkanes....you may already know this if not here it is....solo
http://web.archive.org/web/20040213224536/www.rhodium.ws/che...
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Marvin
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Organic reactions volume 12 is best Ive read on the subject.
A quick summery or preffered methods.
Primary nitroalkanes,
Silver nitrite, alkyl halide. Br or I, DMSO or DMF
Sodium nitrite, alkyl halide. Br or I (Cl may work here I forget), DMSO or DMF,
Aldoxime+ peroxytrifluoro acetic acid.
Secondary nitroalkanes.
Sodium nitrite and alkyl halide (or sulphonate ester).
Amine, peracetic acid.
Ketoxime oxidation.
Tertiary nitroalkanes.
Permaganate (or peracetic acid) + t-carbinamines.
a-nitro esters.
Sodium or silver nitrite, a-haloester.
Acetone cyanohydrin nitrate, sodium enolates of malonic or acetoacetic esters.
The rest is pretty fringe. There may be an electronic copy of this on the FTP, I dont remeber. This volume is forthcoming in electronic form
according to several posts anyway.
Yeilds depend much on the solubility of the chosen nitrite in the organic solvent, DMSO and Silver nitrite is best I think. For less soluable
mixtures nitrous ester scavengers have to be added to suppress furthur reactions (urea works well).
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S.C. Wack
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Just in case, another Rhodium archive:
http://web.archive.org/web/20040213203724/www.rhodium.ws/che...
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solo
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Refa; Nitroalkanes
In the search function under nitroalkanes I found some interesting material......solo
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KABOOOM(pyrojustforfun)
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posted on 13-11-2003 at 11:02 PM
nitroalkanes via nucleophilic substitution
primary alkyl halides yield mostly nitroalkane. the secondaries yield 15% nitroalkane and tertiary alkyl halides practically don't produce
nitroalkane but the nitrous ester.
just found a general procedure for preparation of nitroalkanes in "Organikum, organisch-chemisches grundpraktikum" :
add 0.3 mol alkyl halide to a mix of 0.5 mol sodium nitrite and 0.5 mol urea (increases soloublity of the nitrite in dimethylformamide) in 600 ml
dimethylformamide. mechanically stir at room temperature for 1-6 hour (depends on reactivity of the halide). pour the mix on 1.5 L ice water, extract
with ether several times, dry on calcium chloride, then perform a fractional distillation using a 30cm vigreux column. the nirous ester by product
comes first (has lower bp)
"ethylene chlorohydrine is of course a primary alkyl halide"
when using ethylene chlorohydrine in above procedure. 2-nitroethanol and ethylene glycol mononitrite are expected to form. and both are liquides with
high bp. so one can warm the whole batch at 120°C to tautomerise the glycol nitrite to 2-nitroethanol
the nitroethanol can further react with formaldehyde to form trimethylolnitromethane and this makes NIBGTN upon nitration.
PJFF
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........ads read http://www.sciencemadness.org/talk/viewthread.php?tid=1053
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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chemoleo
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Ok, thanks a lot for the excellent information.
Essentially this seems to boil down to the following:
1) Alkylhalide + NaNO2, using DMF or DMSO as a solvent
2) Alkylhalide + AgNO2, using dry ether.
3) Alkylsulphate (only the Et-sulphate was quoted, but no other alkyllsulphates) and NaNO2, and straight distillation (seems easiest if ethylsulphate
is ample)
4) Dialkylsulphate and NaNO2, distillation again but slow reaction.
5) Alkylamine + peracids (i.e. perbenzoic acid), in 1,2 dichloroethane
6) Alkylamine + KMnO4 - OrgSyn only mentions this method in conjunction with amines attached to tertiary carbons.
7) various others, exotic ones.
Re. the halides, the bromides and particularly iodides seem to be preferred over the chlorides.
The KMnO4 oxidation method mentions a few references, does anyone have access to these:
Org Synth CV 5, 845 (somehow I couldn't access it)
There is a list of others under Method 6, if anyone's got access to those that seem relevant/feasible, please do post!
I am surprised anyway that there aren't widespread oxidation protocols available, with the various oxidation agents that exist!
KMnO4 doesn't seem to work well (except tertiary amines), and peracids aren't exactly easy to make/obtain.
