separation of azines

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Vijaya balachandar
Vijaya balachandar's picture
separation of azines

Hi there,
I tried to synthesize unsymmetrical azines. But I got a mixture of symmetrical (2 Products) and unsymmetrical azines (desired Product). I tried to separate it by column chromatography. When I was choosing the solvent system for column by TLC, I found that the Rf value difference between the 3 Products Is very very small. It appears to be tedious to separate the 3 products and get the desired unsymmetrical azine.
Can any one give an idea for separating the 3 products or any other method to synthesize unsymmetrical azine without any formation of symmetrical azine
 

MUTHUMARIAPPAN ...
MUTHUMARIAPPAN Murugan's picture
Hi Viji,

Hi Viji,
 
You contact Cao weigo,
He published many papers related to your question.
Email : wgcao@mail.shu.edu.cn
and here is the research paper. This will help you. Go through this link..
dspace.mit.edu/bitstream/handle/1721.1/43777/260532059.pdf

Vijaya balachandar
Vijaya balachandar's picture
thank u muthuonco for ur

thank u muthuonco for ur quick response. I will surely follow ur advice.

Dr. Analytical
Dr. Analytical's picture
viji:

viji:
If you know that the Rf difference is very small for your three compounds, then column chromatography will probably never be successful.  It is not a high resolution technique.
HPLC will give you the resolution that you need, but if you do not have a preparative instrument, you will have to make many injections.
There are some medium resolution LC columns that you can buy, and maybe they would give you the separation.  However, it would be better if you can find a way to improve your synthesis.
 

Vijaya balachandar
Vijaya balachandar's picture
Thank u Dr. Analytical. I

Thank u Dr. Analytical. I read your response. Can you give me some more idea about medium resolution LC columns and some improved methods of synthesis of unsymmetrical azines.

Dr. Analytical
Dr. Analytical's picture
You may get better results

You may get better results with pre-packed columns.  This is sometimes called "flash" chromatography.  Some examples are at:
http://www.discoverysciences.com/product.aspx?id=5522
 

Vijaya balachandar
Vijaya balachandar's picture
Thank You Dr.Analytical for

Thank You Dr.Analytical for your quick and wonderful response. But I am afraid that if I could afford for such  flash chromatographic equipments or not.

Dr. Analytical
Dr. Analytical's picture
viji:

viji:
Yes, I understand that this equipment is more expensive.  Some laboratories can not buy this.  However, if you need better resolution, you must buy a column that is prepared by a company with experience in making these columns.  It is a special skill.  You may find some columns that are already prepared, but do not need special equipment.  Try Google or ask your supplier of column chromatography materials.
I will continue to look for other options and will post an answer here if I find something.

Vijaya balachandar
Vijaya balachandar's picture
Thank you Dr. Analytical. I

Thank you Dr. Analytical. I am happy that I have got good friends to guide me all the ways in my research. Thank you once again.