Sciencemadness Discussion Board

The Short Questions Thread (4)

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TheNerdyFarmer - 10-5-2018 at 18:29

Hello everyone, I have a small question on what kind of tubing you guys use to handle sulfur dioxide gas. The only tubing I have on hand is vinyl and i can get silicone or polethylene tubing if necessary. I looked up a chemical reactivity chart online and it said that both vinyl and polyethylene tubing react severely with SO2. So my question is what kind of tubing do you guys generally use to handle this stuff. By the way, the specific reaction that I would be doing would only be running dry SO2 through the tubing for around 2 hours. Thanks!

LearnedAmateur - 10-5-2018 at 22:40

How far does the gas need to go? Maybe you can use glass instead if it’s only a short path (or you can make it so) from the source.

j_sum1 - 10-5-2018 at 23:19

Last time I did SO2 I used aluminium. Seemed to work. Glass would be my first choice though. You need it flexible for a reason?

User13579 - 11-5-2018 at 12:07

Teflon can be useful if you need inert but flexible tubing. To attach it to glassware (because it is quite hard) I put some rubber bands over the glass, then wrap them with Teflon tape, then slide the tube over the bands to create a seal. If it'll get particularly hot, maybe you shouldn't use rubber, but instead think of something suitable.

[Edited on 11-5-2018 by User13579]

TheNerdyFarmer - 11-5-2018 at 12:51

Thanks for all the replies. I guess it doesn't have to be flexible, it was just preferred. Mainly because I am pretty bad at bending glass, but I guess I'll have to just use this as practice :P. Again, thanks!

S.C. Wack - 11-5-2018 at 16:13

Everyone should have an assortment of sizes of tubing on hand. A foot of each diameter plastic and a meter of glass. Fire polish those cut ends.

User13579 - 12-5-2018 at 01:39

Personally I'd get some PTFE tubing and use it with glass tubing. Oftentimes some flexibility is useful if you're clamping things - where a slight knock will break glass tubing easily. PTFE tubing is very cheap and practically as chemically resistant as glass. Heat resistant too - enough for organic chemistry temperatures, anyway.

Panache - 12-5-2018 at 06:26

FFS just use PE tubing, its completely inert to SO2 and unless you need mechanical integrity at temperatures above 100C you are fine. Flexibility will be largely a function of its wall thickness.
If you have time order/acquire the coloured PP tubing commonly used in post mix soft drink carbonation systems. its obviously just as inert as Pe but has a better mechanical strength at !00C

User13579 - 12-5-2018 at 06:47

Who are FFS? A SO2 manufacturer?

DraconicAcid - 12-5-2018 at 07:46

FFS = "For F#$@'s Sake"

User13579 - 12-5-2018 at 10:37

Is that right?! He should shut the fuck up then because I recommend PTFE, for fuck's sake. Stupid fuck.

OldNubbins - 12-5-2018 at 12:09

Quote: Originally posted by User13579  
Is that right?!


Yes he is.

Quote: Originally posted by User13579  
He should shut the fuck up then because I recommend PTFE, for fuck's sake.


Does this apply to everyone? If so, there's a chance it could get rather quiet around here.

Quote: Originally posted by User13579  
Stupid fuck.


You appear to be upset. Is it because his recommendation differed from yours or that you did not understand the acronym?

woelen - 12-5-2018 at 12:39

User13579: Still not grown up? Regard this as a mild warning. Next time it will be less mild.

Bert - 12-5-2018 at 13:09

I would have been less mild, but hey, there's always next time.

ninhydric1 - 12-5-2018 at 20:59

Would the synthesis of triethyl borate be identical to that of trimethyl borate (reflux, distillation, and if necessary, separation of the azeotropes)?

I also assume that sulfuric acid will be a strong enough acid catalyst for this reaction.

clearly_not_atara - 14-5-2018 at 23:54

At least two youtube videos say yes:

https://www.youtube.com/watch?v=JjcShe-YrR8 (warning: bad music)

https://www.youtube.com/watch?v=KiMFOZP9N84

Attached is a paper about the hydrogenation of piperic acid. No idea why...

Attachment: lebedev1929.pdf (377kB)
This file has been downloaded 283 times


karlos³ - 16-5-2018 at 02:28

Well, I have a short question concerning chirality...
If anyone could help, it would be greatly appreciated.

So, if I have a chiral (S)-alcohol, and I want to create a (S)-amine out of it.
Going via an SN2 reaction, a tosylation or halogenation would yield the (R)-tosylate or halogen, that is so far clear.
If I am going to aminate it directly with an amine(but I want a primary (S)-amine), it would lead to this again, going with the umbrella analogy here.
Is that right so far?

So, what I think of, reaction the of the (R)-tosylate or -halogen, with K-phthalimide or -succinimide, that would lead to the (S)-phthalimide or -succinimide protected amine and cleaving the protection group would give me the primary (S)-amine, no?

