Sciencemadness Discussion Board
Not logged in [Login - Register]
Go To Bottom

Printable Version  
 Pages:  1  ..  83    85
Author: Subject: The Short Questions Thread (4)
TheNerdyFarmer
Hazard to Others
***




Posts: 136
Registered: 30-9-2016
Member Is Offline

Mood: No Mood

[*] posted on 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!
View user's profile View All Posts By User
LearnedAmateur
International Hazard
*****




Posts: 503
Registered: 30-3-2017
Location: Somewhere in the UK
Member Is Online

Mood: Free Radical

[*] posted on 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.



In chemistry, sometimes the solution is the problem.

I am now training to manufacture contact lenses for a living. Time to join the lab community!
View user's profile View All Posts By User
j_sum1
Super Moderator
*******




Posts: 3793
Registered: 4-10-2014
Location: Oz
Member Is Offline

Mood: Maintaining a semblance of equilibrium

[*] posted on 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?



A little shameless self-promotion: New stuff on the YT channel. 100 sub celebration. Or you can tour my lab.
View user's profile View All Posts By User
User13579
Harmless
*




Posts: 14
Registered: 27-2-2018
Member Is Offline

Mood: No Mood

[*] posted on 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]
View user's profile View All Posts By User
TheNerdyFarmer
Hazard to Others
***




Posts: 136
Registered: 30-9-2016
Member Is Offline

Mood: No Mood

[*] posted on 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!
View user's profile View All Posts By User
S.C. Wack
bibliomaster
*****




Posts: 1740
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline

Mood: Enhanced

[*] posted on 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.



"You're going to be all right, kid...Everything's under control." Yossarian, to Snowden
View user's profile Visit user's homepage View All Posts By User
User13579
Harmless
*




Posts: 14
Registered: 27-2-2018
Member Is Offline

Mood: No Mood

[*] posted on 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.
View user's profile View All Posts By User
Panache
International Hazard
*****




Posts: 1058
Registered: 18-10-2007
Member Is Offline

Mood: now it seems I’m letting the robots defeat me

[*] posted on 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
View user's profile View All Posts By User
User13579
Harmless
*




Posts: 14
Registered: 27-2-2018
Member Is Offline

Mood: No Mood

[*] posted on 12-5-2018 at 06:47


Who are FFS? A SO2 manufacturer?
View user's profile View All Posts By User
DraconicAcid
International Hazard
*****




Posts: 2508
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline

Mood: Semi-victorious.

[*] posted on 12-5-2018 at 07:46


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



Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
View user's profile View All Posts By User
User13579
Harmless
*




Posts: 14
Registered: 27-2-2018
Member Is Offline

Mood: No Mood

[*] posted on 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.
View user's profile View All Posts By User
OldNubbins
Harmless
*




Posts: 46
Registered: 2-2-2017
Location: CA
Member Is Offline

Mood: Comfortably Numb

[*] posted on 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?
View user's profile View All Posts By User
woelen
Super Administrator
*********




Posts: 6434
Registered: 20-8-2005
Location: Netherlands
Member Is Offline

Mood: interested

[*] posted on 12-5-2018 at 12:39


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



The art of wondering makes life worth living...
Want to wonder? Look at http://www.oelen.net/science
View user's profile Visit user's homepage View All Posts By User
Bert
Super Administrator
*********




Posts: 2605
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".

[*] posted on 12-5-2018 at 13:09


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



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).

View user's profile View All Posts By User
ninhydric1
National Hazard
****




Posts: 298
Registered: 21-4-2017
Location: Western US
Member Is Offline

Mood: Bleached

[*] posted on 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.




The philosophy of one century is the common sense of the next.
View user's profile View All Posts By User
clearly_not_atara
International Hazard
*****




Posts: 1010
Registered: 3-11-2013
Member Is Offline

Mood: No Mood

[*] posted on 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 7 times





[Edited on 04-20-1969 by clearly_not_atara]
View user's profile View All Posts By User
karlos³
Hazard to Others
***




Posts: 248
Registered: 10-1-2011
Location: yes!
Member Is Offline

Mood: gaseous

[*] posted on 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]
View user's profile View All Posts By User
clearly_not_atara
International Hazard
*****




Posts: 1010
Registered: 3-11-2013
Member Is Offline

Mood: No Mood

[*] posted on 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.



[Edited on 04-20-1969 by clearly_not_atara]
View user's profile View All Posts By User
karlos³
Hazard to Others
***




Posts: 248
Registered: 10-1-2011
Location: yes!
Member Is Offline

Mood: gaseous

[*] posted on 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...
View user's profile View All Posts By User
JJay
International Hazard
*****




Posts: 2986
Registered: 15-10-2015
Location: Western Hemisphere
Member Is Offline

Mood: planning a semi-novel acetonitrile synthesis

[*] posted on 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.



This is my YouTube channel: Extreme Red Cabbage. I don't have much posted, but I try to do nice writeups once in a while.
View user's profile View All Posts By User
walruslover69
Hazard to Self
**




Posts: 51
Registered: 21-12-2017
Member Is Offline

Mood: No Mood

[*] posted on 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.
View user's profile View All Posts By User
Sulaiman
International Hazard
*****




Posts: 1778
Registered: 8-2-2015
Location: England
Member Is Offline

Mood: No Mood

[*] posted on 22-5-2018 at 10:40
Question psychically answered above


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]




When doing chemistry, don't forget basic physics.
View user's profile View All Posts By User
mackolol
Hazard to Self
**




Posts: 51
Registered: 26-10-2017
Member Is Offline

Mood: Xanthoproteinic

[*] posted on 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
View user's profile View All Posts By User
Meltonium
Hazard to Self
**




Posts: 97
Registered: 23-9-2016
Location: Home in pajamas
Member Is Offline

Mood: Fluorinated

[*] posted on 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.




"If at first you don't succeed, fail, fail again."
View user's profile View All Posts By User
 Pages:  1  ..  83    85

  Go To Top