Isomerization Problems

[sYnThOmAtIc]

Ok a friend asked me to post this for him.

He told me he distilled his safrole at 55-66c with vacuum. And he took 100g of it and added 1.5g of crushed koh and applied his vacuum till no more bubbling came from the koh pile on the bottom of flask. Then he removed the vacuum and stoppered te condenser. Heated the mix to 130c@aptm for 3-4 hours then cooled and vac distilled. He got forerun at 55-63c ~15ml and then the oil ceases to come over so he applied more heat and then a second fraction was collected at 75-80c.

It seems about right to me but I really don't know. So any of you have any input? He doesn't have the ability to boil at aptmospheric temp or read that high of temp either. I am unable to help as I have little to no experince with isomerizations of any sort cept thc eheh anyway.
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[hCiLdOdUeDn]

yeah...that seems right on target
hcildoduedn

[carboxyl]

Seems like a lot of forerun, in my limited isomerization experience I followed a similar procedure but usually let it run around 6 hours and got pretty acceptable foreruns ~2-3 ml. The temperature numbers seem right though. Sounds like you have a good vacuum source by those numbers.
The above post is purely fictional. Any resemblance to "real-life" is purely coincidental.

[RoundBottom]

procedure is right, but shouldn't it be ~160°C for more like 16-20h?

you should get at worst 5-10% forerun, and reduce your vacuum, that stuff is coming over waaaay too low.
my mouth tastes like burning.

[sYnThOmAtIc]

Yea I made him redistill his oil(s) at as low a temp as possible and compared them and there is no mistake. Besides the new oil has a more fruity smell without that tea tree smell that the safroel has.

Yea it is a lot of for-run but considering that he distilled to dryness and only got a slightly amber colored crystaline pile and no tar completed reaction in three hours and got 90g back plus an unwieghed portion of for-run which he should have measured ~15ml it looked (DOH!)seems pretty reasonable to me.


Round Bottom,,,

What, too low? How can it be too low? Better than damaging the compound with heat, no? Man its perfect. You  just unscrew the ballast wait till it starts to reflux lightly and then screw it in slowly and boom a solid stream of distillate. Hell I'm looking for a vacuum where I could heat the flask with my hand to distill, HHEAHHA. Anyway


Yes, That pic really is me!

[goiterjoe]

You're getting almost no separation whatsoever doing that.  Technically it's not even a distillation, you're just transferring the contents of one flask to the other.  Apply your vacuum well before you get near your approximate distillation temperature, and be patient. 
All paths are the same: they lead nowhere

[sYnThOmAtIc]

Dude, I know! I was being sarcastic. Besides it's not my shit anyway. My friend gets safrole from an asian source as a chemical which has a name that is not mentioned here at all. It is listed in flavoring chemicals and has only one other constituant which boils much higher than safrole and is a viscous yellow liquid making up about 5% of the weight. And is cheaper than dirt. So in his case this is fine for safrole distilaltion since his pumps ballast only changes the bp by a few degrees. Its not different than making yout bath 5-10c higher than the bp for efficient recieving. But anyway he doesnt do it on anything but his starting material.

Anyway, He has an updated isomeriztion which makes him wonder why most people run them so long ad under vacuum the entire time?

The cis to trnas conversion is hardly worth the extra 3 to ten hours and or a vacuum running the whole time. Besides if you just use STRIKE's method of conversion on your pure iso just before using it then you have almost all trans. But hwo cares unless your going to leave schedule1 shit laying around for years.

Ok he did it same as before with a few changes.
1.5g ball milled koh, 100g safrole. Stirred mixture and applied vacuum and haet until mixture reached reflux under vauum ~50c then vacuum is turned off setup stopcocked and haet is upped to 100c for four hours. Then heat is upped to 150c for an additional hour. Mix is allowed to stir and cool until it has reached room temp. 5.6g safrole is collected then 92 grams of iso are collected at 75-80c.

So what is the reson for runnning this any longer? Other than making your glass a pain in the ass to clean and higher trans conversion? So is this just a personal preference thing or doe snobody even really care as long as it works?
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[SPISSHAK]

Would result if you epoxidized the trans isomer you alluded to (syn stereochemistry i guess?) then pinacol rearrrangement w/H2SO4?
Would the ketone yeild a racemic product?

[Osmium]

> Anyway, He has an updated isomeriztion which makes him wonder why most people run them so long ad under vacuum the entire time?

What makes you so sure that the way you do it results in a high conversion? Your 'iso' could be 50% safrol and you wouldn't realise it.

