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All 16 posts Subject: Rediscovery of Pseudonitrosite Synthesis Please login to post Down

Rhodium
(Chief Bee)
04-19-04 20:20
No 501648
User Picture       Rediscovery of Pseudonitrosite Synthesis
(Rated as: excellent)

Convenient and Simple Preparation of Nitroolefins Nitration of Olefins with Nitric Oxide
Teruaki Mukaiyama, Eiichiro Hata, and Tohru Yamada
Chemistry Letters 505-506 (1995) (https://www.rhodium.ws/pdf/alkene.nitration.no-1.pdf)

Abstract
Nitroolefins are conveniently prepared in high yields by nitration of olefins under an atmospheric pressure of nitric oxide at room temperature and subsequent treatment with acidic alumina.
____ ___ __ _

A Convenient Method for the Preparation of Nitro Olefins by Nitration of Olefins with Nitrogen Monoxide
Eiichiro Hata, Tohru Yamada, and Teruaki Mukaiyama
Bull. Chem. Soc. Jpn., 68, 3629-3636(1995) (https://www.rhodium.ws/pdf/alkene.nitration.no-2.pdf)

Abstract
Olefins with a terminal double bond or conjugated with aromatic nucleus are successfully nitrated into nitro olefins in good-to-high yields on treatment with nitrogen monoxide (NO) in 1,2-dichloroethane. Nitro alcohols formed as by-products are dehydrated to yield nitro olefins by the subsequent treatment with acidic activated alumina. By GC analysis, it was confirmed that an equimolar amount of nitrogen gas was evolved during the present nitration. A possible reaction pathway including the formation of nitro nitroso compounds, key intermediates, is described. The key intermediates are transformed into nitro olefins by reaction with nitrogen monoxide.

Oddly enough, they aren't referencing any of the articles listed in https://www.rhodium.ws/chemistry/pseudonitrosite.html - I assume it is due to to the language barrier...

^{The Hive - Clandestine Chemists Without Borders}

starlight
(Hive Bee)
04-19-04 23:18
No 501675
      goes further than the pseudonitrosite!

Wow, those recent refs are really interesting. Fantastic find, good yields.

This is not the classical psuedonitrosite route though is it? - it uses NO rather than N2O3. So the pseudonitrosite intermediate gets converted to the nitro-olefin.

It looks better than the classical route, because the yields are higher. It avoids that need for treatment of a pseudonitrosite dimer with base and then acid to get the final product, which can be somewhat low yeilding for some substances.

I see most of the examples they give are terminal olefins. Would the fact it works on those cyclic olefins suggest that it would work on propenylbenzenes?

If so (which would not surprise me at all), I have to say this looks fantastic.

Antibody2
(LinguisticBee)
04-20-04 02:12
No 501707
      WOW

be nice if that dehydration rxn would work for converting the nitroalcohol byproducts from "conventional" pseudonitrosite hydrolysis to nitropropenes?

Where is the 2nd Hydrogen atom for the dehydration coming from? Is the acidic alumina acting as a hydrogen donor?

We are all just witnesses.

starlight
(Hive Bee)
04-20-04 08:53
No 501747
      i can't see that one is needed

Taking an -OH from the carbon next to the aromatic ring and an H from the carbon with the Nitro group gives you a double bond doesn't it? -> Loss of one water molecule.

starlight
(Hive Bee)
04-20-04 15:47
No 501817
      DCM

NO seems quite expensive to buy. Could possibly generate it from 50% HNO3 and Cu metal I suppose.

DCE is carcinogenic to some degree. Maybe DCM would work instead (good chance I would have thought from looking at the paper).

SpicyBrown
(Hive Bee)
04-22-04 02:47
No 502191
      Making NO

NO seems quite expensive to buy. Could possibly generate it from 50% HNO3 and Cu metal I suppose

NO can be generated from HNO₃ and a few different transition metals. The only thing that one needs to be careful of is to exclude oxygen from the gas generation vessel and piping as much as possible, as NO oxidizes quite rapidly to NO₂ (the brown funk; NO by itself is colorless) in the presence of atmospheric oxygen.

