posted 08-01-99 03:27 AM         

Rather than using a nitrite ester, what about a nitrite salt? Sodium, potassium, or ammonium nitrite all have seemingl the same reducing potential as thier esterified counterpart, or do they?

So would this work, or is there some wierd orbital overlap (or lack of wierd overlap) that would keep this reeaction from proceeding? There are examples galore of nitrite species present without adverse affects on palladium-catalyzed oxidations, but is the electron withdrawing presence of an alkyl group attached to the nitrite really needed to get it to do what we want?

Likewise, what about sulfur-based oxidizing reagents, like something as simple as sulfate salts? Unfortunately, my CRC handbook isn't nearby, but it seems that the redox potentials for many of these compounds are within reason for them to be looked at as potential oxidizing reagents with the Wacker.

The beauty of these methods is that they could combine affordability that pressurized O2 offers, with the convenience of a homogeneous system that more expensive reagets such as benzoquinone have. Theoretically, by judicious use of PTC's, any solubility issues could be taken care of.

So what do people think?

posted 08-02-99 01:04 AM         

Maybee it's a job for that guy in the black tights.

'the curtains dissolve, as the last remnents of sanity has been lazily scraped from the cold wooden stage floor, as the crowed settles into it's seats.
Into the bowl, the masked man places 100ml of his olefinic com-par-dree, along with 120 g of sodium's favourite nitrite, and 300ml IPA just for good measure, the parsleys this time was purposly left out, but not so for the unlucky black pepper of pipperonis.
It boiled like a pot on the stove for three hours, the masked man checked the pot once every five minutes, to find that, mistakingly he was watching the wrong pot.
All was well though,.
Off he then took the saucepot lid, to let this now quiet muther fucker, evap to dryness, upon which he was left with 44g of a white oily chicken fat looking substance, which was washed with toluene, not just to clean it, but as to ensure freshness,
Which eventually gave the quite happy Black tight scoundrel 35g of pure extacy,.

He believed it was extacy, as he had a predisposition to psyco-somatic symptoms,

hell, for a days work, he was more than pissed

posted 08-02-99 08:02 PM         

Actually, it is that easy; for PdCl2, the solibility partitiion greatly favors DCM over H2O. For more solvent choices, look under some of the more recent titles covering precious metal recovery: this is increasingly the choice of industry.

posted 08-05-99 06:17 PM         

This is exactly what I wanted to discuss. To be honest, I can't say with certainty that it would work, but that's why I started this thread. I'd be very interested in hearing why EXACTLY you feel that nitrites wouldn't work without low pH's. Do you have any good information sources backing you on this?

posted 08-06-99 04:50 AM         

JOC 1990, 55, 2924-27

A benzo-Wacker with added acids, like HClO4, HBF4, HNO3. Solvent aq. MeCN, yields >90%, finished in 10mins. 50 times faster than a comparable Wacker without added acids. So acids are indeed compatible with the wacker, at least with this one. They even speed it up! Only ten minutes to completion! Do it in a tubular reactor, and you have a continuous process for ketone production.

posted 08-06-99 06:15 AM         

Wow! I suppose the acids do a nice job homogeneously regenerating the oxidized Pd species (Pd being the "least noble" of the precious metals, it doesn't hesitate to react with HNO3, or even HCl in the right conditions.)

posted 08-07-99 01:19 PM         

How would you suggest engineering this into process?