[ildiTHS]

Dear All,

I am looking for a hydrogenation reaction, which can be included into a curriculum material for undergrads. The reaction should match the following criteria:
- gives good results using heterogeneous catalyst and H2 gas
- the heterogeneous catalyst can be RaNi
- changes color
- interesting for a student
- starting material can be dissolved in a green solvent (ca. concentration: 0.05 M)
- advantage:
  shows different results at atm. pressure and higher
  highly temperature sensitive
  would teach them something about industrial applications...what is waiting for them after graduation

I would use this reaction with a brand new flow system, which allows reaction optimization in hrs,can work up to 100 degree C and 100 bar with in-situ generated hydrogen (I am not kidding, http://thalesnano.com/products/h-cube-series/H-Cube_Mini), so even just "maybe"s would do for me without exact parameters. The more interesting and difficult the better.

Thanks,
Ildi

Edit: fixed the rarrows

[Corribus]

Pyrene (and other PAHs) hydrogenates very well with Raney nickel or Pd/C in a pressurized reactor cell, but you won't see a visible color change. You will see a visible fluorescence color change, however, as pyrene is transformed to tetrahydropyrene... and you can track the changes by absorption spectroscopy if you so desire. Don't know about temperature/pressure sensitivity of this reaction, though.  Probably rate changes only.

If you're looking for a visible color change, you could try a porphyrin or possibly a conducting polymer like MEH-PPV. I've never tried to hydrogenate them, so you'd either have to search the literature or just try it out and see what happens.

Make sure to use a blast shield!!

[Archer]

You could try hydrogenation of a DNP derivative of a ketone, such as acetone



This may change from yellow to orange under lower pressure as the C=N bond is hydrogenated, as the pressure is increased and the nitro groups are hydrogenated the red colour should be removed.

I have never tried this experiment so I make no guarantee that it will work as described above.

There are some other hydrogenations which cannot be discussed on the open forum but I can give you some details in a PM if you are interested.

[ildiTHS]

Hello Corribus and Archer,

Thank you for your answers. The conductive polymer is so cool, I have to get my colleagues to give it a try.

Archer's example is excellent!
Thanks for giving some works for the guys in the lab ;-)

If you have further idea I am happy to receive them. Archer, please send the confidential one(s) to  private message, I am very interested.

Regards,

Ildi

Edit: forum rule violation - post no addresses - please read forum rules

[curiouscat]

That blast shield & "cannot be discussed on the open forum" parts effectively eliminate those from consideration as undergrad curriculum.

[Corribus]

LOL, true. I'd be wary of doing any kind of pressurized reaction with undergrads, but I wasn't sure if this was for a lab or for a demonstration in front of the class or something.

If you can get a conducting polymer like MEH-PPV to react with hydrogen, progressive saturation of the vinyl linkages should lead to a color change (blue-shift) by restricting the exciton delocalization length. This is also a good way to show students the particle-in-a-box model of introductory quantum chemistry. I actually published a paper on this a few years ago, although we used a chemical oxidant to saturate the vinyl linkage rather than hydrogen. Doing it with hydrogen would be an interesting reaction to try actually. I'm intrigued by the possibility.

[ildiTHS]

We can make a video and show the students. The title can be: You are allowed to do such cool things like this....after graduation :-D

[billnotgatez]

@ ildiTHS

If I got this correctly
Your company makes this device that creates hydrogen in a safe environment.
And, you are asking us for experiments that can be used in a safe way to teach students.
In other words, help you with demonstrations so you can sell your products to teaching institutions.

My curiosity has got me here

What is the cost of operating your equipment compared to electrolysis of water producing Hydrogen.
We can neglect the cost of your system purchase (that can be found on your web site).
I am interested in the cost of supplies and energy.

It would also be interesting if one purchases a tank of hydrogen for a gas supplier what the difference in cost with your device (still neglecting the purchase cost of your system).

Notice I am also neglecting safety considerations here (I am assuming your system is safer for this question).

Bill


Edit: The words in red added latter to do a suggested fix from a later post

[ildiTHS]

Dear Bill,

When you wrote "electrolysis of Hydrogen" I believe you meant: electrolysis of water. FYI: this is what is used in our systems to generate hydrogen.

Please let me not to really reflect to your other offensive comments, but recommend you to search for "flow chemistry", you will find many scientific articles and books: green chemistry related, industrial applications from pharma, agrochem, F&F, petrochem etc.; and loads of papers from academia too. They can prove what this technology can do, the benefits and weaknesses too.

Have a great day,

Ildi

[curiouscat]

Please let me not to really reflect to your other offensive comments, but recommend you to search for "flow chemistry", you will find many scientific articles and books

I didn't see any offensive comments. What did you find offensive?

[ildiTHS]

Hi Curiouscat,

Mainly the style, and the fact that instead of offering an answer the whole comment focuses on "it must be just a trying to sell an expensive product".

But actually it opens another question for me: I am realtively young, so I cannot remember, but were the chemists so neglegtive when the first GC, LC, NMR, IR etc instruments were introduced? Was it so "difficult/not wanted" to switch from TLC to e.g. LC, like it is sometimes so unbelievable to do a reaction not in a flask still today?

[curiouscat]

Hi Curiouscat,

Mainly the style, and the fact that instead of offering an answer the whole comment focuses on "it must be just a trying to sell an expensive product".

But actually it opens another question for me: I am realtively young, so I cannot remember, but were the chemists so neglegtive when the first GC, LC, NMR, IR etc instruments were introduced? Was it so "difficult/not wanted" to switch from TLC to e.g. LC, like it is sometimes so unbelievable to do a reaction not in a flask still today?

Ok. I can see what you mean. But I'd characterize it more as skepticism than offensiveness.

Here's my take on it: I get to meet so many clueless sales engineers trying to oversell technology that the few genuine, honest, knowledgeable guys might have to suffer a grouchy me.

So, don't take it personally. If you sell novel technology be prepared to meet skepticism and suspicion. Sales needs a thick skin.

[curiouscat]

In any case, I deal with a ton of hydrogenations myself on a plant scale for the fine chemical industry. We buy merchant gas produced via methanol reforming by steam. By the truckload.

I'd love to hear (just out of curiosity; I'm not sure this is a market you target?) what price per kg H2 your technology works out too.

Hey, who knows? Maybe it might just be the right technology for us. We still do conventional batch hydrogenations, often on a 10 kL reactor scale.  You can imagine we'd love to go flow reactor if only the price works out.

[ildiTHS]

You are right. I am so happy I am not a sales person. Their life must be tough!

[ildiTHS]

Hi Curiouscat,

Hu...you work with such a big scale! I should pass this question to my engineer colleagues, I am "just" a chemist, I can think in mgs and gs. Can you send me in private email your contact data. I do not think the moderators would welcome if I put here the full details of my company and colleague ;-)