Sciencemadness Discussion Board
Not logged in [Login - Register]
Go To Bottom

Printable Version  
Author: Subject: Research question - reduced pyridoxylamino acids and Hello.
C. Runge
Harmless
*




Posts: 3
Registered: 7-6-2018
Member Is Offline


[*] posted on 7-6-2018 at 20:18
Research question - reduced pyridoxylamino acids and Hello.


Hello! I have been a lurker for some time now and have decided to finally make an account and join some discussions.

I guess to get the the point, I am an (almost) third year undergraduate chemistry student doing research for the first time. The project involves determining crystal structures of reduced pyridoxylamino acids. After following the procedure for the creation of the compounds detailed by Heyl et al. (https://pubs.acs.org/doi/abs/10.1021/ja01190a061) and Miyoshe Ikawa (sorry, not open access, and I only have paper copy) I have run into some problems.

My compounds do turn a bright yellow color upon addition and stirring of pyridoxal HCl but even after hydrogenating for four hours the solution does not lose its color as previously reported. I assume that the hydrogenation had failed. Each time the pressure in the container decreases as time goes on. I first hoped that it was just that the hydrogen was being taken up by the solution. But dramatic changes from 40psi to 10psi in under an hour makes me skeptical of that. I checked for H2 leaks on all fittings with soapy water (like one would check a tire for leaks) and did not find any leaks. I also changed from a 5% palladium on carbon catalyst, to the more expensive platinum oxide catalyst used in the papers to no effect. The IR spectra from before and after hydrogenation is also almost identical. Any ideas? The hydrogenation apparatus being used is a parr 3900 if any have experience with it.

Sorry for the very long first post. Thanks very much, and I look forward to future forum participation :).




[edit] Title clarification



[Edited on 8-6-2018 by j_sum1]
View user's profile View All Posts By User
j_sum1
Super Moderator
*******




Posts: 3829
Registered: 4-10-2014
Location: Oz
Member Is Offline

Mood: Metastable, and that's good enough.

[*] posted on 7-6-2018 at 20:24


Hello and welcome to SM.
I am sure you will find some interesting reading here if you stick around. And probably some people who can help with your questions. There are quite a few bright sparks here. (I am not one of them.)

I have changed the title of your thread to better reflect what you are asking for. You should get a better response that way.




A little shameless self-promotion: New stuff on the YT channel. 100 sub celebration. Or you can tour my lab.
View user's profile View All Posts By User
Corrosive Joeseph
National Hazard
****




Posts: 445
Registered: 17-5-2015
Location: Europe
Member Is Offline

Mood: Cyclic

[*] posted on 7-6-2018 at 20:30


Quote: Originally posted by j_sum1  

I have changed the title of your thread to better reflect what you are asking for.


Thank you j...........



@OP - Be welcome. Here is your paper for download so others can better help you.

'The Chemistry of Vitamin B6. VI. Pyridoxylamino Acids1
Dorothea Heyl, Stanton A. Harris, and Karl Folkers
J. Am. Chem. Soc., 1948, 70 (10), pp 3429–3431
DOI: 10.1021/ja01190a061
Publication Date: October 1948'



/CJ

Attachment: The Chemistry of Vitamin B6. VI. Pyridoxylamino Acids.pdf (439kB)
This file has been downloaded 10 times




MSDS Addict and OTC Slut
View user's profile View All Posts By User
DubaiAmateurRocketry
International Hazard
*****




Posts: 772
Registered: 10-5-2013
Location: LA, CA, USA
Member Is Offline

Mood: In research

[*] posted on 7-6-2018 at 21:14


Welcome here, its a great community
View user's profile View All Posts By User
C. Runge
Harmless
*




Posts: 3
Registered: 7-6-2018
Member Is Offline


[*] posted on 8-6-2018 at 21:41


Thanks for the warm welcome and thread title change. Thanks also for grabbing that paper.
View user's profile View All Posts By User
zed
International Hazard
*****




Posts: 1601
Registered: 6-9-2008
Location: Great State of Jefferson, City of Portland
Member Is Offline

Mood: Semi-repentant Sith Lord

[*] posted on 9-6-2018 at 12:20


Ummm. Hydrogenating a pyridine/piperidine type material with a Platinum catalyst.

Something in the mix, could be poisoning your catalyst.

The Amino Acids of today, are not the Amino Acids of yesteryear. Probably produced very differently. Same goes for everything else. When something in the mix is poisoning your catalyst or activating it, it doesn't take much.

It's just a Shiff's base/imine, that you are trying to reduce?

Maybe Sodium Borohydride/ or Sodium Cyanoborohydride, would be more effective.

The 3900 shaker, and its descendants are kind of like fossils, though to be fair, the design has been a standard for a hundred years or so.. And, it works.
https://www.labx.com/item/lab-equipment-parr-instrument-co-s...



Stirring is generally more effective, especially if you are using a very active "Brown" type catalyst; formed by the action of NaBH4 on Chloroplatinic Acid.

Brown published a series of papers on his machines and his methods, and they are interesting reading.

This of course, might be no use to you, if some mystery contaminant is poisoning all Noble metal catalysts anyway.





[Edited on 9-6-2018 by zed]

[Edited on 9-6-2018 by zed]

[Edited on 9-6-2018 by zed]

[Edited on 9-6-2018 by zed]
View user's profile View All Posts By User
C. Runge
Harmless
*




Posts: 3
Registered: 7-6-2018
Member Is Offline


[*] posted on 13-6-2018 at 19:00


Thanks for getting back with me. I have to admit, both the hydrogenation apparatus and the amino acids I am using are somewhat old (not sure on the date, but my lab manager said that all chemicals were required to have a zip code on the label after 1962, and none of these glass bottles do haha).

Last summer a student was tasked with doing the same research as myself, and attempted to do so with sodium borohydride (as Billman and Diesing wrote a paper detailing the reduction of schiff bases with the reagent) with no success as well. They eventually gave up, and I was given it this year and told to reduce it differently.

The lab's HPLC just got serviced, so hopefully I might be able to better analyze the solution to see if maybe some of the sample was reduced, but the presence of the unreduced sample is causing the yellow color to stay...

Thanks again for the input, I will definitely read the papers about the Brown catalyst.
View user's profile View All Posts By User

  Go To Top