Sciencemadness Discussion Board - NITROETHANE: 3 Less Common Procedures

NITROETHANE: 3 Less Common Procedures

AndersHoveland - 10-10-2011 at 17:16

Nitro Ethane from Ethyl bromide and Sodium Nitrite
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, whereafter 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. Ethylene glycol also works as solvent, but the reaction proceeds pretty sluggishly in this medium, allowing for side reactions, such as
CH3CH2-NO2 + CH3CH2-ONO -> CH3CH(NO)NO2 + EtOH. KNO2 can also be used instead of NaNO2. If NaNO2 is used in DMF, 30g 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 2 additions of 75ml water, instead of four of 75ml water as above, to remove trace leftover I2.

Nitroethane from Ethyl Sulfate and Sodium 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 formed. heating is discontinued when the distillation flow slackens considerably, and the crude nitroethane is washed with an equal amount of water, dried over CaCl2, The nitroethane is then re-distilled, collecting the fraction between 114-116°C. Yield 46%

Conversion of Ethyl Nitrite into Nitroethane.

The solution of the nitrite in paraffin oil was placed in a flask provided with an upright spiral condenser, which in turn was connected with a combustion tube about 90 cm. long, filled with asbestos-wool (in order to expose a large surface to the gaseous nitrites), and heated in an asbestos box provided with a thermometer. The gaseous nitrite was carried into the tube by means of a slow stream of dry carbon dioxide. The nitro-compound was collected in a U-tube immersed in cold water, and the escaping nitrite in absolute alcohol or methyl alcohol cooled in ice-water. Fifteen or 20 c.c. of the nitrite solution were used at a time. A 25 % solution is convenient, and a 50 per cent. solution loses nitrite very rapidly. As the gaseous nitrite remains only momentarily in contact with the heated asbestos, the yield of the nitro-compound is small, the greater portion of the nitrite escaping conversion. Within four or five hours the greater part of the dissolved nitrite passes through the heated tube. The oily nitro-compound was easily recognised by the formation of the sodium compound on the addition of alcoholic sodium hydroxide solution. The nitro-compound was also reduced to the corresponding amine, which was converted into the platinichloride.

The conversion commenced at 100°C, and was fairly rapid at 120-130°C, when oily drops began to collect in the empty U-tube. At the end of four to five hours about 1 c.c. of the liquid collected, which responded very readily to the alcoholic sodium hydroxide test. If the temperature is raised to about 135-150°C, acetaldehyde and acetic acid are produced along with the nitro-compound. At 150-180°C the acid is the main product of the decomposition. The formation of the aldehyde and the acid is readily explained by the fact, fact that at a higher temperature the nitrite dissociates into alcohol and nitrous acid, the latter decomposing into nitric acid, and the higher oxides of nitrogen which oxidise the alcohol to the aldehyde and the acid. The best yield of the nitro-compound is obtained at 120-130°C.

Effect of Water and Alcohol on the Reaction
The presence of moisture, which is always present in the rapidly dried nitrites, facilitates the conversion of the nitrite into the nitro-compound. In order to ascertain if the presence of larger quantities of moisture in the gaseous nitrites gives rise to a larger percentage of nitro-compounds, the nitrites were passed through a wash-bottle containing water before entering the heated tube. It was found that when surcharged with moisture the nitrite dissociated more rapidly, yielding larger quantities of alcohols, aldehydes and acids without any appreciable increase in the yield of the nitro-compound. It appears that in the presence of traces of moisture, two reactions proceed simultaneously, the conversion of the nitrite into nitro-compound and the dissociation of the nitrite; and with the increase in the proportion of water the latter reaction proceeds with greater rapidity.

In order to determine if a better yield is obtained when an alcoholic solution of the nitrite is heated in a sealed tube, 10 cc of the solution were sealed in a glass tube and heated over flame. During the act of sealing, the part of the tube containing the solution should be immersed in a freezing mixture, otherwise explosions take place. The yield, however, was not very satisfactory. When heated at 100°C for five to six hours the solution, after distilling off the unchanged nitrite, and alcohol, gave about 1 cc of liquid, which positively tested for a nitro-paraffin, and which boiled at 98-104°C. Because of the mixture with alcohol, the actual boiling point was lowered. If, however, the solution was heated to 150°C for twelve to fifteen hours, the tube was found to, contain acetic arid, formed by the oxidation of the alcohol by nitric acid and higher oxides of nitrogen produced from the decomposition of the nitrite, besides free nitrite. The proportion of the nitrocompound was very small.

Preparation of Ethyl Nitrite
90% Ethanol and 25-30% HCl solution are separately chilled to 0degC. They are then mixed and then gradually pipetted to into a saturated solution of sodium nitrite, roughly 1mL additions, small ammounts of nitric oxide will also be given off as a byproduct. To isolate the Ethyl Nitrite from the acid solution, the as much salt (NaCl) is added as will dissolve, causing the nitrite ester to completely separate out from solution in a separate layer.

[Edited on 11-10-2011 by AndersHoveland]

Sedit - 10-10-2011 at 17:40

This is less common? This has been the talk of the town for years now with no real results being posted. I'm just saying man.