-SpicyBrown

starlight
(Hive Bee)
04-22-04 08:10
No 502227
      concentration

The concentration of the nitric acid is also important as different oxides of nitrogen are formed at different concentrations of acid

starlight
(Hive Bee)
04-28-04 11:24
No 503483
      Related experiments

Here is a fascinating little patent that was published in-between the original pseudonitrosite work and the 1995 work: Patent US3240823

It is related to the above work in that it uses activated alumina catalysts to convert nitroalcolhols to nitro-olefins.

But it also uses activated alumina catalysts to convert dinitroalkanes and nitronitrites to nitroalkenes.

Many examples are given using different types of alumina with varying reaction conditions (e.g. reflux time, amount of water present).

From these experiments, it appears that the activated alumina (presumably acidic) has the ability to convert a range of 1-nitro-2-something-alkanes to nitroalkenes.

I just wonder if it would be possible to conduct a standard pseudonitrosite reaction using NaNO₂/H₂SO₄, but rather than using two phase ether/H₂O, use two phase DCM/H₂O to create a solution of pseudonitrosite monomer in DCM. Given the potentially wide applicability of activated alumina in the preparation of nitroalkenes from the molecules indicated in the patent, it may then be possible to use activated alumina at reflux on this DCM solution in order to achieve the desired product.

I know that other solvents such as petroleum ether did not work nearly as well as ether in this reaction for some substrates when tried, but cannot remember whether DCM was tried and cannot look it up using TFSE as it is not working.

What does anybody think to the possibility of running this type of two phase reaction in DCM and the possibility of subsequent conversion of the psuedonitrosite using activated alumina (the second bit is also important as it appears that the 1995 paper suggests that this is done using NO, and I don't know if it is viable to do this with a mixture of NO and NO₂ as too much of this mixture can lead to ring nitration of some substrates - e.g. asarone).

Antibody2
(LinguisticBee)
04-28-04 13:30
No 503501
      some density issues to consider

DCM is much heavier than water, thus forming the bottom layer, N203 escaping the rxn without ever coming into contact w/ the precurser.

If however the aqueous layer is saturated w/ NaNO2 the densities of the two layers is closer, so close that after a good shake, something that looks like a colloid results and does not readily separate into two layers. And that is at RT!

One way around this might be to use a very low density NP co solvent in an attempt to coax the DCM layer into remaining on top. An even surer bet would be to use Dichloroethane (density 1.24) which is marginially lighter than DCM (density 1.32)

the other thing to consider is that as the acid(H2SO4) is added the NaNO2 is converted into sodium sulfate which will precipitate out of solution, the aqueous layer will become progressily less dense and eventually form the top layer again. Using HCl instaed of H2SO4 might help as the formed NaCl should remain solute, but again NaCl is less dense than NaNO2 so the aqueous layer still might rise.

We are all just witnesses.

Vitus_Verdegast
(Hive Addict)
04-28-04 14:46
No 503505
User Picture       monomer and dimer

"The pseudonitrosites always dimerizes to the bis-pseudonitrosites, all of which are practically insoluble in water, alcohols and most common organic solvents, with the exception of warm chloroform or ethyl acetate, in which a blue-green solution is produced, consisting of the dissociated pseudonitrosite monomer"
https://www.rhodium.ws/chemistry/pseudonitrosite.html

Why not dissolve the dimer in warm chloroform for a trial with the alumina catalyst ?

"It is the declared policy of the US Government to create a Drug-Free America by 1995."

ning
(acetaminophanatic)
04-28-04 14:57
No 503510
User Picture       I have some papers on this topic

Seems the hive always catches up to me....

