pickler (Greenhorn)
03-05-02 07:36
No 277202
      vacuum refluxing  Bookmark   

Swim's vacuum pump boils safrole at 70-72c. So swim wants to do a vacuum reflux to convert safrole to iso. Now in the write up on Rhodium's page, the safrole isomeraton says at 125c to vacuum reflux it overnight. Swim knows since the reflux temp is lower that the reaction will go longer, but how much longer? Any ideas on time for a reflux at that low of a temp?

We'll soon FIND OUT if I'm a chemist or not!
 
 
 
 
    hest
(Hive Bee)
03-05-02 11:50
No 277299
      Re: vacuum refluxing  Bookmark   

Usual 10C gives a factor 2
So 125-70=55 55/10 ~ 5
2^5=32
32*overnight = 16 dayes (give or take
)
 
 
 
 
    pickler
(Greenhorn)
03-05-02 13:44
No 277346
      Re: vacuum refluxing  Bookmark   

Your kidding right.

We'll soon FIND OUT if I'm a chemist or not!
 
 
 
 
    Chromic
(Hive Addict)
03-06-02 07:01
No 277839
      Re: vacuum refluxing  Bookmark   

No, and furthermore, Hest assumes that there is a great enough activation energy at 125C to have this reaction happen at all. You should reflux it at a higher temp. Why not boil safrole and 1.5wt% KOH with no vacuum until the temperature of the vapour hits 254C? It works well and with the monitoring, you're able to stop the rxn as soon as it is finished as to not "overcook" the safrole.
 
 
 
 
    pickler
(Greenhorn)
03-06-02 07:15
No 277853
      Re: vacuum refluxing  Bookmark   

Hydro, swim has a ritchie yellowjacket pump used for hvac. 6cfm. Swim couldn't believe it at first. But sure enough it does.

We'll soon FIND OUT if I'm a chemist or not!
 
 
 
 
    goiterjoe
(Hive Addict)
03-06-02 07:16
No 277854
      Re: vacuum refluxing  Bookmark   

pickler, SWIM has been in your same situation before, and will attest to it being able to work in 18 hours.  Be sure to grease you joints and seal them really well, and proceed to reflux for a period of 18 hours @ 75C.  After about 8 hours, you can turn your vacuum off and let it hold it's vacuum.  The gradual leak down will allow you to hit temperatures around 100-110C after about 4 hours. 

If Pacman had influenced us, we'd run around dark rooms eating pills and listen to repetitive music
 
 
 
 
    RoundBottom
(Hive Bee)
03-06-02 13:34
No 277992
      Re: vacuum refluxing  Bookmark   

SWIM has sucessfully ISOd 2400mL saf using a vacuum for only the first hour, then removing the vacuum and then continuing at ~160C for another 20h.  recovered a stunning 2370mL between 142C-146C.

i learned a thing or two from charlie dontcha know.
 
 
 
 
    pickler
(Greenhorn)
03-06-02 13:53
No 277998
      Re: vacuum refluxing  Bookmark   

nice.shocked

We'll soon FIND OUT if I'm a chemist or not!
 
 
 
 
    LaBTop
(Daddy)
03-06-02 14:39
No 278015
      Re: vacuum refluxing  Bookmark   

Roundbottom, how much KOH did you use there, what grade, and did you have an extensive amount of tar left or not, when distilling the blackish raw Isosafrole?
That's the highest yield of Saf to Iso I saw mentioned till now! LT/

WISDOMwillWIN
 
 
 
 
    Rhodium
(Chief Bee)
03-06-02 18:08
No 278113
      Re: vacuum refluxing  Bookmark   

Roundbottom: 142-6C - at what pressure?
 
 
 
 
    goiterjoe
(Title on BackOrder)
03-06-02 22:33
No 278246
      Re: vacuum refluxing  Bookmark   

I think he means just heating without refluxing.

If Pacman had influenced us, we'd run around dark rooms eating pills and listen to repetitive music
 
 
 
 
    RoundBottom
(Hive Bee)
03-07-02 00:14
No 278285
      Re: vacuum refluxing  Bookmark   

i'm not 100% certain of the vacuum pressure, as my gauge is analog.  it reads about 29.5" maybe a smidgen less (i know i should report it in milimetres, but the gauge doesn't read as well in milimetres, flog me if you must) when the gauge is connected directly to the hose with nothing else attached.

