Author Topic: isomerizing attempts and questions...!  (Read 4405 times)

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hCiLdOdUeDn

  • Guest
isomerizing attempts and questions...!
« on: November 22, 2002, 05:39:00 PM »
Procedure(from Rhodiums site)=100 grams of safrole was placed in a 250 ml RB flask fitted with a water-cooled Allihn reflux condenser, and was heated with good stirring. When the solution started to boil, 1 gram of KOH pellets was added through the condenser, and the safrole immediately took on a brown color. Next, 15 grams of CaO was also added through the condenser, and the solution was allowed to reflux for 15 minutes, and the heat was turned off, and the solution was poured into a beaker and was allowed to cool. The dark brown suspension was vacuum filtered through a pad of celite, and the filter cake was washed with 2x50 ml of CH2Cl2. The CH2Cl2 was removed through distillation at atmospherical pressure, and unreacted safrole was also distilled off at 240°C (bath temperature), and amounted to about 1 ml. The residue was distilled at aspirator vacuum (~25 mmHg), and the isosafrole came over at 120-130°C as a water-white oil, weighing 70 grams (70%).


Experimental:
135grams of distilled safrole was added to a 500mL RB flask attached to a condensor, on a peanut-oil bath and heated until the safrole started to boil at approx ~240C. Then 1.5g of KOH flakes were added. Then 15grams of CaO was added to the safrole and was let to reflux for 15minutes. (just as the procedure calls for). There was some H2O in the safrole but it kept on boiling off and condensing and when it hit the hot oil it made a scary "explosion" on the hot oil surface. Anyway it was left to reflux for 15minutes and then the heat was turned off.

The flask was cooled and it was brownish in color and the CaOH2 formed was black with white specks. It was left to settle and the isosafrole/safrole was poured off. The residue was washed with ethanol and saved. The CaOH/KOH residue in the flask was dissolved with HCl.

The resulting liquid came over at 133-135C and was suspected isosafrole but my H2O boils over at 33C under vacuum leading me to believe that this was just safrole. Under my vacuum isosafrole is supposedly to come over at 150C. I got nothing to come over at that temp.

In the procedure it said their isosafrole came over at 120-130C  @25mm HG. From Chromics distillation safrole html, it would mean that isosafrole would come over at 140C under 25mmHG. Was the procedure true? That looks like safrole and not isosafrole.

---------------------------------------------------

Is there any tests i can do to see if this truely is isosafrole?? Or any other way to purify isosafrole by freezing?

Thanks!
 

Sink or SWIM

abacus

  • Guest
What was the safole bp?
« Reply #1 on: November 22, 2002, 05:53:00 PM »
At around 20mmHg using an asiprator vacuum, I get safrole to distill at around 115-120DegC.  After isomerisation is complete, the liquid comes over at 130-145DegC using same pump and vacuum.

So I know its isosafrole and then proceed with next step without any concerns.  

So isn't the easiest thing to do, find out what your safrole distills over at using the same pump and compare.

Abacus

GOD

  • Guest
swim had this problem, combined with a pump that ...
« Reply #2 on: November 22, 2002, 06:00:00 PM »
swim had this problem, combined with a pump that was too strong.  Just do an ATM with a small amount, that way, theres no questions.  Real fast and easy- swim just followed goiters advise, he put a bit (5mls or so) in a test tube and just heated a pot of oil over the stove.  Doesnt take long at all, but bee careful if your gonna do it that way, you know- fire tends to make things really hot some times  :P .



Im not the bearded man upstairs, Im a bald guy with a healthy penis. So open yer pie-hole!

hCiLdOdUeDn

  • Guest
Its not just that, the procedures are bugging me!
« Reply #3 on: November 22, 2002, 06:11:00 PM »
Its not just that, the procedures are bugging me! What is correct Chromics BP chart or the procedure??

Yeah ill try the atmospheric GOD,

thanks

Sink or SWIM


abacus

  • Guest
what?
« Reply #5 on: November 22, 2002, 10:20:00 PM »
What do you mean the procedures are bugging you? surely you don't give a crap about the procedures, its the RESULT of having isosafrole that is important.

