Sciencemadness Discussion Board - Magnetic stirrer hotplate free to a good home

Magnetic stirrer hotplate free to a good home

Oscilllator - 14-5-2017 at 02:17

I haven't been doing any chemistry lately, but in my travels I came across two magnetic stirrer hotplates and I thought that somebody here could benefit from at least one of them.
One of them is an IKA one with a thermocouple port for holding temperature identical to the one here and the other one which I am willing to give away is a variomag monotherm like this one but with no rods. I live in Australia and I know there are some other young members who perhaps don't have a couple hundred bucks to blow who could benefit from such a useful piece of lab equipment so if you live in Australia and you think you'd have a use for one let me know and I may send it to you at the cost of postage (or free pickup). Just tell me about a cool experiment that you'll be able to do using the stirrer and post about it here after you've done it.
If you'd really like to buy the other one feel free to offer me a price, but I may decide to hold onto it just on the off chance I ever get to break out the old glassware set and do some more chemistry

j_sum1 - 14-5-2017 at 02:23

U2U sent.

Eyeborg - 14-5-2017 at 05:30

I was looking for a hot plate stirrer, too bad I live in USA. Good luck to whoever gets them.

Melgar - 14-5-2017 at 17:27

Quote: Originally posted by Eyeborg

I was looking for a hot plate stirrer, too bad I live in USA. Good luck to whoever gets them.

You should be grateful you live in the US, compared to the poor souls trying to do chemistry in Australia.

Oscilllator - 16-5-2017 at 13:32

I've still only received two requests. I'm surprised, I thought there were more Aussies here!

Melgar to address your point, I'm not sure it's easier to do chemistry in America. I think there might be a bit of a "grass is greener on the other side" mentality here but I always got the impression that places like Texas had very strict laws, although zts16 seems to get along just fine. Personally I never had any big problems doing chemistry in Australia and generally managed to find the same OTC chemicals that Americans could with some notable exceptions, namely isopropyl alcohol.

NedsHead - 16-5-2017 at 23:32

I thought Aussies would be clawing over each other for a free hotplate, I'm sure j_sum1 could use a hotplate/stirrer in his new lab, maybe Tdep could make use of an extra hotplate, I think he's had problems with the one he owns and he probably does enough chemistry to make use of a second, it would be wasted on me unfortunately

diddi - 17-5-2017 at 19:27

I have a nice one and would be happy for j_sum to have it cos he is poor

j_sum1 - 18-5-2017 at 02:13

Wow! How do I respond?
Awfully generous diddi. I said to Oscilllator that I would love a hotplate but I am probably not the most deserving candidate. I too am surprised that so few have jumped at this generous offer. But, on reflection, it seems that the contingent of aussie home chemists has been a bit quiet of late. I know that a few have shelved their stuff while they attend university.

Anyway, to both of you. I am always happy to be on the receiving end of goodies. But do give it to someone who is going to make good use of it. It might be that I am not the best choice and I won't be at all offended if it goes elsewhere.

Melgar - 18-5-2017 at 08:41

Quote: Originally posted by Oscilllator

Melgar to address your point, I'm not sure it's easier to do chemistry in America. I think there might be a bit of a "grass is greener on the other side" mentality here but I always got the impression that places like Texas had very strict laws, although zts16 seems to get along just fine. Personally I never had any big problems doing chemistry in Australia and generally managed to find the same OTC chemicals that Americans could with some notable exceptions, namely isopropyl alcohol.

Isn't DMSO available by prescription only or something silly like that? And doesn't customs go through any package mailed there from overseas, and confiscate anything that looks suspicious? I know there are a lot of sellers who ship international and won't ship to Australia.

Also, can you get stuff like concentrated sulfuric acid, hydrochloric acid, NaOH, MeOH, H2O2, nitrate salts, etc, over the counter? I wasn't sure if those were restricted in just Europe, Australia, or both.

Over here, if people want to kill each other, they just use guns! So there's no point in making bombs. I guess we can grudgingly thank the NRA for that.

Oscilllator - 19-5-2017 at 17:53

I decided to send the hotplate to Harristotle. As for the other hotplate I am willing to sell it, however if someone can successfully carry out the synthesis of at least 100ml of propylene carbonate containing only a small amount of propylene glycol as outlined in this thread by myself, I'll give it to you for free too (but only if you don't already have a hotplate/stirrer). It's a fun synthesis that doesn't require any rare or expensive chemicals but that is potentially very useful (there was a thread somewhere about dissolving alkali metal salts in it to make alkali metals through electrolysis at room temperature).