- measured 2400mL of safrole double crystalized from sassy oil (brazillian)
- measured 60g, (guessing 85%) KOH flakes, ground to small chunks (not to a powder)
- put in 5L 2N RBF with a 24/40 - 45/50 adapter and a 6 bulb ahllin condenser in one neck, and a therm and adapter in second neck, seated in a 5L aluminum heating mantle

- mag stirring was very difficult to get started w/ 1" egg stirrer so switched to 2" octagonal stirrer which worked a bit better
- outlet adapter was put in top of condenser, vacuum hose was attached to nipple
- heating was turned on to 26 (out of 100)
- left vacuum on for 30m (sorry, didn't consult notes in above post)

Time Temp Heat
+   0m 24C 0/26
+  30m 36C 26 vac off
+ 210m 112C 26/30
+ 300m 144C 30/28
+ 540m 156C 28/27
+ 600m 164C 27 sleep
+ 960m 152C 27
+1290m 151C 27/0


- liquid was very dark brown and almost opaque
- set up for vac distillation in the same 5L RBF flask


Time Temp Heat
+   0m 27C 0/30
+ 100m 28C 30/32
+ 120m 28C 32/34
+ 160m 32C 34/36
+ 180m 36C 36/38
+ 210m 42C 38 (added loose tin foil shroud to distillation flask)
+ 212m 138C 38/36 coming over > 1 drop/sec
+ 395m 141C 36/0 replaced receiving flask*, and restarted distillation
+ 570m 144C 38 replaced receiving flask*, and restarted distillation
+ 705m 146C 38 stopped distillation**


* don't ask, SWIM only has a 1L receiving flask, it SWIMs largest 19/22 flask.  owing to breaking SWIMs only 24/40 vac adapter, SWIM must use a 24/40 - 19/22 adapter and a 19/22 vac adapter and, therefore, a 19/22 flask.  SWIM is still awaiting a replacement 24/40 adapter.

** you know you are done when the stir bar no longer spins due to being trapped in the solids

total clear, water white fluid recovered: == 2370mL, 98.7% v/v

the distilling flask had a chunk of brown solids on the bottom, and brown solids splashed on the sides.  when the flask had cooled down a bit, maybe 20m but hadn't cooled off completely, it was easily cleaned with water.  no acetone or other solvent was needed.  SWIM was very impressed by the ease of removal, as ketone distillation tar removal is about as fun as chewing glass.


i learned a thing or two from charlie dontcha know.
 
 
 
 
    RoundBottom
(Hive Bee)
03-07-02 00:21
No 278288
      Re: vacuum refluxing  Bookmark   

now that i think about it, maybe i put the outlet adapter directly on the 24/40 - 45/50 adapter and left the condenser off while vac refluxing.  in fact, i'm certain of this.  the condenser was added after the vac was turned off.

also, a performic has not been performed on this ISO yet.  safrole, with this setup, usually came over somewhere around 110C.

i learned a thing or two from charlie dontcha know.
 
 
 
 
    LaBTop
(Daddy)
03-07-02 03:10
No 278340
      Re: vacuum refluxing  Bookmark   

To be sure that you did not do all that work and are stuck with the same safrole back:

-I-
Please take a dry, clean 1 liter erlenmeyer, put that on a digital scale, add 20C warm distillated water, until your scale shows exactly 1.000 gram, look at the meniscus of the water, and write a thin line with a pen who's ink sticks to glass, around the flask, so that the concave underside of the meniscus is EXACTLY on that line, when the flask is exactly horizontally placed on the scale on a table, and your eyes are at the same height as the meniscus.

Now you have a 1 liter erlenmeyer calibrated as good as can be, to hold nearly exactly 1.000 liter.
You pour out the water, and dry the flask thoroughly, inside and outside, without removing that line.

Then you warm or cool 1.2 liter of your to be expected Isosafrole to 20C.
And fill most of that in the erlenmeyer, untill its meniscus concave underside is exactly on the written thin line. Do NOT leave spilled drops above the meniscus, hanging on the glasswalls, but in case of shaky hands because of drug use or alcohol consumption, remove them with a tissue.

Now you have exactly 1 liter of ?Isosafrole? in there, at a temp of 20C, take care that the glass of the erlenmeyer was ALSO at 20C when you filled it. Do not check the temp NOW with a thermometer, or you remove weight as Isosafrole oil hanging at your thermometer.

Place this now back on your scale.

If it reads 1120 gram then you have at least 97% Isosafrole.
d20=1.120 for Isosafrole.
Density at 20C and at purity 97%.(a mix of cis and trans isosafrole btw, both will rearrange to epoxide and/or diol=glycol with oxone or performic/peracetic methods)

If it reads 1095 gram then you have at least 97% Safrole.(back, nothing happened!)
d20=1.095 for Safrole. Density at 20C and at purity 97%.

If it reads anything inbetween, do the simple math to calculate what % is Safrole and what % is Isosafrole.

Density is gram per cubic centimeter, at 20C.