Also, if you want to know a very easy iso procedure with no hassles search my posts for an answer.  This reaction is so foolproof its funny.

Abacus

Protium

  • Guest
Distillations under vacuum
« Reply #6 on: November 22, 2002, 10:39:00 PM »
Many here are confused about the boiling points of substances distilled under vacuum.  The confusion is caused by the following factors:

Methodical:

Inaccurate vacuum gauges

Improper thermometer readings

Vacuum leakage

Mathematical:

Differing elevation above sea level

The fact that the nomograph to calculate boiling points under vacuum cannot be referenced like a simple ratio, as it is a hyperbolic function, and exponential factors influence the equation.

You will have to determine at what temperature the substance boils using your particular equipment and method at your particular elevation above sea level and then apply this number to the nomograph to devise an equation that reflects accurately the ratio between the reduced pressure boiling point and the recorded atm boiling point.



Pr(+)tium

hCiLdOdUeDn

  • Guest
Nah it wasnt that. The procedure that was on ...
« Reply #7 on: November 23, 2002, 08:57:00 AM »
Nah it wasnt that. The procedure that was on Rhodiums site under isomerization html, for KOH/CaO says that their own isosafrole came over under 25mm Hg @120-130C but at 25mm HG its suppose to come over at 140C. I think that procedure needs clarification.

So far my vacuum measurments are on the dot with water boiling at 33C and safrole coming over at 133-135C. I guess that isomerization failed. I believe i used CaOH2 instead of CaO.

Sink or SWIM

chem_123

  • Guest
the all seeing eye
« Reply #8 on: November 23, 2002, 09:36:00 AM »
SWIM sees two possible issues Cloud-ster:

1. SWIS is using a different type of thermometer which can
   make it's readings different (SWIM's tried an oven
   thermometer - spring type, and a candy thermometer -
   mercury type), and gotten two different readings 10
   degrees apart!)

2. SWIS is reading a different type of oil then the
   original experimentor.

3. there was water in SWIS oil to start with, SWIM's read
   that that'll seriously fuck with things, even though
   SWIS said that it came out during the reflux, SWIM would
   have boiled it off ahead of time...SWIM figures SWIS has
   almost got it, try again. 

* disclaimer, keep in mind, SWIM's never actually done it
  with KOH and CaO, but from what SWIM's read, it should
  bee pretty straight forward...SWIM wishes it had some KOH
  flakes :(  it's bee-n forced to buy large quantities of
  the stuff :(, and SWIM's broke :(

It tastes like burning! :o  :P

hCiLdOdUeDn

  • Guest
I use a digital thermometer accurate to 0.
« Reply #9 on: November 23, 2002, 10:23:00 AM »
I use a digital thermometer accurate to 0.1C and up to 200C. Water boils @1 ATM at 98.9C (i live in a slightly higher altitude) I believe this thermometer is very accurate.

OH well, isomerizations sometimes fail, and its because of the water.. :(

Sink or SWIM

Phemios

  • Guest
errmm...
« Reply #10 on: November 23, 2002, 12:13:00 PM »
If you where at 1 ATM the water would be boiling at 100°C, so your thermometer would be reading 99.9 threw 100.1. But, it's not so your barometric pressure is some where around 31.02 inches of Hg or 1.02 ATM. You can use

http://www.biggreenegg.com/boilingPoint.htm

to calculate the temperature your water should be boiling at based on your barometric pressure.

Sorry for the anal-retentive post, but the statement "Water boils @1 ATM at 98.9C (i live in a slightly higher altitude)" bothers me.

Edit: errmm...2 Of course when I correct some one, I mess up in the math and drop an operator. Those numbers should be 0.96 ATM and 28.82 in of Hg.

hCiLdOdUeDn

  • Guest
The above post is incorrect!
« Reply #11 on: November 23, 2002, 03:15:00 PM »
The above post is incorrect!