To clarify on my conditions for winning:
You must make more than 100ml of propylene carbonate
The propylene carbonate shouldn't contain much if any propylene glycol (say <5%) so that it's suitable for the making of alkali metals

j_sum1 - 19-5-2017 at 19:53

Good choice Oscilllator. Congrats Harristotle.

I am off to the hardware store in a moment to buy some more stuff for building the lab. Once it is ready for use I can begin some syntheses and will begin looking seriously at my hotplate/stirrer options. If it is still around Oscilllator then I will probably be interested in buying it.

J.

Harristotle - 19-5-2017 at 21:04

Thanks Oscillator.
The drooling has already started!
I have sent a U2U.

Cheers
H.

j_sum1 - 20-5-2017 at 06:14

Quote: Originally posted by Oscilllator

[snip]
the synthesis of at least 100ml of propylene carbonate
[snip]

This looks like a pretty cool sort of a synthesis. Nice discovery.
I might have to try it at some stage. But I am afraid it will have to take second place to a synthesis of dioxane from PG (a la Nurdrage). I have some uses for dioxane. I don't know what I would use propylene carbonate for.

Melgar - 20-5-2017 at 07:06

Quote: Originally posted by j_sum1

You can make dimethyl carbonate via a transesterfication reaction with methanol. From there, you can make triphosgene via len1's procedure, which is quite useful for a lot of things.

Harristotle - 30-5-2017 at 02:44

Well, I have received the stirrer and it is great.
There are many good years of chemistry and conservation biology (my other hobby) in this! It is a nice unit.

I want to give back, and I want to grow our community. So I am adding to Oscillators offer.

In addition to the quartz gear that Oscillator has offered, I will add $100 AUD as a prize to the first prepublication detailing the OTC synthesis of propylene carbonate.
Prize will be via by PayPal, photos should also appear in the writeup. Consensus that the work is of suitable quality will be reached between myself and Oscillator.

Have fun, and do great chemistry!
Cheers,
H.

Oscilllator - 30-5-2017 at 18:03

It's good to hear the stirrer arrived safe and sound.
I'm not sure where the idea of quartz gear came from, but like I said I'm happy to hand over the hotplate to someone that can achieve the synthesis as outlined above.
If you attempt the experiment at all be sure to post about it in some fashion, as even the most dismal of failures can be learnt from!

j_sum1 - 30-5-2017 at 21:29

I think JJay was offering a quartz flask in a competition to synthesise oxalyl chloride.

I think it is high time we had some more competitions/challenges. Unfortunately, much as I would love soe quartz, I am not really in a position to go for oxalyl chloride. (My limited OC skills being what they are.) As for the propylene carbonate, cool idea and the thread was a good read (even if some conjectures were hotly contested). But not something I have a need for. There are other things that should take higher priority.

Having said that, this offer by Oscilllator and Harristotle really should be picked up by someone.

Harristotle - 17-6-2017 at 04:14

Any progress on the propylene carbonate?

The offer is still open!

Cheers,
H.

Oscilllator - 20-6-2017 at 04:22

i just received a U2U asking if I would ship the hotplate internationally, and the answer to that is yes, of course I will. The winner will get $100 too don't forget and that is easily enough to pay for the shipping.

Harristotle - 20-6-2017 at 06:15

Good news Oscillator.
Just as an aside - first chance to use that stirrer/heater of yours. I distilled off some ethyl acetate for a student to use for chromatography in a science talent quest. They will 'still off the next set. Its a beauty!

Cheers,
H.

Vosoryx - 12-7-2017 at 13:30

First post.

