Sciencemadness Discussion Board


indiangold - 25-2-2014 at 00:22

Is there a GC or HPLC method for separation of 1-dimethylamino-2-chloropropane and 2-dimethylamino-1-chloropropane?

chemrox - 25-2-2014 at 11:38

Check the physical properties. List the relevant ones. I would think you could make the HCl salts and separate them by crystallization.

Dr.Bob - 25-2-2014 at 13:30

There is likely some simple way to separate them into two peaks for analytical work. Just needs to be tested on a working system. CG will likely work better, with FID, halogen, thermal or other detector, as they might not show up well on most HPLC systems, as such low MW and no UV chromaphore, so hard to detect. Might show up on a refractive index detector if anyone still uses them. Neither system is ideal for prep work of such a compound. I would try to distill them apart if possible.

Maya - 26-2-2014 at 11:17

Dude, That is hard-core VX agent precursor stuff.............

Dr.Bob - 26-2-2014 at 12:32

No, VX would be made from diisopropylaminocompounds. These compounds are related to the nitrogen mustards, but also widely used chemicals. Isopropanol can be used to make Sarin, but it is still a useful chemical and sold in stores.

Maya - 26-2-2014 at 12:54

That's what I meant. I forgot to check the correct chain length , dimethyl vs diisopropyl......

The HCl salts are what is common out there

chemrox - 28-2-2014 at 14:11

What is VX?

Metacelsus - 28-2-2014 at 20:08

Potent nerve gas:

[Edited on 1-3-2014 by Cheddite Cheese]

Chemosynthesis - 1-3-2014 at 10:09

The compounds in question are, at least in my background, more commonly associated with pharmacology than toxicology.

edit: though, I do not believe that is why the poster asks, as the pharmaceutical/medicinal chemistry I am thinking of doesn't require resolution of the two.

[Edited on 1-3-2014 by Chemosynthesis]

Nicodem - 2-3-2014 at 01:31

You cannot analyze rapidly inter-convertible compounds by GC - that's quite obvious.

You could potentially develop a method for HPLC, but think about the work involved:

- You need pure standards, which need to be hydrochlorides, as the free-bases rapidly interconvert;
- You need the standards of the hydrolysis products (for reverse phase HPLC);
- The sample preparation needs to be validated against interconversion;
- You need to use a highly acidic media to prevent interconversion during elution;
- The (consequently present) ammonium compounds are too polar for the common C18 and similar reverse phase HPLC columns, but not suitable for normal phase HPLC (you would therefore need to screen various special and expensive reverse phase HPLC columns);
- You would need to come up with some pretty good excuse on why you need to develop such a demanding method to your boss/supervisor when you could simply use NMR without any particular method development.

Metacelsus - 2-3-2014 at 07:39

The OP wants to separate them, not analyze them. I agree that NMR would be best for analysis, though.

indiangold - 6-3-2014 at 04:27

Thanks a lot Nicodem Sir ! I actually tried to do GC but I get invariably two peaks in about 65:35 ratio. I do not have authentic sample of the 1-chloro-2-dimethylaminopropane HCl. Thanks again!