Edit: And if kept more simple, if the (R)-tosylate is reacted with ammonia, would that yield the (S)-amine directly? I think so...

That makes sense to me, but I fear I might have got it wrong somewhere.

If someone could confirm or disprove my thinking, I would be very grateful :)

Edit2: I am very sorry for being so stupid, of course I was right, the walden inversion takes place in any of the mentioned cases... :o

Edit3: No, actually I am pretty much lost on this case it seems. No walden inversion takes place with a tosylate(due to bulkiness probably?), but when the chiral alcohol becomes halogenated, the inversion takes place, right?
Thus, aminating the halogenated compound will give the starting chirality again through retention, but with the tosylate not?

That seems about right now, but I thought that also earlier...

[Edited on 16-5-2018 by karlos³]

clearly_not_atara - 19-5-2018 at 20:08

There is no inversion when an alcohol reacts with tosyl chloride because the oxygen atom doesn't move and the bonds on the carbon atom are unchanged. Instead tosyl chloride is the electrophile and oxygen is the nucleophile. Contrast with an Sn2 where the protonated alcohol is the electrophile at carbon and bromide is the nucleophile.

karlos³ - 20-5-2018 at 03:29

Thank you, that was very helpful!

So, if the inversed brominated, now (R)-rotating compound, after the inversion, is reacted with ammonia, it would lead to through retention to the (S-)-amine. Right?
But if the (S)-tosylate is reacted with phthalimide, there would be no chiral inversion because it is no nucleophilic substitution...?

That really was a good and helpful answer, I'll write on my list "more learning on nucleophiles and electrophiles" now...

JJay - 22-5-2018 at 10:37

I'd probably try burning off the film, but you'll want to keep the temperature below 600 C or so.

walruslover69 - 22-5-2018 at 10:38

I have dissolved cans in NaOH before and I have never encountered that much of a problem. Usually the reaction starts very slowly but picks up and becomes quite vigorous. You could try tearing the cans or just poking a hole in it just to expose a little bit of fresh aluminum. I would be curious if the plastic film is actually the problem or if it just has a thick oxide coating. Seeing as how you mentioned the acetone dissolving the coating but not helping the reaction along.

Question psychically answered above

Sulaiman - 22-5-2018 at 10:40

APPOLOGY: I did it again, edited/deleted a post and left the thread confused.
The two posts above were posted before I'd finished ... sorry.:(
______________________________________________________________
I want to use aluminium cans and sodium hydroxide to make hydrogen.

There is a very thin plastic film coating the aluminium that is really effective in protecting the aluminium from the sodium hydroxide solution.
(I tried NaOH soution in the 1M to 12M range).

Acetone dissolves at least partially the plastic film,
judging more by the residue left after evaporation of the acetone than any increased reactivity of the aluminium.

Anyone know a quick,easy,cheap method of enabling the sodium hydroxide to get to the aluminium ?

For reference, the scale will be multiple batches of 400 litres of hydrogen,
requiring about 24 aluminium cans and 500g sodium hydroxide per batch.

Pieces of aluminium cooking foil added to the mix react quickly and rapidly,
so I still suspect the plastic rather than the oxide.
The aluminium can I tested by tearing into c1" squares,
plenty bubbling aroung the edges, negligible bubbling on the flat surfaces.

The hydrogen is for filling 400 litre balloons with steel wire tethering as a vertical antenna,
so a reasonable reaction rate is required.

EDIT: pieces of aluminium can each approx. 1" x 2" after five hours in c1M NaOH.
A lot of the aluminium has been dissolved from between the inner and outer plastic layers which remain intact !
Four pieces inside-up, one piece outside-up.
AlCan_NaOH.jpg - 2.1MB

[Edited on 23-5-2018 by Sulaiman]

mackolol - 24-5-2018 at 11:17

I have stupid question as I am not very deeply into practise because im a beginner. If i have to steam distill and in the mixture water is present do i have to connect separate flask with boiling water or not. And what is the difference between normal distillation and steam distillation. Thanks

Meltonium - 24-5-2018 at 12:40

Quote: Originally posted by mackolol  
I have stupid question as I am not very deeply into practise because im a beginner. If i have to steam distill and in the mixture water is present do i have to connect separate flask with boiling water or not. And what is the difference between normal distillation and steam distillation. Thanks


For steam distillations, some just add a whole bunch of water to their pot and distill out their desired product with the water. However, a proper steam distillation actually uses a separate "steam generator" that then runs steam through your product to distill it.

The difference between normal distillation and steam distillation is that in normal distillation, you are directly boiling out your product whereas steam distillation uses the fact that mixtures boil as mixtures (in a lot of cases) and it just uses water (steam) as a carrier for your product. Steam distillations are useful if your product will decompose at its boiling point.

mackolol - 26-5-2018 at 00:31

So would it work if i tried to steam distill formamide or diethyl sulphate?

