[tallec01]

I am currently trying to perform a Hydroboration, at scale (300gal) using 9-BBN on a di-allylated raw material. Unfortunately, there seems to be some unpredictability with the level conversion I am getting. Out of 5 batches, only 3 have converted to 100%. One did not convert at all, the other only 30%. Can anyone speak from experience
as to the sensitivity or unpredictable nature of hydroborations using 9-BBN. I am aware of the sensitivity to water of the 9-BBN, thus we have been performing a Karl Fischer to ensure we have plenty of excess reactant before beginning the addition, trying to even stay below 500ppm water. We are using inhibitor free THF as the solvent, and  also running under a nitrogen sparge. How sensitive are these systems to the inert-ness/oxygen available? Any other thoughts?

[discodermolide]

I am currently trying to perform a Hydroboration, at scale (300gal) using 9-BBN on a di-allylated raw material. Unfortunately, there seems to be some unpredictability with the level conversion I am getting. Out of 5 batches, only 3 have converted to 100%. One did not convert at all, the other only 30%. Can anyone speak from experience
as to the sensitivity or unpredictable nature of hydroborations using 9-BBN. I am aware of the sensitivity to water of the 9-BBN, thus we have been performing a Karl Fischer to ensure we have plenty of excess reactant before beginning the addition, trying to even stay below 500ppm water. We are using inhibitor free THF as the solvent, and  also running under a nitrogen sparge. How sensitive are these systems to the inert-ness/oxygen available? Any other thoughts?

What about the quality of your 9-BBN?
I have often had quality problems with such boron reagents on scale, Bu2BOTf for example and 9-BBN.
Your variability may suggest reagent quality problems.

[tallec01]

This is a great suggestion. Only one way to find out. Bring the cylinders and and try a lab batch.

Thanks

[discodermolide]

This is a great suggestion. Only one way to find out. Bring the cylinders and and try a lab batch.

Thanks

You doing this under GMP conditions?

[tallec01]

What would be considered GMP in this situation?

[discodermolide]

What would be considered GMP in this situation?

Well are you proceeding towards an API or further? Or is this reaction product going to be used for an industrial purpose?