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

Printable Version  
 Pages:  1  ..  64    66    68  ..  76
Author: Subject: The Short Questions Thread (4)
diddi
International Hazard
*****




Posts: 549
Registered: 23-9-2014
Location: Victoria, Australia
Member Is Offline

Mood: Spontaneously combusting in the hot weather

[*] posted on 28-12-2016 at 04:53


visit your local motor mechanic. they buy o ring assortments for air conditioners and general use. you can try them on so to speak and will prolly cost you a whole 50 cents



Celebrating completion of element collection
View user's profile View All Posts By User
Sulaiman
International Hazard
*****




Posts: 1303
Registered: 8-2-2015
Location: Walsall, England
Member Is Offline


[*] posted on 28-12-2016 at 05:35


Quote: Originally posted by j_sum1  
If I wanted to purchase some replacement O rings for thermometer adapters (normal 6mm diameter thermometer) what size should I get? I have now idea how these things are measured.


size just goes by internal diameter, and thickness or outside diameter
but what about the material?
synthetic rubber, butyl rubber, viton, silicone,
and ptfe washers
all available on eBay UK for example

I have two of the cheap Chinese adapters, both have square cross-section rubber, 6mm i.d. x 11.5mm o.d. x 2mm thick,
one is black rubber and one is translucent silicone.

one or more tight-fitting o-rings on the thermometer above the cap
gives hope that my thermometer does not drop into a flask in case of seal disintegration,
but is moveable, because anything fixed is always just in the wrong place to read the scale :)

[Edited on 28-12-2016 by Sulaiman]




Still confused by Chemistry, Life, the Universe and everything.
All my media containing the SM logo are © Science Madness
View user's profile View All Posts By User
Db33
Hazard to Others
***




Posts: 188
Registered: 25-11-2016
Member Is Offline


[*] posted on 30-12-2016 at 13:34
Viable way to pure acetone?


This might be dumb but, at the local pharmacy they sell 100% acetone fingernail polish remover. However it says ingredients are Acetone and Denatonium Benzoate. I know the latter is there in very small amounts as a bitter deterrent so people dont ingest the stuff. Would a distillation get rid of the denatonium benzoate?
View user's profile View All Posts By User
Sulaiman
International Hazard
*****




Posts: 1303
Registered: 8-2-2015
Location: Walsall, England
Member Is Offline


[*] posted on 30-12-2016 at 14:24


I believe that the denatonium benzoate wil be in the region of 10 ppm, equivalent to 99.999% pure acetone.

Reagent grade acetone is not that pure.

I have read that denatonium benzoate may interfere with the precipitation of nucleic acids,
other than that I would not worry about the 0.001% impurity.




Still confused by Chemistry, Life, the Universe and everything.
All my media containing the SM logo are © Science Madness
View user's profile View All Posts By User
aga
Forum Drunkard
*****




Posts: 6033
Registered: 25-3-2014
Member Is Offline


[*] posted on 30-12-2016 at 14:31


Quote: Originally posted by Db33  
Would a distillation get rid of the denatonium benzoate?

Yep.

Maybe nobody has mentioned it yet, so here goes.

Use Google with the search term like this :-

site:sciencemadness.org acetone denatonium

TFSE will have been U'd, and you'll find many posts about this particular topic.

Be careful taking this Dark path : most are old posts from the Bad Old Days when some naughty amateur chemists posted about experiments they were planning to do, did, then even posted the results as they were so interested in actual Chemistry.

The horror !

[Edited on 30-12-2016 by aga]




Madness is thinking i'm not drunk.
View user's profile View All Posts By User
zts16
Super Moderator
Threads Merged
30-12-2016 at 22:40
zts16
Super Moderator
*******




Posts: 2422
Registered: 11-1-2014
Location: Austin, TX
Member Is Online

Mood: Phenolic

[*] posted on 30-12-2016 at 22:40


Generally if you have to preface a post with "this might be dumb," it doesn't need to be its own thread.



Come check out the Official Sciencemadness Wiki
Have a particular topic you're really interested in currently? Why not make a page for it? The wiki can always benefit from more contributors.

