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Posts 16 - 29 of 29   Subject: Another easy route to P-2-P´s   Page:  Previous  First  All   New  Down

 
    Rhodium
(Chief Bee)
06-15-02 05:15
No 321478
User Picture 
      "Rhodium's Chapter"  Bookmark  Reply   

Page 164-181 in TSII is called "Rhodium's Chapter", and has a very flattering introduction by Strike (I don't think nearly as much about myself though):

This is a chapter written entirely by a chemist named Rhodium (with guest speaker Osmium!). Rhodium is, as far as Strike is concerned, the world's leading underground scientist. Knowledgeable in nearly every aspect of drug chemistry, this chemist has been the savior for many a person that was lost. Here he has contributed some new reactions for your reading pleasure. Radical stuff that you can bet will become the next wave of synthesis protocol. The rest of the chapter is Rhodium's voice.

The chapter contains the following:

1) https://www.rhodium.ws/chemistry/mdp2np.html
2) https://www.rhodium.ws/chemistry/phenylacetone.html#p2np (the reaction using NaBH4/K2CO3/H2O2)
3) The above sodium stannite and tin(II)chloride reductions of nitropropenes to oximes
4) Some oxime cleavage reactions, to form phenylacetones from the above oximes
5) https://www.rhodium.ws/chemistry/peroxotungstate.html
6) A discussion of using various metal salts as catalysts for the NaBH4 reduction of nitrostyrenes
7) https://www.rhodium.ws/chemistry/mmda.mescaline.html (Which was written together with Osmium)

Today I'm almost ashamed of some of the things I wrote, I wasn't nearly as knowledgeable in chemistry in 1998 as I am now, and can directly point out oversights here and there, there are even a few spelling and grammar errors in the texts!
 
 
 
 
    Barium
(Newbee)
06-17-02 15:49
No 322410
      Now it´s even easier
(Rated as: excellent)
 Bookmark  Reply   

This has been a good weekend.

This is a very general procedure and it has so far worked with every single phenylnitropropene I´ve tried. The yields has been in the range of 85-92%. The lower yields are very likely a result of my impatience. Longer time for hydrolysis should have given higher yields.


100mmol of the phenylnitropropene
220mmol Tin(II)chloride dihydrate
200mmol HCl (as a calculated amount conc. aq HCl)
50ml toluene
200ml water
NaCl (solid)

Procedure:

Dissolve the tin(II)chloride in water mixed with the hydrochloric acid. Add the substrate to a rb flask and rinse it all down with the toluene. Now add the aqueous solution to the rb flask in one portion. With good stirring bring the mixture to a gentle reflux for 2 hours. Chill the flask to room temp and saturate the aqueous phase with NaCl, separate the two layers and transfer the top organic layer to a 1L flask containing 500ml water. Steam distill until no more oily drops comes over. This means between 500ml to 1,5L distillate is to be collected depending on the volatility of the ketone. When the steam distillation is over the distillate consits of two layers, one top layer of touene and the major part of the ketone. Separate the layers in a separatory funnel and extract the aqueous phase with 2x100ml toluene. Combine the toluene extracts, dry them with MgSO4 and remove the toluene in a rotovap. This leaves the ketone as a yellow oil ready for whatever you might have in mind for it.

The tin(II)chloride can be regenerated by electrolysis of the formed tin(IV)chloride.
 
