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Hockeydemon
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Can you help me figure out some safe reactions to do?
I spend a significant amount of time trying to figure out what reactions I can do, and it's tedious. I ideally would like to not have to buy a bunch
of new chemicals (a couple is fine), and I'd like the reaction to be relatively safe. I still haven't gotten around to building a fume hood (bought
glassware from Dr.Bob instead). I prefer to not need to go outside - I'm not too keen on having my neighbors see me. I do have a window directly
behind my desk with a fan, and a P100 respirator.
I have most everything I could need as far as laboratory equipment is concerned.
As far as chemicals go:
Sulfuric Acid
Hydrochloric acid
Sodium Hydroxide
Sodium Nitrite
Potassium Chlorate
Acetone
Ethyl Acetate
Diethylene glycol
Ethylene glycol
Urea
IPA 99%
(I also have whatever misc. chemicals your common household has)
Sodium Acetate - (made)
Aluminum Hydroxide - (made)
Copper(II) Sulfate - (made)
Nitric Acid - (made, but out of)
Acetic Acid - (made, but out of)
I don't really want a step by step guide - I want to learn from it. Just looking for some suggestions.
Thanks 
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Finnnicus
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Get yourself some methanol son! Make methyl salicylate!
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Hockeydemon
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I'll definitely make that in the near future, thank you for the suggestion... I'd need to order salicylic acid online right?
[Edited on 2-5-2013 by Hockeydemon]
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Finnnicus
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No! Use aspirin! React with xOH solution, then with an acid that forms a soluble salt, NaOH and HCl work a charm. I believe!
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The_Davster
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I second methyl salicylate.
Take Aspirin (acetylsalicylic acid) and heat in sodium hydroxide to hydrolyse the ester. The acidify to precipitate the salicylic acid. Keep the
solution nice and concentrated so that the salicylic acid crystallizes out.
You could also use your acetone and sodium hypochlorite (bleach) to make chloroform.
Chloroform and acetone with some sodium hydroxide will make chlorobutanol, which is well documented on this forum.
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binaryclock
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The Wikipedia page on chloroform is odd. It mentions it's "moderately hazardous," but then goes on to say even 10ml can cause a fatal dose, and "It
is immediately dangerous to life and health at approximately 500 ppm, according to the U.S. National Institute for Occupational Safety and Health. "
BTW, cool suggestions I'm going to try both sometime this week.
Current Project: Playing with my new Laboy advanced distillery kit!
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Prometheus23
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Actually methyl salicylate can be synthesized in a one-pot reaction with methanol and catalytic sulfuric acid. The conversion of acetylsalicylic acid
to salicylic acid and methyl acetate happens quite quickly, followed by the slower esterification of the salicylic acid with methanol to form the
final product.
Give it a shot and let us know how it goes!
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chemcam
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I Performed the Experiment
Quote: Originally posted by Prometheus23  | Actually methyl salicylate can be synthesized in a one-pot reaction with methanol and catalytic sulfuric acid... ... ...
Give it a shot and let us know how it goes! |
I just tried the one pot method and I got very dark green oil which smells strongly of wintergreen. I believe the methanol was not pure and of course
the salicylic acid wasn't either. I recorded the experiment with my camera. I will edit it and upload to YouTube later today. I will post a link when
its up. Here is a photo of end result for now:
[Edited on 5-2-2013 by chemcam]
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DraconicAcid
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| Quote: Originally posted by chemcam | | Quote: Originally posted by Prometheus23 | Actually methyl salicylate can be synthesized in a one-pot reaction with methanol and catalytic sulfuric acid... ... ...
Give it a shot and let us know how it goes! |
I just tried the one pot method and I got very dark green oil which smells strongly of wintergreen. I believe the methanol was not pure and of course
the salicylic acid wasn't either. I recorded the experiment with my camera. I will edit it and upload to YouTube later today. I will post a link when
its up. Here is a photo of end result for now:
[Edited on 5-2-2013 by chemcam] |
Weird. My students do this, and we often get a slight purple impurity, but never anything that dark.
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.
