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aurelius prefers some of the ones near the bottom of this list
Nitroethane synthesis: a compilation
Method 1: from sodium ethyl sulfate and a metal nitrite
1.5 mole sodium nitrite (103.5g) is intimately mixed with 1 mole of sodium
ethyl sulfate (158g) and 0.0625 moles of K2CO3 (8.6g). The mixture is then
heated to 125-130°C, at which temperature the nitroethane distills over as
soon as it is formed. The heating is discontinued when the distillation flow
slackens considerably, and the crude nitroethane is washed with an equal
amount of water, dried over CaCl2, and if needed, decolorized with a little
activated carbon. The nitroethane is then re-distilled, collecting the
fraction between 114-116°C. Yield 46% of theory
(another ref says max. 42%)
Chemical Abstracts, Vol 49, pg 836.
Method 2: from diethyl
sulfate and sodium nitrite
Initial run - Into a stoppered bottle was placed a mixture of diethyl sulfate (120g) and sodium
nitrite solution (120g in 160ml of water.) The bottle was shaken mechanically
for 20 hours, the pressure being released at intervals. The contents were
then poured into a separating funnel, and the upper layer separated, dried
over calcium chloride. and distilled at 14 mmHg, the distillate up to 60°C
being collected (the residue, ca. 230g., consisted of ethyl sulphate and was
used again). The distillate was fractionated at atmospheric pressure, and the
fraction of bp 114-116°C collected. This was shaken with water, dried over
calcium chloride, run through charcoal, and redistilled; bp 114-115.5°C.
Yield, 17.7g. (31%, or allowing for recovered ethyl sulfate, 43.5%).
Routine run - A second experiment was then carried out using the same
quantity of ethyl sulfate as above. The recovered nitrite solution (lower
layer) from the first run was concentrated by adding approximately 16 g. of
sodium nitrite per 160ml of solution. Yield 26.4g (46%, or allowing for
recovered ethyl sulphate, 65%). For each additional subsequent run
approximately 16 g. of nitrite per 160 ml of solution were added, although
this represents a rather diminishing concentration in view of the increased
yield of nitroethane
Method 3: from ethyl bromide (iodide) and sodium nitrite (dmf)
32.5 grams of ethyl bromide (0.3 moles) was poured into a stirred solution of
600ml dimethylformamide and 36 grams dry NaNO2 (0.52 mole) in a beaker
standing in a water bath keeping the solution at room temperature as the reaction is slightly exothermic. Always
keep the solution out of direct sunlight. The stirring was continued for six
hours. After that, the reaction mixture was poured into a 2500 ml beaker or flask,
containing 1500 ml ice-water and 100 ml of petroleum ether. The petroleum
ether layer was poured off and saved, and the aqueous phase was extracted
four more times with 100 ml of petroleum ether each, where after the organic
extracts were pooled, and in turn was washed with 4x75ml of water. The
remaining organic phase was dried over magnesium sulfate, filtered, and the
petroleum ether was removed by distillation under reduced pressure on a water
bath, which temperature was allowed to slowly rise to about 65°C. The
residue, consisting of crude nitroethane was distilled under ordinary
pressure (preferably with a small distillation column) to give 60% of
product, boiling at 114-116°C.
The ethyl bromide reacts with NaNO2, forming nitroethane and ethyl nitrite.
This method can be varied in a few ways. Firstly, dimethyl sulfoxide (DMSO)
can be substituted for the dimethylformamide (DMF) as solvent. Ethylene
glycol also works as solvent, but the reaction proceeds pretty sluggishly in this medium,
allowing for side reactions,
such as this: RH-NO2 + R-ONO => R-(NO)NO2 + R-OH. KNO2 can also be used
instead of NaNO2. If NaNO2 is used in DMF, 30g (0.5 mol) of urea can also be
added as nitrite scavenger to minimize side reactions, as well as simultaneously
increasing the solubility of the NaNO2 and thereby significantly speeding up
the reaction.
If the ethyl bromide is substituted
with ethyl iodide, the required reaction time is decreased to only 2.5 h instead of 6 h.