Question

idk_something - 30-5-2018 at 04:27

How well does Helium store? I'd like to buy a tank from a gas supplier for a rainy day as the price of Helium is set to rise in the coming years. How much should I expect to lose if I store it properly in a fairly cool and dry environment? <26c

DavidJR - 30-5-2018 at 07:21

I wouldn't have thought you'd lose any at all, the cylinder shouldn't leak appreciably.

Panache - 30-5-2018 at 23:30

Quote: Originally posted by mackolol  
So would it work if i tried to steam distill formamide or diethyl sulphate?


The general rule is your substrate (the compound you are wanting to distill) should be between 1-3% soluble in water, any more or less no go. This is if you are using the shit method (no external steam).
I highly endorse using external steam. At home i simply use one of those handheld steam units for cleaning curtains they are like $30. With higher pressures a greater range of compounds can be steam distilled and your efficiency is maximised.
If your current setup can't handle condensing all that steam simply lead the outlet vapours onto a big block of ice sitting in a bowl or something.

Σldritch - 4-6-2018 at 04:50

Are carboxylate groups electron donating or withdrawing?

Question

egret - 15-6-2018 at 13:41

Hello everybody
Its my first post here. I atempt a reduction of nitrobenzene by zinc in sulphuric acid. I got a purple coloured solution after filtration of unreacted zinc. Do anybody knows why the the filtrate has a such colour? May be an oxidation product of aniline?

filtrate.jpg - 170kB

ninhydric1 - 17-6-2018 at 19:56

Does methanol and ethanol form an azeotrope? If yes, what temperature and what composition? (I tried googling but I couldn't find any data on it)

j_sum1 - 17-6-2018 at 21:21

Quote: Originally posted by ninhydric1  
Does methanol and ethanol form an azeotrope? If yes, what temperature and what composition? (I tried googling but I couldn't find any data on it)

Not according to Wikipedia. Not that I would put too much confidence in that -- the data appears to have gaps and is set out like a dog's breakfast. However, if one existed it would surely be mentioned...?

stamasd - 18-6-2018 at 03:41

Quote: Originally posted by egret  
Hello everybody
Its my first post here. I atempt a reduction of nitrobenzene by zinc in sulphuric acid. I got a purple coloured solution after filtration of unreacted zinc. Do anybody knows why the the filtrate has a such colour? May be an oxidation product of aniline?


I haven't done anything with aniline for many years (20 or so) but I remember back in the day that aniline stored in non-airtight conditions would become a similar color after a while. So yes, probably oxidation products is correct. Also probably some condensation products caused by the sulfuric acid. IIRC HCl is typically used for the reduction instead of H2SO4 to minimize such side reactions.


[Edited on 18-6-2018 by stamasd]

ninhydric1 - 18-6-2018 at 11:41

That's what I thought too, j_sum. I'll search around a bit longer and see but there most likely isn't one.

egret - 18-6-2018 at 13:36

Quote: Originally posted by ninhydric1  
Does methanol and ethanol form an azeotrope? If yes, what temperature and what composition? (I tried googling but I couldn't find any data on it)


Acording source below it does not form azeotrope
http://www.ddbst.com/en/EED/VLE/VLE%20Ethanol%3BMethanol.php

stamasd thank you for explanation

[Edited on 19-6-2018 by egret]

CharlieA - 18-6-2018 at 16:14

My Lange's Handbook of Chemistry, 15th edition, did not have an EtOH/MeOH binary azeotrope, nor a ternary water/EtOH/MeOH azeotrope.

mackolol - 19-7-2018 at 03:32

Is there any reagent that helps detecting oximes in mixture? (changes color if oxime is present)

clearly_not_atara - 19-7-2018 at 10:53

Quote: Originally posted by egret  
Hello everybody
Its my first post here. I atempt a reduction of nitrobenzene by zinc in sulphuric acid. I got a purple coloured solution after filtration of unreacted zinc. Do anybody knows why the the filtrate has a such colour? May be an oxidation product of aniline?

Likely a complex involving p-aminophenol:

http://labmonk.com/synthesis-of-p-aminophenol-from-nitrobenz...
http://www.sciencemadness.org/talk/viewthread.php?tid=27849
http://shodhganga.inflibnet.ac.in/bitstream/10603/126633/11/...

Apparently zinc and acids converts nitrobenzene to phenylhydroxylamine which rearranges to p-aminophenol. Usually this is done in two steps with Zn/NH4Cl for reduction and H2SO4 for rearrangement.

clearly_not_atara - 25-7-2018 at 11:56

Can methylsulfuric acid quaternize amines? For example, could trimethylammonium methylsulfate -- (Me3NH+)(MeOSO3-) -- rearrange to tetramethylammonium bisulfate?

