| Pages:
1
..
25
26
27 |
Bert
Super Administrator
Posts: 2821
Registered: 12-3-2004
Member Is Offline
Mood: " I think we are all going to die. I think that love is an illusion. We are flawed, my darling".
|
|
Shaking NG in wash water is done by some. Swirling the NG in a stoppered flask with a basic wash water until the NG is broken up into droplets, then
shaking it fairly hard to break up the droplets still further and speed the washing process did not kill me as a teenaged experimenter.
Wet NG suspended in wash water is not very sensitive. As an emulsion in water, it has been pumped between various operations in industrial production-
That way, transport pipes don't propagate explosion between buildings.
If NG really behaved like I3N, it would not have been (and still be!) an industrial chemical routinely made and handled by the ton.
Even after separating from the final wash water, residual water needs to be dried from the NG before one can do sensitivity tests and get a true idea
of how sensitive dry, pure NG can be. Hammering a small drop of damp NG fresh from the washing operation on a scrap of filter paper (steel hammer on
steel anvil) often failed to get so much as a pop- Once dried, a good tap made my ears ring.
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
|
|
|
ecos
Hazard to Others
Posts: 464
Registered: 6-3-2014
Member Is Offline
Mood: Learning !
|
|
Quote: Originally posted by Bert  |
Shaking NG in wash water is done by some. Swirling the NG in a stoppered flask with a basic wash water until the NG is broken up into droplets, then
shaking it fairly hard to break up the droplets still further and speed the washing process did not kill me as a teenaged experimenter.
Wet NG suspended in wash water is not very sensitive. As an emulsion in water, it has been pumped between various operations in industrial production-
That way, transport pipes don't propagate explosion between buildings.
If NG really behaved like I3N, it would not have been (and still be!) an industrial chemical routinely made and handled by the ton.
Even after separating from the final wash water, residual water needs to be dried from the NG before one can do sensitivity tests and get a true idea
of how sensitive dry, pure NG can be. Hammering a small drop of damp NG fresh from the washing operation on a scrap of filter paper (steel hammer on
steel anvil) often failed to get so much as a pop- Once dried, a good tap made my ears ring. |
what is I3N ?
since you mentioned "drying NG".
I found a video that uses AN for drying NG. it is a cool idea since it depends on the Hygroscopic effect of AN.
do you think it is effective in drying ?
[Edited on 25-8-2015 by ecos]
|
|
|
greenlight
National Hazard
Posts: 737
Registered: 3-11-2014
Member Is Offline
Mood: Energetic
|
|
He means nitrogen triiodide, sensitive touch explosive.
The photo you uploaded is a makeshift desiccation jar (desiccator).
You can probably use other compounds as the desiccant like anhydrous calcium chloride or concentrated sulfuric acid in them if you wanted as well.
I don't know how effective it would be if with drying a liquid as I have only ever used that method to dry solids.
[Edited on 25-8-2015 by greenlight]
Be good, otherwise be good at it 
|
|
|
Bert
Super Administrator
Posts: 2821
Registered: 12-3-2004
Member Is Offline
Mood: " I think we are all going to die. I think that love is an illusion. We are flawed, my darling".
|
|
Water is less dense than NG, and merely leaving the NG out in atmosphere on a low humidity day, in an open container with a wide surface area relative
to depth was sufficient to dry it within a day, as far as I can recall. But I never made very much, a porcelain "ramekin" less than 100ml capacity
served to dry 20-30ml of NG, and also to hold it for subsequent processing- Such as gelatinizing with NC, gently warming on a water bath and addition
of any dynamite making "dope".
I might choose a Polyethylene container instead, these days. Just in case of an issue?
Using a dessicator would probably be faster, but I never bothered. It would be helpful in a humid climate, and even required for careful analytical
work.
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
|
|
|
Hennig Brand
International Hazard
Posts: 1284
Registered: 7-6-2009
Member Is Offline
Mood: No Mood
|
|
From Wiki:
"
For molecules of a liquid to evaporate, they must be located near the surface, they have to be moving in the proper direction, and have sufficient
kinetic energy to overcome liquid-phase intermolecular forces. When only a small proportion of the molecules meet these criteria, the rate of
evaporation is low. Since the kinetic energy of a molecule is proportional to its temperature, evaporation proceeds more quickly at higher
temperatures. As the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid
decreases. This phenomenon is also called evaporative cooling. This is why evaporating sweat cools the human body. Evaporation also tends to proceed
more quickly with higher flow rates between the gaseous and liquid phase and in liquids with higher vapor pressure. For example, laundry on a clothes
line will dry (by evaporation) more rapidly on a windy day than on a still day. Three key parts to evaporation are heat, atmospheric pressure
(determines the percent humidity) and air movement."
