Sciencemadness Discussion Board - Can you help me figure out some safe reactions to do?

Can you help me figure out some safe reactions to do?

Hockeydemon - 2-5-2013 at 02:16

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

Finnnicus - 2-5-2013 at 02:54

Get yourself some methanol son! Make methyl salicylate!

Hockeydemon - 2-5-2013 at 03:19

Quote: Originally posted by Finnnicus

Get yourself some methanol son! Make methyl salicylate!

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]

Finnnicus - 2-5-2013 at 03:58

No! Use aspirin! React with xOH solution, then with an acid that forms a soluble salt, NaOH and HCl work a charm. I believe!

The_Davster - 2-5-2013 at 04:18

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.

binaryclock - 2-5-2013 at 04:49

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.

Prometheus23 - 2-5-2013 at 04:55

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!

I Performed the Experiment

chemcam - 2-5-2013 at 12:05

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]

DraconicAcid - 2-5-2013 at 12:37

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!

[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.

chemcam - 2-5-2013 at 13:29

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)

Hockeydemon - 2-5-2013 at 20:15

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.

chemcam - 2-5-2013 at 20:21

What color is that, Is it very dark green like mine? What was your source of methanol?

elementcollector1 - 2-5-2013 at 20:22

How concentrated and pure was your H2SO4? If something went wrong, that's the likely suspect.

Hockeydemon - 2-5-2013 at 20:27

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.

HEET

chemcam - 2-5-2013 at 20:36

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]

Finnnicus - 3-5-2013 at 00:43

Iodoform from iodine tincture? That would be pretty cool.

maxpayne - 3-5-2013 at 12:29

Don't forget to check your IPA for possible explosive peroxides when distilling or evaporating to dryness.

Hockeydemon - 6-5-2013 at 01:42

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?

Quote: Originally posted by maxpayne

Don't forget to check your IPA for possible explosive peroxides when distilling or evaporating to dryness.

How would I test for this? What reaction were you referring to where this is an issue?

Finnnicus - 6-5-2013 at 02:16

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?

Hockeydemon - 6-5-2013 at 02:29

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?

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.

Nicodem - 7-5-2013 at 10:05

Quote: Originally posted by Hockeydemon

I mixed 10.6g aspirin with 31.8mL of methanol, in a rb flask and drip wise added 10.6mL of H2SO4.

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.

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.

Hexavalent - 7-5-2013 at 12:26

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.

Hockeydemon - 7-5-2013 at 19:43

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]

Hockeydemon - 7-5-2013 at 19:44

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?

MrHomeScientist - 8-5-2013 at 06:49

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?

chemcam - 8-5-2013 at 07:43

Quote: Originally posted by MrHomeScientist

(cut)...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?

Yes! I have gotten the precipitate of white crystals and you're right I have never found a mention of this either. I think it is unreacted salicylic acid since that is not really soluble in water. I have read also that this esterification take a long time, like refluxing for 12-18 hours depending on the material.

[Edited on 5-8-2013 by chemcam]

Nicodem - 8-5-2013 at 11:31

Quote: Originally posted by Hockeydemon

I assume your reference is http://phs.prs.k12.nj.us/clee/LabEsterificationSalicylic.pdf (make sure you always properly cite references)

Note that only one equivalent of water forms and note the MW of water is 18 g/mol. That does not cause much dilution to the methanol which is commonly in large excess (though in your case the excess was not really that large).

Quote:

How do you determine the appropriate catalytic amount of something?

By experiment, by literature, by experience, by mechanistics, or by the combination of these.
Since the literature says that benzoic acids and in particular the hydroxybenzoic acids are poorer substrates to the Fischer esterification reaction when compared to most aliphatic acids, you can assume you need more sulfuric acid (see also the Kirk-Othmer chapter on esterification). Since methanol has a low reflux temperature and the methyl acetate side product even lower, you can assume the esterification will either take several days of reflux or the reaction temperature will need to be increased by applying autoclave conditions (like in the procedure you tried to follow). It seems to me that this esterification is not as easy as I initially thought.

In my experience, the esterification of 2&4-hydroxybenzoic acids with methanol is a very slow reaction. I never applied it to salicylic acid, but the few related substrates that I used required at least two or three days of reflux to achieve >70% yields (using about 1 eq. sulfuric acid or thereabout, can't really remember). It was bad enough to gave up on using reflux and thus switched to higher temperatures via autclaves (I actually already mentioned this here). In retrospective, my previous suggestion for using 0.3 eq. of sulfuric acid only makes sense for aliphatic acids (kind of forgot that I already dealt with this problem in the past).

