couple questions about HI setup

[superman]

in making HI via KI+phosphoric, is there any reason why i'd wouldn't want my condenser to be vertical?   i was planning on just using two 90* glass elbows betweed my RXN flask and condenser so i could distill it right off the edge of my table, straight down (into a recieving vessel of course).  that way i can simply bore out a hole in the recievers stopper big enough to fit the end of the condenser.

is this ok?  I ask simply because the still heads i've seen tend to be only slightly angled downward.

also, how dangerous of a procedure is this to do without ventillation?   i'm using  a thick 250ml flat bottom pyrex flask as the rxn vessel, on a homemade, but solid hotplate,  all other equipment is the real deal except for tube connecting the two glass elbows between the cond and rxn flask, and two more glass elbows between the recieving vessel and the water trap, which is made of clear vinyl.

[SHORTY]

Having your condenser vertical will work fine but i would bee concerned about ventilation.  As long as everything goes as its supposed to then ventilation is not a problem but if something were to happen like a leak then you could bee in trouble.  You should always have adequate ventilation when working with HI. It probably won't kill you but it can bee pretty nasty and painful if your not careful.
You might want to check this thread out:

Post 446436 (missing)

(SHORTY: "Trying the above HI preparation procedure", Stimulants)

[biotechdude]

It is best to use elbows and vertical distillation.  It 'separates' the reaction vessel from the recieving vessel better.

If using a 250mL flask, and <50g reagents; the reaction is quite tame.  When you scale up and HI production happens quickly, you can quickly create a mini disaster if not careful.

How hot does your hotplate get?  The fb flask may not get hot enough just sat on top.  A gas burner or decent heating mantle nay be required as you need alot of heat to get this baby cranking...

Use glass only... NO plastic, rubber tubing or the like in any 'HOT' zone.  It will melt.  

Water traps and the like can be more trouble than their worth for small reactions.  A simple flask, glass bend to vertical condenser, and recieving vessel with a little dH20 inside...will absorbe all HI produced.  Furthermore, just nestle (not seal)your recieving vessel closely around the bottom of the condenser and wrap a little wet face washer round the join zone.  This then absorbes any wayward HI(g) that cannot be absorbed in the recieving flask.  Lastly, dont seal or pressurise the system

[superman]

i am using the guts of a coffee maker for my hotplate.  just the element and plate that sits on top of it, suspended from the 4 finger clamp on one end, and the other sits on a little carbon loop which seems to conduct very little heat.  i've only tested it with a flask of water however it got it hot fast and wasn't near full power

how should i connect my two elbows then if not with some kind of tubing?

[SHORTY]

I doubt that a coffee maker is going to get hot enough for this rxn.  Most of the HI is produced towards the end of the rxn and the heat needs to bee very high.

As far as connecting your elbows, i used a rubber stopper and glass elbow with plastic tubing and it will work but only for one rxn.

[superman]

what temprature must it reach?   assuming it is insufficient could i simply put an empty pot on the stove and use the interior of the pot as a hotplate?

[Organikum]

I suppose you talk about a gas-stove? Yes? Ok, just fill your pot with sand or salt for better heatdistribution (2cm from the bottom, put flask in and add more sand/salt). Now you have a sandbath and this will work fine for high temperatures.

Search for SHORTY´s posts on this, but use 100% H3PO4 and catch the anhydrous HI gas in cold water. Put the receiver in a icebath.

ORG

PS: Another way to make HI is by tin(II)chloride/HCl and KI or I. But H3PO4 and KI works just fine.

[superman]

electric stove, ok sandbath it will be if my plate won't do the trick.   now i have 85%, which isn't pure, however it's stronger than what argox suggests.  should i use this strength?   would this affect the temprature required to do the rxn??

[biotechdude]

Swix uses 86% H3PO4 and it works fine.  All that happens is that some water will distill over first and then the anhydrous H3PO4 solid will be left with the KI and it will continue on its merry way.  Using anhydrous H3PO4 from the start bunnyhops this first step so u can get straight to the rigorous HI production phase...And purity may be better.

Use what you've got.  But Org's advice is spot on as well...

[borolithium]

It has been stated to me that if 100% phosphoric acid is used fom the start, a much lower reaction temp will be needed. This doesn't make any sense to me, as the use of 75% phosphoric will eventually become 100% as the H2O is distilled off, yet the very high temps are required regardless, if good yields are desired.

When the reaction is heated at a lower power setting, it is my experience that the reaction takes much longer and produces a lower yield. Full power on your mantle is needed.

The problem for me is that it keeps cracking my glass! A thermal blanket works but it will still often crack right on the bottom.

I have heard this is because of the expansion rate(or contraction rate) difference between the glass and the solid phosphates that form during cooling.

Maybe I am experiencing this more than other bees because my dreams are much bigger.

I have been trying to find a vessel that is an alternate to glass. Stainless steel would be great if I could find the right coating to protect it. Teflon and Viton are only good till around 260C, while a good reaction seems to need around 400C.

Any ideas?

[Organikum]

I suggest you just give the 100% H3PO4 a try. Chemistry doesnt work as you described it, adding another compound - here KI - can change all parameters completely, if this makes sense to you or not doesnt matter at all.

But thats just a suggestion of mine.
ORG

[borolithium]

I will definately be trying dehydrated phosphoric this weekend and I will report the results.

[biotechdude]

Org...

Is METAPHOSPHORIC ACID solid the anhydrous stuff you are referring to?

It can get confusing with the pryo, poly, metas phosphorics etc

[fnord]

i use a coffee maker hotplate for my reaction i have a rheostat hooked up to controll the temp and its always given good results, give it a shot

[superman]

thanks for the advice everyone.   i'll report back how the hotplate works.   i suspect it will be fine because it was got hot enough to melt the coffee maker before i devised my suspension system (i'll post a pic) which really simplified the process and it extremely functional since the hotplate can be suspended at the top of the retort stand if needed.

thanks again everyone

[SHORTY]

i use a coffee maker hotplate for my reaction i have a rheostat hooked up to controll the temp and its always given good results, give it a shot
Are you saying that you have made HI from KI and H3po4 on a coffee maker hotplate?

The rp/i rxn to reduce meth can bee done with this type of heatsource but i doubt that the rxn to make HI from KI and H3po4 would work.

[fnord]

i used a coffee maker to kick in a slow rp/i rxn, and it worked for that not this particular synth