Will post more later, after I see what's already up.
NO is an awesome tech. It doesn't seem to generate dimers, just straight nitrostyrenes.

I have a paper that talks about making NO electrolytically. If you put nitric acid with copper and constantly plate the copper back on as the nitric acid dissolves it, it works.
Decomposition to NO requires a small amount of copper salt, as well.

You need about 4 NO for every nitrostyrene produced.

I've been chased by both cops and robbers. So what does that make me?

starlight
(Hive Bee)
04-28-04 18:47
No 503561
      how dense!

Antibody, I should have realized about that density issue - how dense of me! Don't fancy trying to separate colloids or emulsions - had enough of those without trying to cause them (mainly in extraction of root barks etc.). Thanks for pointing out the erroneous, sloppy nature of my thinking.

Vitus - yes this seems like it might be the best route towards finding out if this idea will work. The pseudonitrosite dimer is easy as hell to make. I will run a small trial late next week. Then we will see.

starlight
(Hive Bee)
05-06-04 20:52
No 505382
      test of concept

Encouraged by Vitus' idea, the following was attempted:

Preparation of Isodillapiole pseudonitrosite.

In a 1l, three-neck roundbottom flask, vented out of doors through a hose, 0.1 moles (22.8g) of Isodillapiole was dissolved with stirring in 190mls Et2O and chilled to 3C in an ice/water bath. To this was added 0.5 moles (34.5g) NaNO2 dissolved in 100mls dH2O, forming a lower layer. Stirring was continued at the lowest setting and 0.25 mole of H2SO4 (24.5g) dissolved in 100mls ice cold dH20 was added dropwise over 4 hours, and allowed to sit an additional 3 hours with no stirring. Ice bath was maintained throughout. After shaking rxn vessel, entire contents were decanted into a 2l beaker containing 0.5l dH20. After some swirling, the etheral layer with light yellow precipitate was decanted and vacuum filtered. The filtercake was washed with water, then IPA then ether and allowed to dry for twenty minutes.

Yield: 79% (25g)

Preparation of the Nitropropene

The psuedonitrosite was immediately transferred to a 250ml flask and 100ml of chloroform was added. The flask was put in a water bath at 40C and stirred vigorously. Some of the psuedonitrosite dissolved to form a slightly green/yellow tinted solution, but most if it stayed in suspension. 20g of Acidic acivated (gamma) Alumina of Activity grade I was added to the flask (stirring was stopped for this). The alumina immediately turned orange. A reflux condenser was attached and stirring was resumed whilst holding the temperature at 40C for the next 1.5 hours. After this time, the alumina was still orange, but the majority of the psuedonitrosite was still in suspension in the slightly green/yellow tinted solution. It seemed clear that the catalyst is unable to convert the pseudonitrosite to the nitropropene in any great amount at 40C. Accordingly the temperature of the water bath was raised to 55C for the next three hours, after which time the solution was a deep orange color. This was left to stand overnight.

The following morning, the chloroform was removed on a rotovap to leave around 20g of a red oil that was very similar in appearance to the crude nitropopene prepared by digesting the pseudonitrosite with KOH/EtOH. Attempts at recrystallizing this oil from IPA, EtOAC, IPA/EtOAc all failed as the product was too impure to isolate successfully. Attempts to form seed crystals using dry ice also failed.

I have always found that with Isodillapiole, the formation of the pseudonitrosite works just as in Antibody's description on Rhodium's page, but that the subsequent conversion to the nitropropene using EtOH/KOH produces a lot of side products that lower the yields even when the temperature is kept below 30C. When the temperature is kept low, the reaction can take 24hrs, due to the extremely poor solubility of this particular pseudonitrosite in ethanol. The pseudonitrosite is also seems far less soluble that that of Asarone in chlorinated solvents.

