[Urbanium]

Hello,

I'm trying to set up one reaction and I have a very unusual issue: I need the density of thiodioxane (CAS: 291-13-4), which is one of the starting materials and I tried to find the data on the SciFinder, Merck Index, commercial producers webpages, even on Wikipedia, but I wasn't able to find it. It seems like the compound doesn't exist, and we have a bottle (approx 15 yrs old) full of it!?

I also have a second question: what would be the most convenient way to leave a reaction mixture to stir overnight in a flask at -30°C? We have one cryostat in our lab, but it's currently being repaired. Is there some elegant (or less elegant) solution other than using the cryostat?

[TheUnassuming]

Well if you cant find it published you could always just measure it yourself. 
If this needs to be super accurate you should do it a bare minimum of three times and get the average and standard deviation ect to make sure you are good to go. 

For overnight reactions that need to be kept cold I just put them in the freezer.  Most of your chem freezers should get into that range, and as long as your reaction is in solution then it doesn't actually need to be stirred. 

[Urbanium]

I considered measuring the density, but the real issue is that I have a starting material that has no entries in SciFinder/Merck Index/etc. I mean, how is it possible that such a compound which was commercially produced is not in these libraries??

Does anyone at least know some other source where I could check for physical data or at least if it exists?

as long as your reaction is in solution then it doesn't actually need to be stirred.

the idea is nice, but are you sure about the last thing you wrote?

[TheUnassuming]

If those sources don't have the data then you can always try contacting the manufacturer directly to see if they have the info.  Who made it?  It is definitely strange that its not in one of the main databases if it was commercially produced.   
As to the stirring I am very sure on the scale you are likely running your reaction.  On production scale some manner of stirring might become necessary for practical purposes, but I haven't worked at that scale so perhaps someone else can comment there.  The key is it has to be in solution, this trick doesn't work if there are solids that need to be kept in suspension. 
Also make sure its sealed extra well before you put it in the freezer(if its under inert atm).  When you have your reaction under positive pressure of argon you can get away with less than perfect septa, something you won't have in a freezer unless you get tricky. 

[billnotgatez]

@Urbanium

Is this the stuff you are talking about
Product Name:   1,3,5-Dioxathiane
CAS:   291-13-4

or do you have a typo

[discodermolide]

Why do you want to leave the reaction at -30° overnight? Is it for some sort of stereochemical control or what?
Given no other reason run the reaction at a higher temperature, it will go faster.

[Urbanium]

1,3,5-Dioxathiane

It is the same substance, unfortunately it's not a typo.

Why do you want to leave the reaction at -30° overnight? Is it for some sort of stereochemical control or what?
Given no other reason run the reaction at a higher temperature, it will go faster.

The reaction should be (not "is" but "should be" done, since it's something unreported) under these conditions because one of the reagents is quite unstable and degrades within 3 hours if everything is done at 0°C. Unfortunately the reaction is not complete within that timescale, and I can't use any catalysts.

[discodermolide]

Then you need to have a large excess of that unstable reagent say at -15 to -10°C and add your other reactant to it. Try and make the reaction addition controlled. Check it out on a small (TLC) scale for the exact conditions first.

[billnotgatez]

Not being elegant
If you have a freezer that can go to -30°C
Put reaction mixture on top of stirrer
put stirrer cord outside freezer
close door on cord so that grommet around door is deformed around said cord
Duct tape door close
Duct tape around the door as to seal it (if truly needed )
[I have a Tshirt that says I can most anything with Duct tape]

Do not do this with a freezer that may have food inside it during or after process
Regular household freezers  are kept just below zero °C, so you may not have a freezer that goes low enough.
You said I did not have to be elegant.

[billnotgatez]

[Urbanium]

Then you need to have a large excess of that unstable reagent say at -15 to -10°C and add your other reactant to it. Try and make the reaction addition controlled. Check it out on a small (TLC) scale for the exact conditions first.

I use the compounds in the ratio 1:2 eq, there is 1 eq of that unstable reagent and I add the 2 eq of stable substrate dropwise over a period of 2 hours (it worked of the other substrate, the reaction was done within 1 hour and the unstable reagent does not decompose), but this one should be left overnight. It's a bit confusing. And when it comes to TLC, both the product and unstable reagent are triflates, and they stick to the baseline of the TLC plate.

Not being elegant
If you have a freezer that can go to -30°C
Put reaction mixture on top of stirrer
put stirrer cord outside freezer
close door on cord so that grommet around door is deformed around said cord
Duct tape door close
Duct tape around the door as to seal it (if truly needed )
[I have a Tshirt that says I can most anything with Duct tape]

Do not do this with a freezer than may have food inside it during or after process
Regular household freezers  are kept just below zero °C, so you may not have a freezer that goes low enough.
You said I did not have to be elegant.

Yep. I was thinkig about the same thing, and this not elegant, it's hilarious. We have fridges that cool down to -30°, I'm only affraid that the stirrers are a bit too big and I don't know if they will get damaged by cold. But it might work.

Exactly. Yet there is no entry in the SciFinder or Merck Index. I really don't know what to do or where to check. The last thing would be to contact the producer. However, even if they say that the product is discontinued, I'm still in trouble because I need a proof that this product actually exists, I mean, how I can't find it in the databases??

[discodermolide]

This is indeed confusing! Are you attempting some sort of cross-coupling reaction?

Regards TLC if they are both triflates it is likely they are hydrolysing on contact with the silica-gel giving the triflate precursors, which must be more polar.

[Urbanium]

This is indeed confusing! Are you attempting some sort of cross-coupling reaction?

Regards TLC if they are both triflates it is likely they are hydrolysing on contact with the silica-gel giving the triflate precursors, which must be more polar.

It is a reaction in which one nucleophile (part of unstable species, which is a triflate salt) is displaced with another (the product is also a triflate, and I did not do any stability predictions, however a simpler analogue has been made).

Could you suggest what might I do when it comes to TLC? Should I switch to reversed phase TLC? It's not a happiest solution since we don't have these, but only reversed phase silica powder for columns or silica plug filtration.

[discodermolide]

Let them hydrolyse on the plate. The original starting materials you must have. If the RM is hydrolysed on the plate and developed with a solvent which moves up the hydrolysed product you should see the disappearance of the minor reaction component (actually its starting material) as it reacts.

At least I know what I mean, I hope you do:)

[Eloquentia]

For your first question: There is a calculated density value for your compound (CAS: 291-13-4) of 1.205±0.06 g/cm3 at Temp: 20 °C Press: 760 Torr  in SciFinder. It says it was "Calculated using Advanced Chemistry Development (ACD/Labs) Software V11.02". Hope it helps.

For the second question: I know that a cooling bath of o-xylene with dry ice should give you about -29°C. I once left a reaction on a cooling bath for over-night. However, it was a higher temperature bath.