Titrating GBL/water

[Chromic]

Okay, in attempts of trying to minimize the solution volume of a 2 mol post GABA rxn to GHB, it was decided to boil it down. (otherwise 2.5L of DCM would be required to extract from the volume)

So 560ml was distilled off.. my question is, how does one determine how much GBL is present there?

My first guess was to titrate with 10% NaOH. Okay, failure... the rxn doesn't happen until the temp heats up, which destroys phenolphthalein.

My next guess was to add excess Na2CO3 (NaOH was avoided as boiling concentrated NaOH might destroy the glass) then boil it down to see what the weight difference is, great, but unfortunately Na2CO3 forms a crystalline hydrate that makes determining the weight particularly hard. (105.3g beaker, 4.4g stir bar, 4.5g Na2CO3, 15ml distillate containing GBL, refluxed 20mins, distilled to apparent dryness and the beaker weighed 118.0g... impossible! too much GBL, as I know GBL won't distill over in concentrations more than 10%)

Any ideas here?

[Chromic]

Perhaps I should conduct the NaOH rxn at reflux, then just draw out small samples using a capillary tube and test on pH paper? Is there any other easier way people can think of?

[Rhodium]

That last idea sounds like the best possible procedure.

[Chromic]

Are there any water insoluble GHB salts?

[pHarmacist]

Are there any water insoluble GHB salts?

I don't think so, for instance, even Pb(II)acetate is soluble in water. So even if you made a toxic lead II salt out of GHB it would probably bee soluble in water. Of course, GHB has 2 C longer chain in contrast to acetate, but it also has the terminal -OH function that is strongly hydrophilic and thus contributes to more solubility in water...