 
 
 
    Barium
(Hive Bee)
06-19-02 17:07
No 323065
      Update  Bookmark  Reply   

When the hydrolysis (reflux) is over there is actually no need to separate the layers. Just stem distill it as it is. Toulene, ketone and water will pass over, not the tin compounds. One step less.smile
 
 
 
 
    Barium
(Hive Bee)
06-20-02 17:51
No 323366
      1-(2,4,5-trimethoxyphenyl)-2-propanone
(Rated as: good read)
 Bookmark  Reply   

5g (19,8mmol) 1-(2,4,5-trimethoxyphenyl)-2-nitropropene
12,3g (55mmol) tin(II)chloride dihydrate
15ml conc. hydrochloric acid
20ml toluene
15ml water
100ml EtOAc


Tin(II)chloride was dissolved in 15ml water and 15ml conc hydrochloric acid and the resulting solution was added to a 200ml rb flask containing 20ml toluene and 5g substrate. The mixture was heated to 80 deg C on a water bath with good stirring for 1,5 hours. During this time the color changed from a deep yellow to dark orange and then to light yellow.
After 1,5 hours 200ml water was added and the toluene was removed by steam distillation. The now bright yellow aqueous phase containing dark yellow oily droplets was saturated with NaCl and extracted with 2x50ml EtOAc which removed all color. The ethyl acetate was washed once with 50ml saturated NaHCO3 solution, once with 50ml water, once with brine and then dried with MgSO4. The solvent was removed in a rotovap leaving 3,7g of a yellow oil which slowly partially solidified to something reminding of honey.

Yield; 3,7g (83,8%) 1-(2,4,5-trimethoxyphenyl)-2-propanone     
 
 
 
 
    Rhodium
(Chief Bee)
06-20-02 18:18
No 323373
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      No polymers?  Bookmark  Reply   

What? The nitropropene from asarone stable in hydrochloric acid? Could you please recrystallize your product and verify the melting point of the supposed ketone? Asarylacetone should melt at:

mp(°C) Source
-------------------------------------------
47-48  Gazz.Chim.Ital.; 36 I; 1906; 283
47-48  J.Chem.Soc.; 1937; 1338,1340
46-47  Helv.Chim.Acta; 47; 1964; 1996-2017
44-46  J.Med.Chem.; 23; 12; 1980; 1318-1323
 
 
 
 
    GC_MS
(Hive Addict)
03-05-04 12:01
No 493114
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      1-phenyl-2-propanone  Bookmark  Reply   

I was a long time ago since I tested the procedure on Rh's page, and I am currently in the need of some phenyl-2-propanone analogues, I wanted to re-evaluate the applicability of the method.

Substances: 32.6 g 1-phenyl-2-nitropropene (recrystallized from toluene), 100 g tin(II) chloride dihydrate, water and hydrochloric acid.

I allowed hydrolysis of the ketoxime for ca 1.5 h at 85-90°C. The reaction mixture was steam distilled to yield a yellow oil. The distillate was extracted with DCM and the combined organic phases washed with water. It is claimed that this procedure yields a reasonably pure product. On this, a little bit of comment... smile

For the most amongst us, this oil indeed is pure enough. However, when washing the organic phase with aqueous NaOH instead of water, a discoloured aqueous phase is noticed. Some chromatography showed me that there was some benzyl alcohol present. Also, the "purified" oil contained some benzaldehyde (ca 5%). Depending on what the purposes are of the P2P, benzaldehydes are an interfering factor (reductive amination).

Advanced clitoris massage specialist. 32 years of experience. PM me for a "sample".
 
 
 
 
    stratosphere
(Hive Bee)
03-06-04 21:34
No 493463
      i apologize if this is reduntant, but here is...  Bookmark  Reply   

i apologize if this is reduntant, but here is a procedure using Fe/HCl to reduce 1-(o-Methoxyphenyl)-2-nitro-1-propene to o-methoxyphenylacetone.

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv4p0573
 
 
 
 
    armageddon
(Hive Bee)
04-22-04 15:40
No 502241
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      Fe versus Sn  Bookmark  Reply   

Hi Stratosphere!

The advantages of the above method (compared to iron/HCl) are:

a) magnetic stirring is made possible

b) yields are slightly higher

c) it avoids messy cleaning up afterwards (no red rust)

d) not sure 'bout that, but I think Fe/HCl needs 5 hours?
   Sn/HCl only 2h...

e) iron salts cannot be "regenerated", the SnCl4-soln. from above rxn. is easily converted to SnCl2 again by
    electrolysis...wink

There are other threads about Fe/HCl reductions, too - but I think Tin(2)chloride is the reducing agent of choice for making ketones (see a) to e))...

