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Author: Subject: The Short Questions Thread (4)
clearly_not_atara
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[*] posted on 4-6-2019 at 14:48


Anyone have any references discussing the Lucas reagent and other acidic Sn2 reactions on vicinal diols?

In particular, I’m interested in the practicality of converting propylene glycol into 2-chloro-1-propanol. The secondary alcohol should be substituted faster than the primary, but I don’t know if there are any side reactions to worry about.

Incidentally, while researching this transformation, I was unable to find any references discussing the conversion of ethylene glycol to 1,2-dichloroethane, even though this transformation is commonly suggested as a route to DCE.




[Edited on 04-20-1969 by clearly_not_atara]
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Abromination
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[*] posted on 14-6-2019 at 14:42


Anyone have any suggestions on paints they have found chemically resistant? I am painting my fumehood soon.
Much appreciated




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Pumukli
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[*] posted on 27-6-2019 at 11:20
TLC Quiz


It seems that after a lot of struggle I could finaly prepare that nicotinonitrile I asked about months ago.

I ran the starting niacinamide and the crude product side by side on a tlc plate (Kieselgel on aluminum) in 6:14 denatured EtOH : Chloroform. They each gave one spot only.

I'm curious who would guess the resulting Rf values most accurately?! ;)

This "challenge" is open for a few days then I'll announce the results!

Anyone for a ride?
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Abromination
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[*] posted on 26-7-2019 at 18:01


According to pubchem.gov, 2 ethylhexanol is a brown liquid, however various images of the substance show it to be clear. Which one is it? I feel like the images are just showing a generic liquid in a flask.
Here is an example:


38B2D701-D086-47E5-93FF-FF9C9E578ED0.jpeg - 25kB




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Pumukli
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[*] posted on 26-7-2019 at 20:01


2-ethylhexanol why should it be brown? It is a simple aliphatic alcohol of which the C-chain isn't too complicated (no conjugated double or triple bonds) so there are no chromofors.
I imagine it should look exactly like 1-octanol, maybe slightly more viscous.
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Herr Haber
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[*] posted on 29-7-2019 at 03:41


Quote: Originally posted by Abromination  
Anyone have any suggestions on paints they have found chemically resistant? I am painting my fumehood soon.
Much appreciated


I recently discovered "graffitiy proof" paints based on a fluorinated polymer that also takes advantage of a phenomenon I didnt look into.
It could be great for fumehoods.

The price was not so great though... Almost 200 Euros / liter !




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[*] posted on 29-7-2019 at 18:06


Quote: Originally posted by Pumukli  
2-ethylhexanol why should it be brown? It is a simple aliphatic alcohol of which the C-chain isn't too complicated (no conjugated double or triple bonds) so there are no chromofors.
I imagine it should look exactly like 1-octanol, maybe slightly more viscous.

Thanks, just checking, pubchem has usually been a reliable source in the past.




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--------------------------------
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Panache
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[*] posted on 1-8-2019 at 19:32


Quote: Originally posted by bipolar  
Does acetonitrile react with sodium metal? If so, what are the products of this reaction?
I'm hoping this might be the way to make some sodium cyanide. :D


[Edited on 21-4-2019 by bipolar]


gaseous acetonitrile decomposes to HCN, a simple tube furnace (600-900C if i recall, anyway the process has 4768543983465430 references online as it is critical for fire fighters in buildings with certain types of polymers, acetonitrile became the test standard for assessing this risk) connected to a boiling flask of acetonitrile with the exiting gas stream cooled with a long air condenser then bubbled through two NaOH or KOH wash bottles, indicated to clearly show when exhausted. Clever use of three way taps will allow for changeover of the solutions.
Less safe in some respects is condensing the HCN, however it does allow one greater flexibility, ie you can weigh precise amounts out to neutralise.
Be very careful, i hear HCN has deliterious health consequences to the human organism.
Always run a lengthy test cycle at temp through your setup with compressed air or something testing for leaks.
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[*] posted on 9-8-2019 at 08:18


So I have heard this a few places, some easily dismissed as technobabble (eg The X-Files) and others less so (Mythbusters iirc). This is that at high temperatures, the dissociation of water will create hydrogen and oxygen, which will then go on to fuel and augment the fire.

Am I completely missing something??? Isn't the whole point of their dissociation at high temperature that their combination is unfavorable? Isn't any energy released by their eventual combustion energy that the flame had previously lost? Is there some sort of potential energy transport effect I'm neglecting?




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C6(NO2)5CH2CH(CH3)N(NO2)2
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[*] posted on 5-9-2019 at 16:09


@Mayko, I know this thread is dead, but I think your reasoning is right, and that theory is a crock of crap. The dissociation takes a certain amount of heat, but as soon as the gas gets to the flametip and even cools down by a few degrees, it recombines and makes water, releasing precisely as much energy as it took to heat it. They might as well say that pouring liquid water into a fire will heat it up, since it makes so much hot steam. The only difference is that most laymen know about evaporative cooling, but don't know about the reversible pyrolysis of water, so poorly informed popular TV shows can speculate about it without too many people calling BS. Now, if the steam stays well insulated at a few dozen megakelvins for years on end, nuclear reactions will slowly heat it up. Also, if you started out with room temperature hydrogen and oxygen and mixed them, then that will obviously heat up quite rapidly when ignited. other than those two possibilities, adding extra water into a fire will just cool it.

Dissociation does have an effect in making the peak flame temperature a bit lower, and the total moles of gas at peak temperature a bit higher, but to say it raises the temperature or adds any energy is grossly inaccurate.

