The Vespiary

The Hive => Methods Discourse => Topic started by: SPISSHAK on July 03, 2002, 01:33:00 AM

Title: O2 wacker (alkyl aryl ether isomerization?)
Post by: SPISSHAK on July 03, 2002, 01:33:00 AM

I don't know if this is true but some info was relayed pertaining to wacker oxidations.
Something like isomerization of methylenedioxy ether to the  2,3 positional isomer being the main problem with getting a wacker oxidation to work.
Does this really happen?
I did'nt think so, but some input from some of you more educated bee's would be appreciated.

Title: No, the problem is that the alkene is isomerized.
Post by: Osmium on July 03, 2002, 01:37:00 AM

No, the problem is that the alkene is isomerized.

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I'm not fat just horizontally disproportionate.

Title: Yeah it sounded like B.S.
Post by: SPISSHAK on July 03, 2002, 01:48:00 AM

Yeah it sounded untrue  to me, never hurts to ask though.

Title: To Osmium
Post by: PrimoPyro on July 03, 2002, 05:19:00 AM

What is the product of the Wacker-oxygenated phenylpropene? Is it the propiophenone instead of the phenylacetone?

Title: From what i've read
Post by: SPISSHAK on July 03, 2002, 06:16:00 AM

And this was verified via NMR, that a typical wacker is 85%
Phenylpropanone, %15 phenylpropylaldehyde.
No propiophenone is formed although isosafrole is a by-product.
You can add inhibitors (free radical i think not sure though) like hydroquinone to prevent aldehyde formation, even read that this increases yeilds in alcoholic wackers and reduces temperature sensitivity, it's a patent, have it somewhere.
You know how patents are with thier inflated sometimes bogus claims though.

Title: Using Pd(NH3) 4 Cl 2 will inhibit the ...
Post by: lab_bitch on July 09, 2002, 08:20:00 AM

Using Pd(NH3)₄Cl₂ will inhibit the isomerization.  Alkyl nitrites also inhibit the isomerization, as hardly no isosafrole is produced by a nitrite wacker.