For example water boils at 50-70C on some mountains!

I live at an altitude slightly higher than sea-level therefore the atmosphere is slightly less dense where swim lives than at sea-level!

The higher the atmosphere pressure the higher the boiling point, and the lower the pressure the lower the boiling point  (such as under vacuum)

DUH!!! :)

Sink or SWIM

hCiLdOdUeDn

  • Guest
Abacus, SWIM is trying your "easy iso".
« Reply #12 on: November 23, 2002, 03:24:00 PM »
Abacus,

SWIM is trying your "easy iso". Hopefully this will be swims best way of isomerizing if all goes well!

Thanks again, ;D

Sink or SWIM

goiterjoe

  • Guest
if you're having trouble now, rethink this
« Reply #13 on: November 24, 2002, 07:52:00 PM »
Isomerization with KOH/CaO is about the easiest reaction you will perform.  If you're having trouble with this, then you might want to do some more reading.  As far as your boiling point goes, you can't really confirm you have isosafrole or safrole under vacuum if you don't know how much vacuum you are pulling.  Just take a few mls of your questionable liquid and perform a boiling point test at atmospheric pressure to determine what you have. 

If at first you don't succeed, try, try again. Then give up. There's no use being a fool about it.

hCiLdOdUeDn

  • Guest
I did the CaO/KOH and NaOH isomerizations and it ...
« Reply #14 on: November 25, 2002, 01:30:00 PM »
I did the CaO/KOH and NaOH isomerizations and it still comes over at 133C leading me to believe even after these isomerizations its still safrole??? What are the chances that it is stills safrole? I think it was sucessfully isomerized the first time and i will plug it into the oxone rxn to see if it has! :)

Sink or SWIM

dr_ruthenium

  • Guest
SWIDR has done numerous KOH vacuum ...
« Reply #15 on: November 25, 2002, 04:15:00 PM »
SWIDR has done numerous KOH vacuum isomerizations.  Funny thing is, at ATM iso boils from 240-250 C (H2O boils at 100 C, and safrole at 230-234 C).  SWIDR knows that the cis isomer boils somewhat lower than trans and that longer reaction times favor trans formation, but iso never boils >250 C.  WHAT GIVES?  Also, all oxidation attempts have yielded not-ketone which is somewhat less viscous and boils about 10 C more than MDP-2-P should (164 C @25mm HG instead of around 155 C).  This no-ketone does not aminate (all successful dreams dreamt via wacker).  SWIDR would think this is glycol d/t higher BP, but glycol should be MORE viscous, right?!

TRISMUS!!!

GOD

  • Guest
you can also try freezing it for another ...
« Reply #16 on: November 25, 2002, 04:52:00 PM »
you can also try freezing it for another semi-quick test.

Im not the bearded man upstairs, Im a bald guy with a healthy penis. So open yer pie-hole!

goiterjoe

  • Guest
how sure are you of your CaO
« Reply #17 on: November 25, 2002, 11:15:00 PM »
Are you sure you have calcium oxide and not calcium hydroxide?  If this is the case, then you could not be getting enough water out of the reaction.

What reaction are you using to oxidize your supposed iso?

If at first you don't succeed, try, try again. Then give up. There's no use being a fool about it.

dr_ruthenium

  • Guest
Does anyone have thoughts for SWIDR's last post?
« Reply #18 on: November 26, 2002, 06:48:00 AM »
Does anyone have thoughts for SWIDR's last post?  Has anyone never been able to get iso to distill at >250 C?!  Also, The Isomerization of Safrole: A Review on Rhodium's site citing boiling iso at 120-130 @25mm Hg (Isomerization with KOH/CaO) is wrong indeed.  At 25mm Hg the B.P. of trans-iso should be 137.5 C.  (The cis-iso might boil in the upper end of that range though.)

TRISMUS!!!

chem_123

  • Guest
GOD...freezing it?
« Reply #19 on: November 26, 2002, 05:53:00 PM »
and hope it doesn't freeze?

It tastes like burning! :o  :P