In case ethyl iodide is employed, a slight change in the above procedure
needs to be done. The pooled pet ether extracts should be washed with 2x75ml
10% sodium thiosulfate, followed by 2x75ml water, instead of 4x75ml water as
above. This to remove small amounts of free iodine
Method 4 : from ethyl halide and silver nitrite
Cool 100 g of silver nitrite (0.65 mol) in 150 ml of dry ether to 0°C in a 3
neck 500 ml flask (in a darkened room or using yellow light). Add 0.5 moles
of ethyl halide (78g ethyl iodide or 55g of ethyl bromide) dropwise over a 2
hour period while stirring constantly and maintaining the temperature at 0°C
and dark conditions. Stir for 24 hours at 0°C, then 24 hours at room temp if
using ethyl bromide, and 48h if using ethyl bromide. (Test for halogens to
see when the reaction
is completed, through adding a few drops of the reaction mixture to a test tube
containing an alcoholic solution of silver nitrate and note if a precipitate
appears. If so, the reaction
is not complete. The Beilstein test can also be used, it uses a small coil of
copper wire in a test tube to which a small portion of the reaction mixture is added and it is
noted if reaction
occurs, where elemental silver will deposit on the surface of the copper
coil.) Silver iodide (or bromide) will precipitate in the solution during the
course of the reaction.
Filter off the silver salt, and wash it with several portions of ether.
Evaporate the ether at room temperature. (This may be substituted with
distillation of the ether using a water bath at atmospheric pressure. A 2x45
cm column packed with 4 mm pyrex helices is used. A more efficient column is
not used due to the instability of the ethyl nitrite formed as a by-product
in the reaction.
Maintain anhydrous conditions since the ethyl nitrite will hydrolyze to
ethanol and will be difficult to separate.) Then vacuum distill the residue
at about 5 mmHg. The ethyl nitrite will be the initial fraction, followed by
an intermediate fraction, then the nitroethane will distill. The yield is
about 83% of theory
Method 5: oxidation of ethyl amine with peracids (m-perbenzoicacid)
General Procedure for the Oxidation of Primary & Secondary amines using
m-chloroperbenzoic acid.
m-Chloroperbenzoic acid (4.1g, 0.02mol, 85% pure) is dissloved in 30 mls of
1,2-dichloroethane in a three-neck flask equipped with a condenser and a
pressure-equalising dropping funnel. The amine (0.005 mol) in 3-5 mls of
1,2-dichloroethane solvent is added drop-wize to the refluxing
m-Chloroperbenzoic acid/1,2-dichloroethane solution. Refluxing temperature
83oC for 3 hours.
After the addition of the amine and refluxing time, the reaction mixture is cooled, filtered and
washed with three 50 ml portions of 1M sodium hydroxide solution and dried
over anhydrous magnesium sulphate. The removal of the 1,2-dichloroethane
solvent by distillation (rotary) gives a crude nitroalkane. Purification of
the crude crude nitroalkane with vacuum distillation. Yields vary, approx 62
%.
Oxidation of n-propylamine and higher alkane amines give nitroalkane at
approx 62 %.
[Note] Nitromethane and nitroethane form sodium water-soluable salts with 1M
sodium hydroxide solution
Refs: W.D. Emmons, Am.Soc. 79, 5528 (1957)
Method 6: oxidation of ethyl amine with potassium permanganate
Perhaps by the method in Org Synth CV 5, 845.
REFS for methods 5 + 6:
Chem.Ber. (1902) 35, 4294
Eur.J.Med.Chem. (1991) 26, 2, 167-178
Eur.J.Org.Chem. (1998) 4, 679-682
Heterocycles (1998) 48, 1, 181-185
J.Amer.Chem.Soc. (1954) 76, 4494
J.Amer.Chem.Soc. (1956) 78, 4003
J.Amer.Chem.Soc. (1957) 79, 5528
J.Chem.Soc.Chem.Commun. (1995) 15, 1523-1524
J.Org.Chem. (1960) 25, 2114-2126
J.Org.Chem. (1979) 44, 659-661.
J.Org.Chem. (1992) 57, 25, 6759-6764
J.Org.Chem. (1993) 58, 5, 1118-1121
Magn.Reson.Chem. (1997) 35, 2, 131-140
Org.Synth. (1963) 43, 87
Tetrahedron (1991) 47, 28, 5173-5184
Tetrahedron (1995) 51, 41, 11305-11318
Tetrahedron Lett. (1981) 22, 18, 1655-1656
Tetrahedron Lett. (1986) 27, 21, 2335-2336
Tetrahedron Lett. (1996) 37, 6, 805-808
Z.Naturforsch.B (1989) 44, 11, 1475-1478
Method 7: destructive distillation of alpha-bromopropionic acid with
sodium nitrite
K2CO3 + NaNO2 + H2O + a-br-propionic acid à nitroethane 50%yield
Add 20g of the acid to a solution of K2CO3 in the amount of base that causes
the solution to be basic to phenolphthalein. The add 20g of NaNO2—there
should be approx. 100ml of solution. Place in a 250ml rb flask and
distill quickly- the first 100ml will come over before the rxn takes place. Then the
nitroethane comes over. Distill until no more product comes over.