The following vapor pressure data for NG came from the attached document:
Vapor pressure of NG at 20C:
0.00012 - 0.011 mmHg
Vapor pressure of water at 20C:
17.54 mmHg
IIRC, density is the key factor when separating things like saturated hydrocarbons and the intermolecular forces in the liquid phase are fairly
constant from one species to the next and obey the idealized laws very closely. For many other liquids, though, the intermolecular forces in the
liquid phase are of much greater significance and much less consistent with the idealized laws. I suppose we should also consider the intermolecular
forces between the water and the NG, not just the water and NG separately, but simply looking at the extremely low solubility of NG in water tells us
that these forces are very small in comparison and of little concern.
I have left beakers sit out with NG sitting in them, in a safe location undisturbed, for days with very little loss of NG. It is so easy to dry NG by
simply leaving it sit out for a day or so that I never bothered doing anything else once I learned this.
Regarding sensitivity of NG, temperature is very significant. I remember that on a cool day in the fall, between 15-20C, it would take a very hard
smack with a hammer on steel to effect detonation, however, on a hot 30C day even a fairly gentle snap from a small hammer could easily result in
detonation.
I just found the following information sheet on NG and EGDN online. It has vapor pressure information as well as other key values for both nitric
esters. The sheet also has a lot of occupational health and safety information, which is actually the main focus of the document.
Attachment: Nitroglycerin & Ethylene Glycol Dinitrate Information Sheet.pdf (324kB)
This file has been downloaded 710 times
[Edited on 27-8-2015 by Hennig Brand]
"A risk-free world is a very dull world, one from which we are apt to learn little of consequence." -Geerat Vermeij
|
|
|
ecos
Hazard to Others
Posts: 464
Registered: 6-3-2014
Member Is Offline
Mood: Learning !
|
|
Thanks Hennig and Bert, The information you provided are really valuable.
It scares me when I leave NG to dry for a day or several days. I am just afraid that impurities would make it acidify. I remember that molecules would
break down to Glycerol and HNO3 because of impurities or other stuff I don't remember. This means risk is increasing by time.
It is a common rule not to leave NG dry and always dissolve it in Acetone or underwater with small bicarbonate ratio.
I found this way in a document :
| Quote: |
The resulting emulsion was transferred to a separatory funnel and extracted four times With 25 mL methylene chloride. The combined organic extracts
Were dried With MgSO4 and then concentrated to produce NG as a clear pale yellow liquid |
The author used separation funnel to remove as excess water. but I don't understand what he would do with methylene chloride or MgSO4 !
unfortunately the stopcock can cause hazards ! 
I was thinking of two solution:
1- make air path that dry NG faster, This can be achieved using a small fan inside a PVC tube.
2- use AN as desiccator. AN should act as magnet to water in NG. This would make NG wet and cold. AN can be dried later under lamp. but since AN is
colder won't that make the evaporation slower ?
[Edited on 27-8-2015 by ecos]
[Edited on 27-8-2015 by ecos]
|
|
|
Bert
|
Thread Split
17-9-2015 at 10:07 |
greenlight
National Hazard
Posts: 737
Registered: 3-11-2014
Member Is Offline
Mood: Energetic
|
|
Just curious as to what your guys opinions are on whether it is dangerous to use a seperatory funnel to seperate the NG from the aqueous phase during
extraction and washing.
Be good, otherwise be good at it
|
|
|
NeonPulse
Hazard to Others
Posts: 417
Registered: 29-6-2013
Location: The other end of the internet.
Member Is Offline
Mood: Isolated from Reality! For Real this time....
|
|
This is done pretty frequently in small lab scale preparations and as long as the stopcock is Teflon and very well greased there should be no
problems. This is how I do this. It is probably the easiest and no fuss way to separate your Ng from the spent acids/wash waters.
|
|
|
greenlight
National Hazard
Posts: 737
Registered: 3-11-2014
Member Is Offline
Mood: Energetic
|
|
I have used my small sep funnel with a well greased glass stopcock when doing small batches but was quite worried while doing it.
Would a better option be decanting until the final separation and then using a well greased funnel and doing so in small portions.
Be good, otherwise be good at it
|
|
|
| Pages:
1
..
25
26
27 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