Probably the problem with the above trial is just that acidic alumina in chloroform is just not the way to go. It requires too high a temperature - one at which the pseudonitrosite decomposes to a variety of products without catalyst. I was hoping that maybe the catalyst would encourage the formation of the nitropropene in preference to the side reactions (as it appears to help convert other substrates in the patent above), but it looks like this may have been wrong.

However, maybe it's not worth writing this off completely. Its just possible that the reason it is not working well is due to the low solubility of the pseudonitrosite in chloroform, meaning that not much substrate is getting in contact with the catalyst. Maybe it would be worth giving it a go in ethyl acetate or with a different pseudonitrosite (I have always found asarone better yielding than isodillapiole even with the traditional technique of converting the psuedonitrosite to the nitropropene; isodillapiole pseudonitrosite seems to make very dirty nitropropene on digestion).

Wish I could find a reliable, high yielding process for converting Isodillapiole pseudonitrosite to the nitropropene. Maybe H2SO4 would work? (works for styrene pseudonitrosite I believe).

Oh well, another 2 days wasted.

Antibody2
(LinguisticBee)
05-07-04 20:01
No 505634
      the formation of the pseudonitrosite works...

the formation of the pseudonitrosite works just as in Antibody's description on Rhodium's page glad to hear it

the subsequent conversion to the nitropropene using EtOH/KOH produces a lot of side products that lower the yields even when the temperature is kept below 30C. When the temperature is kept low, the reaction can take 24hrs shaking actually works alot better than mag stirring to digest the pseudonitrosite. But it heats up and cooling is required periodically.

If there is alot of byproduct after the acid hydrolysis it may be because the acid was added to quickly, it should be added dropwise with heavy cooling. Not just ice in the rxn vessel but external cooling as well.

Ab2's impression was that the major byproduct of the acid hydrolysis was the nitroalcohol and it is this product (which usually precipitates during the hydrolysis first) that should be reacted with the alumina IMHO not the pseudonitrosite. The above refs seem to imply that the nitroalcohol and nitropropene don't need to be isolated beforehand as the alumina does not react with the nitopropene, so just take the whole post hydrolysis mess and react w/ acidic alumina

We are all just witnesses.

starlight
(Hive Bee)
05-08-04 14:34
No 505792
      thanks antibody

Tnanks for those tips Antibody.

In the experiments I was referring to, HCL was added dropwise and slowly, but no ice was put into the ethanol (only external cooling was used). Maybe the problem has indeed been not keeping the temperature low enough. Maybe it is worth throwing the odd chunk of dry ice into the heavily stirred mixture to keep the temperature at around -5C. I like the tip about shaking as well. This is really interesting.

With regard to your opinion (and there is no need to be humble here because you are spot on), the idea of reacting the nitropropene/nitroalcohol mix with the acidic alumina in chloroform is definitely the way forward. I just wanted to see whether the other way would work (long shot I know, but would have been quicker if it had).

Another trial will be run in the next couple of weeks in order to try and get the best yeild out of this method.

thanks again, starlight.

Rhodium
(Chief Bee)
05-14-04 13:48
No 507127
User Picture       Related methods of NO nitration of alkenes
(Rated as: good read)

One-Pot Synthesis of Nitroolefins Using Zeolite
R. Sreekumar, Raghavakaimal Padmakumar and P. Rugmini
Tetrahedron Letters 39(18), 2695-2696 (1998) (https://www.rhodium.ws/pdf/nitroalkenes.no-zeolite.pdf)
DOI:10.1016/S0040-4039(98)00408-0

Abstract
Nitroolefins, versatile intermediates in organic synthesis, are conveniently prepared in good yields by nitration of olefins using nitric oxide and zeolite as described.
____ ___ __ _

Preparation of Nitroolefins in the Presence of Ether Solvents
C. A. Drake
Patent US3658922

Abstract
A method of preparing nitroolefins by contacting olefins with nitric oxide (at 10-60°C and 75-300 psi) in the presence of an ether solvent without the formation of significant amounts of nitro-alcohols, nitro-nitroso or dinitro compounds.