I really want to see Ammonium ethyl sulfate being used to generate anhydrous Sodium Ethyl Sulfate or a simple safe means of mono Nitro acetone which could possibly be reduced using various means assuming the nitro compound would not be reduced to an amine as well.

Also I want to see more options on the oxidation of Ethylamine without the use of DMDO. This would all be great leaps forward as these other methods where as they look good on paper seem to have been kicked around for over a decade now without any meaning full results leading me to suspect they are relatively worthless.

starman - 10-10-2011 at 20:29

Original references should be included. Sounds like rhodium recycle.

overload - 11-10-2011 at 20:17

Here's a way to make ethyl bromide starman.... and then a way to turn it into nitroethane.

Synthesis of ethyl bromide

Into a standard flask with an addition funnel and thermometer, place 45 milliliters of ice water. Thereafter, slowly and carefully add in 75 milliliters of 98% sulfuric acid. Then place this acid mixture into an ice bath, and chill to about 0 Celsius. Place 75 milliliters of 95% ethyl alcohol into the addition funnel and slowly add this ethyl alcohol drop wise to the acid mixture. Stir the acid mixture and maintain its temperature around 0 Celsius at all times while adding the alcohol. Now slowly add 60 grams of potassium bromide or 52 grams of sodium bromide bit by bit while keeping the reaction mixture at 0 Celsius. After the addition stir for 30 minutes then pour the entire reaction mixture into a distillation apparatus. Distill off the ethyl bromide at 38 Celsius. When no more ethyl bromide passes over or is collected, stop the distillation process and then recover the ethyl bromide from the receiver flask. Then add 10 grams of anhydrous calcium chloride to this collected ethyl bromide and stir the entire mixture for about 10 minutes. Filter off the calcium chloride. Distil this ethyl bromide using a fractional distillation apparatus at 38 Celsius. Store it in an amber glass bottle in a refrigerator until use.

Turn ethyl bromide into nitroethane..

Into a standard flask place 500 milliliters of dimethylformamide followed by 30 grams of sodium nitrite. Stir this entire mixture to form a uniform mix, and then place this mixture into a cold-water bath. Afterwards, carefully and gradually add in, 27 grams of ethyl bromide over a period sufficient to keep the reaction mixtures temperature below 25 Celsius at all times. During the addition, rapidly stir the reaction mixture and maintain its temperature below 25 Celsius. After the addition of the ethyl bromide, continue to rapidly stir the reaction mixture for about 6 hours at a temperature below 30 Celsius. After 6 hours, pour the entire reaction mixture into a suitable sized beaker, and then add in 1250 milliliters of ice water. Thereafter, extract this aqueous mixture with five 90- milliter portions of diethy ether and combine all ether portions. Then wash this combined ether portion with three 75-milliliter portions of ice cold water. After the washing portions, dry the collected washed ether portion by adding to it, 15 grams of anhydrous magnesium sulfate, and then stir the entire mixture for about 10 minutes- thereafter, filteroff the magnesium sulfate. Now, place this dried filtered ether mixture into a distillation apparatus, and distill-off the ether at 40 Celsius. When no more ether passes over or is collected, stop the distillation process, and then recover the left over remaining residue. Finally, place this left over recovered residue into a distillation apparatus, and distill over the nitroethane at 115 Celsius. When no more nitroethane passes over or is collected, stop the distillation process, and recover the nitroethane. Then place this nitroethane into an amber glass bottle and store it in a cool dry place until use.

Sedit - 11-10-2011 at 21:51

Typical..... Its all be said to death and relatively typical!

overload - 12-10-2011 at 07:06

Quote: Originally posted by Sedit

Typical..... Its all be said to death and relatively typical!

Ha there are more ways if want to know them too.

stygian - 12-10-2011 at 09:21

I agree the alkyl halide/sulfate + nitrite is well enough known, id be interested to hear about retro-nitroaldol of 2-nitropropene or perhaps a trans-nitroaldol with another aldehyde expelling formaldehyde to drive the reaction

Also I believe the nitrite-nitro with asbestos method has been debunked. Rhodium recycle indeed.

AndersHoveland - 7-1-2013 at 13:24

Quote: Originally posted by Sedit

I really want to see Ammonium ethyl sulfate being used

I am not sure "ammonium ethyl sulfate" even exists. Ethyl sulfate is an alkylating agent, so would likely react with the ammonia. "Ethyl-ammonium sulfate" exists, but that is another compound entirely (actually ethylamine sulfate).

weiming1998 - 7-1-2013 at 15:11

Quote: Originally posted by AndersHoveland

Quote: Originally posted by Sedit

I really want to see Ammonium ethyl sulfate being used

Ammonium ethyl sulfate does exist. It is the salt of ethyl hydrogen sulfate (not diethyl sulfate) and ammonia.
http://en.wikipedia.org/wiki/Ethyl_sulfate

AndersHoveland - 7-1-2013 at 16:48

Quote: Originally posted by weiming1998

Ammonium ethyl sulfate does exist. It is the salt of ethyl hydrogen sulfate (not diethyl sulfate) and ammonia.
http://en.wikipedia.org/wiki/Ethyl_sulfate

That link did not have any reference to the ammonium salt. The only reference to ammonium salts I can find of methyl- or ethylsulfate are quaternary ammonia compounds, which one would not expect to react because it is a non-nucleophilic cation.