Anyway, it seems that making nitroalkanes will almost certainly require decent amounts of solvents 
Edit: Thanks for pointing this out, yes, I meant a primary amine on tertiary carbon in 6)
[Edited on 13-12-2004 by chemoleo]
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BromicAcid
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| Quote: | | 2) Alkylhalide + AgNO2, using dry ether. |
Some preps I have found use acetonitrile instead of ether.
Particularly the preparation of trimethylsilyl nitrate and nitrite, a fine precipitate of AgCl appears instantly in this method.
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Mendeleev
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"6) Alkylamine + KMnO4 - OrgSyn only mentions this method in conjunction with tertiary amines. "
Are you sure this works? I thought it required a primary amine, and I could not find any reference to it on orgsyn.
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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Marvin
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Tertiary amine is the wrong term, that would indicate a NR3 type compound. He means an amine on a tertiary carbon and the term for that I've
posted t-carbinamine. It might have helped if I'd explained it.
(from the quote of the KABOOM post)
"so one can warm the whole batch at 120°C to tautomerise the glycol nitrite to 2-nitroethanol "
This wont work, nitrites do not convert to nitro compounds. There is missleading information on Rhodiums site on this, it isnt true.
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UpNatom
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When does the edit function expire
I was hoping to add this to my post above but cannot. Anyway...
This is the original text by aurelius on method 17 from the compilation.
| Quote: | Method 17: Distillation of alpha-bromopropionic acids with NaNO2 in the presence of Magnesium Sulfate in DMSO
US pat # 4319059
(the alpha-bromo acid can be obtained using propionic acid in the procedure from Org. Synth. CV 1, 115.)
This patent shows an easy route from alpha-bromopropionic acid to nitroethane in excellent yield. The patent also say that Magnesium chloride, bromide
or sulfate may be used instead of the magnesium methoxide, but it doesn't say if this affects yields.
The reaction proceeds as follows: In the polar aprotic solvent DMSO, the alpha-bromopropionic acid reacts in an SN2 fashion with nitrite ion to give
alpha-nitropropionic acid and bromide ion. The role of the Mg2+ ion in the reaction is to facilitate the decarboxylation (removal of CO2) from the
intermediate nitro acid, as it forms a chelate between one of the oxygen atoms on the nitro group and the oxygen anion of the carboxylic acid. The
electron-withdrawing nature of the nitro group makes the carboxylic acid group labile, and it can easily be given off as carbon dioxide. If magnesium
methoxide is used in place of the other magnesium salts, the carboxylic acid is directly deprotonated, probably making the reaction go even faster.
There is no workup mentioned in the patent, but I'd suggest flooding with water (or using large amounts of dilute (5%) HCl in the hydrolysis
step), and then extract the nitroethane with dichloromethane, ether or possibly petroleum ether. Then the combined organic layers are washed first
with water and then with a concentrated NaCl solution, followed by drying the organic phase over anhydrous MgSO4, which is then filtered off. Then the
solvent is removed distilled, and the residual crude nitroethane is fractionally distilled at 114-115°C.
alpha-Bromopropionic acid can be made from propionic acid and phosphorous tribromide (from red phosphorous and bromine, the Hell-Volhard-Zelinsky
reaction, http://www.geocities.com/chempen_software/reactions/RXN099.h... or http://www.orgsyn.org/orgsyn/default.asp?formgroup=base_form... , or by HBr bromination of lactic acid (alpha-hydroxypropionic acid).
[uNa: the gist of my post further up this thread]
Example 1
To a mixture of magnesium methoxide (0.11 mole) and dimethyl sulfoxide (50 ml) a-bromopropionic acid (0.11 mole) was added at 20°C. with stirring. To
this mixture a solution of sodium nitrite (0.145 mole) in dimethyl sulfoxide (65 ml) was added at room temperature. Then, the reaction mixture was
stirred at room temperature for 6 hours and was neutralized upon addition of diluted hydrochloric acid. Analysis of the reaction mixture indicated
more than 99% conversion of alpha-bromopropionic acid and 94.5% yield of nitroethane.
Example 2
In the manner of Example 1, sodium nitrite, alpha-bromopropionic acid and magnesium methoxide were reacted in dimethyl sulfoxide as the aprotic
solvent. The reaction time was 2 hours for one run and 22 hours for another. Reaction was conducted at room temperature. The run at 2 hours converted
only 94.5% of the acid and yielded 72.7% nitroethane. The second run at 22 hours gave a conversion of > 99% and a yield of 100%.