Quote: Originally posted by mackolol  
Is there any reagent that helps detecting oximes in mixture? (changes color if oxime is present)

"Oximes couple in alkaline media with aryldiazonium salts to give arylazobis(oximes) which develop an intense blue color with ferric chloride; 50 micrograms of oxime can be detected in 25 mL of solution"

https://link.springer.com/article/10.1007%2FBF01219641 (attached)

[Edited on 25-7-2018 by clearly_not_atara]

Attachment: bhargava1970.pdf (100kB)
This file has been downloaded 274 times


arkoma - 26-7-2018 at 06:22

is the carbonyl on urea reducible with NaBH4?

clearly_not_atara - 26-7-2018 at 19:58

Maybe with in situ formation of diborane?

http://www.thevespiary.org/rhodium/Rhodium/chemistry/borohyd...

Are you hoping to obtain formamidine? Or something else? If you reduce to formaldehyde aminal, it will probably rearrange to hexamine + NH3. Maybe it will go all the way to methylamine?

[Edited on 27-7-2018 by clearly_not_atara]

arkoma - 27-7-2018 at 08:23

No particular desires. Got 30g NaBH4 and hunting a project and I have lots of clean urea and anhydrous isopropanol. I always forget about the vespiary.....

JJay - 4-8-2018 at 01:01

Did Chem Player have a video on making nickel boride? I'm not seeing it on Bitchute....

Σldritch - 4-8-2018 at 10:09

Quote: Originally posted by JJay  
Did Chem Player have a video on making nickel boride? I'm not seeing it on Bitchute....


I believe they did; https://smvideo.djr.pw/watch/4/nickel-chloride-and-boride/

chemplayer... - 9-8-2018 at 22:49

Damn. Is that one we missed in the Bitchute upload?

JJay - 10-8-2018 at 00:43

I think so. I hope you post some more. I keep watching for new Chem Player videos. :cool:

chemplayer... - 10-8-2018 at 08:08

Insanely busy with other projects at the moment unfortunately, but will try to keep them coming!

chemplayer... - 10-8-2018 at 19:57

Just for you ;)
https://www.bitchute.com/video/46uwCCGlPMA1/

JJay - 10-8-2018 at 20:21

Thanks! :)

Can sodium metal be used for THF drying?

experimenter_ - 13-8-2018 at 00:53

How to dry tetrahydrofuran (THF)? Can you use sodium metal like you use when drying ether? Or THF will react with the sodium metal?

[Edited on 13-8-2018 by experimenter_]

mackolol - 13-8-2018 at 01:05

No it won't. Even in some procedures it says that you use "tetrahydrofuran freshly distilled from sodium".

Tsjerk - 13-8-2018 at 01:31

How dry do you need your THF?

gluon47 - 19-8-2018 at 19:49

So the other day I made quite a large amount of bromine from NaBr/HCl/TCCA. I plan to use it to brominate vanillin to 5-bromovanillin. Problem is, the bromination requires dry/anhydrous bromine and I'm out of sulfuric acid which is the obvious choice for drying bromine.

So my question is: is it likely anhydrous MgSO4/CuSO4/CaCl2 would be effective for drying bromine?

EDIT: why the hell this pictures here I cant work out, can't get rid of it. It's not related...:mad:
[Edited on 20-8-2018 by gluon47]


[edit by moderator]
Offending picture removed (hopefully).

[Edited on 20-8-2018 by j_sum1]

karlos³ - 20-8-2018 at 22:39

I have a short question I wonder about lately, and can't seem to find anything conclusive for.
Is it possible to prepare bromine in some solvent to use that instead of doing a distillation for purification of the bromine?

Since I would need a solution of bromine in a solvent anyway, I thought that it could be possible to directly prepare the bromine solution, in-situ one could say?
Anything similar to overcome the need to do a distillation of the bromine would be helpful.

JJay - 21-8-2018 at 00:10

Woelen has a writeup on his site where he prepares bromine without distillation. I think MrHomeScientist has a video of the process.

karlos³ - 22-9-2018 at 07:15

Thanks JJay, for your knowledge, I overcame that problem by iodinating my substrate instead, even in much higher yield :)

Sadly I have a stupid question again...

Right now, I need a Cu(II) salt and only have the metal.
The last attempt using 30% H2O2+H2SO4 and NaCl+Oxone both weren't that fruitful, also wasteful or obnoxious...
Quite a lot of possibly useful chemicals for this are on hand, but what is in the chemical cabinet is lacking in the head...
In short, I do not know what would be a fast, effective and least annoying(i.e. possibly no evaporation of lots of water, least gasses as possible involved, things like that) way to make the piece of copper to a neatly handled Cu(II) salt?