-II-
You can also use a refractometer, MUCH faster:
n20/D Safrole=1.5370 (at 20C and purity 97%)
n20/D Isosafrole=1.5760 (at 20C and purity 97%)

-III-
And you can fast check the boiling points of both at atmospheric pressure in a test tube, a few ml, heated with a gas flame, and a thermometer inside, untill the fluid boils, hang the thermometer 0.5 cm above the boiling fluid, so you measure the temp of the saturated vapour of the boiling oil!
bp Safrole=232-234C at 1 atm.
bp Isosafrole=254-255C at 1 atm.

-IV-
And you can just aminate and see/hope if it works, the wacko way.

-V-
And you can use TLC to compare to a known sample.

-VI-
And you can use NMR.

-VII-
And you can use a gaschromatograph.

Thank you for your patience reading this, wink. LT/

WISDOMwillWIN
 
 
 
 
    RoundBottom
(Hive Bee)
03-07-02 11:25
No 278475
      Re: vacuum refluxing  Bookmark   

wow, that is some detailed writeup to confirm my writeup!  thank you very much, SWIM will try the weight method today.  should SWIM use a graduated cylinder instead of an erlenmyer?  SWIM has a 250mL.  this would increase the margin of error 4 fold, though.

> And you can just aminate and see/hope if it works, the wacko way

this is the fourth ISO SWIMs done this way.  both performics done on the first three ISOs worked, but with less yield than SWIM was used to with the benzo wack (as is to be expected).  the yields on the previous three were:

94mL saf, 1.6g KOH -> 79mL ISO (bad distil technique lowered yield)
500g saf, 8g KOH -> 478g ISO
1000mL saf, 19.8g KOH -> 954mL ISO

SWIM keeps detailed but non-professional notes (doesn't know what a proper lab report looks like). 

and thx again for detailed response.

i learned a thing or two from charlie dontcha know.
 
 
 
 
    RoundBottom
(Hive Bee)
03-07-02 13:57
No 278547
      Re: vacuum refluxing  Bookmark   

well, SWIM did the first procedure as best SWIM could.  final result, 1000mL of above ISO == 1120.50g.  there was about 0.11g of fluid that wouldn't evaporate from the flask; probably water, not acetone (acetone was user to remove as much excess water as possible).  SWIM was disappointed, as SWIM thought the scale was to read 1200g.  when SWIM checked LTs post again, SWIM was elated. 

SWIM knows of someone who had access to a NMR and is trying to find if it is still available.  if so, a test will be performed.

also of note: man those graduated erlenmyers are inaccurate.  1000mL was slightly above 950mL on the graduations.  granted, it does state +- 5%, but that is about the most accurate data on the flask wink

i learned a thing or two from charlie dontcha know.
 
 
 
 
    Vibrating_Lights
(Hive Bee)
03-08-02 08:53
No 278986
      Re: vacuum refluxing  Bookmark   

Swim does his Iso the same as round bottom.  the initial vaccume cuts down on the tar produced by the reaction by first removing the H2O. Cleaning is a breeze and yeilds are high.
VL_
 
 
 
 
    RoundBottom
(Hive Bee)
03-08-02 11:43
No 279002
      Re: vacuum refluxing  Bookmark   

no luck accessing an NMR.  the window has passed.

VL, did you do the measuring method as per LT?  it really points out the inaccuracies of your glassware's graduations.

i learned a thing or two from charlie dontcha know.
 
 
 
 
    Vibrating_Lights
(Hive Bee)
03-09-02 01:33
No 279385
      Re: vacuum refluxing  Bookmark   

no safrole forrun ever. havn't bothered to check the density.
VL_
 
 
 
 
    wyndowlicker
(Hive Bee)
03-18-02 12:56
No 284409
      Re: vacuum refluxing  Bookmark   

swiw has the 1.5 cfm yellowjacket and If swiw is pulling safrole over at 72c then hes just stupid That cant bee possible.It cant bee!Are you trying to say you get better than perfect vacuum.How those pumps are rated at 15-20 microns.I believe this is bullshit.

I will choke untill I swallow!Who are you to judge or strike me down!
 
 
 
 
    pickler
(Greenhorn)
03-18-02 13:08
No 284416
      Re: vacuum refluxing  Bookmark   

PLease don't try to tell swim what temp his safrole comes over at. Believe swim when he's says 70-72c. Swim really doesn't care what you think.

We'll soon find out if I'm a chemist or not!
 
 
 
 
    wyndowlicker
(Hive Bee)
03-18-02 14:02
No 284443
      Re: vacuum refluxing  Bookmark   

sorry but Swiw doesnt think his does this good.Didnt mean to offend.

I will choke untill I swallow!Who are you to judge or strike me down!
 
 
 
 
    Rhodium
(Chief Bee)
03-18-02 16:04
No 284486
      Re: vacuum refluxing  Bookmark   

What is a micron? Microbar? In that case the temperature is fully reasonable. A perfect vacuum does not exist in real life, and if there was such a thing all liquids would boil below room temperature.
 