^{The Hive - Clandestine Chemists Without Borders}

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	All 16 posts		Subject: Rediscovery of Pseudonitrosite Synthesis		Please login to post		Down


		Rhodium (Chief Bee) 04-19-04 20:20 No 501648				Rediscovery of Pseudonitrosite Synthesis (Rated as: excellent)
						Convenient and Simple Preparation of Nitroolefins Nitration of Olefins with Nitric Oxide Teruaki Mukaiyama, Eiichiro Hata, and Tohru Yamada Chemistry Letters 505-506 (1995) (https://www.rhodium.ws/pdf/alkene.nitration.no-1.pdf) Abstract Nitroolefins are conveniently prepared in high yields by nitration of olefins under an atmospheric pressure of nitric oxide at room temperature and subsequent treatment with acidic alumina. ____ ___ __ _ A Convenient Method for the Preparation of Nitro Olefins by Nitration of Olefins with Nitrogen Monoxide Eiichiro Hata, Tohru Yamada, and Teruaki Mukaiyama Bull. Chem. Soc. Jpn., 68, 3629-3636(1995) (https://www.rhodium.ws/pdf/alkene.nitration.no-2.pdf) Abstract Olefins with a terminal double bond or conjugated with aromatic nucleus are successfully nitrated into nitro olefins in good-to-high yields on treatment with nitrogen monoxide (NO) in 1,2-dichloroethane. Nitro alcohols formed as by-products are dehydrated to yield nitro olefins by the subsequent treatment with acidic activated alumina. By GC analysis, it was confirmed that an equimolar amount of nitrogen gas was evolved during the present nitration. A possible reaction pathway including the formation of nitro nitroso compounds, key intermediates, is described. The key intermediates are transformed into nitro olefins by reaction with nitrogen monoxide. Oddly enough, they aren't referencing any of the articles listed in https://www.rhodium.ws/chemistry/pseudonitrosite.html - I assume it is due to to the language barrier... ^{The Hive - Clandestine Chemists Without Borders}



		starlight (Hive Bee) 04-19-04 23:18 No 501675				goes further than the pseudonitrosite!
						Wow, those recent refs are really interesting. Fantastic find, good yields. This is not the classical psuedonitrosite route though is it? - it uses NO rather than N2O3. So the pseudonitrosite intermediate gets converted to the nitro-olefin. It looks better than the classical route, because the yields are higher. It avoids that need for treatment of a pseudonitrosite dimer with base and then acid to get the final product, which can be somewhat low yeilding for some substances. I see most of the examples they give are terminal olefins. Would the fact it works on those cyclic olefins suggest that it would work on propenylbenzenes? If so (which would not surprise me at all), I have to say this looks fantastic.



		Antibody2 (LinguisticBee) 04-20-04 02:12 No 501707				WOW
						be nice if that dehydration rxn would work for converting the nitroalcohol byproducts from "conventional" pseudonitrosite hydrolysis to nitropropenes? Where is the 2nd Hydrogen atom for the dehydration coming from? Is the acidic alumina acting as a hydrogen donor? We are all just witnesses.



		starlight (Hive Bee) 04-20-04 08:53 No 501747				i can't see that one is needed
						Taking an -OH from the carbon next to the aromatic ring and an H from the carbon with the Nitro group gives you a double bond doesn't it? -> Loss of one water molecule.



		starlight (Hive Bee) 04-20-04 15:47 No 501817				DCM
						NO seems quite expensive to buy. Could possibly generate it from 50% HNO3 and Cu metal I suppose. DCE is carcinogenic to some degree. Maybe DCM would work instead (good chance I would have thought from looking at the paper).