DraconicAcid - 22-9-2018 at 09:08

Electrolysis of copper wire in a an acid solution. Hydrogen peroxide and hydrochloric acid (or NaCl and sulphuric). Precipitate the copper with sodium carbonate, and dissolve in your choice of acid.

Slow crystal formation on recrystalization of FeSO4

RogueRose - 22-9-2018 at 10:21

I am trying a recrystalization of FeSO4 and I'm wondering why it is taking so long. I had about 120g of heptahydrate and it lists the solubility at 51.35g/100ml @ 54C, so I used 210ml of water, dissolved and filtered 2x. It has cooled to below room temp and is in the fridge but no crystals.

Do some comounds take a lot longer to form crystals? When I would work with things like Ca(NO3)2 and (NH4)2SO4 I would dissolve in boiling water until saturated and then they would fall out very quickly as it cooled. Pretty much the same with CuSO4 but a little slower due to lesser solubility, but it is very close to FeSO4.

pid power supply question

SHADYCHASE54 - 7-10-2018 at 05:28

I bought a used thermolyne 21100 tube furnace one of the old analog types, unfortunately the pyrometer is broken and completely useless. Anyway, at first I was going to swap the pyrometer for the same or a similar model. However, I soon found, what I thought would be a simple swap, was cost prohibitive. Thusly, it is my intent to hollow out the base and install a pid with a SSR-40AA relay.

My first question is will I burn out the heating tube if I use the SSR-40AA when the furnace is a 110v 50/60hz AC 12-15 amp system? I, as you may have concluded from the content I have provided thus far, am relatively new to electronics. Therefore I ask some indulgences on what might be your frayed patience, as I sincerely appreciate any help or advice offered, if it will aid my project and expand my understanding.

I am also confused with how amperage effects a system when V is in line with specs. Obviously it is good form to match everything as closely as possible to the (V) (I) requirements. However I also know that sometimes exact matches are not possible and at other times unnecessary. although in this case I suspect a difference +25 amp might be testing the limits of tolerance a tad. In either case, I ask for some guidance. Should I buy a SSR-15AA or will the 40AA model work as is. If neither of these will work and the pid for ac control is a shit plan altogether, pleas offer your assessment as well as an explanation. thank you in advance of any replies.

Attachment: download.jfif (163kB)
This file has been downloaded 596 times

Sulaiman - 7-10-2018 at 05:45

The original controller would have been able to go to near 'full' power,
i.e. you could connect the heating element directly across the ac supply for full power.
An SSR controller cannot supply more than full power,
so should cause no harm.
________________________

Generally electronic components are rated for maximum allowable limits to variables,
so if you use a lower voltage/current/power than specified for the semiconductors,
usually there will be no problem.
In this specific case I would use an SSR with the highest rating practicable,
and a little spare,
so a 40A SSR is quite suitable for a 15A load,
I would choose it over a 15A SSR

either a 15A or 40A SSR should be 'heatsinked'.

I use a 40A SSR for my 1.6 A heating mantle.

If you go to extremes then secondary considerations such as leakage currents may become significant,
but not in this case.

[Edited on 7-10-2018 by Sulaiman]

SHADYCHASE54 - 7-10-2018 at 05:53

thank you very much for your reply I will get it up and working today.

Ubya - 7-10-2018 at 05:56

does silica gel desiccant expires?
i found some old desiccant packets in my university lab, it clearly says "blue=active pink=activity reduced" so i suppose is the kind with cobalt chloride. i removed the powdered silica gel from the packets and put it into a beaker, i then heated it to 110-120°C with stirring, but after about 1 hour just a few crystals were blue, most of them were this orange/pink (more on the orange side) color, i kept heating but nothing happened, just a few crystals turned blue, the 95% of them kept their original color, so my question is: can i regenerate old silica gel? am i doing something wrong?

S.C. Wack - 7-10-2018 at 10:52

Quote: Originally posted by SHADYCHASE54  
Should I buy a SSR-15AA or will the 40AA model work as is.


I would not cheapskate and get an SSR without a heat sink...you may even want a small fan.

Quote: Originally posted by Ubya  
i then heated it to 110-120°C with stirring, but after about 1 hour


More heat and time.

Mesa - 8-10-2018 at 04:58

Quote: Originally posted by Ubya  
does silica gel desiccant expires?
i found some old desiccant packets in my university lab, it clearly says "blue=active pink=activity reduced" so i suppose is the kind with cobalt chloride. i removed the powdered silica gel from the packets and put it into a beaker, i then heated it to 110-120°C with stirring, but after about 1 hour just a few crystals were blue, most of them were this orange/pink (more on the orange side) color, i kept heating but nothing happened, just a few crystals turned blue, the 95% of them kept their original color, so my question is: can i regenerate old silica gel? am i doing something wrong?


remove the beads from soln. spread on a ceramic tray. bake in oven at 200*c+ for a few hours(until pink beads turn blue again.)

voila. regenerated silica gel dessicant.