I am a young aspiring chemist on the lookout for lab and glassware. I have found a great many things in yard sales and thrift stores in my area, as well as some of the broken equipment from my school’s chemistry lab, but a hotplate has proved elusive to find. I even tried, and spent a lot of money, in an attempt to make one, which ended in me pouring molten aluminum onto my kitchen counter after I miscalculated the resistance of the nichrome wire. One slap back to reality and countertop replacement later, I discovered this challenge, and decided to try my complete lack of useful chemistry skills at creating propylene carbonate. I did the reflux twice and distillation once, just because my largest flask was 500ml, and you (Oscillator) called for a 1000ml flask. However, I did not experience the extreme bumping you mentioned. Both reactions were more or less the same, the only difference in setup that I used was that I used an ammonia bubbler the second time because I ended up gassing myself out of my lab (shed) the first time.
My chemicals:
Urea, taken from instant cold packs and powderized. I made sure they weren’t the NH4NO3 kind.
Propylene Glycol, ordered online. Link here:
https://www.amazon.ca/Mystic-Moments-RMPROPGLYC250-Propylene...
Zinc Oxide, made myself from zinc metal extracted from canadian pennies minted between 1997 and 1999:
Zn - ZnCl - ZnCO3 - ZnO.
These notes are just copied, and slightly altered, from my lab journal.
The first time, 37 grams of urea and 57 grams of propylene glycol (Henceforth referred to as PG because i’m lazy.) were mixed along with slightly less than one gram of Zinc Oxide in a 500ml Erlenmeyer flask. A reflux with a 200mm Liebig condenser was set up, and the heating was turned on. (Just using a small electric hotplate and sand bath) Both times I had the gas being piped out through a vacuum take-off adapter from a distillation that I had put on top of the Erlenmeyer, but I do not have the required vacuum pump for this purpose. All reactions were carried out under atmospheric pressure. With the heating on, the white opaque liquid that neither the Urea or ZnO had fully dissolved into yet started to boil off and condense into the condenser. A white solid covered the inside of the condenser, as was described in the original post by oscillator. (More on this later.)

(Note: The orange colour at the joint is the grease I use, and the slightly yellow colour inside the cooling tube is because I use rainwater as my coolant.)
3 hours later, no more ammonia was being produced, and the final yield was 71 grams, about 67ml, of an amber coloured liquid.

While I was doing cleanup, I noticed an extreme amount of the mystery solid in the condenser. Unlike Oscillator’s reaction, that only a small amount was produced and ended up on the inside, my condenser was completely opaque with this solid. Near the bottom of the condenser, there was only a tiny pinhole through which any gases could leave.

While cleaning, I managed to pull some bits out and put them in a small baggy. Canadian 25 cent piece for scale, not actually inside the bag. I might look more into them in the future, but I don’t really care enough to bother trying to find out right now.

I believe it is recrystallized urea, forming on the inside of the cooler condenser. The second reflux I did, I used slightly less urea and slightly more PG because I didn’t want to end up plugging my condenser. The arbitrary ratio was 35:60 grams urea: PG respectively. Two and a half hours later, the trap was producing no more bubbles, and the reaction was stopped. The final yield for this time was 90 grams, and about 90 mls, but it was contaminated with water from the ammonia trap that ended up sucking back into the reflux setup. It was also a slightly different colour. However, there was noticeably less of the mystery material in the condenser, so I guess a step in the right direction.

(First attempt on the left, second attempt on the right.)
Nonetheless, I decided to combine them in a 250 ml RBF and proceed with the distillation. Again, it was put in a sand bath, with a bubbler trap. Over an hour, the temperature rose to 90 C., and a large amount of water (and probably some other stuff.) came over into the receiver flask. Over the next half hour though, the temperature at the still head remained steady just around 90 C, no matter how much tin foil I wrapped around it. An hour and a half after starting, I accepted defeat and turned off the heat.
In the receiver was 25mls of what was, according to my knowledge and limited test equipment, water.
The boiling flask contained 125mls of an amber coloured liquid. Comparison below.

(Boiling flask contents on the left, the distillate on the right.)
Interestingly, there was a large amount of some off white precipitate in the bottom of the RBF.

Oh well. It was a failure for the main reason that I didn’t get >100 mls of <5% impurity propylene carbonate. If anyone knows ways I could get the temperature at the still head up by almost 300%, i’ll continue this, but otherwise I’ll leave the hotplate for someone with greater ability than me.

Sorry if that was a bit of a long post for a failure...

Harristotle - 12-7-2017 at 18:09

Nice work, well done!
What a great first post!

You are very close, it seems.

deltaH suggested that the white powder in the condeser might be ammonium carbonate. Perhaps a drop of HCl (to observe fizzing), followed by a drop of NaOH solution might resolve this?

I'm excited that you are working on this, well done!.

Can you get to an oil bath (I sometimes use baby oil - cheap, clean, safe)?

Keep us all posted!

ps: a work in progress is not a failure, and certainly not when so nicely written up.