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It's by this method I'm certain I have seen 70%+ yields from experimenters (not quite the >99% mentioned, but not bad) and lactic acid
is a cheap homebrew chemical. Pity DMSO isn't so OTC (outside the US anyway) Worth a try if its specifically NE you're after.
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Mendeleev
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Preparation of Diethyl Sulfate
Procedure
Ninety grams of sodium sulfate is placed in a dry 1 liter flask connected with a condenser and a receiver arranged for vacuum distillation. The flask
is heated by means of an oil bath to 155-165°C. The apparatus is exhausted as nearly as possible by means of a filter pump, and misture of 50 grams
of ethanol and 104.5 grams of concentrated sulfuric acid is allowed to drop through a capillary tube on the sodium sulfate at a rate of 120-150 drops
per minute. The distillation of the mixture requires about one and one half hours for completion. The distillate, which consists of ethanol and
diethyl sulfate is poured into a separatory funnel, the ethanol may be recovered for further use. The diethyl sulfate is washed with a dilute solution
of sodium carbonate and then several times with cold water, then dried with anhydrous sodium sulfate, yielding 32.4 grams.
Reference: JACS 46, 999-1001 (1924)
Will that work with magnesium sulfate?
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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Mendeleev
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http://chemlabs1.tripod.com/chemistry/alcohol2nitro.html
Preparation of Nitroalkanes Directly from Alcohols
--------------------------------------------------------------------------------
Spengler described the synthesis of a few simple primary and secondary nitro aliphatic nitro alkanes using a mixture of NaNO2-H2O-HCl,however their
method was not tested on a wide varity of substrates including tertiary alcohols. In continuation of our interest on the chemistry of nitro aliphatics
and their application in the synthesis of bioactive natural products, we have observed that when a mixture of NaNO2-AcOH-HCl is treated with a varity
of alcohols the corresponding nitro compounds are formed in excellent yields. The results are shown in the table below.
Substrate Reaction time Product Yield
Benzyl alcohol 6h Phenylnitromethane 85%
1-Phenylethanol 5h 1-Phenylnitroethane 90%
4-MeO-Phenethylalcohol 6h 4-MeO-Phenylnitroethane 90%
4-Cl-Phenethylalcohol 6h 4-Cl-Phenylnitroethane 87%
Octyl alcohol 6h Nitrooctane 80%
Typical Procedure:
To a mixture of the benzyl alcohol (9.24 mmol) in CH2Cl2 (30 mL) was added NaNO2 (2g, 29 mmol). To this mixture was added acetic acid (1.5 mL,
26.2mmol) and left at room temperature for five minutes. Then concentrated HCl (0.5 mL) was added to this mixture and left at room temperature without
stirring for about 14 hours while monitoring the reaction on TLC. The reaction mixture was diluted with CH2Cl2 (150mL) and the preceptiated NaOAc was
filtered off. The organic phase was evaporated in a rotavapor and the gummy residue was dissolved in hexane (100 mL) and washed with cold water
(5x200ml) to remove the acid. The organic phase was dried over anhydrous sodium sulfate to furnish the nitroalkane.
Reference: Synlett, No. 7, yr 2000, pages 1064-1066
This is a very simple procedure, will it work with ethanol?
[Edited on 15-12-2004 by Mendeleev]
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Marvin
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I was thinking for some considerable time that I'd made a horrific mistake and I should give up chemistry and make baskets out of reeds for a
living. The claim makes no sense with regard to conventional chemistry.
Then after much searching I found this abstract.
| Quote: |
Can Nitroalkanes be Obtained Directly from Alcohols and Sodium Nitrite in Acetic Acid - Hydrochloric Acid Mixture?
Mieczysław Mąkosza*, Michał Barbasiewicz, Krzysztof Wojciechowski
*Institute of Organic Chemistry Polish Academy of Sciences, ul. Kasprzaka 44/52, P.O.Box 58, PL 01-224 Warszawa 42, Poland; E-mail: icho-s@icho.edu.pl
The report that nitroalkanes can be obtained from aliphatic alcohols and sodium nitrite in acetic acid - hydrochloric acid mixture was shown
erroneous. Under these conditions no nitroalkanes but alkyl nitrites were formed.
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Dated a year after that information in the same journal and presumably in reply to it.
So will it work with ethanol? No. It doesnt even work with any of the substances listed.