> ad under vacuum the entire time?

You don't have to do that
.
> Besides if you just use STRIKE's method of conversion on your
> pure iso just before using it then you have almost all trans.

Huh???

> 1.5g ball milled koh,

Oh really?! And how do you handle your superfine, ball-milled KOH? I suppose it's powdery, isn't it?
I'm not fat just horizontally disproportionate.

[sYnThOmAtIc]

The idea was to make a powder. But the two seconds it hit the aptmosphere it turned into little granules. Not really worth the trouble a mortar and pestle does the jod jsut as wel since it will stil stick together once it gets around the slightest moisture.

How would the safrole not be released? There is a very distinct start and stop in the distillation. It is heated and safroel is distilled out at 55-60c and then it is heated to 65c till it ceases to come over for several mnutes. Then at about twenty degrees higher it begins to distill again?

Please explain how it could reatin safrole as I was unaware of that possiility. Especially since I understood that it has a sharp enogh difference in temps to be effectively separated. As this may be someting of interest to my friend.

 Eitherway he will find out once he electroizes it

Oh and strike mentioned that heating the cis to 160 or somethign I don't remember the exact temp for six hours would conver the cis to the trans isomer. It was a while ago when my frend had a ketone hook and we didn't care baout that shit so it kina got disregarded though i am under the impression it is detailed in his book tsII but I don't ahve it maybe someone who does your post the exerpt for that procedure.
Yes, That pic really is me!

[ChambeRed]

In tsII strike says that it might possibly rearrange if heated to 160c for a couple hours,might help,can't hurt,why not.
Bee's don't die,we just multiply.

[Rhodium]

The cis/trans isosafroles will react just the same, there is nothing wrong with either isomer, regardless of what Strike wrote in TSII.

[placebo]

Synth, belt up buddy! You post a thread asking for help and then have every reputable bee in the place post in your thread offering assistance, and you argue with every one of them. Do you want their help or not. Sometimes you can't question why because the answers are above your comprehension, or more then likely, a bee is trying to help you, they are going out of their way to spend the time to reply to you. Sometimes they can't be bothered (I know I can't) typing an answer as well as a detailed essay of why the answer is valid. In this case the question is redundant as there is more then enough info on Rhodium's page and in the search engine to explain it all.
I think the elder-bees have been more then patient with your attitude. I would have locked your thread after your intitial post.

Call me a cunt, but my hard-earned dollars could be better spent on bandwidth that wasn't so wasteful!
Now stop being a prick, look how much you made me type!!!

[sYnThOmAtIc]

But I have never seen here anyting discussing 50% safrole being retained just because? I did not argue with anybody. Goiter joe tried to ensure a good separation but is not nessecary my friend has tested his pump extensively and the bp only changes by 3c with the ballast in. But it really doesn't matter since the only other fraction is 75c higher! I wasnt arguing with him I was just stating that I knew of what doing that means and could do that to the product without contamination. Every ballast is different and I know what he was trying to tell me but I am aware of that.

The main reason for the post was why lower temp reactions ensuring less to no tar build up under vacuum or not are run overnight or longer. And by reading here for the last year have concluded that it is to ensure high trans conversion and high yields. And even in the document at rhodiums and everywhere else state that they are both as good as the other for reacting to the ketone. So why run a reaction for 12 @ 150-160 making alot ot tar and a catalyst that cant be reused with good results when you can make a ceaner reusable catalyst at 100c for 3.5 hrs? The overall procedure is redundant but it is a slight step up.

Man everytime you come out of the wood work you waste your precious time with the lamest posts. For one it wasn't my reaction it was a friends and I couldn't be sure of what he was observing. If osmium says 50% can be reatained and I ask him to pelase explain so that this may be checked before he reacts it how is that fending of help? I simply asked him for more info. He is the one who has an attitude toward me about he ball milled koh getting sarcastic abouts it being powdery. Since the finer it is cruched the better the more area of teh product will come in contact with the oil since it is suspended. 

And btw pre and post distilled suspect iso were froze in the freezer. The undistilled iso had a little oil that did not freeze about 5ml when inverted and poured off. The distilled froze solid and never gave off any un frozen liquid. So aparently no safrole is still in the iso mix. Which makes me even more curious to osmiums statemnt. Azeptropes only form when distilling? right? So what other temporary or permanant bond can be made between two isomers that can cause this to happen?  If its over my head then by all means please explain then I will be that much more educated and aware of similar problems with other reactions or or whatever.
Yes, That pic really is me!