		SpicyBrown (Hive Bee) 04-22-04 02:47 No 502191				Making NO
						NO seems quite expensive to buy. Could possibly generate it from 50% HNO3 and Cu metal I suppose NO can be generated from HNO₃ and a few different transition metals. The only thing that one needs to be careful of is to exclude oxygen from the gas generation vessel and piping as much as possible, as NO oxidizes quite rapidly to NO₂ (the brown funk; NO by itself is colorless) in the presence of atmospheric oxygen. -SpicyBrown



		starlight (Hive Bee) 04-22-04 08:10 No 502227				concentration
						The concentration of the nitric acid is also important as different oxides of nitrogen are formed at different concentrations of acid



		starlight (Hive Bee) 04-28-04 11:24 No 503483				Related experiments
						Here is a fascinating little patent that was published in-between the original pseudonitrosite work and the 1995 work: Patent US3240823 It is related to the above work in that it uses activated alumina catalysts to convert nitroalcolhols to nitro-olefins. But it also uses activated alumina catalysts to convert dinitroalkanes and nitronitrites to nitroalkenes. Many examples are given using different types of alumina with varying reaction conditions (e.g. reflux time, amount of water present). From these experiments, it appears that the activated alumina (presumably acidic) has the ability to convert a range of 1-nitro-2-something-alkanes to nitroalkenes. I just wonder if it would be possible to conduct a standard pseudonitrosite reaction using NaNO₂/H₂SO₄, but rather than using two phase ether/H₂O, use two phase DCM/H₂O to create a solution of pseudonitrosite monomer in DCM. Given the potentially wide applicability of activated alumina in the preparation of nitroalkenes from the molecules indicated in the patent, it may then be possible to use activated alumina at reflux on this DCM solution in order to achieve the desired product. I know that other solvents such as petroleum ether did not work nearly as well as ether in this reaction for some substrates when tried, but cannot remember whether DCM was tried and cannot look it up using TFSE as it is not working. What does anybody think to the possibility of running this type of two phase reaction in DCM and the possibility of subsequent conversion of the psuedonitrosite using activated alumina (the second bit is also important as it appears that the 1995 paper suggests that this is done using NO, and I don't know if it is viable to do this with a mixture of NO and NO₂ as too much of this mixture can lead to ring nitration of some substrates - e.g. asarone).



		Antibody2 (LinguisticBee) 04-28-04 13:30 No 503501				some density issues to consider
						DCM is much heavier than water, thus forming the bottom layer, N203 escaping the rxn without ever coming into contact w/ the precurser. If however the aqueous layer is saturated w/ NaNO2 the densities of the two layers is closer, so close that after a good shake, something that looks like a colloid results and does not readily separate into two layers. And that is at RT! One way around this might be to use a very low density NP co solvent in an attempt to coax the DCM layer into remaining on top. An even surer bet would be to use Dichloroethane (density 1.24) which is marginially lighter than DCM (density 1.32) the other thing to consider is that as the acid(H2SO4) is added the NaNO2 is converted into sodium sulfate which will precipitate out of solution, the aqueous layer will become progressily less dense and eventually form the top layer again. Using HCl instaed of H2SO4 might help as the formed NaCl should remain solute, but again NaCl is less dense than NaNO2 so the aqueous layer still might rise. We are all just witnesses.



		Vitus_Verdegast (Hive Addict) 04-28-04 14:46 No 503505				monomer and dimer
						"The pseudonitrosites always dimerizes to the bis-pseudonitrosites, all of which are practically insoluble in water, alcohols and most common organic solvents, with the exception of warm chloroform or ethyl acetate, in which a blue-green solution is produced, consisting of the dissociated pseudonitrosite monomer" https://www.rhodium.ws/chemistry/pseudonitrosite.html Why not dissolve the dimer in warm chloroform for a trial with the alumina catalyst ? "It is the declared policy of the US Government to create a Drug-Free America by 1995."