(don’t distill to dryness)
V. Auger. Bull. Soc. Chim. France Post no. 3, 23, 333 (1900) by the
kolbe method.
Method 8: oxidation of ethyl amine to nitroethane with
dimethyldioxirane
A new synthesis of nitro compounds using dimethyldioxirane(DMDO)
Tetrahedron Letters,Vol.27,No.21,pp 2335-2336,1986
Abstract: Dimethyldioxirane oxidizes primary amines to nitro compounds in a
facile, mild, high yield process.
Here we report that aliphatic and aromatic primary amines are rapidly and
efficiently oxidized to nitro compounds by dimethyldioxirane, DMDO. Indeed a
survey of some general methods for the preparation of nitro compounds (2)
suggests to us that the use of DMDO may be the method of choice. The
conditions used are exceedingly mild and give the nitro compound as a
solution in acetone. Table 1 summarizes our results with some representative
amines.
Table 1. Oxidation of amines with Dimethyldioxirane(DMDO).
Amine Product
Yield (Product m.p.(C)
~~~~~~~~~~~~~~~~~~~~~~~--~~~~~~--~---~~~~~~~~~~~--
Aniline Nitrobenzene
91
p-Anisidine p-Nitroanisole
94 54
n-Butylamine 1-Nitrobutane 84
sec-Butylamine 2-Nitrobutane 81
tert-Butylamine 2-Methyl-2-nitrobut 90
1-Aminoadamantane 1-Nitroadamsntane 95
159
Cyclohexylamine Nitrocyclohexane 95
trans-Azobenzene Axoxybenzene 96
36
In a typical reaction
n-butylamine (0.052g; 0.7 mmol) in 5 ml of acetone was treated with 95 ml of
DMDO, in acetone solution (ca 0.05M)(4) The solution was kept at room
temperature for 30 min. with the exclusion of light. Analysis of the reaction mixture by capillary GC
indicated the presence of l-nitrobutane only. The oxidations are believed to
occur by means of successive oxidations by,1. In the aniline case the blue
color of the nitroso conpound is observed immediately upon adding the
solution of DMDO. In separate experiments we have shown that both
phenylhydroxylamine and nitrosobenzene are readily oxidized to nitrobenzene
by DMDO. The blue color of intermediate nitroso compound was observed in all
of the amine oxidations.
Dimethyldioxirane is a powerful oxygen atom donor, which oxidizes a variety
of substrates 'including hydrocarbons'. Work is continuing on the oxidation
of nitrogen-containing compounds by DMDO.
1. Chemistry of Dioxiranes. 5. Paper 4 of this series is J. Am. Chem. Soc.,
in press (1986).
2. H.O. Larson in The Chemistry of the Nitro and Nitroso Groups, H. Feuer,
Ed., J. Wiley and Sons. N.Y. 1969.
4. The concentration of,DMDO in acetone was determined by titrating an
aliquot with phenyl methyl sulfide. The synthesis of DMDO has been described
(5).
5. R.W. Murray and R. Jeyaraman, J. Org. Chem., (50) 2847 (1985).
Dioxiranes: synthesis and reactions of methyldioxiranes.
J. Org. Chem. (1985), 50(16), 2847-53.
Abstract
The peroxymonosulfate-acetone system produces dimethyldioxirane under
conditions permitting distn. of the dioxirane from the synthesis
vessel. The same conditions were used to prep. other
methyldioxiranes. Solns. of dimethyldioxirane prepd. in this manner
were used to study its chem. and spectroscopic properties. The
caroate-acetone system was also used to study the chem. of in situ generated
dimethyldioxirane. cis- And trans-stilbenes were converted
stereospecifically to the corresponding epoxides with dimethyldioxirane in
acetone
Other refs: Oxidation of primary amines by dimethyldioxirane:
Murray, R.W.,S.N. Rajadhyaksha, L. Mohan, J. Org. Chem., 1989, 54, 5783
Method 9: isomerization of ethyl nitrite to nitroethane over asbestos
catalyst
J. Chem. Soc. 109, 701 (1916)
(pass over asbestos in a tube furnace @ 120-130*C for best results/best
yield)
Method 10: ethyl bromide, DMSO, NaNO2 and phloroglucinol dihydrate
By Ritter, in Strike’s book- TSII.
