The Vespiary

The Hive => Chemistry Discourse => Topic started by: roger2003 on November 25, 2002, 04:01:00 AM

Title: Hydrogenation
Post by: roger2003 on November 25, 2002, 04:01:00 AM
a,a-Dimethylphenethylamine ( Journal of Organic Chemistry,1972, 1862)
A mixture of 5,0g (0,027 mol) of (2-Methyl-2-nitropropyl)benzene, 63 ml ethanol, 12 ml glacial acetic acid, an 1 g of 10% palladium on charcol (50% water wet) was hydrogenatet at 40° an 50 psi until the hydrogen uptake ceased in ca. 3 hr. The yield was 4,1 g (0,027 mol, 100%)

SWIM ask me:

1.Does it also work with ispopropanol instead of ethanol
2.If the compound was changed to 1-Phenyl-2-nitropropene or others will it also yield 100 %



roger2003
Title: No, not with the propene, but if you first reduce ...
Post by: Rhodium on November 25, 2002, 05:52:00 AM
No, not with the propene, but if you first reduce the double bond with NaBH4, then you can go on to this step.
Title: It should work, but remember that many reactions ...
Post by: Barium on November 25, 2002, 10:52:00 AM
It should work, but remember that many reactions which should work doesn´t. If you plan to scale up this reaction, be very careful with the exothermic nature of it. Especially with the huge amount of catalyst. On a 500 g scale it could be nearly impossible to control unless you know exactly what you´re doing.
Catalytic hydrogenation freak
Title: SWIM told me, that he tried the hydrogenation in ...
Post by: roger2003 on November 26, 2002, 12:22:00 AM
SWIM told me, that he tried the hydrogenation in further time with Raneynickel in Methanol, by the description in German Patent 848197. These reaction was unsuccessfull, because the reaction stops by the oxim ?

Now he had the idea, to start with Raneynickel in Isopropanol, than stop the reaction an makes the next step with Pd/C in the same Isopropanol with acetic acid.

Does it work ?


roger2003
Title: German Patent 848 197 (in English -:) ) 165 g ...
Post by: roger2003 on November 26, 2002, 07:56:00 PM
German Patent 848 197 (in English -:) )

165 g 1-Phenyl-2-nitropropene mixed with 1500 g Methanol and 10 g Raney Nickel was hydrogenated at 20 – 50 degrees and 50 to 80 bar until the hydrogen uptake ceased.
Yield : 83 g of  1-Phenyl-2-aminipropan.

roger2003
Title: Re: and 50 to 80 bar ho ho ho, ill think ill try ...
Post by: hest on November 27, 2002, 01:44:00 AM

and 50 to 80 bar

ho ho ho, ill think ill try this at home

Title: Raney Nickel drawbacks.
Post by: terbium on November 27, 2002, 06:22:00 AM
and 50 to 80 bar
This is _one_ of the drawbacks to using Raney Nickel.


Baseline Does Not Exist.
Title: You take a seamless stainless steel tube (St. 1.
Post by: roger2003 on November 27, 2002, 12:57:00 PM
You take a seamless stainless steel tube (St. 1.4571), length 500 mm, outside 70 mm, wall thick 4 mm, closed with 2 fittings an you have a hydrogenation bottle up to 200 bar for a price less than 200 US $
roger2003
Title: Whoa, slow down roger!
Post by: Barium on November 27, 2002, 01:21:00 PM
You do not want to mess with pressures from 40 bar and up without having properly manufactured vessels. If you are an experienced engineer and know how to weld, then it is another story. If such a pipe you mentioned is the slightest stressed in some spot...well you do not want to be aroud whren it gives in to the pressure.

How do you propose to get proper stirring in your pipe?
If you UTFSE you´ll se how I describe a two-step method using very low pressure to get amines from nitrostyrenes.
Catalytic hydrogenation freak
Title: Mass transfer.
Post by: terbium on November 27, 2002, 07:06:00 PM
length 500 mm, outside 70 mm, wall thick 4 mm, closed with 2 fittings an you have a hydrogenation bottle up to 200 bar for a price less than 200 US
As Barium mentions, a big problem with this setup will be mass transfer. With the large length to width ratio it will be hard to get good mass transfer even if you devise some way to shake the tube, which you neglected to mention. But it is easy to buy off-the-shelf, Type 316, stainless steel vessels in sizes of 1 or 2 liters that are rated to 60 bar. Still, obtaining the pressure vessel solves only a small part of the problem. You still need to provide for shaking/stirring, gas connections and overpressure relief.
Baseline Does Not Exist.
Title: Thanks Barium ! I found your two-step-reduction ...
Post by: roger2003 on November 27, 2002, 07:18:00 PM
Thanks Barium !

I found your two-step-reduction with 94% overall yield. It`s a nice way. Stirring is no problem, under 6 bar with a magnetic gearwheel pump and over 6 bar with a magnetical stirrer described here:

http://www.buchiglas.ch/dt_prod/mag_funk.htm (http://www.buchiglas.ch/dt_prod/mag_funk.htm)

:

roger2003