Oscilllator - 12-7-2017 at 21:40

Good stuff vosoryx

I seem to recall at some point that I used an aspirator as a vacuum during the refluxing of PG and urea. This is probably what caused me to have less of the mystery white substance (probably ammonium carbonate) than you, because ammonium carbonate tends to sublime away at low pressures. I think maybe one way you could improve your reaction in lieu of a vacuum is to find some other way to help remove the ammonia from the reaction to drive it forward. Perhaps bubbling plain air through the apparatus could work? That's just an idea though...

With regards to not being able to raise the temperature above 90 degrees, you didn't mention if something was coming over then? if it wasn't then having a temperature like that just means that you are measuring the temperature of the hot air inside your flask and not anything meaningful. If you did have any propylene glycol present the best way to remove it would be to raise the temperature only slowly, discarding the first fraction (like you did) until the temperature reached near the boiling point of PG. the fact that this didn't happen to you is either because you didn't have any PG, or because your heating wasn't powerful enough. Looking at you sand bath the sand seems quite thick so I would recommend placing a thermometer in the sand to measure its temperature too. If it is less than the b.p. of PG, then you know what your problem is.

Either way you've done some great work here and made an excellent first post, well done. I look forward to your future efforts!

Vosoryx - 13-7-2017 at 19:06

Thanks for the suggestions.
I'm going to try the distillation again with an oil bath instead of a sand bath.
I'm just going to use mineral oil though, as I don't have any baby oil. (As far as I know anyway, baby oil is just scented mineral oil)
I'm part of crew for a local music festival this weekend, so i'll try it out on Monday.
Thanks so much for the support and suggestions!

Melgar - 13-7-2017 at 19:22

Baby oil is indeed just mineral oil with added fragrance, and that's just a mixture of long-chain hydrocarbons. Increase the chain length further, you have petroleum jelly. Increase it further and you have paraffin wax. I'd actually planned to have a dedicated wax bath container to use for things like this, that I could make by melting down a $1 candle from one of the Bronx (Hispanic part of NYC) dollar stores. Incidentally, the jars from those candles are really good for TLC. They're about 20 cm tall and 5 cm wide on the inside.

Anyway, if you had a dedicated wax bath container, you could just allow it to solidify before storing it when you were done with it, that way you wouldn't have to pour the liquid in a separate container for storing it.

Vosoryx - 18-7-2017 at 17:21

My findings on the ammonium carbonate test. (I also posted this on to the propylene carbonate thread on the organic chemistry forum)
I was curious to see if it was indeed ammonium carbonate, so decided to run a test utilizing the low MP of ammonium carbonate.(54 C)
I put some of the powder I had in a beaker in a water bath with a thermometer, and turned on the heat. It passed 54, and the water started bumping quite heavily around 80. I was worried about dislodging the beaker from my lab stand, so I turned down the temp and tried to keep it in the 75-85 C range for about 10 minutes. (Just to make sure the inside of the beaker came up to temperature.) When poked, the material crumbled slightly easier than when it is cold, but did not melt. I believe that is evidence against the ammonium carbonate theory.
I will try this with an oil bath in the future to see at what point it does melt at.
I am also working on redoing the distillation. Should be posted here tomorrow.

Oscilllator - 18-7-2017 at 17:55

That's very interesting Vosoryx. Normally I would suggest testing if it's urea by heating with sodium hydroxide to see if any ammonia gas came off, but I don't think this would be a good test in this instance as it could easily provide a false positive. Do any other members know of a more selective test for urea?

Tellurium - 18-7-2017 at 23:10

Quote: Originally posted by Oscilllator

Do any other members know of a more selective test for urea?

One way to test for urea is to heat it to around 140°C (this converts the suspected urea into biuret) and then do the Biuret test using Sodium hydroxide and Copper sulfate.
This test indicates even the presence of small amounts of urea, but also indicates small amounts of proteins/peptides, but I strongly doubt them to be in there.
A more specific way to test for urea is to bring some of the unknown substance into solution and add a little bit of phenolphthalein. The solution should not be pink at this moment, but when adding the enzyme urease it converts the urea to ammonium carbonate, which makes the PH higher and causes the solution to go pink.

subskune - 19-7-2017 at 02:27

Vosoryx replied to my short report of making propylene carbonate and made me aware of this thread. Maybe I can help someone with it. Here is the link: http://www.sciencemadness.org/talk/viewthread.php?tid=75332

Harristotle - 20-7-2017 at 14:32

Very impressive.
Nice write up too.

What do you think, Oscillator?

Boiling point is a bit low, perhaps an azeotrope with an impurity, but still looks good.