Sydenhams chorea - 9-10-2018 at 13:45

I found a reference for a Czech journal that is stated as:


Bohumil, P., Unsaturated androstanes. Czech. 127,564, 1968;
Bohumil P. Chem Abstr 1969;70:68637.

Anyone have any idea what the full name of this "Czech" journal is?

clearly_not_atara - 9-10-2018 at 18:06

From the list:

http://images.webofknowledge.com/images/help/WOS/C_abrvjt.ht...

the only chemical journal containing "Czech" is the Collection of Czechoslovak Chemical Communications, but that seems to be a miss. A search on Google Scholar turns up a few works by a "Bohumil, Provaznik" who may be Czechoslovakian:

https://patents.google.com/patent/US3340961A/en

but this could just be a coincidence.

Benzocaine synthesis

Frankie1 - 2-11-2018 at 23:58

Hi i am looking for help on a test I am running would it be possible to recrystallise benzocaine using diethy ether and Hydrochloric acid

[Edited on 3-11-2018 by Frankie1]

ninhydric1 - 18-11-2018 at 20:43

Is it viable to prepare stearoyl chloride by chlorinating stearic acid with triphenylphosphine dichloride?

I'd rather not deal with (the difficulty of obtaining) phosphorus chlorides and (the mess that is) thionyl chloride, so I would like some expert input on if the chlorination reaction above is possible.

ninhydric1 - 24-12-2018 at 11:33

Can you dry THF with calcium chloride? I know that alcohols, ketones, etc. can't, but there hasn't been anything on using it to try THF.

wg48 - 25-12-2018 at 02:14

Quote: Originally posted by ninhydric1  
Can you dry THF with calcium chloride? I know that alcohols, ketones, etc. can't, but there hasn't been anything on using it to try THF.


See http://delloyd.50megs.com/moreinfo/drying.html

Sulaiman - 25-12-2018 at 02:28

The document pointed to above suggests 4A molecular sieves to dry THF,
I'd use 3A sieves ... because I have 3A sieves and they are cheap and generally re-usable.

S.C. Wack - 25-12-2018 at 07:45

Quote: Originally posted by Sydenhams chorea  
I found a reference for a Czech journal that is stated as:


Bohumil, P., Unsaturated androstanes. Czech. 127,564, 1968;
Bohumil P. Chem Abstr 1969;70:68637.

Anyone have any idea what the full name of this "Czech" journal is?


That of the Czech patent office.

Quote: Originally posted by ninhydric1  
Can you dry THF with calcium chloride?


Quote: Originally posted by Tsjerk  
How dry do you need your THF?

Metacelsus - 25-12-2018 at 10:33

I second the recommendation to use molecular sieves. 3Å or 4Å will both work fine and they can get the THF quite dry. Molecular sieves are a good investment, since they're reusable. They can be regenerated by heating in a microwave oven (I think there's a thread about this here on Sciencemadness).

Amphoteria - 6-1-2019 at 12:30

Hey peeps,

So I'm planning to do a blanc chloromethylation reaction, but unfortunately my formaldehyde seems a bit outta wack. The bottle says it's a 37% solution, but it is very old and there's a lot of white residue in the bottle. I assume this is paraformaldehyde that formed over time. So I'm wondering how to redissolve the paraformaldehyde as formaldehyde so i can trust i actually have a 37% solution?

Any advice would be appreciated. This CH2O shit is causing me pains!

TheMrbunGee - 6-1-2019 at 12:33

Quote: Originally posted by Amphoteria  
Hey peeps,

So I'm planning to do a blanc chloromethylation reaction, but unfortunately my formaldehyde seems a bit outta wack. The bottle says it's a 37% solution, but it is very old and there's a lot of white residue in the bottle. I assume this is paraformaldehyde that formed over time. So I'm wondering how to redissolve the paraformaldehyde as formaldehyde so i can trust i actually have a 37% solution?

Any advice would be appreciated. This CH2O shit is causing me pains!


wiki:
Paraformaldehyde can be depolymerized to formaldehyde gas by dry heating and to formaldehyde solution by water in the presence of a base or heat. The high purity formaldehyde solutions obtained in this way are used as a fixative for microscopy and histology.

The resulting formaldehyde gas from dry heating paraformaldehyde is flammable.

mayko - 7-1-2019 at 09:24

When I harvest lithium foil from batteries, I try to store it under mineral oil, but between its low density and entrained bubbles, it floats to the top. I could probably add paperclips and a weight or something to keep it submerged, but I wondered if anyone else had protips?

