Author Topic: Calcium GHB problems!  (Read 1698 times)

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Dextrose

  • Guest
Calcium GHB problems!
« on: July 23, 2003, 11:53:00 AM »
SWIM gave the CaGHB synth, from Rh's GHB-FAQ, a shot yesterday, but ran into problems.

The synthesis was scaled up to 200 ml. GBL (from the original 160 ml. in the FAQ).

88.8 gr. Calcium Hydroxide was suspended in 250 ml. water, in a 500 ml. Erlenmeyer.
10 ml. GBL was added, with vigoriously stirring...
10 more ml. was added, the temperature didn't rise, so the rest was added in one portion.

The mixture got slightly exothermic, a thermometer was put in (45 celcius), and it was allowed to stir for 30 minutes.

After 30 minutes, temperature was raised to ~60 celcius, and allowed to stir for another 30 minutes.

The mixture was still not clear, so it was refluxed (which happened at 105-110 celcius) for another hour.

Still a white pudding - what to do? Think, think...  :o

The GBL was prepared from BDO, using the Copper Chromite catalyst, and was pretty water-white - but earlier trials using NaOH, yielded an overbasified, and slightly (yellow) discolored product - SWIM better practice his destilling techniques, and take a look at Foxy's GBL cleanup.

With this in mind, SWIM concluded that the pudding consisted of a super-saturated CaGHB-solution, excess CaOH and probably also melted CaGHB.

The Buchner was set up, and SWIM tried to filter the hot solution, sloooowly yielding slightly yellow water. (This was somewhat a good sign to SWIM), but the filter soon choked in the CaOH that was settling at the bottom.

More water (100 ml.) was added to the Buchner to try to thin the solution, but it soon choked again.

TFSE gave absolutely no results about the Calcium-salt! (Anyone actually dreamed about this one?)

The pudding was poured back in the Erlenmeyer, and put aside along with the filtration...

SWIM has had many NaGHB dreams, causing the "creative" improvation - he sure doesn't hope he has completely fucked this one up.  :-[

How to safe this mess?

SWIM's idea, is to take small portions of the pudding, thin it with enough water to dissolve the (proposed) CaGHB, pour in sep. funnel, and wait for the only slightly water-soluble CaOH to settle to the bottom, then drain it and discard it.

Repeat this, and filter the combined solutions in the Buchner, neutralize the PH with HCl, then evap the water and recrystallize using alcohol and acetone...

Any bee's care to comment on this one?

(And yes, i know - stick to the fucking established routes!  :P )


methyl_ethyl

  • Guest
I am glad you added that
« Reply #1 on: July 23, 2003, 04:32:00 PM »
(And yes, i know - stick to the fucking established routes! )

     I am glad you added that because I was ready to flame your ass, for trying to scale up before actually running the reaction as per rhodi's site.  Why can't people just run the reaction as written, at least for the first run, if you are successful, then you can start thinking about the scaleup. IMHO. 
    
     good luck,

     methyl_ethyl


Rhodium

  • Guest
Saving the day...
« Reply #2 on: July 27, 2003, 04:11:00 AM »
To me it seems like you did not use pure GBL, but rather a mixture of that and 1,4-BD, therefore it did not all react with the calcium hydroxide...

You must dilute it a little with methanol so that you can filter it through Celite (diatomaceous earth, UTFSE), and then use the acetone dilution method found in my FAQ (also read the original patent,

Patent US4393236

) to isolate the salt.

Next time, be better prepared.