Do we have/need another simple test for identity?

Vosoryx - 21-7-2017 at 20:26

My final success. (Faliure.)
I finally had time to do the distillation. First, I tried a mineral oil bath, but it started boiling at about 120C (The temp of the bath, not the temp of the stillhead.) I guess exact brand (From the superstore) mineral oil isn't good enough. Then, I tried a thinner sand bath, which worked amazingly well. With only about 1 cm of sand between the pot and the RBF, and sand packed along the sides, the temp rose quite nicely. It passed the water BP point with nothing coming over, (I distilled it all out last time) and then I kept it at around 200C until no more distillate came over. I switched out the receiver for a clean one, and my remaining fluid came over. I was dismayed to find that it was still amber in colour, and even more when I discovered how little of it there was, clearly disqualifying me on the >100mls rule. Picture of the two distillates, side by side. (PG on the right, PC on the left.)

The condenser ended up filling up (again) with the mystery crystal, but the trap didn't seem to be capturing any ammonia, (The bubbles didn't dissolve into solution the way that I know ammonia does.) but I honestly wasn't giving it my full attention.
Doing the math, I can see that I would have to repeat the reflux 2 more times to get >100mls of PC, and (Just ignoring the cost of PG, the chemicals required to make ZnO, electricity and my own time) I would want to try to increase my yield with a vacuum pump. As a vacuum pump is below a hotplate on my list of tools to acquire, I think I'm probably done trying.
I will try to remove the orange colour of the polymerized PC later, but I just wanted to do the update here. (I think activated charcoal, as described in the PC thread on the organic chemistry forum, should work. Am I wrong?)
Good luck to whoever else tries this challenge.

Oscilllator - 22-7-2017 at 01:29

It's not quite clear from your post whether you tried another run of the experiment or distilled the stuff from a previous run, but it's a nice effort regardless. Did you make any effort to dry your reagents like subskune suggested? Anhydrous Magnesium sulphate is quite cheap and works well. That might also be a cause of the orange colour.
With regards to the 100ml requirement, it's much less important than the purity requirement. If you get a bit under 100ml but can show that it is reasonably pure then I'd let that pass. Also as an alternative to a vacuum pump you could use an aspirator. I bought one online for like 20 bucks an it works OK for this although it does use a lot of water.

subskune - 22-7-2017 at 03:08

In my case the aspirator trap worked very well. It caught all the ammonia and left me with a lot of ammonium sulfate. That amber colour means that you either refluxed too long or destilled too long (to dryness). If you use the quantities I described you should leave ~ 60ml behind. Activated charcoal helps to remove impurities but only to a certain degree. Destillate that dark I once had was not recoverable. But it might be worth a try.

The ZnO is really the smallest problem. I did 200g once and this will last forever. You really need to do larger quantitied this is way more controllable during destillation in large flasks.

This is REALLY useful to get a purer product: http://www.sciencemadness.org/talk/viewthread.php?tid=63013

[Edited on 22-7-2017 by subskune]

CalAm - 27-7-2017 at 23:34

I am going to give this a go this saturday / sunday as my PG arrived today.

Oscilllator - 28-7-2017 at 16:12

I look forward to your efforts CalAm. If you can I would suggest drying your PG somehow before your conduct the reaction, as this may affect the formation of the mystery white substance.

Vosoryx - 10-8-2017 at 22:22

I used activated carbon and (Anhydrous) MgSO4 to dry and clean the material that I had at the end. Both materials absorbed some of the PC, and some of the MgSO4 passed through the filter and turned the liquid green, and both the carbon and MgSO4 were quite wet with the PC. In the end I had only 6mls left, of a very green coloured liquid. I abandoned that route and tried again with my last PG. Everything was the same as the last time I did it, so i'm not going to show the two reflux's and the distillation, except that this time I stopped as soon as the reaction started to colour orange. When I did the distillation I got much more PG than the previous time, and then added in some carbon, let it sit for some time, and then put through a proper filter. My final yield was 15 Mls and has the density of PG. (Wikipedia says PC is at 1.205 g/cm^3) and I measured, on my very crappy scale, 1.15 g/cm^3.
I also agree with the description of the scent being "Burned urea." It smells startlingly similar at first.
It's a bit off colour though, slightly more yellow than proper PC, or even some of the other ones I have seen here, with a very slight brown/orange tint.

