Problems with so-called "easy-iso"

[raffike]

450 grams of 3 times freezed safrole with sg of 1.096 was put in 3 necked rb flask,attached termometer and heated to 150C.Safrole immediatly turned brown and then almost black.Left to stir at same temp with overhead stirring.Came back 16 hours and tried to distill at atmospheric,most of it came over between 235-240 degrees C.KOH flakes were completely decomposed to small particles.Distillate smells wierd,not like safrole nor isosafrole.Was put in freezer 10 minutes ago to see if it froze.Will post results soon.Raf thinks water might have been problem.He has followed many of these "easy-iso" procedure without success,only CaO/KOH has worked without much problems.Maybe vacuum isomerization will work,not sure,will try someday.

[Organikum]

Looks like you are the greatest writeup field-tester outa here! Congratulations, no kidding, I think thats great work and reallife help for all. Go on!
And more luck in scaling up.

ORG

[raffike]

There is also a possibility that my termometer might have been off(it's from year 1975 or so).Raf might test his iso with some fresh KOH like abacus suggested in one thread.Sg test is also in order and maybe nD if he could get his refractometer to work.

[RoundBottom]

yeah, those older thermometers used the old style celsius.  in 1981, they were 're-adjusted' to better suit 'merican attempts at joining the rest of the metric world.  so, a pre-1981 celsius is really 0.000918 of a 'modern' celsius.  this rarely has any affect on anyone who was born after 1981, though... so you're probably ok.

and what ever happened to 'merica joining the rest of the world chuggin' a 1,125mL's instead of chuggin' a 40??

see previous posts by me about vacuuming out the water at the begining of an isomerization.

btw, the whole thing about old celsius is a joke.

[raffike]

Actually thermometer age too.I have one that shows 94 C when water is boiling.

[raffike]

hmmm...seems to be complete failure,raf dumped some fresh KOH in and heated,solution turned quickly brown and raf broke his 3 necked 2 liter flask also...not good,not good...maybe it's easier to just order some palladium chloride,it's not watched and not very expensive also.

[GC_MS]

Phenoles in alkaline solution are very often brown, or deep-red.

[raffike]

It was probably safrole as it's density was close to 1.1 or little lower.

[raffike]

ok,raf got his motivation back and choosed new victim:LaBTop

Post 208821 (missing)

(LaBTop: "The ONE and ONLY buffered Performic", Methods Discourse)

Here's first the conversion from Safrole to Isosafrole done by LaBTop, Osmiums simple route was followed, yields are ~95% without vacuum, ~99% with vacuum :

No vacuum:
Weight 130 kg distilled safrole and add 2% = 2.6 kg KOH grinded flakes or pellets >98%.
KOH flakes are in some countries 85%, the 15% rest is water, check it on the label.
Then heat up. At 100 C the eventual 15% water will start evaporating, or, when 98% KOH was used, only a small amount of water will come off.
This removal of water is critical to the reaction, water present when refluxing will totally stop all isomerization.
Add more heat until all water is evaporated. Then at last connect a reflux condenser vertical on your vessel and continue heating until the safrole starts boiling, without vacuum, reflux will be constant at circa 232 C until boiling stops, that means it has nearly all converted to higher boiling Iso.
Do NOT crank up the heat then, but disconnect heating and let cool to roomtemperature. Reaction takes roughly 3 hours for non vacuum. You now have ~95% Isosafrole which you use for the MDP2P conversion step. You could vacuumdistillate it now, to get >99% Isosafrole, but that seems to be no option for the ones who choose for this approach, they probably have no vacuum source, and ~5% safrole will not really interfere with the MDP2P step, so do it under atmospheric pressure.

LaBTop says to use 98% KOH,according to Sigma-Aldrich,there is no such thing as 98% KOH,at least they don't carry such thing,their purest is 90%,raf has probably 85% as other bees.At 100C,nothing will start to evapourate,at 150 some water evapourates,at 200C we could assume most is out and start the actual reflux.Raf doesn't know how he is going to measure the rx temp,but he'll figure out something,hopefully.LaBTop mentions nothing about stirring but raf thinks some is necessary,we'll see .This time he uses 250 grams of safrole rather than 500 gr.Loss of 500 gr is worse than loss of 250 gr.

[raffike]

hmm...this time raf thinks he has succeeded.
Temp of condensing vapours from refluxing mix was over 250 C.Let's see how are yields.May i say that LaBTop is the best?

[raffike]

Everything came over at 108-114 C at my 10 or little less mm pump.Yields were in mid 80's and distillation flask was extremely easy to clean,first rinsed with cold water and then with some warm soapy water and it was clean.This procedure surely has an advantage over KOH/CaO procedure,with CaO rx flask was extremely difficult to clean and even conc H2SO4 had to be used to clear things up.I could even write a writeup if anyone's interested.IsO in 3 hours in 85-90% yields,not bad i'd say.