My (now defunct) YouTube Channel: Texium
My blog: Texium
View user's profile Visit user's homepage View All Posts By User
gluon47
Hazard to Self
**




Posts: 74
Registered: 20-9-2015
Location: oceania
Member Is Offline

Mood: fluorinated and dying

[*] posted on 1-1-2017 at 00:19
Williamson ether synthesis


I'm planning to make some tert-butyl ethyl ether via Williamson ether synthesis. Although I understand how the reaction works, I'm not exactly sure how to go about performing the reaction.

NaOH + t-BuOH <==> t-BuONa + H2O

t-BuONa + EtBr ==> NaBr + t-BuOEt

This is what I propose to do:

Add sodium hydroxide to a large excess of tert-butyl alcohol which will act as a solvent as well as a reactant. Reflux this mixture for around 30 minutes to reach the point of equilibrium between The tert-butoxide anion and tert-butyl alcohol. Add ethyl bromide through the condenser and continue to reflux for a further 2.5 hours.

Allow to cool to room temperature, then pour the mixture into a beaker containing water and mix thoroughly. The tert-butyl ethyl ether should form a layer above the later.

Wash tert-butyl ethyl ether with two more portions of water in succession. Dry the tert-butyl ether over anhydrous CaCl2 then finally distill, collecting the fraction coming over at around 69-71 C.

I'm thinking using a slight excess of NaOH to make sure all the EtBr reacts would probably be a good idea.

Any advice would be much appreciated. Does this sound like it has a good chance of working?



[Edited on 1-1-2017 by gluon47]




reality is an illusion :D
View user's profile Visit user's homepage View All Posts By User
CuReUS
International Hazard
*****




Posts: 740
Registered: 9-9-2014
Member Is Offline


[*] posted on 1-1-2017 at 01:56


Quote: Originally posted by gluon47  
I'm planning to make some tert-butyl ethyl ether via Williamson ether synthesis.I'm not exactly sure how to go about performing the reaction

see this - http://www.sciencedirect.com/science/article/pii/S0040402001...
View user's profile View All Posts By User
Sulaiman
International Hazard
*****




Posts: 1303
Registered: 8-2-2015
Location: Walsall, England
Member Is Offline


[*] posted on 1-1-2017 at 02:28
micelles (Williamson ether synthesis)


interesting, self-arranging mollecular structures that I could confuse with biological structures.

In physics entropy tends to increase
whereas in biology and chemistry, often the opposite seems to be true.
Isn't life wonderful.

Happy New Year

[Edited on 1-1-2017 by Sulaiman]




Still confused by Chemistry, Life, the Universe and everything.
All my media containing the SM logo are © Science Madness
View user's profile View All Posts By User
Geocachmaster
Hazard to Self
**




Posts: 99
Registered: 5-3-2016
Location: Maine, USA
Member Is Offline

Mood: Eutectic

[*] posted on 1-1-2017 at 18:01
How legal is a list 1 precursor?


Does anyone from the US know the legality of DEA list 1 precursor chemicals? Specifically iodine, red phosphorus, and benzaldehyde, as those are the only three on the list that I can see myself working with. I've done some research but it has only confused me. I know that the sale of said chemicals is restricted but what about only possession. For example, if I made some iodine, would it's synthesis or me storing it be illegal? Druggies getting every good chemical watched/banned makes me very mad!:mad:

Any help is appreciated

[Edited on 1/2/2017 by Geocachmaster]
View user's profile View All Posts By User
Db33
Hazard to Others
***




Posts: 188
Registered: 25-11-2016
Member Is Offline


[*] posted on 4-1-2017 at 05:34
red phos purity check?


I have some red phosphorus i bought a few months ago, i was wondering if there is a way to check the purity such as a melting point test or some other simple way.
View user's profile View All Posts By User
zts16
Super Moderator
Threads Merged
4-1-2017 at 07:38
Tsjerk
International Hazard
*****




Posts: 545
Registered: 20-4-2005
Location: Germany
Member Is Online


[*] posted on 4-1-2017 at 08:08


Quote: Originally posted by gluon47  
I'm planning to make some tert-butyl ethyl ether via Williamson ether synthesis. Although I understand how the reaction works, I'm not exactly sure how to go about performing the reaction.

