Author Topic: p-benzoquinone MM ways (Read 123 times)

newbiechem · « **on:** August 23, 2011, 06:56:05 PM »

hello,
on Drool´s work he had used the p-benzoquinone in methanol, and said to have problems, after extracting and all; then satureted nacl wash, seemed to have lots of emulsion, mentioned it had to be freezed to broken up.
well could this had happened because of methanol instead of DMF ? or because of hard shaking and not dh2o on wash? also heard spice say that MM p-benzoquinone makes a real mess!
also Drool mentioned that no heat was added to reaction only started and got kicked in, is this a exothermic reaction?
is MM and Drool work up on methanol p-benzoquine reliable?
could anybody clear this up? main difference on the reaction using methanol or DMF, im aware of the loss in yield.
also filtering the solution by gravity doesnt seem like an eternity?
well thanks for clrearyfing this up for me and sorry about my rusty english
Peace

lugh · « **Reply #1 on:** August 23, 2011, 10:46:15 PM »

According to a very old post from the Hive, naptha works very well for isolating the ketone from a MM wacker

It's very important to do the washes as specified

Maybe Methyl Man can help further

newbiechem · « **Reply #2 on:** August 24, 2011, 03:12:11 AM »

thanks

so nafta will reduce the chance of emulsions?.....not very easy where i live, could be found at lighter fluid? they still make it with nafta? will have to destill right?
after flooding with 10% hcl, extract with nafta should give me good results?
i know benzo can be scaled up, scaling down should also be fine huh
maybe
1gr- pdcl2
500ml- meoh
150ml- dh2o (too much water?)
100gr- olefin and 40ml meoh
60gr- P-benzoquinone

would scale above work?
where i live can get only IPA, MEOH, some DCM (from acrylic glue) but no toluene, xilene even acetone hehe
heard sassa had good results extracting ketone with DCM.

well thanks alot!
peace

RoidRage · « **Reply #3 on:** August 24, 2011, 07:42:03 PM »

Never had too much problem with toluene and DCM with emulsions. What is critical is to filter the post-reaction mixture perfectly. Gravity is much much better than pressure filtration in my experience.

As for scaling down, why had more water ? Just stick to the original reagents amount listed in the synthesis. That's what I always used and I always get 65-70% yield.

newbiechem · « **Reply #4 on:** August 24, 2011, 08:31:02 PM »

thank you!
so better stick with 50ml dh2o.... (i found 150ml dh2o from sassa work up on the "scaling up benzo" thread) which wasnt modified no matter the scale of olefin etc...
well scaling down this way since pdcl2 is extremely expensive here....
rather make 1gr pdcl2 to make sure its done right, so can be scale up....
also cutted the p-benzo a lil bit to help work up, you think should stick with 75gr instead 60gr?
so pretty much cutted in half the amount of reagents, so wont lose precious pdcl2 *

would you recomend do more than 1 filtration?

also since its been scaled down aditional heat should be added? read on a topic here (cant remember) that should become more exotermic scaling up and less exotermic scaling down, so i wonder if extra heat needed for the reflux....or its a matter of observation on the reflux. drool said he didnt added any heat when followed the MM paper. meoh being used not DMF.

really thankful for the help
peace

RoidRage · « **Reply #5 on:** August 25, 2011, 12:36:41 AM »

I would just stick with 50ml personally. Maybe sassa can clarify why he uses more ?

As for benzoquinone quantity, I've read the amount used by MM isn't optimized. I normally use the same as he do, but I'm using impure green/black benzoquinone (which contains a certain proportion of a quinhydrone complex). I would use less with pure yellow quinone. If you have pure stuff, I'm pretty sure you can use 60g instead of 75g without any reduction in yield. There are more info on that in another thread related to this subject somewhere.

I only gravity filter it once after putting the mixture in the freezer beforehand for a couple hours. I never had any problems with emulsions during washes/extractions when done perfectly. That's when using toluene (I don't remember how it went when using DCM...It's more emulsion-prone if I remember correctly).

Just heat it to a slow reflux and you're fine. It won't reflux on it's own for sure. It doesn't either using the ''MM scale''. I always need to add some external heat to get the mixture refluxing. NeilPatrickHarris says he's been told it's reflux on it's own at bigger scale. External heat probably isn't even needed since the reaction his ran for 8 hours. I reflux it for 6.5 hours and still get the same yield. The reaction time probably can be shortened a lot considering the paper attached says the reaction at 1/10 MM scale runs to completion in 3 hours!

newbiechem · « **Reply #6 on:** August 25, 2011, 01:30:46 AM »

that clear much things up....
worth pre stirring pdcl2 benzo more than 6 hrs?
believe the little details can make big diference how everything goes.
but if done right i believe its not so "messy"...

thank you very much!!!

RoidRage · « **Reply #7 on:** August 25, 2011, 02:50:31 AM »

Never bothered stirring it more than 1-1.5 hours so I can't tell you if it really makes a difference or not. Maybe others can shed some light on this.

Sedit · « **Reply #8 on:** August 25, 2011, 03:27:55 PM »

This is a general chemistry topic where I am going to move it to not a drug synthesis and extraction question.

newbiechem · « **Reply #9 on:** August 25, 2011, 08:39:31 PM »

sorry sedit....
i will pay more attention next time!

Author Topic: p-benzoquinone MM ways (Read 123 times)

newbiechem

p-benzoquinone MM ways

lugh

Re: p-benzoquinone MM ways

newbiechem

Re: p-benzoquinone MM ways

RoidRage

Re: p-benzoquinone MM ways

newbiechem

Re: p-benzoquinone MM ways

RoidRage

Re: p-benzoquinone MM ways

newbiechem

Re: p-benzoquinone MM ways

RoidRage

Re: p-benzoquinone MM ways

Sedit

Re: p-benzoquinone MM ways

newbiechem

Re: p-benzoquinone MM ways