TheMrbunGee - 7-1-2019 at 10:10

Quote: Originally posted by mayko  
When I harvest lithium foil from batteries, I try to store it under mineral oil, but between its low density and entrained bubbles, it floats to the top. I could probably add paperclips and a weight or something to keep it submerged, but I wondered if anyone else had protips?


I think it would float even without bubbles. Try less dense inert liquid or put something heavy (also inert) on top.

You could also store it in inert gel, or even solid. (maybe paraffin wax) not sure about compatibility, so research.

ninhydric1 - 7-1-2019 at 20:50

I know MrHomeScientist ampouled some lithium metal in an inert atmosphere, which eliminates the density issue entirely.

what will precipitate first? Calcium hydroxide or ammonia gas?

C6(NO2)5CH2CH(CH3)N(NO2)2 - 14-1-2019 at 15:33

I have been wondering if you can produce ammonia and a calcium salt from hydrated lime and an ammonium salt. According to this post: http://www.sciencemadness.org/talk/viewthread.php?tid=7464&a... You can add calcium hydroxide to ammonium chloride to produce ammonia 2NH4Cl+Ca(OH)2-->CaCl2+2NH3+ 2H20. I'd assume that this reaction would go in this direction due to all the different ions being in solution, and the unstable combination (NH4OH) decomposing and "precipitating" ammonia gas. But in this post: https://www.sciencemadness.org/whisper/viewthread.php?tid=83... it says that you can make ammonium nitrate out of calcium nitrate by adding ammonia solution: 2NH4OH+Ca(NO3)2-->2NH4NO3+Ca(OH)2. I suppose that makes sense that the calcium hydroxide would precipitate too, since it is poorly soluble in water (unlike ammonium nitrate) But it also means that adding the calcium hydroxide to an ammonium salt would probably fail to produce any reaction.

So I guess my question is this: Which compound comes out of solution first? and (sorry if this is spoonfeeding) if you hypothetically added calcium hydroxide to a saturated solution of Calcium nitrate-ammonium nitrate double salts, would I get calcium nitrate and ammonia vapor, or would nothing happen? or would it be a partial reaction, and the calcium hydroxide would stop dissolving prior to all the ammonium nitrate being converted?

[Edited on 14-1-2019 by C6(NO2)5CH2CH(CH3)N(NO2)2]

purple zinc chloride

j_sum1 - 14-1-2019 at 19:13

I discovered today that I don't have any zinc chloride. Never mind I thought. I have some zinc from a D cell and plenty of hardware-store HCl of reasonable purity.
After reacting, the resultant solution was a purple/lilac colour. Berating myself, I concluded that stray manganese dioxide from the battery was the most likely culprit. So I repeated with some reagent grade zinc powder.
Same result. It must be some impurity in the HCl. But what? I know that Fe is common but I have tested the acid for Fe in the past with a negative result. Is Mn or Co likely?

[Edited on 15-1-2019 by j_sum1]

2019-01-15 13.12.19.jpg - 313kB

clearly_not_atara - 14-1-2019 at 20:11

^Also, solutions of iron chloride are brown.

The HCl itself isn't colored, but with zinc it is? If it were a simple metal chloride the addition of zinc should not change the color. Mn or Co will be present as the divalent salt which should not undergo any sort of redox in this condition.

However, maybe the HCl is a little greenish? That would indicate chromium, as CrCl3 gives a green solution and CrCl2 a blue one. Additionally various aqua-chloro chromium complexes are slow to interconvert and have many different colors.

clearly_not_atara - 29-1-2019 at 01:07

I noticed that the reaction:

N2 + 5/2 O2 + 2 KOH >> 2 KNO3 + H2O

has ΔH = [2 * -494] + [-285] - [2 * -426] = -421 kJ/mol

Is it possible to induce this reaction somehow?

walruslover69 - 29-1-2019 at 05:42

I can't imagine you would be able to on a small scale. You would probably need a really specialized catalyst. That nitrogen triple bond has a huge activation energy.

I am really surprised how favorable the reaction is though.

[Edited on 29-1-2019 by walruslover69]

SHADYCHASE54 - 29-1-2019 at 14:04

I am wondering if anyone can suggest a way to remove a palladium chloride stain from a glass frit. I have tried conc. HCl acid which has reduced the discoloration by approx. 80% however 80% is still not complete. Any suggestions would be appreciated as the funnel was brand new. Thanks .

UC235 - 29-1-2019 at 15:19

Quote: Originally posted by SHADYCHASE54  
I am wondering if anyone can suggest a way to remove a palladium chloride stain from a glass frit. I have tried conc. HCl acid which has reduced the discoloration by approx. 80% however 80% is still not complete. Any suggestions would be appreciated as the funnel was brand new. Thanks .


Hot aqua regia.

3,4,5-Trimethoxyben?