Greetz A

"..ein Trank von unterschiedlicher Farbe, in ihm ist Heilung für die Menschen."
 
 
 
 
New: Posts 24 - 29 of 29   Subject: Another easy route to P-2-P´s   Top   Down
 
 
    armageddon
(Hive Bee)
08-30-04 20:53
No 528289
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      improved purity / suggestion  Bookmark  Reply   

To achieve less benzaldehyde contamination of final ketone, I suggest the following:

Suspend SnCl2 in EtOAc and stir to dissolve as much as possible, place in cooling bath. Dissolve nitropropene of choice in just enough EtOAc, and add that via addition funnel to the SnCl2 suspension at such a rate that the temp. doesn't exceed 30°C. When done, stir for 1 hour, then add H2O, and again stir for 1h (white oxime stannate precipitates). Remove the solvent using slight vacuum, then add HCl and reflux to hydrolyze the ketoxime to its ketone. Steam distill as usual.

(to be honest, I haven't tried this yet; but the thought behind it is to remove solvent before changing the oxime's structure - I believe the reason for the BA impurities is the presence of solvent other than water during hydrolysis. Experimental data will follow soon - promised...)

Greetz A

Pleased to meet you hope you get my name.
But whats puzzlin you is the nature of my game!
 
 
 
 
    Barium
(Heavyweight Chempion(eer))
08-31-04 01:16
No 528320
      Ok  Bookmark  Reply   

What is the reasoning behind the solvent-theory? Why would the solvent disturb the hydrolysis?
I do indeed encourage improvements and welcome any and all suggestions. I'm just curious.

Severe Aztecoholic and President of Sooty's fanclub - Sooty for President!!
 
 
 
 
    armageddon
(Hive Bee)
08-31-04 01:50
No 528325
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      just some feeling in my stomach ;^)  Bookmark  Reply   

The idea came to me when I thought about the hydrolysis being a reversible reaction, but the ketone (once it has formed) being rather stable towards further reduction (to benzaldehyde and nitroalkane), in contrast to the oxime.

And a substance being not in solution is not as reactive as a dissolved substance is, right? (I thought this was why solvents are used at all!)

Maybe the key lies just in keeping temp. low during nitrostyrene addition and using as little SnCl2 as possible (like 2.05 eq.) - but I have some strange feeling that the solvent plays an important role in the unwanted further reduction of oxime. Experiment will tell...

(unluckily I don't know any other possibility for removing benzylalcohol from product, besides shaking with dilute NaOH - I think this is the more annoying side product, and I don't know if a careful procedure will avoid its formation... - we'll see! wink)

Did I mention that despite aldehyde and OH impurities, your method still simply fuckin rocks, seen yield- and workwise?!! cool


Greetz A

Pleased to meet you hope you get my name.
But whats puzzlin you is the nature of my game!
 
 
 
 
    amine
09-01-04 03:43
      already answered
(Rated as: insignificant)
 Bookmark  Reply   
 
 
 
    armageddon
(Hive Bee)
09-01-04 04:14
No 528630
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      umm..  Bookmark  Reply   

As stated above (the 11th post in this thread): no. Maybe you should read the whole thread? wink

Greetz A

Pleased to meet you hope you get my name.
But whats puzzlin you is the nature of my game!
 
 
 
 
    dextro
(Newbee)
09-22-04 14:46
No 532685
      right ammount of HCL  Bookmark  Reply   

swim will try this with 115g SnCl in 150ml EtOAc and 40,75g p2np in EtOAc.
after addition of water and removal of the solvent:
WHAT IS THE RIGHT AMMOUNT OF HCL 36% ?
in the original post by barium 140ml conc. HCL was used, but in other threads the ammount was not exactly described.

Thx for help
 
 

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