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chemcam
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Alright guys, I'll post my video now but please realize that this was a very crude method just to test it out, I have no reflux condenser so I had to
improvise, I used glassware for other reasons than it was meant for, a tiny piece of rubber fell into the flask (maybe that caused color?), and I
forgot boiling chips (duh!). I will eventually remove the video and replace it with a proper, clean synthesis.
Oil of Wintergreen (improper synth)
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Hockeydemon
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Okay so I went out and bought some methanol, and I found 10.6g of aspirin laying around.
I mixed 10.6g aspirin with 31.8mL of methanol, in a rb flask and drip wise added 10.6mL of H2SO4.
I refluxed this for ~35 minutes, and pulled it to see where I was. I don't have two layers formed so I am currently refluxing it for longer.
Does everything appear correct, and I just didn't wait long enough for the reaction to complete?
I used the claisen adapter in order to add the sulfuric acid since I've never had a chance to use it - I normally use a 1L 3-neck rb flask so I don't
need a way to add anything.
This is the result after ~35 minutes. There is definitely a wintergreen aroma.
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chemcam
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What color is that, Is it very dark green like mine? What was your source of methanol?
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elementcollector1
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How concentrated and pure was your H2SO4? If something went wrong, that's the likely suspect.
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
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Hockeydemon
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I used Rooto Professional drain cleaner which is 18M H2SO4, and is very clean for being OTC (it is in the 25ml graduated cylinder in the pic). I used
HEET fuel additive for my methanol.
And no the product was not overly viscous - at least I wouldn't say so just by looking at it.
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chemcam
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HEET
I had a feeling that HEET was the cause of my discoloration since that was the only questionable quality reagent. Now that I see you used it as well
and got dark color I have to strongly assume that is it, my H2SO4 is 98% Lab Grade, the salicylic acid I used was made and recrystallized by me, so I
know that probably wasn't the cause.
I looked at the MSDS for HEET and it says methanol 99% and Proprietary Additive 1%, who knows what the hell that is. I will order some lab grade
methanol and go pick it up on Monday, then redo the procedure.
---------------------
Can anyone think of any more organic synths? I have a hard time thinking of some to try. I have all the reagents listed by the OP plus quite a few
more so keep spitting things out please. I have done chlorobutanol already with great success, I would like to do more with nice smells and ones that
are not going to make me throw flasks around.
[Edited on 5-3-2013 by chemcam]
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Finnnicus
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Iodoform from iodine tincture? That would be pretty cool.
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maxpayne
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Don't forget to check your IPA for possible explosive peroxides when distilling or evaporating to dryness.
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Hockeydemon
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Okay so I wasn't sure why I wasn't seeing two visible layers in my methyl salicylate, but after transferring my product into another container from
the rb flask I noticed small droplets of insoluble methyl salicylate in whatever fluid (water?) was present.
So in order to separate them I threw it into a sep funnel with water, and ethyl acetate with the thought any unreacted methanol, water or sulfuric
acid would be more soluble in water than ethyl acetate (yes?). This gave me two distinct layers with my methyl salicylate in the ethyl acetate layer.
I then transferred this to a beaker, and heated it a bit to evaporate off any ethyl acetate. Now I have a decent amount of methyl salicylate that as
far as I know has essentially nothing else in it?
How would I test for this? What reaction were you referring to where this is an issue?
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Finnnicus
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Good work HD! Anyone got ideas why you got such problems? From your description, it looks lik you made an emulsion... Did you shake it up at any
point? What color is the product? Green? Purple?
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Hockeydemon
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| Quote: Originally posted by Finnnicus | | From your description, it looks lik you made an emulsion... Did you shake it up at any point? What color is the product? Green? Purple?
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I didn't shake it at all, and after it was refluxed and it sat for a good 12hrs while I was out doing other things. It is a very dark purple - you can
really only notice the purple when you hold it up to the light.
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Nicodem
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You used 3.4 equivalents of sulfuric acid for an esterification? Where did you read that such huge excesses are used? Usually amounts of up to 30 mol%
work just fine. Sulfuric acid reacts with methanol to give methyl sulfuric acid and water. It is thus pointless to use such enormous excesses which
can only lead to charing.
