Author Topic: New synthesis of Phenyl-2-propanones  (Read 8837 times)

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Rhodium

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Re: New synthesis of Phenyl-2-propanones
« Reply #20 on: February 23, 2001, 07:26:00 PM »
Could you try the reaction out on benzene, just to verify that it works with 2-nitropropene? The original article used other (cyclic) nitroalkenes.


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Scooby_Doo

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Re: New synthesis of Phenyl-2-propanones
« Reply #21 on: February 25, 2001, 03:37:00 AM »
Sorry Rhod I probably can't get my hands on any Benzene because of its general unpleasantness.
I am positive that the MD bridge was the problem. A little separate experiment showed the Titanium tetrachloride reacted instantaneously with 1,2 methylendioxybenzene turning it into red tar. As for the actual reaction it definitely produced some sort of complex which fell out of solution. However the mixture had turned so black (from a fluro clear green) it was obvious that something had gone wrong.

Scooby

Rhodium

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Re: New synthesis of Phenyl-2-propanones
« Reply #22 on: February 25, 2001, 07:45:00 PM »
Toluene then? 4-methyl-P2P isn't that useful, but at least you can prove that the reaction works.


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Scooby_Doo

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Re: New synthesis of Phenyl-2-propanones
« Reply #23 on: February 26, 2001, 02:37:00 AM »
I was thinking the same thing, I also wouldn't mind looking at catechol which would be a little more useful.

Osmium

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Re: New synthesis of Phenyl-2-propanones
« Reply #24 on: February 26, 2001, 01:02:00 PM »
Those OH groups will bind to the TiCl4, rendering it ineffective.
Did you work your reaction up? Never judge your reactions by what they look like, only after proper workup can you be sure of the results.

Use another catalyst, what about SnCl4? Or anhydrous ZnCl2. Activated aromatics like anisole, methylenedioxybenzenes and other phenolethers should undergo that reaction much easier than benzene, which is terribly unreactive compared to them, meaning that the reaction might take place at lower temps, with more selective (=lower reactivity) catalysts etc.

Rhodium

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Re: New synthesis of Phenyl-2-propanones
« Reply #25 on: February 27, 2001, 08:24:00 AM »
The original article used toluene and nitrocyclohexene with the reaction conditions described.


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Scooby_Doo

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Re: New synthesis of Phenyl-2-propanones
« Reply #26 on: February 27, 2001, 08:57:00 AM »
Your right I should have finished with a proper workup. However whatever it was I spent hours getting it out of the flask with the blob having a texture of tary charcoal.

A lower temp is a definite possibility, the reaction temp got to around 38-39 deg. With the color starting as a ketone fluro yellow/green going to a really dark brown to charcoal black after a temp of 35 was reached. Maybe 0 or even colder might be quite a good idea. (I might try adding the TiCl4 to the 1,2 methylenedioxybenzene at different temps the one that doesn't produce tar is the temp to run with.)

As for using different types of catalysts could this change the regioselectivey of the reaction products being only para substituted?

Scooby

Osmium

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Re: New synthesis of Phenyl-2-propanones
« Reply #27 on: February 27, 2001, 04:42:00 PM »
The bulkier they are the more para product you should get (steric control). Another factor is that all those catalysts like the oxygen a lot and will bind to it, possibly favoring the o position. That's why weaker (=more selective) catalysts might give better yields. Difficult to say without hitting the books.
Also limiting the reaction time works for reversible reactions due to kinetic control (once all has reacted the reaction is stopped to avoid rearrangements). Dunno if that applies to this kind of reactions though.

Scooby_Doo

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Re: New synthesis of Phenyl-2-propanones
« Reply #28 on: April 15, 2001, 08:58:00 AM »
Here is some very useful refs in the production of 2-Nitro Propene:

JACS 98 4679 (1976)
Synthesis 407 (1980)

The one which the above lead to J. Chem. Soc 1947 1471-2

I can't find the above one but I did find the CA for it. (Either 1947 or 1948 4907 and in the same CA in the patents section Brit 595,282 which is pretty much the same as the first one.)

Nitro alcohols are heated with a phthalic anhydride to give nitro olefins, here's the deal.
1 mole of 2Nitro-1-Propanol and 1.35 mole of phthalic anhydride were placed in a distillation app. A vacuum of 80 mm was applied and the flask was heated. Everything melted a 130-140 deg tiny bubbles became evident at 150-160 deg. The reaction began and heating was adjusted to control the rate. It stayed around 162 deg and then dropped down to 155 deg. More heat was applied and the reaction stopped when it reached 180 deg. (all these temps are at 80mm of Hg)

The receiving flask contained water and a ketone yellow colored oil. The vac was released with N2 being drawn in. Don't let any air into the flask otherwise the 2-Nitro Propene breaks down extremely fast as well a being very volatile, the receiving flask was in an ice bath for the entire reaction. If air does get to it a orange vapour is emitted form it which as the same hurt factor as Bromine. The oil will rapidly turn green and will break down into tar in a few days. The oil however stores very well in the freezer under N2, for months.