32g or 26ml EtBr is poured into 250ml of DMSO with 36g NaNO2 and 52g
phloroglucinol already present in solution. (Pglucinol is expensive but
can be recycled) put on good mag. stirring and stopper the flask. Stir
for two hours in emulsion form, then dump into a 600ml of ice water and
extract twice with DCM. (2x200ml) dry the extracts with
MgSO4 or CaCl2 the evap off the DCM. Distill and collect the fraction
from 113-116*C--- yields about 20g of nitroethane (80%) (another ref
say maybe over 90% consistently)
Other notes: catechol and resorcinol have the same nitrite scavenging
abilities as phloroglucinol. And ethylene glycol can be used as a
solvent. A simple NaOH wash of the final solution (nitroethane removed) will give the
sodium salt of your phloroglucinol catalyst. Acidification of the
solution will precip the catalyst for recovery by filtration.
JACS 79, 2507 (1957)
Tetrahedron vol 46, No 21, pp 7443-57 (1990)
Ber. 11, 1332 (1878)
Ber. 12, 417 (1879)
JACS, Vol 78, 1497-1501
Method 11: 3-chloropropionic acid sodium salt, and NaNO2
ClCH2CH2COONa + NaNO2 à NO2CH2CH2COONa + NaCl
NO2CH2CH2COONa + H2O –heatà NO2CH2CH3 + NaHCO3
From Organic Syntheses, Collective Vol. I, pp 401-403
To 500 g of chloroacetic acid in 500 g cracked ice add enough 40% NaOH solution to make the resulting
mixture slightly alkaline. Do not let the temperature rise above 20 degrees
C. This solution is mixed with 365 g sodium nitrite dissolved in 500 ml water
in a 3 liter round-bottom flask. This flask should then be equipped with a
thermometer dipping into the liquid and a distillation condenser. The mixture
is carefully heated until the first bubbles or carbon dioxide appear (at
about 80 C). The heat is then withdrawn and the heat of the reaction keeps it warm. If the reaction becomes too vigorous, it should
be cooled. After the reaction ceases, heat cautiously until 110 C is reached.
Nitromethane will distill over during this heating and the previous
spontaneous heating. Separation of the nitromethane / water mixture and
redistillation will give approx. 35 % yield after drying and redistillation
Method 12: most complicated synth
CH3CH=NOH + Cl2 à CH3CH (Cl)(NO) (ß gem-chloronitrosoethane)
Gem-comp + O3 à CH3CH (Cl)(NO2)
CH3CH (Cl)(NO2) + NaOH
+ H2 + Pd/C à nitroethane (50%) + HCl
JOCS, Vol 41, pg 733-735 (1976)
Method 13: electrochemical oxidation ---- not possible by method below
Ethyl amine is oxidized to methyl nitrile in anhydrous solvent. In the
presence of water it is oxidized to the imine, then acetaldehyde which is further
oxidized to acetic acid.
Method 14: Vapor Phase nitration of propane.
The propane is bubbled through nitric acid heated to 108*C and lead into a
reactor at 420*C. the product is then condensed and fractionated.
(26% nitroethane formed)
Industrial and Engineering Chemistry, Vol 28, Mar, 1936. Pg 339-344.
JOC, Vol 17, pg 906-944.
Method 15: Vapor Phase nitration of ethane.
Same as propane but at least 80% yields.
Industrial and Engineering Chemistry, Vol 28, Mar, 1936. Pg 339-344.
JOC, Vol 17, pg 906-944.
Method 16: Vapor Phase Nitration of Ethanol using Group II oxides or
halides as a catalyst (works for methanol and propanol too)
US pat # 4431842
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.htm
or http://www.orgsyn.org/orgsyn/default.asp?formgroup=base_form_group&dbname=orgsyn),
or by HBr bromination of lactic acid (alpha-hydroxypropionic acid).
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%.
At room temperature the reaction apparently takes about 4-5 hours to go to completion.
At higher temperatures of 40°C. up to about 75°C. the reaction time is shorter. Thus, one or
two hours or even less time at 75°C. will completely convert the bromoacid to
the intermediate which can then be decomposed to the nitroalkane.
When using dimethyl sulfoxide as solvent temperatures approaching 100°C
should be avoided since the solvent will volatilize and decompose at about
100°C. Other aprotic solvents may not have this disadvantage
Method 18: Oxidation of alanine with permanganate followed by decarboxylation
Nitroethane via oxidation of alanine?
Theory
------
MeCH(NH2).COOH + 3(O) --> MeCH(NO2).COOH + H2O.
MeCH(NO2).COOH + NaOH
--> MeCH(NO2).COONa.
MeCH(NO2).COONa + H2O --> MeCH2(NO2) + NaHCO3.