NaOH + t-BuOH <==> t-BuONa + H2O

t-BuONa + EtBr ==> NaBr + t-BuOEt
[Edited on 1-1-2017 by gluon47]


I think you better use KOH, as what I understand from the potassium thread gives a alkoxide that is more soluble.
View user's profile View All Posts By User
Sedit
International Hazard
*****




Posts: 1921
Registered: 23-11-2008
Member Is Offline

Mood: Manic Expressive

[*] posted on 6-1-2017 at 20:42


Quote: Originally posted by PHILOU Zrealone  
Quote: Originally posted by Sedit  
Can i turn an amino acid into an amide rather easily by any chance? Im looking for the best method of converting the Amine in the amino acid into an electron Withdrawing group. Any suggestions. There is Oxidation i believe to convert it to a Nitro compound but from what i understand this is finicky and Its better if i have something reversible with relative ease.

IDK Suggestions anyone.

There are many ways but it is better to know what you intend to do and the initial starting molecule...otherwise answer may be too general and vague for your specific application.

To increase the EWG power of an amine, you have to reduce its basicity...

Oxydation of the amine to nitroso or nitro may help decarboxylation of the alfa carboxylic acid group (spontaneous for nitroacetic acid).
If H is available into alfa position then the nitroso can be seen as C=N-OH

If you turn your amine into amide with an organic acid anhydride or organic acid halide, it will be more EWG.

If you add formaldehyde to it also because of CH2=N- or (HOCH2)2N-.

Halogenation of amino-acids provides haloamines that may decarboxylate and on further treatment turn into ketons or nitriles...all depends onto the struture of the carbon holding the NH2 (primary, secondary, ternary)...

Nitrosation may afword diazo-carboxylic acids which display very special chemistry see diazoacetic esters from glycine esters.

[Edited on 26-12-2016 by PHILOU Zrealone]



Cross Coupling Via 5x and up molar excess of the minor species in the Kolbe electrolysis using Acetic acid(minor) and an amino acid(major). Adding formaldahyde would indeed make it into an EWG because I considered something similar in the past but was unsure. A direct conversion of the Carboxyl group into a methyl is totally within the realms of possibility I believe.





Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
View user's profile View All Posts By User
CuReUS
International Hazard
*****




Posts: 740
Registered: 9-9-2014
Member Is Offline


[*] posted on 6-1-2017 at 23:20


Quote: Originally posted by PHILOU Zrealone  

If you turn your amine into amide with an organic acid anhydride or organic acid halide, it will be more EWG.

Conversion of the amine to amide would be the best way.But the carbonyl group of the amide should have EWG likes triflouro.See rhodium's post - "A two-step method for the preparation of homochiral cathinones" -http://chemistry.mdma.ch/hiveboard/novel/000360879.html
View user's profile View All Posts By User
Sedit
International Hazard
*****




Posts: 1921
Registered: 23-11-2008
Member Is Offline

Mood: Manic Expressive

[*] posted on 7-1-2017 at 00:25


http://www.sciencemadness.org/talk/files.php?pid=161264&aid=...


Seems to suggest that its going to instead methylate the amino acid as well as decompose some of the amino acid releasing methylamine or is it just late and Im reading this wrong?





Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
View user's profile View All Posts By User
JJay
International Hazard
*****




Posts: 2092
Registered: 15-10-2015
Location: the Internet
Member Is Offline

Mood: underinfatuated

[*] posted on 7-1-2017 at 00:46


Quote: Originally posted by Db33  
I have some red phosphorus i bought a few months ago, i was wondering if there is a way to check the purity such as a melting point test or some other simple way.


I wish I had some! I think you could do an iodometric titration with starch and potassium iodate in an aqueous medium, but it would be tricky, and first you'd have to be very careful to remove any white phosphorus by refluxing in carbon disulfide.

[Edited on 7-1-2017 by JJay]




Check out my nascent YouTube channel: Extreme Red Cabbage
View user's profile View All Posts By User
laserlisa
Harmless
*




Posts: 38
Registered: 5-2-2016
Member Is Offline


[*] posted on 11-1-2017 at 00:41


I want to dry K2CO3 for use in a phenolic alkylation reaction. Is it enough to dry it in an ordinary oven?
Which temperature and what duration is advisable to get it anhydrous?

