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diddi
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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
Beginning construction of periodic table display
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Sulaiman
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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]
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Db33
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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?
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Sulaiman
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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.
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aga
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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 <i>even posted the results</i> as they were so interested in actual Chemistry.
The horror !
[Edited on 30-12-2016 by aga]
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Texium
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Threads Merged
30-12-2016 at 22:40 |
Texium
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Generally if you have to preface a post with "this might be dumb," it doesn't need to be its own thread.
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gluon47
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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 
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CuReUS
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| 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
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see this - http://www.sciencedirect.com/science/article/pii/S0040402001...
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Sulaiman
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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]
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Geocachmaster
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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!
Any help is appreciated
[Edited on 1/2/2017 by Geocachmaster]
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Db33
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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.
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Texium
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Threads Merged
4-1-2017 at 07:38 |
Tsjerk
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| 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.
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Sedit
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| 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.
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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
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CuReUS
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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
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Sedit
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http://www.sciencemadness.org/talk/files.php?pid=161264&...
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
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JJay
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| 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]
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laserlisa
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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]
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TheNerdyFarmer
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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?
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j_sum1
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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]
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TheNerdyFarmer
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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!
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fastbre4k
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Hey,
it is possible to hydrolyse an aldoxime with HCl to yield an carboxylic acid?
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Crowfjord
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It would yield an aldehyde, which could be oxidized to a carboxylic acid.
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fastbre4k
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mhm ok, so i guess K2Cr2O7 is a suitable reagent
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PHILOU Zrealone
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And hydroxylamine hydrochloride what has some value too.
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)
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biomechem
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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?
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