		ning (acetaminophanatic) 04-28-04 14:57 No 503510				I have some papers on this topic
						Seems the hive always catches up to me.... Will post more later, after I see what's already up. NO is an awesome tech. It doesn't seem to generate dimers, just straight nitrostyrenes. I have a paper that talks about making NO electrolytically. If you put nitric acid with copper and constantly plate the copper back on as the nitric acid dissolves it, it works. Decomposition to NO requires a small amount of copper salt, as well. You need about 4 NO for every nitrostyrene produced. I've been chased by both cops and robbers. So what does that make me?



		starlight (Hive Bee) 04-28-04 18:47 No 503561				how dense!
						Antibody, I should have realized about that density issue - how dense of me! Don't fancy trying to separate colloids or emulsions - had enough of those without trying to cause them (mainly in extraction of root barks etc.). Thanks for pointing out the erroneous, sloppy nature of my thinking. Vitus - yes this seems like it might be the best route towards finding out if this idea will work. The pseudonitrosite dimer is easy as hell to make. I will run a small trial late next week. Then we will see.



		starlight (Hive Bee) 05-06-04 20:52 No 505382				test of concept
						Encouraged by Vitus' idea, the following was attempted: Preparation of Isodillapiole pseudonitrosite. In a 1l, three-neck roundbottom flask, vented out of doors through a hose, 0.1 moles (22.8g) of Isodillapiole was dissolved with stirring in 190mls Et2O and chilled to 3C in an ice/water bath. To this was added 0.5 moles (34.5g) NaNO2 dissolved in 100mls dH2O, forming a lower layer. Stirring was continued at the lowest setting and 0.25 mole of H2SO4 (24.5g) dissolved in 100mls ice cold dH20 was added dropwise over 4 hours, and allowed to sit an additional 3 hours with no stirring. Ice bath was maintained throughout. After shaking rxn vessel, entire contents were decanted into a 2l beaker containing 0.5l dH20. After some swirling, the etheral layer with light yellow precipitate was decanted and vacuum filtered. The filtercake was washed with water, then IPA then ether and allowed to dry for twenty minutes. Yield: 79% (25g) Preparation of the Nitropropene The psuedonitrosite was immediately transferred to a 250ml flask and 100ml of chloroform was added. The flask was put in a water bath at 40C and stirred vigorously. Some of the psuedonitrosite dissolved to form a slightly green/yellow tinted solution, but most if it stayed in suspension. 20g of Acidic acivated (gamma) Alumina of Activity grade I was added to the flask (stirring was stopped for this). The alumina immediately turned orange. A reflux condenser was attached and stirring was resumed whilst holding the temperature at 40C for the next 1.5 hours. After this time, the alumina was still orange, but the majority of the psuedonitrosite was still in suspension in the slightly green/yellow tinted solution. It seemed clear that the catalyst is unable to convert the pseudonitrosite to the nitropropene in any great amount at 40C. Accordingly the temperature of the water bath was raised to 55C for the next three hours, after which time the solution was a deep orange color. This was left to stand overnight. The following morning, the chloroform was removed on a rotovap to leave around 20g of a red oil that was very similar in appearance to the crude nitropopene prepared by digesting the pseudonitrosite with KOH/EtOH. Attempts at recrystallizing this oil from IPA, EtOAC, IPA/EtOAc all failed as the product was too impure to isolate successfully. Attempts to form seed crystals using dry ice also failed. I have always found that with Isodillapiole, the formation of the pseudonitrosite works just as in Antibody's description on Rhodium's page, but that the subsequent conversion to the nitropropene using EtOH/KOH produces a lot of side products that lower the yields even when the temperature is kept below 30C. When the temperature is kept low, the reaction can take 24hrs, due to the extremely poor solubility of this particular pseudonitrosite in ethanol. The pseudonitrosite is also seems far less soluble that that of Asarone in chlorinated solvents. Probably the problem with the above trial is just that acidic alumina in chloroform is just not the way to go. It requires too high a temperature - one at which the pseudonitrosite decomposes to a variety of products without catalyst. I was hoping that maybe the catalyst would encourage the formation of the nitropropene in preference to the side reactions (as it appears to help convert other substrates in the patent above), but it looks like this may have been wrong. However, maybe it's not worth writing this off completely. Its just possible that the reason it is not working well is due to the low solubility of the pseudonitrosite in chloroform, meaning that not much substrate is getting in contact with the catalyst. Maybe it would be worth giving it a go in ethyl acetate or with a different pseudonitrosite (I have always found asarone better yielding than isodillapiole even with the traditional technique of converting the psuedonitrosite to the nitropropene; isodillapiole pseudonitrosite seems to make very dirty nitropropene on digestion). Wish I could find a reliable, high yielding process for converting Isodillapiole pseudonitrosite to the nitropropene. Maybe H2SO4 would work? (works for styrene pseudonitrosite I believe). Oh well, another 2 days wasted.