Now, I've got a question. At a hardware store, I saw some Klean-Strip "green" muriatic acid, which claimed to have 90% less fumes than normal muriatic. The safety datasheet says it's 20% HCl. Do you think it simply gives off less fumes due to being diluted to <30%. or is there some other additive to supress fuming?

[Edited for format, and because I just realized the last question was old)

[Edited on 6-9-2019 by C6(NO2)5CH2CH(CH3)N(NO2)2]




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[*] posted on 6-9-2019 at 05:42


My thermometer adapter popped up and out at the end of my last distillation because I was negligent in using a keck clip..ugh. so ordered a new one but it's different and didnt realize the system will be open using this(I use my multimeter for thermometer). I thought of filling hole with aluminum foil but I'm sure that would react with something sooner or later. Any ideas how to seal around wires? Sorry about volume level thru pic..damn phone is a pitas to screen shot.

Screenshot_20190906-070342_Chrome.jpg - 168kB

[Edited on 6-9-2019 by magnet]
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[*] posted on 6-9-2019 at 06:13


Four options.
  • Hot glue gun
  • Lots of teflon tape
  • Silicone sealant
  • Buy the adapter you want



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    Sulaiman
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    [*] posted on 6-9-2019 at 06:15


    Heat seal (melt) the end of some 8mm o.d. borosilicate tubing and put the thermocouple in the glass tube.



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    Pumukli
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    [*] posted on 6-9-2019 at 06:21


    To polynitrosomeone: yes, just dilution. Why, what did you think? :) No special additives, nothing. It would cost money, anyway! Dilution is cheap - but can be explained away as the most important scientific breakthrough in the XXI century. :) Like "x % less fuming"! :)
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    [*] posted on 6-9-2019 at 06:55


    Thank you for the suggestions.
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    [*] posted on 6-9-2019 at 17:45
    Organic reactions with chlorate?


    I recently obtained a large amount of Sodium Chlorate, and have been looking for some use for it - aside from pyrotechnics. I like the idea of using it for some kind of organic reaction, but it doesn't seem to have many uses in organic chemistry.. After a bit of searching, the only interesting use I could find was NaClO3/HCl being used to selectively chlorinate ketones..

    Any others ideas of organic syntheses which use NaClO3 a a reagent? Maybe oxidation of benzyl alcohol to benzaldehyde.. would that be possible with chlorate?

    Cheers folks,




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    karlos³
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    [*] posted on 27-9-2019 at 14:44


    I want to do a chiral resolution on methylbenzylamine.
    However, I do not want to use a fractional crystallisation but I want to apply a selective extraction using monosodium tartrate in a two-phase system of toluene and water.
    Like this here: https://erowid.org/archive/rhodium/chemistry/amphetamine.res...
    I already applied that successfully on the amine used in there, and since it was easier and quicker, I would like to use it on 1-PEA too.
    Any objections?
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    [*] posted on 24-10-2019 at 02:24


    Question

    Is lye (for soap making) NaOH or NaOH.H2O? Should I factor in the H2O when calculating stoichiometry?

    According to wiki, "The commercially available "sodium hydroxide" is often this monohydrate".

    [Edited on 24-10-2019 by artemov]
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    [*] posted on 24-10-2019 at 02:32


    Question

    Is 70%-80% sulfuric acid any useful for making esters, ethers, nitric acid (from nitrates), nitrating mixture, and removing thiophenes from toluene? What about dehydration works like drying bromine?

    I have some battery acid and only able/dare to boil it down til 70-80%.

    [Edited on 24-10-2019 by artemov]
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    [*] posted on 24-10-2019 at 04:17


    Quote: Originally posted by artemov  
    Question

    Is lye (for soap making) NaOH or NaOH.H2O? Should I factor in the H2O when calculating stoichiometry?

    According to wiki, "The commercially available "sodium hydroxide" is often this monohydrate".

    [Edited on 24-10-2019 by artemov]


    I did titration to check that, and now I know that some specific brand (De Parel) available on Dutch market is perfectly dry. It looks like small globules.

    [Edited on 24-10-2019 by teodor]
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    [*] posted on 24-10-2019 at 06:46


    Quote: Originally posted by artemov  
    Question

    Is 70%-80% sulfuric acid any useful for making esters, ethers, nitric acid (from nitrates), nitrating mixture, and removing thiophenes from toluene? What about dehydration works like drying bromine?

    I have some battery acid and only able/dare to boil it down til 70-80%.


    Generally yes, although for nitrating mixture it might not work as well.




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    karlos³
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    [*] posted on 3-11-2019 at 09:58


    I found this method here for the deprotection of N-alkyl phthalimides to the primary amine: https://www.organic-chemistry.org/abstracts/literature/523.s...
    Would it work with N-alkyl saccharin too?
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    [*] posted on 4-11-2019 at 18:43


    Has anyone been able to make acetyldehyde from readily available chemicals?
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    [*] posted on 10-11-2019 at 14:51


    Quote: Originally posted by Cou  
    Has anyone been able to make acetyldehyde from readily available chemicals?

    I don't know if KMnO4 is readily available for you, but I think you should be able synthesizing it by dripping EtOH in a warm/hot acidified KMnO4 solution and distilling of the Aldehyde right away. Boiling point of acetaldehyde is just 20°C, so a lot of it should escape before being oxidized to Acetic acid.
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    [*] posted on 10-11-2019 at 14:56


    Well I Just cleaned a really messed up flask with H2SO4/CrO3.
    The stir bar was White before(and told to be PTFE coated) and now it is completely black. Did this happen to someone before? Because I thought PTFE was inert to this and with other stirbars this did not happen at all. Or did I maybe get ripped of with a few of my stir bars?:o

    IMG_20191110_234232.jpg - 4.1MB
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