Ramium - 9-2-2019 at 01:04

Hey chemoforumers,

Purchased some 3,4,5-trimethoxybenzaldehyde from a (seemingly) reliable source, however, I have my doubts. Material appears as white flakes/granules. very hard and brittle, and doesn't seem to have any real smell.

I would have expected the compound to have very different physical properties, as similiar subst benzaldehydes (vanillin, 5-bromovanillin, syringaldehyde) have very strong smells and form fine , non-brittle crystals. This might seem obsesive, but want to be sure I have the right stuff;) .

Anyone familliar with the substance? Does this sound like 3,4,5-trimethoxy ben, or definitely something else?

fusso - 22-2-2019 at 15:12

Some time ago, I heated some sugar to make elemental carbon. The resulting mass is very brittle and won't make black marks on paper, unlike graphite. Is it amorphous C?

clearly_not_atara - 22-2-2019 at 15:49

It's called "sugar charcoal".

https://en.wikipedia.org/wiki/Sugar_charcoal

mayko - 7-3-2019 at 19:09

I've been reading about molybdenum chemistry, and it seems surprisingly complicated. One pathway I'm interested in trying out would include an oxidation of molybdenum (V) oxytrichloride to molybdenum (VI) trioxide:
MoOCl3 ----????----> MoO3
it's not obvious to me how to do this. I can't find a lot of detail on the oxytrichloride; the book I'm reading says that it decays in cold water, but doesn't give any further information. Any ideas?

SHADYCHASE54 - 8-3-2019 at 08:47

I am wondering if someone might have a user manual for Parr pressure vessels pre-magnetic stir drive? I recently aquired a 600ml stirred reactor gland type stirrer however I am finding it quite impossible to source any of the 1980-90 Parr manuals or user guides. Any help would be appreciated.

SHADYCHASE54 - 30-3-2019 at 03:47

Another quick question, would anyone have a suggestion regarding a reasonably accurate vacuum gauge with error limit not exceeding (+)(-) 25-40torr. I mean to connect it to a vacuum tank to determine (manual) on off cycles so as to maintain max. vacuum, as it isn't convenient in this circumstance to connect a glass Hg Manometer. I am looking for one that is analog pressure gauge style. The reason i am bothering to ask, what may on the surface appear a dim question, is that my previous purchase turned out to be useless junk. When i tested the vac. gauge and measured for accuracy it was off between 110-118torr. and these values fluctuated considerably. So if anyone has bought an analog vac. gauge that is resonably accurate as well as resonably priced could you please provide a link or a brand/model number I would appreciate it.

As alway thanks for any suggestions.

mayko - 9-4-2019 at 17:36

I've been turning some of my copper collection into copper sulfate, using sulfuric acid + peroxide. I decided to try a less hands-on approach by using an aquarium pump to aerate sulfuric acid, copper, and water in a jug. It's taking longer than I'd expect, but there is also something happening that I just can't wrap my head around. The air bubbling tube has collected several inches of crystal growth *inside the tube*, that is to say, the growth has taken place against the flow of the air, and indeed has plugged the tube at least once. How could this happen? I could believe that a little spray might sometimes make it a little bit up the tube, but surely it would be quickly cleared from the air flow?

karlos³ - 17-4-2019 at 10:19

Would the reaction of a bromoketone and theobromine actually take place at 1-, on the amide between both carbonyls?
I believe it would due to their directing effect, but I am not sure.
And since I need to isolate the theobromine from cocoa, I will very likely only have a rather tiny amount of it to experiment.

RedDwarf - 17-4-2019 at 17:33

Mayko

I'm guessing that what is happening is that you get capillary flow of the liquid up the tube. Aquarium air pumps are quite gentle so I'm imagining laminar flow with very low flow rates at the walls to counter the capillary action. The air dries the liquid so that you get a smaller diameter tube which increases the capillary action even more. This is as I said a guess :)

DraconicAcid - 17-4-2019 at 18:01

Is there am acidic derivative of theobromine called chocolic acid (which would have the conjugate base chocolate)? Why the hell not?

bipolar - 20-4-2019 at 23:20

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]

fusso - 24-4-2019 at 00:21

For amide/protein hydrolysis, which one is faster, basic or acidic? (assume base/acid has same initial concentration in both rxns)

fusso - 26-4-2019 at 01:42

Can piranha solution oxidize gold, Pt and other PGMs?

TheMrbunGee - 26-4-2019 at 02:54

Quote: Originally posted by fusso  
Can piranha solution oxidize gold, Pt and other PGMs?


No, piranha solution is sometimes used for cleaning of gold or Pt plated stuff.

TheMrbunGee - 26-4-2019 at 03:23

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]


Seems like reducing acetonitrile yields acetic acid and ammonia, at least in ethanol.

Acetonitrile metabolizes in to cyanide, so all you need is volunteer as an one time reactor and a way to extract cyanide from dead body and you are good to go.

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