 
 
 
    wyndowlicker
(Hive Bee)
03-18-02 16:09
No 284489
      Re: vacuum refluxing  Bookmark   

How if a 15 micron mbarr torr whatever what is the propper terms to use here.It says factory micron rating 15 that makes this pump pull safrole at 114c no better.H20 distills at 24c

I will choke untill I swallow!Who are you to judge or strike me down!
 
 
 
 
    Chromic
(Hive Addict)
03-18-02 16:58
No 284514
      Re: vacuum refluxing  Bookmark   

A vacuum of 15 microns is 15 mtorr is 0.015 torr = 0.015 mmHg, which could easily pull safrole in the 70 degree range, probably even lower... I too doubt he's getting that good of a vacuum without a liquid nitrogen trap and new pump oil, but he's likely getting something close to 15 microns if his sassy is coming over at 70 degrees.
 
 
 
 
    Vibrating_Lights
(Hive Addict)
03-18-02 17:59
No 284550
      Re: vacuum refluxing  Bookmark   

The pump he has does pull safrole at the temps he mentions. With the OEM oil without any special apparatus
VL_
 
 
 
 
    Chromic
(Hive Addict)
06-06-02 19:51
No 318438
      RB: your iso is awesome.  Bookmark   

RB: your iso is awesome. The glycol made from the isosafrole as prepared in your procedure gave a thick slightly yellow glycol (made by peracetic in DCM). After H2SO4 reflux it turned to a light tan brown oil. 200L of the crude ketone in 5mL of sat. sodium metabisulfate filled the test tube with tons of white crystals. Keep up the good work dude, now it's definitely safe to say that everyone can lose the continuous use of a vacuum throughout the KOH isomerization. smile
 
 
 
 
    riobard
(Hive Bee)
06-07-02 13:38
No 318633
      Wyndowlicker, his 6 CFM pump is definitely able ...  Bookmark   

Wyndowlicker, his 6 CFM pump is definitely able to pull that, considering that a 6CFM flowrate is total overkill for his setup.  The things that make inefficient vacuum for the rest of the smaller pumps are less considerable considering such a volumnous flowrate(things like using nonmetallic vac hose or using any hose with a flexible nature, things like waiting for the vacuum to equilibrate forever, etc. etc.).

Pickler, i hope you use cold traps.smile
 
 
 
 
    pickler
(Greenhorn)
06-07-02 15:31
No 318652
      Never used a cold trap riobard, just changed the ...  Bookmark   

Never used a cold trap riobard, just changed the oil a lot. But alas, the pump finally broke and swim had to get a new one.frown

We'll soon find out if I'm a chemist or not!
 
 
 
 
    sYnThOmAtIc
(Hive Addict)
04-29-03 23:28
No 430353
      wyndowlicker your just mean, jsut mean man.  Bookmark   

If you don't know what the fuck your talking about then shut up and quit giving people a hard time(i have(finally) and only speak when I have a question or something to add). You obviously know nothing of these pumps. Their sole purpose is removing water from refridgeration units. These units can be inside outside in florida or alaska. The point is they need to be able to remove water at almost any normal enviromental temp. Do the math wiht the vacuum calculator on rhodiums. Safrole 234c boils now 55c water 100c well you figure it out.

I have the same ritchie (almost) pump but it's 3cfm and rated at 5micron. It refluxes safrole at 50c and distills it at 55c. Iso is collected from 65-80c range.

They only reason you would ever need and dry ice or ln2 encapsualted flasks or traps is to collect someting that is not to be collected. Like water or anythign else below 200c. With the gas ballast open you can save your oils purity. Like I stated in my isomerization thread I unscrewed the ballast after distillation started to get it to flow quickly. And I GOT FUCKING FALMED about it but it doesn't even change the vacuum that much and the separations had already been conducted this was jsut done to isolate the last fraction quicker like raising the bath temp 3c and that little differnece will not distill the resin left over. I have a friend that has a newer ritchie vacuum pump with regular ritchie vacuum oil that boils safrole at 38c. Now that is too low in my opinion 55c-70c is perfect. Though if your distilling liters of goods at a time then you would want the recieving flask in an ice bath to prevent too much evaporation.

Ever heard "Don't knock it till you try it"?

My opinion is these are the best pumps cause their cheap. Fuck em up ohwell. Get another only $200. Go find a robinair on labx that pulls the same vacuum and see what you pay. I've distilled acids and all kinds of nasty shit with mine and it still hasn't affected it. Though I change the oil after doing an acid distillation withthe ballast open. THough I have used the same oil for regualr distillations for months now with no ill affects (yet) some the solvents flushes and sealers used in refridgeration are much harder on gaskets and seals than any sassy derivative so change after every use is not nessecary but is worht not having to buy another pump.

Yes, That pic really is me!