Sciencemadness Discussion Board

Picryl Chloride

quicksilver - 29-1-2008 at 07:42

Could common parachlorobenzene (moth balls, etc) be used in a synthesis of Picryl Chloride?

A straight forward synthesis exists but continually mentions chlorobenzene.
In the chemical industry what does the utilization of the term "para" mean in terms of the chemical's structure ("para"-formaldehyde, parachlorobenzene), etc?

sparkgap - 29-1-2008 at 07:51

"para" in the case of "para-dichlorobenzene" means you have two chlorine atoms attached to benzene at positions 1 and 4 (the opposite corners, if you have trouble visualizing).

The problem of making picryl chloride then is removing one of the chlorines so that you can put nitro groups at positions 2, 4, and 6. That, however, is a pipe dream, I think. :(

sparky (~_~)

quicksilver - 29-1-2008 at 07:56

In re-reading a related thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=8027
It seems to be problematic. I had hoped there was a reasonable work-around. It's such a damn fine OTC source.

vulture - 29-1-2008 at 14:59

You can remove one chlorine by reaction with one equivalent of Mg or BuLi. Then quench with water. It's an awful waste of material though.

chemrox - 29-1-2008 at 15:18

An eq of Mg? Is this making the Grignard and then hydrolizing? Terrible waste but can this even be done with PDB?

The_Davster - 29-1-2008 at 21:08

Problem is, that the electron withdrawing nature of the chlorine only allows synthesis to 2,4 dinitrochlorobenzene. The third is almost imossible to get on, short of using oleum and fuming nitric(IIRC, what is the chlorobenzene procedure you speak of?).

Luckily as illustrated in the pentryl thread, once the chlorine has been substituted off the 6 position is easier to nitrate.

quicksilver - 30-1-2008 at 05:38

Quote:
Originally posted by The_Davster
.... what is the chlorobenzene procedure you speak of?

Direct nitration using higher percentage acids was what I had seen. The concepts were all straight forward. I was hoping that the starting material was available without attempting to work with liquid benzene.

vulture - 30-1-2008 at 14:35

Quote:

An eq of Mg? Is this making the Grignard and then hydrolizing? Terrible waste but can this even be done with PDB?


It works with a variety of organic halides, so I don't see why this wouldn't work. Usually the formation of the grignard reagent is easier if the substrate is more electron poor.