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subskune - 11-8-2017 at 08:36

honestly, that is looking way better the density og pg is 1.06 so you are in between which serms to be quite frequent at high temp destillations. on the other hand with some patince and a loss you can catch the 238c - 242c fraction. (if you wonder why i stick to 238, my thermometer has an inaccuracy of +-3c at these temps.

Vosoryx - 11-8-2017 at 10:15

I'm sure there is an azeotrope of PG and PC here. I would do the entire process again, but I'm out of PG and am honestly a bit tired of smelling ammonia. My mercury thermometer has the same inaccuracy, and I switched out the receivers when the temp at the still head was around 230. (There was nothing coming over above 200 anyway)
I'm also pretty sure my crappy scale is highly inaccurate at measuring tiny changes in weight, so my density calculation could be off.
I don't really have any motivation to try it again, and even less to buy more PG. I suppose I could use the stuff I recovered in the distillation, but I know it's contaminated with ammonia (I can smell that) so it probably also contains other by-products that might mess up the reaction.
Have you tried this CalAm? Even if you didn't get the desired product, I'd love to know how it went for other people.

subskune - 12-8-2017 at 03:02

Yeah, I can understand, ammonia sucks. Thats why I used an acid trap. This avoided any ammonia smell. I needed 5 runs until I had optimized all. To start this and not to run out of reactants I bought 5kg urea, 5l PG and made 200g ZnO. All together this was 25€, which is quite acceptable. Precise measurment equipment is a must! One ml or one g off can change you density form 1.2 to 1.17.

Vosoryx - 12-8-2017 at 08:40

That's very impressive for the price you bought your chemicals for. I could have bough 2L of PG for $60 CAD. (~40 euro for less than half as much. Instead, I opted to just buy some of the stuff online.) Urea, which I removed from instant cold packs, is pretty cheap, and I made the ZnO myself with zinc I took out of zinc-carbon batteries.
I could consider doing it again if I had the reagents cheaper. You're lucky wherever you live.

Vosoryx - 29-8-2017 at 10:05

I tried this one last time with the PG I recovered from the distillation, and I re-dried my urea in the oven. I guess the PG (Which stank of ammonia) contained water. I was checking it every five minutes or so, coming out from my house to my shed. I saw a lot of solid accumulating in the condenser, much more than before, so I was worried that it would plug. When I came out next the flask and condenser were full of water, and the ammonia trap I had set up was quite low on water. Here's my theory:
The condenser plugged, and the joint between my flask and the condenser didn't pop, (Unfortunately) so the vapours above the block in the condenser cooled and dropped in pressure enough to suck some of my ammonia trap water back into the condenser through the take off adapter at the top, which instantly washed the solid out and unblocked the condenser. The water siphoned into my flask and condenser. I tried to boil it down, but that proved difficult. The bumping kept splashing water out of the E. flask, so I decided to call it quits after all.
Is the offer still open? Should I buy more PG and try again?

Harristotle - 30-8-2017 at 02:58

My end is, but we have agreed between us that Oscillator will judge, as it was his proposal and work that brought this to a contest. Make him happy, and I will pay!

Cheers,
Harristotle

Vosoryx - 10-9-2017 at 18:05

I was ready to give this up, until I found out that my work (Aquaculture) buys Propylene Glycol by the literal bucket load, and, let's just say they didn't notice a litre going missing.

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So I tried this again, and got another completely different result. All reagents were dried using anhydrous magnesium sulphate. Once I refluxed it for about 2 hours, I set up a distillation around the flask. I distilled over the tiny amount of water, then a large amount of PG over a bit of time. The receiving flask turned yellow as the distillation continued, and the Erlenmeyer flask's contents turned a deeper and deeper red.

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Eventually, the temperature at the stillhead started dropping, even though the flask still contained a liquid, and my hotplate was at max heat. I know my crappy kitchen hotplate can reach well over 300 C, so I'm not sure why it did this. In the E. flask was left a slightly tarry deep red liquid with the smell I have heard is around after the distillation of PC; Burned urea, slightly fruity.

I left it on the heat for almost half an hour, and the temp at the stillhead even reached as low as 80 C., with the hotplate on full. I'm trying this again, and when I do I'll not let it reflux for as long.

For anyone who has tried this, is it just because I'm not getting hot enough to boil the PC? I had it wrapped in aluminum foil, all up to the thermometer adapter. Another thought I had was to attach it to a crappy goodwill vacuum cleaner, as this might lower the pressure enough to help it boil without the required 244 C. (Which my hotplate should be able to reach anyway) The vacuum also might help pull off the ammonia during the reflux. Perhaps that would help reduce by-products?

