Sciencemadness Discussion Board

What to do with heavy water and barium deuteroxide

Stibnut - 14-2-2016 at 19:29

I recently acquired 40 g of D2O, and I'd like to play around with isotope effects, observing how reaction rates and other properties differ between molecules with normal hydrogen versus with deuterium.

I've already done one very simple experiment. I bought 2 g of barium metal, cut it into pieces of 125-225 mg, and put a piece in 10 mL of distilled water in a volumetric flask. Obviously it dissolved with the release of H2, making Ba(OH)2, which dissolved completely in the 10 mL of water. I repeated this a total of four times (with new water each time). Full dissolution took between 3m 34s and 4m 14s for the three largest chunks (172, 184, 224 mg) and only 1m 37s for a 127 mg piece, and all stayed dissolved after cooling back to room temperature.

Then I did it with 10 mL of D2O and a 164 mg piece of Ba. The reaction took much longer, at 10m 44s. Additionally the solubility of Ba(OD)2 in D2O was not as great - some of it precipitated out. I was happy to see that work so clearly, and I collected it and put it in a sample bottle.

I still have about 26 g of D2O after the 11 g for the Ba experiment and ~3 g after tasting it and sinking a little chunk of heavy ice in normal water. What sorts of fun and relatively simple things can you think of to do with it and with the barium deuteroxide? There must be several things, but I'm rather new at amateur chem and am drawing a blank.

And a related question: under what circumstances will deuterium exchange with hydrogen? I tried looking up H/D exchange but all I've turned up so far is that they'll exchange at an amide group so it's a useful tool for looking at proteins. Which is cool, but I want to know about some relatively simple chemicals that will exchange H for D.

Ozone - 14-2-2016 at 19:58

Any exchangeable proton. This includes NH and OH. Check out the term with respect to NMR, and you'll gain a lot of insight.

O3

Stibnut - 14-2-2016 at 20:28

Any NH or OH will do? So if, for instance, I were to dilute 30% H2O2 to 3% in D2O, the resulting H2O2 would be mostly deuterated? If so, I could do that, get catalase, and look at how quickly the 3% H2O2 gets destroyed in ordinary water vs in mostly D2O. Or if I wanted, say, deuterated methanol, then a similar thing could be done, although I would get CH3OD rather than CD3OD?

[Edited on 15-2-2016 by Stibnut]

Ozone - 14-2-2016 at 22:31

It's pH dependant:

http://pubs.acs.org/doi/abs/10.1021/ja01544a008

Regardless, exchange isn't 100% per go (there is an equilibrium, see HOD). Typically, if I wanted to approach full deuteration, I'd exchange, lyophilize, and exchange again (repeat several times). This isn't a reasonable approach for H2O2.

O3

Deathunter88 - 15-2-2016 at 00:20

Ampule some of your remaining D2O and a similar sample of H2O. Then you will be able to demonstrate how D2O freezes faster than H2O (place both in an ice bath). This way you will have a reusable demo kit without having to waste D2O demonstrating some of its other properties. (such as sinking in water)

j_sum1 - 15-2-2016 at 01:06

iirc cody's lab on yt shows his process for making D2O and several experiments with it. Worth a look.

Stibnut - 15-2-2016 at 08:20

Quote: Originally posted by Ozone  
It's pH dependant:

http://pubs.acs.org/doi/abs/10.1021/ja01544a008

Regardless, exchange isn't 100% per go (there is an equilibrium, see HOD). Typically, if I wanted to approach full deuteration, I'd exchange, lyophilize, and exchange again (repeat several times). This isn't a reasonable approach for H2O2.

O3


Okay, I see. Thanks for the link - that paper is very helpful.
Quote: Originally posted by Deathunter88  
Ampule some of your remaining D2O and a similar sample of H2O. Then you will be able to demonstrate how D2O freezes faster than H2O (place both in an ice bath). This way you will have a reusable demo kit without having to waste D2O demonstrating some of its other properties. (such as sinking in water)


I forgot to mention it, but I already tried that. I didn't quite ampule it, just put ~1.5 mL in a microcentrifuge tube alongside another tube with H2O, placed them both in an ice bath, and observed the D2O freezing while the H2O stayed liquid. But yeah, it would be worthwhile to keep a sample like that.
Quote: Originally posted by j_sum1  
iirc cody's lab on yt shows his process for making D2O and several experiments with it. Worth a look.


I saw those videos, actually. It was pretty cool how he was able to turn the equivalent of several liters of water in lead-acid batteries into more and more enriched water by repeated electrolysis and distillation, until he finally had less than a gram of homemade D2O pure enough to sink in water. I didn't see any experiments other than tasting it, weighing it, and sinking it in water though, which is totally understandable given how little he had.

Does anybody have any suggestions for the Ba(OD)2?



[Edited on 15-2-2016 by Stibnut]

Heavy Walter - 15-2-2016 at 13:16

Stibnut
I am trying to deuterate poly aromatic hydrocarbons (PAH) with a technique known as HTDA (High Temperature Diluted Acid).

It is needed a deuterated acid, so I am importing Sigma Aldrich benzoyl chloride in order to react it with D2O and get DCl, needed for the HTDA technique.

With reference to the Ba(OD)2 I have no experiments in mind now...