/sci/ - Science & Math » Thread #12102325

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Anonymous Wed 09 Sep 18:56:08 2020 No.12102325 View Reply Original Report

Quoted By: >>12102389

Dear /sci/,

I would like to appeal to your goodwill and your legendary willingness to help others and ask you if you know some good ol' wet method for quantitative determination of silicon in organic liquids/ solvents? Unfortunately I don't have access to modern equipment so the test has to be done in a good ol' labor intensive wet chemistry fashion.

Anonymous

Anonymous Wed 09 Sep 2020 19:14:39 No.12102368 Report

Quoted By: >>12102391

silicon is generally not found in anything other than rock/sand

Anonymous

Anonymous Wed 09 Sep 2020 19:21:51 No.12102389 Report

Quoted By: >>12102446

>>12102325
Like siloxanes? I can ask one of my professors

You're unlike to find silica dissolved in Organic solvents though. Can you give a little more detail/context

Anonymous

Anonymous Wed 09 Sep 2020 19:22:00 No.12102391 Report

Quoted By:

>>12102368
Well...not exactly, but let it be. I should say silicon as silicic acid.

Anonymous

Anonymous Wed 09 Sep 2020 19:40:00 No.12102446 Report

Quoted By: >>12103105

>>12102389
I'm doing nitration of different alcohols in a continuous flow reactor. After the process I have to separate the product from spent acids mixture (SA+NA+water). In some cases I get a white, gelly-like residue in my centrifuge which is a pain to clean. I asked my friend who has access to modern lab equipment to identify this compound and he said it was silica.

I really do not have any idea where it came from, because the solubility of silicic acid in higher liquid alcohols should be virtually zero. As far as I know it is the same for concentrated sulfuric and nitric acid. The same friend suggested that I should check the alcohols for silicon based compounds but the problem is, that I couldn't find any relatively easy to follow, wet chemistry method.

The only thing that I could think of is, that PERHAPS some of these alcohols are prepared by distillation. Sometimes during the distillation there is a problem with foaming and therefore - again: PERHAPS - some silicon based antifoaming agents are added to prevent this. But this is just a blind guess. I really don't know.

Anonymous

Anonymous Wed 09 Sep 2020 20:41:22 No.12102661 Report

Quoted By:

>type post explaining those old ass wet lab algorithms to detect elements
>realize silicon wasn't one of the things you could detect in either cation nor anion flowcharts
Interesting, lemme check

Anonymous

Anonymous Wed 09 Sep 2020 22:55:21 No.12103105 Report

Quoted By: >>12104065

>>12102446
Where are you getting these alcohols from? Do you access to COA s? What's the identity of these alcohols, give me an example scheme culminating in the gelly like thing you observe.

Have you ruled out anything coming from the reactor? Do you have zero access to any spectroscopy instrument?

Apparently there's a colorimetric detection method using a molybdenum salt.

Anonymous

Anonymous Thu 10 Sep 2020 04:22:07 No.12104065 Report

Quoted By:

>>12103105
An typical example may be 2-ethylhexanol, which you can use to make a fuel additive (2-ethylhexyl nitrate). At least this is the most extreme example where I get the supposed silicon gelly on the centrifuge nearly every time when I run the reaction. The alcohol is basically pure with trace/ neglegible amounts of aldehydes.

I do not think it is something from the reactor because the thing seems to be alcohol specific. Also there is really no part in the reactor which would point to be the source of the problem.

I have access to a standard VIS spectrometer. I also tried to adapt the molybdenum salt method which one use for determination of silicon as silicic acid in water, but without success. Basically I tried to do simple extraction with water assuming (wrongly) that whatever silicon compounds are present in the alcohols (not miscible with water) they will have a greater affinity to water and I should be able to use this method. This proved to be garbage, as expected, and gave absolutely inconclusive and unrepeatable results.

So either it's not silicon or it is not inorganic or it is some organosilicon compound which I don't know how to assess.

Anonymous

Anonymous Thu 10 Sep 2020 11:44:28 No.12104795 Report

Quoted By:

Sorry bro, couldn't find a way to check for silicon
I'd say you could try to melt the substance and see if, after burning away most of it, the rest crystallizes in "glass" or something similar. Best of luck.

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