posted 10-27-1999 04:49 PM         

BS's Benzoquinone writeup calls for the combination of 300mL DMF, 50mL H2O, 120g Benzoquinone, 2g PdCl and then 160g (~ml) safrole in 50mL DMF dropwise. It says to use a 500mL Flask. Thus my drama begins.

After I started adding the safrole/DMF, I began to realize that everything wasn't going to fit in my 500ml flask. ie. I had filled up to 500ml and still had ~100mL to go! Fine. Break out the 600mL beaker, but in the middle of transferring the solution I learned that a wingnut on the clamp holding the addition funnle had grown tragically loose. It did a 180 and about 40mL liquid (~30g safrole) was loosed and danced upon the table.

So my questions:

1) Is it normal to have 600mL total solution after all additions?

2) I figure I've lost ~20% of my safrole (I didn't have any extra laying around to replace it). So will my ketone yield decrease by ~20%, or is the relationship more complex?

posted 10-28-1999 08:40 AM         

But keep going ... If I remember ... it should have fit in a 500mL ... Just barely ... but do keep going ... You'll bee fine.

posted 10-28-1999 02:16 PM         

When the reaction mixture was flooded with water, alot of black solid precipitated. I filtered before continuing and washed the cake with a little DCM. The solid was very soluble in 25% NaOH, so I'm assuming it was hydroquinone.

I take it that this isn't normal.

The writeup mentions that hydroquinone is a side product. Does this mean that it is the product of a competing reaction, or the byproduct of the oxidation of safrole?

If it's the former, then that would perhaps indicate that the excess of benzoquinone formed hydroquinone. But my solid was coal black and chemfinder says hydroquinone's gray. Fuck.

Well, we'll see as soon as I summon the energy to distill.

posted 10-29-1999 11:19 AM         

you can't expect to get *pure* hydroquinone, or any thing *pure* out of a chemical reaction ... thats why we take such PURIFICATION steps!

The black crap is polymerized stuff from the xidation... Not to worry! continue!

posted 11-02-1999 10:08 AM         

The organics from the wacker oxidation above were distilled. Under ~24" Hg, DCM came off at < 10C, water came off at ~70C. Water was still coming off and I only had ~30mL of black liquid left in the distilling flask, so I aborted.

How I screwed up:

I thought I'd be cheap and do a mix/decant routine instead of buying a real sep funnel. This was a horrible idea, as I only wound up with 150 mL organics out of ~300 mL DCM added.

Also, I didn't recover any oil prior to the washes. The formation of ~100g black precipitate when I flooded the reaction contents with slightly acidic water made it impossible to see if there was any separation between layers.

Things I will do differently next time:

I will filter the contents of the reaction flask before flooding them with water, to recover some of the PdCl2.

I will add acidic water to a small amount (~1 mL) of the reaction mixture to see if I get the same horrible precipitate. If so, I'll be ready to filter.

I've got a 2L sep funnel on order.

I won't spill 20% of my damn safrole.

--

posted 11-08-1999 03:21 AM         

Would be much obliged if you have any new dreams to share.