Standard Performic. Hypothetical question!

[FriendlyFinger]

Hi there,
When running a standard performic using B-Methylstyrene, after dripping in while keeping the tempreture under 40°C, what would happen say if you deceided to the reflux the mix for an hour or two before hydrolysis?

Would you still end up with Glycol and esters or a different ratio of? What products would end up with?

Thanks,
FF

[Rhodium]

I think over-oxidation with concomitant side chain cleavage may result from running the reaction too hot.

[FriendlyFinger]

Thanks,

The only reason I'm asking is because of the way I keep reading this sentence;

By using a modification of Fujisawa and Deguchi's [2] synthesis of 3,4-methylenedioxybenzyl methyl ketone, the trans-beta-methylstyrene by-product of the previous reaction was also converted to P-2-P. This conversion was accomplished by dropping an acetone/trans-beta-methylstyrene solution into a stirred solution of hydrogen peroxide in formic acid [2,3]. The acidic solution was refluxed and, then, neutralized and extracted with CH2Cl2.. After Evaporating most of the CH2Cl2, the extracted mixture of glycol and glycol esters was stirred stirred and heated in a solution of methanol and dilute sulfuric acid. The resulting solution was neutralized with aqueous base and extracted with CH2Cl2 to yield phenyl-2-propanone (93%). The sequence shown in Fig. 3 was adapted from Fujisawa and Deguchi.

I keep seeing this sentence as being written in sequence. First he says that it was refluxed and extracted. In the next sentence, he refers to the "extracted" glycol and esters being used for hydrolysis. So when he says "acid solution was refluxed", I don't think he's talking about hydrolysis. That's the way I see it. And I think that's the modification he's refering too. Am I reading right?

Thanks,
FF.

[GC_MS]

Keep in mind that scientists sometimes publish misinformation on purpose.

[FriendlyFinger]

Are you sugguesting that I should regard Dal Carsons paragraph as misinformation?

Regards,
FF.

[Rhodium]

As no reflux is performed in the japanese patents he is referring to¹, and the fact that he is a DEA employee², what do you think?³

Trying it out yourself and comparing the results is the only way of knowing if he is full of it or if he has invented something which increases the yield in this reaction (for plain unsubstituted propenylbenzene that is, it will not help when using isosafrole).


[1]

Post 437230

(Rhodium: "Fujisawa/Deguchi original performic oxidation", Methods Discourse)
[2]

Terry Dal Cason, Biography

(http://www.scs.northwestern.edu/pdp/npdp/biographies/index.cfm#forensics)
[3]

Source Criticism of Internet Documents

(http://www.bib.slu.se/kurser/sss-proj/samla/ekallintern.html)

Source Criticism of Printed Documents

(http://www.bib.slu.se/kurser/sss-proj/samla/ekalltry.html)

[Antibody2]

or you could add some DCM after the addition and reflux at 40C

[placebo]

Antibody2,
Are you suggesting that after addition of the performic that a reflux be held at 40c (with mild heating) instead of just letting it run it's own temp during the further ~18 hours stirring?
Is this what you do?
Are yields better?

[Antibody2]

that is exactly what i suggest, i assumed most others were doing this way too, that is the whole beauty of using DCM instead of acetone, it maintains the perfect temp for that rxn. a light reflux is all you want.

There was alot of discussion  on the subject a couple years ago.

[abolt]

it maintains the perfect temp for that rxn. a light reflux is all you want.

AB2, I always assumed that DCM was used to keep the reaction from exceeding 40. Celcius and that temperature increase was an unnecessary side effect of the reaction. Are you saying that a reaction temperature of 40. Celcius is beneficial? In what way is a "light reflux" beneficial?

[RoundBottom]

SWIMs performics were always done without heat, just the heat generated by the exothermic addition of performic acid.  controlling the addition rate controls how vigorous the reflux will be, although if it gets too hot the loss of DCM through the top of the condenser could lead to problems.

[placebo]

AB2,

that is exactly what i suggest, i assumed most others were doing this way too, that is the whole beauty of using DCM instead of acetone, it maintains the perfect temp for that rxn. a light reflux is all you want.

There was alot of discussion  on the subject a couple years ago.

I have been reaading here for about 5 years and have never seen this. Labtop doesn't mention this in the latest/best method for the buffered performic. I respect you and I'm not saying it hasn't been discussed. I may have missed it, could you give post numbers? Actually, fuck that, are you saying that you do this (with heating after addition) and it is good and improves yield?

RB, this is also what I thought most bees did.

[Antibody2]

Just spent 15minutes on TFSE and couldn't find the threads that reference this innovation, but they are there. This variation doesn't belong to Ab2, I'll look more when i have the time.

When Ab2 wants to do things the right way he refluxs the DCM (with a proper condenser DCM loss is not an issue). Don't keep a lab note book anymore, so cannot quote yeilds, but when Ab2 did it thatway the 1st time he was pleased eneough with the results that he continues to do it that way.

[Antibody2]

here is one of the threads that inspired the reflux idea, there were more but for now . . .

Post 208344 (missing)

(Rhodium: "Re: 2,3-DM-4,5-MD-P-2-P", Methods Discourse) (thanks)

[Rhodium]

If you write [208344] instead of [post no 208344], the result will be this:

Post 208344 (missing)

(Rhodium: "Re: 2,3-DM-4,5-MD-P-2-P", Methods Discourse)