Sciencemadness Discussion Board

N-nitroso-N-methyl-p-toluenesulphonamide

Boffis - 28-3-2020 at 10:24

Recently I acquired some chemicals and amongst them was a jar that was labelled as this compound. It has its original label from the company that supplied it (Koch Light) and the label states that the jar held 100g but it mentions nothing else. This compound is a well known precursor of diazomethane and is described as a pale yellow powder, insoluble in water. It was sold as Diazald by Sigma Aldrich as it is consider less toxic than other diazomethane precursors.

However the jar is full of a slightly viscous almost colourless, odourless, liquid which on a cold day deposit a small crop of large well formed pale yellow crystals. When the liquid is diluted with water is turns milky white at first but on further dilution

Has anyone every used this compound? Does it decompose on keeping to a liquid? Is it deliquescent? Is it supplied as a solution? If so in what? I did notice that one MSDS sheet described it as potentailly explosive and so I wondered if it had been shipped as a solution for safety.

Anyone have any experience of this material or a means of testing it so see if it yield diazomethane?

clearly_not_atara - 28-3-2020 at 14:27

"CH2N2 may explode in contact with sharp edges, such as ground-glass joints, even scratches in glassware.[16] Glassware should be inspected before use and preparation should take place behind a blast shield. Specialized kits to prepare diazomethane with flame-polished joints are commercially available."

"The compound explodes when heated beyond 100 °C, exposed to intense light, alkali metals, or calcium sulfate. Use of a blast shield is highly recommended while using this compound."

I suppose you might consider adding KOH and covering your ears...

DavidJR - 29-3-2020 at 07:18

I can smell the cancer from here...

wg48temp9 - 29-3-2020 at 10:33

"CH2N2 may explode in contact with sharp edges"

I wounder how a sharp edge can cause it to explode. Presumable the edge catalyses decomposition and thermal runaway causes the explosion. But how can an edge do that? I searched but found no explanation. Does anybody know the mechanism and can explain it or provide a link?

clearly_not_atara - 29-3-2020 at 10:41

If you consider the Navier-Stokes equations in presence of a sharp corner, you find that the flow rate diverges. Possibly this generates some localized heating which acts like a spark. See e.g.

https://demonstrations.wolfram.com/FluidFlowAroundACorner/

To be fair I have only done the math for the 2D case which is much simpler thanks to the fact that R^2 has a field structure while R^3 does not.

wg48temp9 - 29-3-2020 at 11:56

Quote: Originally posted by clearly_not_atara  
If you consider the Navier-Stokes equations in presence of a sharp corner, you find that the flow rate diverges. Possibly this generates some localized heating which acts like a spark. See e.g.

https://demonstrations.wolfram.com/FluidFlowAroundACorner/

To be fair I have only done the math for the 2D case which is much simpler thanks to the fact that R^2 has a field structure while R^3 does not.


Presumably the increase in temperature caused by local increase in pressure can be be calculated from the change in velocity, density and compressibility of the fluid though given how incompressible most liquids are I would expect the heating to be less than 1C even if it is stirred vigorously.

I thought perhaps if the surface is catalytic the intersection of two surfaces at the corner could double the decomposition which then causes the thermal run away.

Boffis - 31-3-2020 at 04:53

Ha guys, you are getting way of topic! I am not asking about diazomethane. I have heaps of data on the stuff and detailed descriptions of its preparation as an ether solution, however, my question is about the specifics of one particular commercial precursor. In particular what what form it comes in solid or solution.

S.C. Wack - 31-3-2020 at 11:16

Rough surfaces in general.

A solution would be more unstable. Vogel should answer everything. If a sample is denitrosated, perhaps it can be restored.

Dr.Bob - 2-4-2020 at 16:36

We would dissolve it in a mixture of aq. NaOH and ether and mix for a while. The diazomethane dissolves in the ether and the rest stays in the water, so you can use a sep funnel to separate them, and then react the diazomethane as a solution. It is stable as a dilute solution, the hazards are much worse when it is concentrated or distilled to be pure, then it is extremely unstable to sharp edges, heat, loud noises, and near about everything. There was special polished glassware available for that, but much simpler to just use it as a solution. If you make a small amount, then react the solution with a simple acid, like benzoic or such and see if the methyl ester forms. We used it often to make methyl esters, occasionally methyl ethers.

UC235 - 2-4-2020 at 20:21

I think the stuff is probably long since garbage, having reverted to some sort of hygroscopic tosylate salts or tosic acid.

Boffis - 3-4-2020 at 00:02

I'm inclined to agree with UC235 and this stuff has long since passed its sell-by date.

Dr.Bob - 5-4-2020 at 16:39

Quote: Originally posted by Boffis  
Ha guys, you are getting way of topic! I am not asking about diazomethane. I have heaps of data on the stuff and detailed descriptions of its preparation as an ether solution, however, my question is about the specifics of one particular commercial precursor. In particular what what form it comes in solid or solution.


It comes as a solid. Not sure how unstable it is, but it may be hygroscopic, not sure what it would look like if wet.

Your stuff is likely crap now, but you could try to purifiy the material. It is highly carcenogenic, but it sounds like you are aware of that. Might be easier to find some new stuff.