Meanwhile, you used a pretty modest amount of methanol. At least twice that volume would be advisable.
| Quote: | | I refluxed this for ~35 minutes, and pulled it to see where I was. I don't have two layers formed so I am currently refluxing it for longer.
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No layers should form. If that would be the case, it would only mean something went wrong. You can generally follow such reactions by quenching a
sample of the reaction mixture and make a TLC comparison with the starting material (aspirin), the intermediate (salicylic acid) and the product when
available (methyl salicylate). You can also do TLC monitoring intuitively and skip the use of standards (by monitoring from the time 0 and stop the
reaction when no more change occurs). Either that, or use published procedures and trust that the given reaction time will suffice for your scale and
setup as well.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Hexavalent
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It's important to ensure also that your methanol is quite dry: because acid catalyses the reaction equilibrium in both directions, the main limiting
factor is the concentration of water. Essentially, more water means more hydrolysis and you will end up with more reactants than products at the end,
in addition to the potential of forming an emulsion.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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Hockeydemon
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| Quote: Originally posted by Nicodem |
You used 3.4 equivalents of sulfuric acid for an esterification? Where did you read that such huge excesses are used? Usually amounts of up to 30 mol%
work just fine. Sulfuric acid reacts with methanol to give methyl sulfuric acid and water. It is thus pointless to use such enormous excesses which
can only lead to charing.
Meanwhile, you used a pretty modest amount of methanol. At least twice that volume would be advisable.
No layers should form. If that would be the case, it would only mean something went wrong. You can generally follow such reactions by quenching a
sample of the reaction mixture and make a TLC comparison with the starting material (aspirin), the intermediate (salicylic acid) and the product when
available (methyl salicylate). You can also do TLC monitoring intuitively and skip the use of standards (by monitoring from the time 0 and stop the
reaction when no more change occurs). Either that, or use published procedures and trust that the given reaction time will suffice for your scale and
setup as well. |
I follow the instructions off some K12 New Jesery AP chemistry lab - they indicated that the stopping point was when two layers form, and I used their
ratios. Why would two layers not form? The equation is C7H6O3 + CH3OH → C8H8O3 + H2O and methyl salicylate is not soluble in water.
How do you determine the appropriate catalytic amount of something? I tried to find some sort of formula - which is when I found the lab instructions
instead. I thought that TLC required special equipment to actually view the results? If I'm able to do this at home, and you know of a set of decent
instructions on how to do it please direct me to it.
[Edited on 8-5-2013 by Hockeydemon]
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Hockeydemon
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| Quote: Originally posted by Hexavalent | | It's important to ensure also that your methanol is quite dry: because acid catalyses the reaction equilibrium in both directions, the main limiting
factor is the concentration of water. Essentially, more water means more hydrolysis and you will end up with more reactants than products at the end,
in addition to the potential of forming an emulsion. |
I assumed that a car fuel additive would be relatively dry because water in your gas tank is undesirable. It this incorrect?
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MrHomeScientist
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I just successfully performed the wintergreen synthesis last weekend, with entirely over-the-counter reagents. I followed the procedure in Robert
Bruce Thompson's book, The Illustrated Guide to Home Chemistry Experiments. You can read the experiment here.
I used 13.0g of aspirin (actual weight of the tablets was greater, of course), 50mL of methanol, and 10mL of sulfuric acid for the synthesis step. My
sources were Equate generic brand aspirin, HEET antifreeze methanol straight out of the bottle, and 98% sulfuric acid drain cleaner (dyed orange). My
final product was 2.7g of wintergreen oil with a light tan color, which is about a 25% yield (pretty poor, really, and I'm not sure why).
The only troublesome part of the experiment was the precipitation of a good amount of white crystals when I added the water for the first water wash.
I looked at quite a few procedures online, but nobody mentioned the generation of any solids. I managed to gravity filter it off, but it was VERY slow
and I'm sure I lost some oil in the filter paper and trapped in the crystals. Has anyone else seen such a precipitate?
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