I have kept everything from the distillation, on both sides, just if anyone can offer any suggestions on how to get the PC out.

On a completely different note: I'm not sure why this post has my pictures in the downloaded link form, where I have posted others and they show up as pictures within the post.

Suggestions on any of my many problems?
Thanks.

subskune - 11-9-2017 at 04:14

Vosoryx, you must be really desperate to own a hotplate stirrer that you even "steal" pg from your employee

Now to your attempt:
- How do you know that you collected only water and pg? Whats your temperature data?
- Yes temperature is a problem! Its a balancing act. If you use too much aperatus, everything will polymerize and decompose before anything came over BECAUSE at this high temperatures every inch of glassware is a superior condenser, which makes your destillation essentially a reflux. If your plate is too hot you might destroy the mixture at the contact point. I didn't do it but a heating mantle would be perfect. If you don't have one, insulate. Pack in AL first to reflect the IR radiation. Then pack all in fibreglass or if you have no, kitchen towel. Use a MINIMUM AMOUNT OF GLASSWARE for the destillation. If you can pull a vac do it.
- Did you pull vacuum during reflux? This is crucial!
The erlenmeyer residue looks horrible, toss it.
Everything else: Measure density and decide whether there is enough pc in it for another destillation.

CalAm - 19-9-2017 at 00:35

Sorry for the disappearance i am now on a 2 week break with uni so i should be able to finally give this an attempt. I do think i will need to order a bit more PG though after looking at the previous attempts as i only have 250ml or 400ml to have a shot at this.

Vosoryx - 19-9-2017 at 16:21

If you do it well you only need one shot.
My advice: Use a vacuum, even if it's just the pull from a vacuum cleaner, especially during the reflux. Good luck!

Finally! A success!

Vosoryx - 9-12-2017 at 21:52

Bump!
It's been an interesting past few months. As soon as my last attempt failed gloriously, I decided a vacuum pump was a necessity, and so ordered an aspirator online along with a 12v pump. The pump took two months to ship, so when it finally arrived I was ecstatic and exited to get back out and try this - only to have my condenser shatter on me. Three weeks later, here I am. In the time all that was happening, I also got gifted a nice heating mantle for my birthday. It seems I now have every piece of lab equipment I could use except a hotplate stirrer.
I have no idea if the offer is still open, or if you've passed it on. However, your initial goal of increasing the community has worked - this thread turned me from a lurker to a user, and that has turned into me coming here daily.

So here is my latest attempt.
The urea, propylene glycol, and zinc oxide was mixed together in an RBF. A reflux was setup, and the heating mantle and vacuum pump was turned on. An hour later, i turned off heat and set up for a distillation, and distilled under vacuum. All the fractions < 210 C (My vac isn't that strong) was discarded, and the fraction from then up was collected. It was about 25 mLs.
The density was recorded as being 1.17 g/mL. Theoretical is 1.21.
This could be because my scale isn't great, which it isn't - I'll weigh some on my schools balance, which does this: 00.0000g on Monday, but I think it's more likely that it is contaminated with some leftover propylene glycol. I considered re-distilling, but due to the large amount of dead-space in 24/40 glassware, and the fact that I don't have that PC much to begin with, I decided against it. If a higher purity is needed, i'll go ahead and make another batch so i have enough to do a distillation and to separate the PC from the PG unless anyone else has a method for separating the two?
Pics below, and a link to a yt video for some of the videos I took.
https://www.youtube.com/watch?v=1t-J1QGbupw

Density proof.

My distillate of PC.

Remnants left in the RBF, along with the boiling stones included to prevent bumping. Bumping proved to be a serious issue, and I had to stop the distillation at one point to put them in. I probably could have squeezed a bit more of the product out of this, but I cut it short anyway.

The flask during distillation. As you can see, the vacuum pump unfortunately did not prevent the ammonium carbonate from forming. This sucks, (Vacuum puns!) because that was a major motivation for me getting the pump.

The flask was left in after the reflux. For some reason, these photos are going backwards in time... Go figure.

Picture during the reflux.

I'd like to make enough of it so that I can do a mass distillation to purify it. As I said, i'm concerned about how much I would lose if I were to distill my only 20 mLs. If I had 100 mLs, then I would be outside distilling it, not posting this now.
I have the glassware and chemicals required to do a large batch, because I hate doing lots of small batches. However, I fear that the ammonium carbonate would fill up and plug the condenser. Without someway of removing that, i'm stuck doing lots if little batches, which is not my favourite idea. The time it takes is a major consideration. I try my best to have a life outside chemistry, however much my attempts at a life fail.

