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Author: Subject: Magnetic stirrer hotplate free to a good home
Oscilllator
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[*] posted on 14-5-2017 at 02:17
Magnetic stirrer hotplate free to a good home


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 :).
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[*] posted on 14-5-2017 at 02:23


U2U sent.
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[*] posted on 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.
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[*] posted on 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.
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[*] posted on 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.
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[*] posted on 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
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[*] posted on 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 :)




Beginning construction of periodic table display
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[*] posted on 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.
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[*] posted on 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.
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[*] posted on 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
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[*] posted on 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.
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[*] posted on 19-5-2017 at 21:04


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

Cheers
H.
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[*] posted on 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.
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[*] posted on 20-5-2017 at 07:06


Quote: Originally posted by j_sum1  
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.

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.
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[*] posted on 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.
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[*] posted on 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!
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[*] posted on 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.
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[*] posted on 17-6-2017 at 04:14


Any progress on the propylene carbonate?

The offer is still open!






Cheers,
H.
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[*] posted on 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.
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[*] posted on 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.
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[*] posted on 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.)
img1.png - 163kB
(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.
img2.png - 307kB
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.
img3.png - 197kB
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.
img4.png - 260kB
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.
img6.png - 286kB
img7.png - 520kB
(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.
img8.png - 871kB
(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.
img5.png - 1.1MB
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...
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[*] posted on 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.

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[*] posted on 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!
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[*] posted on 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!
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[*] posted on 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.




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