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Vitus_Verdegast
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not that good in practice
Destillation of an intimate mixture of Na alkylHSO4, NaNO2 and a dash of K2CO3 seems to work, but yield is low for nitromethane, and even lower with
nitroethane.
It's the most OTC way though, IIRC Antoncho or another Russian did some interesting experiments with at the Hive.
Use one of the patented methods to make NaEtHSO4 from ethylsulphuric acid (EtOH/H2SO4/MgSO4), instead of the cumbersome and horribly messy route via
the calcium salt.. You just need to monitor the pH constantly on basification, as water + acid will hydrolize a great part of your ethylsulphuric
acid.
[Edited on 16-12-2004 by Vitus_Verdegast]
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Mendeleev
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Have you read the msds for diethyl sulfate? It is one nasty-ass carcinogen. I would much rather go the sodium ethyl sulfate route, just because
it's not as toxic.
http://www.weblakes.com/toxic/DIETHYL_SULFATE.HTML
[Edited on 16-12-2004 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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FloridaAlchemist
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Diethyl Sulfate
Diethyl Sulfate is not too dangerous to use. It is one of the byproducts when you make Diethyl Ether. Dimethyl Sulfate is the dangerous one
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Mendeleev
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Maybe not dangerous as in kill you in a few seconds due or make you violently ill, but it seems like it is a very nasty carcinogen.
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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sparkgap
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In any case, both are freakishly good alkylating agents, so they'll most likely muss up you DNA. Right up there with the mustards and alkyl
bromides/iodides
Wait a minute...
QUOTE from FloridaAlchemist
...It is one of the byproducts when you make Diethyl Ether...
Just how?
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FloridaAlchemist
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Yes diethyl sulfate
Diethyl sulfate and ethyl hydrogen sulfate are intermediate esters formed when ethyl alcohol and sulfuric acid are reacted together.. The conditions
of the reaction ,and /or conc of the sulfuric acid is what determines if you get diethyl ether or the sulfate esters.
Show me the references where diethyl sulfate messes up your DNA or for that matter a carcinogen.
Comparing diethyl sulfate to dimethyl sulfate is like comparing methyl alcohol to ethyl alcohol.
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sparkgap
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Yeah, I found out just the other day when I researched industrial scale preparation of ether. Thanks for answering my question.
The key word was "most likely" in my comment on mutagenicity/carcinogenicity.
All the MSDS's I've seen on lower alkyl sulfates say they're either carcinogens/mutagens or suspected carcinogens. As far as I know, I
was confident in my remark since both dimethyl and diethyl sulfate have the alkylsulfate moiety, which makes them susceptible to nucleophilic attack.
My second beef, the analogy you gave, doesn't make much sense to me. Both alcohols are toxic at the proper doses. What distinguishes methanol
from ethanol in terms of toxicity is in the metabolites they produce. In the case of methanol, formaldehyde and formic acid are the metabolites that
deal heavy damage to the unfortunate swigger. Ethanol is oxidized by alcohol dehydrogenase in the liver, however, to acetaldehyde (one of them
hangover culprits) and acetic acid (p.u.!).
The alkyl sulfates, on the other hand, are both susceptible to SN2 attack. It's in the functional groups, dude.
Damn, this post is too long...
My two cents worth.
sparky
[Edited on 18-1-2005 by sparkgap]
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FloridaAlchemist
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Comparison
The comparison I was giving was just for comparing relative toxcity in a general way, of the alkyl groups methyl versus ethyl . ie methyl alcohol
more toxic than ethyl alcohol... or dimethyl sulfate being more toxic than diethyl sulfate.
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sparkgap
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Or to make your statement more precise, you were referring to acute toxicity. In that regard, I have to agree with you regarding both the alcohols and
the alkylsulfates.
However, I still stand by my statement regarding DNA damage. I believe that is in the chronic toxicity department. DNA damage is not a readily
apparent sign in humans, except in a few special cases.
But we're going off-topic here. I'm kind of surprised the admins aren't screeching at us for this.
The only nitroalkane synthesis I can attest to is the route from chloroacetate. It's quite clean. Then again, I do this not in my home lab, so
that might make a difference. Maybe I'll try the backyard synthesis one of these days.
sparky
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sparkgap
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Just found a book on nitration by George Olah. Got it from our library. Here is a link about it:
http://as.wiley.com/WileyCDA/WileyTitle/productCd-0471186953...
When I get to reading it, I'll be posting a bit.
Till then,
sparky
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