Re-using solvents…..

[Rabidreject]

Okay so I don’t have a rotary evaporator - I would love one and maybe one day but I have had success from knowing 0 chemistry to having created a couple compounds now…

Okay so I bought a shit load of tryptamine - probably too much really but hey ho! Actually nah you can never have too much!

So long as you can keep switching up the correct aldehydes and ketones.

Aaaaaanyway, seeing as all the actual reaction mechanism is exactly the same across the board (so far) I am ending up with a shit load of really basic methanol.

Now I did just buy 5 more litres really cheap, however, it isn’t good for the ecosystem just dumping it or whatever. I can’t bring myself to do that, it’s pretty evil.

So my question is - do I need to use an acid to neutralise it before distilling the methanol from the water?
If it’s anything like ethanol I shall have to do it a few times but still, what’s the best way to deal with its basic nature atm?

cheers

 

[Metribolone]

I’d assume you can distill the methanol and leave behind whatever’s making it basic as long as the boiling points are far enough apart.

 

[Rabidreject]

Okay cool. It’s only methanol and KOH solution, so yeah that makes sense - I was just wondering if it would bring accross any of the water, as it does with ethanol when you distill it out of water…

 

[Metribolone]

I believe so. It’s hard to remove 100% of water through distillation alone. You’ll have to use another method to remove the remaining percentage of water if you need it to be anhydrous.

 

[Metribolone]

To add to my reply, you can use a molecular sieve to remove the water from solution after distillation.

 

[CCL4 huffer]

just destill dry and redestill thats how i always do it with my solvents

 

[Rabidreject]

Yeah that makes sense and is in line with what I thought…. I added sili colour change balls after and now it’s purple so gonna have to re-dist and add a shit load MgSO4! Gah being green is such a p.I.t.a on the cheap! I just ordered 5l of anhydrous methanol and I’m f’ing about with like 200ml haha so stupid…

 

[CCL4 huffer]

i mean tbh u can never have enough solvents anyway

 

[Rabidreject]

Yeh. I do agree with that the - providing you have safe space to store, of course!
I am looking forward to the 5l of methanol turning up though!!
I think when I run out of DCM this time I’ll order a 5L as well - it’s just annoying how heavy DCM is in comparison!
I do eventually want to get a rotovap but I think I’m waiting to move into a house first…

 

[CCL4 huffer]

tbh rotovap is useless and a waste of money unless ur a rl big lab with 0 time to spar.e otherwise normal vacuum destilation is better imo

 

[Rabidreject]

I guess so, I like the automation of a rotary evaporator - also, it’s just as much for crashing things out at RT than would be for re-using solvents.
I like the automation it provides - also rotary vane pumps are LOUD and so I imagine I would buy one of the diaphragm pumps that the rotovaps run their vacuum from, purely because I have a small diaphragm pump that is MUCH quieter than the rotary vane pump - it just can’t be used for more than like half an hour, which is obviously un-useful for vacuum distillation.
Trouble is, I have neighbours to consider at the moment. The walls here are thin and I have people below me and next to me as I live in a flat at the mo.

To be fair, the more molecules I actually work on, it may well be the case, the less I want a rotovap - I’m working with n,n-DMT (mostly) at the mo and it can be a bitch to crystallise, doing it at RT is just not going to happen and I don’t particularly enjoy freeze precip’s as it hurts your hands but also can easily introduce water to the product. It’s just annoying in general in my opinion,

I am planning on doing my first Henry reaction either today or tomorrow so hopefully I’ll see that some things DO crystallise JUST FINE at RT, when making the corresponding styrene.

 

[Loki12]

Learn to work without a rotovap. You do not need one if you are working in a flat with people around it, I am assuming if you are taking such a risk then you are not doing anywhere near the quantities that would warrant such an expense or make it even make sense.

Perfect your technique without the rotovap, if you need it to make your life easier with crystallizing, the simple answer is that your tek is shit and you should perfect that first, a rotovap is something you use once you master vacuum distilling and everything else, when you do not have time to spare because youre producing kilograms and youre sure you can work the rotovap while doing another step of the synth at the same time to cut down on your workload.

I do not re-use solvents. I perfect the method I am working with, then I process all my material in clean laboratory-grade solvents, once I am done with the synthesis, I clean up and get rid of the waste., If I had to re-distill and dry 10-20L of IPA for example, then yeah, I guess I would be using a rotovap, but for me personally, it makes more cost-sense to buy the reagents and produce a high quality product that is worth a lot of money, rathr than sit in place doing nothing trying to save the couple hundred euro while I could be spending that couple hundred euro to make couple thousand euro worth of prodeuct. At a bigger scale, time is money.