Thoughts?

Harristotle - 16-12-2017 at 05:21

Nice job. Are you close to 100ml yet?

It seems you are getting close to nailing it.

Cheers,
H.

Pupper - 17-12-2017 at 04:15

Quote: Originally posted by Oscilllator

I've still only received two requests. I'm surprised, I thought there were more Aussies here!

Melgar to address your point, I'm not sure it's easier to do chemistry in America. I think there might be a bit of a "grass is greener on the other side" mentality here but I always got the impression that places like Texas had very strict laws, although zts16 seems to get along just fine. Personally I never had any big problems doing chemistry in Australia and generally managed to find the same OTC chemicals that Americans could with some notable exceptions, namely isopropyl alcohol.

Where do you get your chemicals? I can't find stuff like sulfuric acid etc

Vosoryx - 17-12-2017 at 11:58

Harristotle: Yeah i need to try it again to get enough, probably after christmas because of how busy I am. The Ammonium Carbonate is a serious problem, as I get afraid when doing large batches that the condenser will plug itself.

Pupper:
It takes looking to find the good ones. Sulphuic acid, for example, can be bought impure as SOME types of drain cleaner. Make sure it says sulphuric acid on it though.
There's a nice useful OTC list that works well as a starting place for beginners, here:
https://en.wikipedia.org/wiki/List_of_commonly_available_che...
As a last resort, though sometimes an expensive one, order online.

Pupper - 18-12-2017 at 20:58

Quote: Originally posted by Vosoryx

Harristotle: Yeah i need to try it again to get enough, probably after christmas because of how busy I am. The Ammonium Carbonate is a serious problem, as I get afraid when doing large batches that the condenser will plug itself.

Pupper:
It takes looking to find the good ones. Sulphuic acid, for example, can be bought impure as SOME types of drain cleaner. Make sure it says sulphuric acid on it though.
There's a nice useful OTC list that works well as a starting place for beginners, here:
https://en.wikipedia.org/wiki/List_of_commonly_available_che...
As a last resort, though sometimes an expensive one, order online.

Sorry, I meant specifically in Australia. Here you can't buy sulfuric acid drain cleaner

Harristotle - 18-12-2017 at 21:10

Drain Cleaner H₂SO₄ is almost impossible. I have seen it at Masters before they shut down.

However, you can be a bit creative, and in fact the lack of an ability to buy concentrated H₂SO₄ led me to an insight that increases the amount of H₂SO₄ chemistry my students can do.

Most of the time, when conc H₂SO₄ is required, you really need anhydrous H₂SO₄.

So for example, take vanillin staining. I add non-fuming pool acid H₂SO₄ (Clarke Rubber, 30%) to my ethanol, and then store for a couple of days over desiccated MgSO4. This hydrates, giving me the few percentage H₂SO₄ I need, in the anhydrous form needed. This is especially useful for esterification, when water promotes hydrolysis, and makes a lot of lab chemistry available to the lower years.

Your mileage may vary, but sometimes hardship is a good spur to creativity, and can lead to better ways of doing things more safely.

Having said that, I envy places where concentrated H₂SO₄ is OTC !

Pupper - 19-12-2017 at 16:39

Quote: Originally posted by Harristotle

Drain Cleaner H₂SO₄ is almost impossible. I have seen it at Masters before they shut down.

However, you can be a bit creative, and in fact the lack of an ability to buy concentrated H₂SO₄ led me to an insight that increases the amount of H₂SO₄ chemistry my students can do.

Most of the time, when conc H₂SO₄ is required, you really need anhydrous H₂SO₄.
Do you have the link? I can't find non fuming pool acid at Clark Rubber

So for example, take vanillin staining. I add non-fuming pool acid H₂SO₄ (Clarke Rubber, 30%) to my ethanol, and then store for a couple of days over desiccated MgSO4. This hydrates, giving me the few percentage H₂SO₄ I need, in the anhydrous form needed. This is especially useful for esterification, when water promotes hydrolysis, and makes a lot of lab chemistry available to the lower years.

Your mileage may vary, but sometimes hardship is a good spur to creativity, and can lead to better ways of doing things more safely.

Having said that, I envy places where concentrated H₂SO₄ is OTC !