Could you perhaps find a link to an example?

I realise that the ethylsulfate ion is a weaker alkylating agent than diethylsulfate, and that it is more difficult to alkylate the ammonium ion than it is amines or free ammonia, but still the fact that there are no references to this compound, or any related ones, makes me suspicious.

[Edited on 8-1-2013 by AndersHoveland]

zed - 7-1-2013 at 17:16

Ah. The software is resisting me.

Nitroethane apparently can be easily produced, if you have some otherwise useless propenyl benzenes around. P-Propenyl Anisole is a good example. You can convert it to Anisealdehyde, and obtain Nitroethane as a bonus.

Here is a Shulgin proceedure. In those less troubled times, it might not have occured to folks, that the pure Nitroethane produced, might be worth saving.

(from Oil of Nutmeg) The careful distillation of Oil of Nutmeg (or the Oil of Mace) allowed the isolation of a number of compounds in varying degrees of purity. The fraction that boiled in the 110-115 °C range at about 1.0 mm/Hg was myristicin (3-methoxy-4,5-methylenedioxyallylbenzene). It constituted some 7% of the original oil of commerce and, in its original isolated form, was obtained with a purity of 87%. The major contaminant was elemicin (3,4,5-trimethoxyallylbenzene). A solution of 100 g myristicin in 100 g absolute EtOH was treated with 200 g solid KOH and heated on a steam bath overnight. Removal of the volatiles under vacuum, flooding the residue with H2O, and extraction with 3x100 mL CH2Cl2 gave, after removal of the solvent from the combined extracts, a residue of crude isomyristicin (a mixture of the cis- and trans-isomers). This product was distilled, and the fraction boiling at 125-130 °C at 1 mm/Hg gave 63 g of isomyristicin as a pale yellow oil that spontaneously crystallized. The mp was 41.5-42.5 °C. Part of the losses associated with the purification of these solids was due to formation of the cis-isomer of isomyristicin, which was an oil.

A solution of 50 g isomyristicin in 300 mL dry acetone containing 24 g pyridine was vigorously stirred and cooled to 0 °C with an ice bath. To this there was added 54 g tetranitromethane which had been pre-cooled to 0 °C. Stirring was continued for exactly 2 min, and then the reaction was quenched by the addition of a cold solution of 16.8 g KOH in 300 mL H2O. Stirring was continued until the temperature had again been lowered to near 0 °C. The product was removed by filtration. Extraction of the filtrate with CH2Cl2 and removal of the solvent provided additional nitrostryrene, for a combined yield of 50.7 g with a mp of 103 °C due to the presence of a small amount of free myristicinaldehyde. A recrystallization from MeOH produced 1-(3-methoxy-4,5-methylenedioxyphenyl)-2-nitropropene with a mp of 109-110 °C. This material was completely adequate for the above-described reduction to MMDA. The conversion of this nitropropene to myristicinaldehyde is an alternative to the lengthy synthesis given above), and can be used in the preparation of LOPHOPHINE.

A mixture of 50 g 1-(3-methoxy-4,5-methylenedioxyphenyl)-2-nitropropene and 26 g racemic a-methylbenzylamine was heated on the steam bath. The mixture gradually formed a clear solution with the steady evolution of nitroethane. When the reaction became quiet, there was added a mixture of 20 mL concentrated HCl in 100 mL H2O. The reaction mixture dissolved completely, and as the temperature continued to rise there was the abrupt solidification as the formed myristicinaldehyde crystallized out. This product was removed by filtration and, when combined with a second crop obtained by the hexane extraction of the filtrate, gave 36.9 g of myristicinaldehyde. The mp of 128-129 °C was raised to 133-134 °C by recrystallization from hexane.

Nitroethane just boils out of the reaction mixture. Why not condense the vapor and use it for another project?

[Edited on 8-1-2013 by zed]

[Edited on 8-1-2013 by zed]

UnintentionalChaos - 7-1-2013 at 17:39

Quote: Originally posted by AndersHoveland

Quote: Originally posted by weiming1998

Ammonium ethyl sulfate does exist. It is the salt of ethyl hydrogen sulfate (not diethyl sulfate) and ammonia.
http://en.wikipedia.org/wiki/Ethyl_sulfate

We have a large section of a methylamine thread wherein several members made ammonium methylsulfate from sulfamic acid in refluxing methanol. I have several hundred grams in my lab, and on heating, a mixture of alkylation and decomposition occurs. On adding base to the post-heated salt, I got kicked in the face with the smell of fish from methylamine and possibly higher methylated amines.

Using ethanol would presumably give ammonium ethylsulfate, which the literature on ammonium methylsulfate claims is a poorer alkylating agent, generating mostly or solely ethylene and ammonium bisulfate on heating.

[Edited on 1-8-13 by UnintentionalChaos]