In the ref they went and distilled straight away which Batman tried but was pretty silly since the water causes problems. A better approach is to dry with molecular sieves (which worked really well) then distil.

Scooby

jim

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Re: New synthesis of Phenyl-2-propanones
« Reply #29 on: April 20, 2001, 06:56:00 PM »
From Rhodium's site, the microwave Henry condesation text:

"...

Several reagents such as phthalic anhydride,[12,13] methanesulfonyl
chloride,[14] dicyclohexylcarbodiirnide (DCC), [15] pivaloyl chloride, [16,
17] ammonium acetate-acetic acid [18, 19] and amines[7, 19] have been used
for the dehydration of the ensuing b-nitro alcohols.  ..."

I was thinking that the mere addition of the formaldehyde to the nitroethane with ammonium acetate and acetic acid would afford the nitropropene directly.  Perhaps even the addition of microwave heating would improve yields or speed up the process.  I can't imagine that nitropropene reacts too differently from other nitropropenes...

If one were to use a substituted ring one could substitute the nitroethane with nitromethane (which is easier to obtain OTC) and produce a substituted phenethylamine.

?

Rhodium

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Re: New synthesis of Phenyl-2-propanones
« Reply #30 on: April 21, 2001, 02:50:00 AM »
Nitroalcohols (from the condensation of nitroalkanes and aldehydes) dehydrates to the nitroalkene MUCH easier if the aldehyde is aromatic.


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Scooby_Doo

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Re: New synthesis of Phenyl-2-propanones
« Reply #31 on: September 04, 2001, 05:10:00 PM »
Application of this synthesis to the preparation of MDP2P

To a 3-necked 500 ml flask under a nitrogen atmosphere was added 300 mls of dry DCM, 0.1 mole of 2-Nitropropene (8.7g) and 0.5 mole of 1,3-Benzodioxole (61g). The flask was then secured within a dewar flask sitting on top of a magnetic stirplate. Dry ice was added to the dewar flask which was filled with acetone until a temperature of approx -78º C was acquired. Once the internal flask temperature of -70º C was reached, 0.1 mole (19g) of TiCl4 was dripped slowly into the stirred solution. The temp started to rise so the addition was controlled to keep the internal flask temp around -60 to -70º C. The flask was then stirred for 30 mins at -70º C, by which time the precipitate which formed from the addition had dissipated.
The dewar flask was removed and the stirring solution was allowed to warm up to room temperature. (The black solution will change viscosity and colour.)

NEF REACTION

100 mls of water was added to the solution which was then  refluxed for 2 hours. During the reflux a brown gas (probably NO2) is evolved.

WORKUP

The flask was cooled and vac filtered (cleans it up a lot) the water layer seperated and discarded. The organic layer was then washed with 3x 200 mls of 10% NaOH sol and 1x 200 mls of a brine solution. It was then dried with magnesium sulfate, the DCM evaporated and resulting orangey/yellow oil vac distilled. The 1,3-Benzodioxole came over at 40-45º C at 10 mbar then a fluoro yellow/green oil (MDP2P) started distilling at 135º C at 3 mbar.
Yields 8g of MDP2P, 45% form 2-Nitropropene or 23.5% form 1,3-Benzodioxole. (Worked out from the 1,3-Benzodioxole not recovered during the vac distillation.)

foxy2

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Alternate 2-nitropropanol synthesis
« Reply #32 on: October 02, 2001, 11:50:00 PM »
Technology of 2-nitro-1-propanol.    
Polovnyak, V. K.; Kolpashchikov, M. V.
Khim. Khim. Tekhnol.  (1975),  18(3),  497. 
CODEN: IVUKAR  Journal  written in Russian.  CAN 83:9077 

Abstract

Optimal conditions for prepn. of O2NCHMeCH2OH from EtNO2 and HCHO (as paraformaldehyde) were: 10N KOH as catalyst, use of elevated temp., and reaction time 2-3 min.
 

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jim

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Re: Alternate 2-nitropropanol synthesis
« Reply #33 on: October 03, 2001, 06:48:00 AM »
Great job.

Rhodium

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Re: Alternate 2-nitropropanol synthesis
« Reply #34 on: October 03, 2001, 08:45:00 AM »
Another reference of the nitropropene/benzene condensation can be found in JOC 54(4), 733-734 (1989), but they use CF3SO2H instead of TiCl4 (85% yield in 1 min, at -40°C).