[LaBTop]

I advice you to use that 10mm vacpump (tapwater aspirator?) to distillate the remaining safrole out first, before proceeding. A 15% safrole content in your iso is too much to trust the next steps with. I thought you had no vacuum source this morning, did you run to a brewery shop to get a aspirator? Do you have at least another multi neck flask left? Easier to work with than rubber stoppers with 2-3 holes in them for a thermometer and a condenser or reflux setup. But if needed,  the brewery shop guy will be able to drill nice slick holes in a rubber stopper he also sells, using dry ice to make the stopper hard as metal first, before he drills the holes in it. LT/

[raffike]

There seemed to be no safrole forerun.I find this reasonable as it was heated to 250 C and held there about 10 minutes with heavy stirring.I have a vac source but no magnetic stirring devices,i have distilled everything included MDP-2-P without stirring.I have no capillary also,little bumping but no problems when flask isn't over 1/3 full.I don't have multi-neck flasks,not anymore but will get few soon.Termometer was in via condenser and was held with fingers(it wasn't very hot as my termometer is pretty long).

[LaBTop]

no magstirrer/heating plate! You really better find a solution for that problem first, you will find out that MDP2P distillation with it and your 10 mm pump goes much faster and safer. That pump will do fine for any quantities  between 1-2 liter btw, I used always a good model aspirator for <2 liter testruns, your MdP2P will come over at about 155-165 °C then.
Write me that iso testrun down please, check data (density, bp) on safrole and isosafrole and put them in also, if you can and would be so kind. LT/

[raffike]

It's hard to get precise bp data,for me it large depends how hardly i heat the flask(like when heater on 4,iso comes over at 112C,when on 6 it comes over at 120C).But we could say that safrole comes around 104 or so,iso over 110 and ketone around 150C(again depending on heater setting) but not lower than 140C.My starting safrole sg was around 1.080 because it wasn't purified via freezing and iso sg is around 1.1,again due lighter impurities.Raf will try this same procedure on pure safrole with sg of 1.096 but it'll have to wait few days(safrole is in freezer ).Raf still says that safrole conversion was probably nearly 100% cuz vapour temp measured in condenser during the reaction reached 252 C.

[Chromic]

You must use a vacuum to distill off the water from the flask... even a small amount of water from the KOH will fuck things up. The alternative, is to add a fair amount of 99% IPA, then distill that off--it will carry the water with the azeotrope.

The safrole going black is expected, but if you get a black sludge that is from water/KOH/safrole reacting.

[raffike]

Don't worry,LaBTop's nethod works as charm.Yields might be bit lower than with vac reflux but i can live with that.

[abolt]

Swim's Safrole was extracted from "Sassafras Albidum". Swim distilled the first 85-90% and isomerised it via this method:

Post 306186

(abacus: "Easy iso", Methods Discourse). Swim only had aspirator and basic Hotplate/stirrer and got isosafrole in ~ 90% yield (B.P. test). This isosafrole was then utilised in Labtops buffered performic to achieve a 68% w/w yield of P2P/isosafrole on first ever attempt using poor equipment and questionable technique. Using the technique in abacus's writeup is the simplest there is and it works. No need for CAO or additional filtering. It doesn't get any easier.

[raffike]

Yeah,if i had a magnetic stirrer with heating i could try this out someday but in meantime i'll stick with LaBTop's method.85-90% yields are achievable and rx itself takes only an hour.

[abolt]

You could always use a double hole stopper with a capillary, next to your thermometer, on the stillhead and leave your aspirator running. Apply your heat underneath. If you can keep your heat in the oil bath at the 140-150 C range, this setup would provide sufficient heat and and agitation to isomerise your Safrole over a 12-18 hr period and provide enough heat to drive out any water at the same time.

[raffike]

About 50 grams Iso made via LaBTop method was put in RB and added few grams of KOH,heated to 230 and held there few minutes with stirring.Iso turned a bit brown(probably due impurities or traces of safrole) but no noticeable reaction.Then turned up heat and iso was constantly boiling around 250 C.I think we could say that this method really works.

Writeup:

Put your safrole(sg >1.095) in a roundbottom flask,add 2% of KOH(technical grade is ok).Heat mix to 230 C(do NOT use condenser or water doesn't get out) and stir constantly for 30 minutes or so.Vacuumdistill directly from rx flask to obtain ~90% yield.Rx flask is easily cleaned with warm water,no soap,let alone acids and other nasty stuff like that,needed.Test via abacus method described above to make sure you got iso(i can't really see how this rx could be screwed up but to be 100% sure,test it).