I just can't seem to get this to work well. I can lower titration to a target (say from 10 to around 3g/L), using 55% methanol and DKenny's .2 formula for the H2SO4.

I have tried settling (in a beaker, I can't tell that any separation has occurred when using 55% methanol in the acid stage) and tried NOT settling before the base stages. The base stages have failed all three times I've tried them.

In another thread (see my first "Basic Questions" thread) I posted more detail, but I think that I'm either starved for methanol in the base stage (45% of the total), or water is killing the reaction, or both.

Question 1: if I lower the amount of methanol used in the acid stage, will separation be more likely/apparent? What is a good minimum amount of methanol to try in the acid stage?

2. Has anyone tried improving this separation with high-voltage-low-current? Any luck?

3. I'm wondering if I could have my cake and eat it, too: has anyone tried prewashing after the acid stage with glycerine from a non-water-wash batch, to suck out water, neutralize remaining FFA, etc.?

Puzzled,

I would use 40% of your methanol for the acid stage and 60% for the base stage.
DD

quote:

Originally posted by greiswig:
I just can't seem to get this to work well. I can lower titration to a target (say from 10 to around 3g/L), using 55% methanol and DKenny's .2 formula for the H2SO4.



Question 1: if I lower the amount of methanol used in the acid stage, will separation be more likely/apparent? What is a good minimum amount of methanol to try in the acid stage?


3. I'm wondering if I could have my cake and eat it, too: has anyone tried prewashing after the acid stage with glycerine from a non-water-wash batch, to suck out water, neutralize remaining FFA, etc.?
Puzzled,

Yes, I'm trying this right now, but to remove water rather than neutralize anything. I assume it'll force separation of water that normally wouldn't separate for any other reason. I'll report back on what I find- I think it'll be a huge help in esterification work. There are several really big drawbacks.

If it's undesirable to neutralize FFA (like you want to use glycerine to force separation but don't want to have alkaline stuff in there) you can probably also use non-alkaline glycerine. More info to follow.

quote:

Originally posted by girl mark:
If it's undesirable to neutralize FFA (like you want to use glycerine to force separation but don't want to have alkaline stuff in there) you can probably also use non-alkaline glycerine. More info to follow.

Thanks, gm... I'm not following something here, though: why would it not be desirable to have the base catalyst in this stage? It seems to me that since this is the step that immediately precedes the base stage, there's no harm done, and you could potentially reduce the amount of base you need for neutralization. What am I missing?

I"m thinking that there are times you want to force separation of 'water/acid' so as to get a second acid stage in. That's the situation where it would be bad to use caustic. you can deal with that using my second-favorite solvent, neutralized glycerine that's been dried a bit (neutralized glycerine, with no soap in it, seems to be super high in water).

That's not the problem you're having though, sorry if I misled you.

quote:

That's not the problem you're having though, sorry if I misled you.

No worries at all...I just needed some clarity. Thanks mucho!