Procedure
---------
A solution of potassium permanganate (0.3 mol) in water was made by
dissolving 47.41 g KMnO4 in 400 mL hot water in a 1 L 3-necked flask fitted
with a reflux condenser, a stirbar[note 1], thermometer, and a 100-mL
addition funnel. As the solution cools to room temperature fine crystals of
KMnO4 crystallise out of solution[note 2]. A solution of alanine (0.1 mol,
8.91 g) in 65 mL of water was placed in the addition funnel and added
dropwise with stirring over a 20 minute period. The temperature slowly rose.
When the addition was complete, the reaction mixture was heated to 60º over a period of
approximately 2 hours. 40 mL of acetone was added [note 3] and then the reaction mixture maintained at 70-85º
[the sludge was extremely viscous and the stirbar was of no use] for 2 hours.
0.1 mol sodium hydroxide in 20 mL of water was then added through the
addition funnel.
Pause (to be completed).
-----
The flask showed no sign of heating up after addition of the NaOH. By now the black/brown sludge
will not mix (with the stir-bar). The next step is to heat to 80-100C to
decarboxylate any nitro-propionic acid and then to steam distil.
Notes:
------
1. An overhead stirrer is essential - the stirbar will get clogged with MnO2.
2. KMnO4 solubility is 1 in 3.5 parts of hot water and 1 in 14 parts of cold
water.
3. The acetone was added to try to clear the sludge. I would have added more
but I had second thoughts.
Refs:
1. Synthesis Of Aliphatic And Alicyclic Nitro Compounds; Org. Syn. p 131-132
[The Oxidation of Amines]
2. Organic Syntheses, Vol. 52, pp 77-82, 2-Metryl-2-Nitrosopropane and its
Dimer, A. Calder, A. R. Forrester and S. P. Hepburn.
3. Vogel's Practical Organic Chemistry, 4th ed. P 564 'Nitromethane'.
Questions.
----------
1. Is it safe to heat this mixture to 90C without a stirrer? [the next step
to make sure that nitro-propionic acid is decarboxylated]
2. Should I improvise an overhead stirrer to finish this off?
3. Nitroethane will steam distil won't it?
4. Should the permanganate have been buffered?
5. I think the NaOH
should have been in there from the start. The sodium salt of alanine would
have been a better idea?
6a. Would the reaction
benefit from taking place in an organic solvent?
6b. If so, what solvents are suitable apart from acetone?
I will repeat this - with an overhead stirrer and the addition of sodium salt
of alanine rather than alanine followed by NaOH.
Method 19: Reduction of acetaldehyde oxime and oxidation of the product
Good work ! An alternative method to alanine amino oxidation and
decarboxylation is the reaction : CH3CHO + NH2OH ==>> CH3CH=NOH,
Then carfully reduced to CH3CH2NHOH, and then oxidized as proposed by you
above to get CH3CH2NO
nitroethane from acetaldoxime
J.H. Boyer / H. Alul, Am.Soc. 81, 4237 (1959)
Method 20: Oxidation of ethyl amine with CrO3
Somewhere in Vogel’s (the oxidation)
Method 21: Nitroethane from propyl nitrate
J.B. Levy / F.J. Adrian, Am.Soc. 77, 2015 (1954)
Method 22: Nitroethane from nitroethene (and nitroethanol)
Nitromethane and formaldehyde will produce nitroethene in vapor phase, over
silica-supported lead catalysts at 200o. You can always use Baker's
yeast. Nitroalkene in Pet. Ether with bakers yeast for a couple days will
reduce it to the nitroalkane.
CH3NO2 + HCOH == NaOH
==>> HOCH2CH2NO2 Aldol Condensation.
HOCH2CH2NO2 == heat ==>> H2C=CH-NO2 + H2O
nitromethane and formaldehyde are reacted in alkaline solution, they give
nitroethanol; this can bee dehydrated to nitroethene by concentrated acid, or
again in vapor phase, passing over phosphoric acid or boric anhydride.
Suppose one wanted to use such means to convert nitromethane, which is easy
to get, to nitroethane, which is not. A selective reduction of the double
bond, in the presence of the nitro group, would do the trick
As an alternative: in general, aldehydes and ketones will also react in the
presence of alumina and KF ( at r.t.) to form beta-nitroalcohols, which
typically dehydrate to nitroalkenes in very acidic conditions. See
Tetrahedron Letters, Vol 27, 1986, p493. This article doesn't specifically use
nitroethene as an example, but the other compounds tested (which are larger)
gave yields of nitroalcohol around 70%. The conversion to the nitroalkene
*should* be stoichiometric. I expect this method may also yield nitrostyrenes
with a similar degree of success
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