		Antibody2 (LinguisticBee) 05-07-04 20:01 No 505634				the formation of the pseudonitrosite works...
						the formation of the pseudonitrosite works just as in Antibody's description on Rhodium's page glad to hear it the subsequent conversion to the nitropropene using EtOH/KOH produces a lot of side products that lower the yields even when the temperature is kept below 30C. When the temperature is kept low, the reaction can take 24hrs shaking actually works alot better than mag stirring to digest the pseudonitrosite. But it heats up and cooling is required periodically. If there is alot of byproduct after the acid hydrolysis it may be because the acid was added to quickly, it should be added dropwise with heavy cooling. Not just ice in the rxn vessel but external cooling as well. Ab2's impression was that the major byproduct of the acid hydrolysis was the nitroalcohol and it is this product (which usually precipitates during the hydrolysis first) that should be reacted with the alumina IMHO not the pseudonitrosite. The above refs seem to imply that the nitroalcohol and nitropropene don't need to be isolated beforehand as the alumina does not react with the nitopropene, so just take the whole post hydrolysis mess and react w/ acidic alumina We are all just witnesses.



		starlight (Hive Bee) 05-08-04 14:34 No 505792				thanks antibody
						Tnanks for those tips Antibody. In the experiments I was referring to, HCL was added dropwise and slowly, but no ice was put into the ethanol (only external cooling was used). Maybe the problem has indeed been not keeping the temperature low enough. Maybe it is worth throwing the odd chunk of dry ice into the heavily stirred mixture to keep the temperature at around -5C. I like the tip about shaking as well. This is really interesting. With regard to your opinion (and there is no need to be humble here because you are spot on), the idea of reacting the nitropropene/nitroalcohol mix with the acidic alumina in chloroform is definitely the way forward. I just wanted to see whether the other way would work (long shot I know, but would have been quicker if it had). Another trial will be run in the next couple of weeks in order to try and get the best yeild out of this method. thanks again, starlight.



		Rhodium (Chief Bee) 05-14-04 13:48 No 507127				Related methods of NO nitration of alkenes (Rated as: good read)
						One-Pot Synthesis of Nitroolefins Using Zeolite R. Sreekumar, Raghavakaimal Padmakumar and P. Rugmini Tetrahedron Letters 39(18), 2695-2696 (1998) (https://www.rhodium.ws/pdf/nitroalkenes.no-zeolite.pdf) DOI:10.1016/S0040-4039(98)00408-0 Abstract Nitroolefins, versatile intermediates in organic synthesis, are conveniently prepared in good yields by nitration of olefins using nitric oxide and zeolite as described. ____ ___ __ _ Preparation of Nitroolefins in the Presence of Ether Solvents C. A. Drake Patent US3658922 Abstract A method of preparing nitroolefins by contacting olefins with nitric oxide (at 10-60°C and 75-300 psi) in the presence of an ether solvent without the formation of significant amounts of nitro-alcohols, nitro-nitroso or dinitro compounds. ^{The Hive - Clandestine Chemists Without Borders}

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