Thanks

[Edited on 11-1-2017 by laserlisa]
View user's profile View All Posts By User
TheNerdyFarmer
Hazard to Self
**




Posts: 85
Registered: 30-9-2016
Member Is Offline


[*] posted on 11-1-2017 at 19:30
Question


Im sure this is a stupid question but I got to know. When a solution is a certain percentage (especially an acid) such as 30% HCl or 98% H2SO4. Is that percentage referring to the percent of weight or volume or some other form of measurement?
View user's profile View All Posts By User
j_sum1
International Hazard
*****




Posts: 3055
Registered: 4-10-2014
Location: Oz
Member Is Offline

Mood: inert even with vigorous stirring.

[*] posted on 11-1-2017 at 19:41


Not a stupid question at all. It refers to weight percent. Thus a kg of 30% HCl contains 300g of hydrogen chloride molecules and 700g of water molecules.
(It does not occupy a litre since the density is not the same as the density of water. This makes conversion between weight% and moles per litre problematic since it is density-dependent and that density is itself a function of concentration.)

For anything analytical it is normal to use moles per litre (and much lower concentrations.) But the % figure is useful for most work. I have gotten into the habit of weighing my acids and other liquids rather than measuring volume since it correlates with the information on the label.

[Edited on 12-1-2017 by j_sum1]




View user's profile View All Posts By User
TheNerdyFarmer
Hazard to Self
**




Posts: 85
Registered: 30-9-2016
Member Is Offline


[*] posted on 12-1-2017 at 05:28


Thanks a bunch for the reply. It really clarified things up. I will start trying to weigh my acids and solutions rather than measuring their volume. Thanks!
View user's profile View All Posts By User
fastbre4k
Harmless
*




Posts: 21
Registered: 29-11-2016
Member Is Offline

Mood: BENZIN

[*] posted on 12-1-2017 at 17:11


Hey,

it is possible to hydrolyse an aldoxime with HCl to yield an carboxylic acid?
View user's profile View All Posts By User
Crowfjord
National Hazard
****




Posts: 348
Registered: 20-1-2013
Location: Pacific Northwest
Member Is Offline

Mood: Ever so slowly crystallizing...

[*] posted on 12-1-2017 at 18:27


It would yield an aldehyde, which could be oxidized to a carboxylic acid.
View user's profile View All Posts By User
fastbre4k
Harmless
*




Posts: 21
Registered: 29-11-2016
Member Is Offline

Mood: BENZIN

[*] posted on 12-1-2017 at 21:18


mhm ok, so i guess K2Cr2O7 is a suitable reagent
View user's profile View All Posts By User
PHILOU Zrealone
International Hazard
*****




Posts: 2779
Registered: 20-5-2002
Location: Brussel
Member Is Offline

Mood: Bis-diazo-dinitro-hydroquinonic

[*] posted on 13-1-2017 at 12:03


Quote: Originally posted by fastbre4k  
Hey,
it is possible to hydrolyse an aldoxime with HCl to yield an carboxylic acid?

And hydroxylamine hydrochloride what has some value too.

Quote: Originally posted by Crowfjord  
It would yield an aldehyde, which could be oxidized to a carboxylic acid.


Quote: Originally posted by fastbre4k  
mhm ok, so i guess K2Cr2O7 is a suitable reagent

Yes with an acid just like KMnO4, Ni peroxyde, ... but first isolate the aldehyd and avoid residual HCl ...otherwise dangerous Cl2 gassing!




PH Z (PHILOU Zrealone)

"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
View user's profile View All Posts By User
biomechem
Harmless
*




Posts: 28
Registered: 8-8-2016
Member Is Offline


[*] posted on 15-1-2017 at 08:26


Predicting yield of Grignard reaction. How do chemists know which rxn will give better yield when there are 2 posiblle routes of it? For example in reaction as presented below.
R1-CHO + R2MgX or R2CHO + R1MgX
Is it possible to predict which option would be better just by taking into account ease of creating a carbcation on carbonyl atom? Or there is no simple rule, and every case should be considered separately?
View user's profile View All Posts By User
 Pages:  1  ..  64    66    68  ..  76

  Go To Top