Quote:

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.

TLC is the simplest chromatographic analytical tool available to home chemists. There are several threads on the topic of making TLC plates and using them.

Quote: Originally posted by MrHomeScientist

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.

Poor conversion is the most likely reason, which makes salicylic acid a good candidate to be those white crystals.

Hexavalent - 8-5-2013 at 11:43

Quote: Originally posted by Nicodem

Poor conversion is the most likely reason, which makes salicylic acid a good candidate to be those white crystals.

Perhaps also hydrolysis of the product, if there was any additional water present in the reaction mixture? As I mentioned upthread, acid catalyses the reversible reaction in both directions, so the main limiting factor is the amount of water present; more water pushes the equilibrium to the left, meaning you will invariably end up with some salicylic acid crystallizing out in addition to what would be unreacted, anyway.

Hockeydemon - 9-5-2013 at 05:06

Quote: Originally posted by Nicodem

TLC is the simplest chromatographic analytical tool available to home chemists. There are several threads on the topic of making TLC plates and using them.

Well what do you know I happen to have a TLC reagent sprayer, but I haven't the fainest idea how to use it. Though I do understand how to use TLC (in theory). How would one use the sprayer? I couldn't find anything through google other than the sale of it.

Nicodem - 10-5-2013 at 12:04

Quote: Originally posted by Hockeydemon

You use it just like any other sprayer. You just spray the visualization reagent on the developed plates. It is not very useful though, as the simplest visualization reagent is a basic aqueous solution of KMnO₄ (which I assume is the most available to amateurs) and works best if you simply dip the TLC in it for a second and then heat it up. The second simplest is to use UV detection on fluoroscein stained TLC plates (254 nm UV lamps are not prohibitively expensive, good ones can be bought for 100 EUR). For these two methods you do not need a sprayer. Some reagents are best applied by a sprayer rather than dipping the plate, but most of these reagents are functional group specific. They are most often used as a qualitative test in order to tentatively identify compounds in the TLC spots (for example, when one does not have any reference standard).

MrHomeScientist - 12-5-2013 at 08:45

I did another run making wintergreen oil, and the results were much much better. I followed the exact same procedure as outlined in the link I posted earlier, except this time I added a reflux condenser to my flask and properly refluxed the solution for three hours instead of just one. This time, there was absolutely no solid precipitate at any stage. I ended up with 6.7 grams of slightly tan methyl salicylate oil - over double what I got the first time! This is a 61% yield.

I think that seals it that Nicoderm was right: the solid precipitate that appeared in the water washing stage was unreacted salicylic acid / aspirin.

Here's a picture of my products - the first run is on the right, and this second trial is on the left. The first run's product is noticeably darker and quite a bit more cloudy.

chemcam - 12-5-2013 at 09:05

Quote: Originally posted by MrHomeScientist

I think that seals it that Nicoderm was right: the solid precipitate that appeared in the water washing stage was unreacted salicylic acid / aspirin.

Did you even read my post BEFORE nicodem's? I clearly was the first person to tell you about the unreacted salicylic acid.

It's okay though, listen to the mods not the new guy.

MrHomeScientist - 13-5-2013 at 07:55

All power to the hypno-mods!

You did indeed mention it first, I just hadn't read the thread in a few days and the last response stuck with me. Apologies.

chemcam - 13-5-2013 at 09:26

Oh, its all good, MrHomeScientist, I was just giving you a hard time.

BTW, I enjoy your videos on YouTube will you ever upload new ones?

DraconicAcid - 13-5-2013 at 09:39

For TLC detection of salicylates, perhaps you could dip/spray the plate with iron(III) chloride? Both the oil of wintergreen and salicylic acid should give a strong colour with iron(III), due to the phenol functional group (I know salicylic acid goes very purple with iron).

MrHomeScientist - 13-5-2013 at 12:23

Quote: Originally posted by chemcam

Oh, its all good, MrHomeScientist, I was just giving you a hard time.

BTW, I enjoy your videos on YouTube will you ever upload new ones?

Thanks! Yes, I'll definitely be uploading more. I tend to go through spurts of activity where I'll get 2 or 3 up in a short period then go a few months before doing another. Now that I've got the wintergreen synthesis down, I'll make one of that. I actually tried to record it while I did it this time, but the damn camera keeps running out of batteries. I think the indicator is broken, and it thinks brand new batteries are empty.

I've got plans for the "golden rain" demo as well, and the lead nitrate I made for it is just now crystallizing.