KrZ, you said:
> Here is the wacker mechanism;
> R-CH=CH2 + PdCl2 + H2O -----> C(=O)-CH3 + Pd + 2(H+) + 2(Cl-)
> Pd + 2 Cu(2+) + 6 Cl- ------> PdCl2 + 2 (CuCl2)-
This is the mechanism for the real original Wacker procedure, where lower alkenes are oxidised in an all AQUEOUS solution. This reaction is much slower that the one in alcohol.
When the solvent is an alcohol and no water is present something else takes place:
R"-CH=CH2 + PdCl2 + R'-OH -------> R"-C(-OR')2-CH3 + Pd + 2(H+) + 2(Cl-)
The product for anhydrous conditions is R-C(-OR')2-CH3, the so called ketal. Semiketal would be R"-C(-OR')(OH)-CH3, a side product when sub-stoichometrical amounts of water are present.
Note the following similarity:
H---O---H
R'---O---H
Meaning the reaction doesn't mind if it is done in H2O or ROH solvent, it just happens that the latter is much faster. In that 1969 ref they clearly found that increasing amounts of water slow down the reaction considerably.
So, the product of an all-ROH-no-H2O Wacker will be R2-C(O-R')2-CH3. This is quickly hydrolysed in acidic aqueous media. Since the Wacker mix is slightly acidic adding water alone would already work, but everybody uses diluted HCl for that step anyway so the hydrolysis to the ketone is very fast, forming two moles of the alcohol and one mole of the ketone.
I'm not doubting your results, but in my experience no water is needed in that reaction. It worked well without for me. The catalysts recycled well in the alcohol solvent, or with that little water that was preent due to CuCl2.2H2O usage.
The DMF wacker needs water because the DMF can't add across the double bond like water or alcohols can. Haven't thought about it yet but I think that benzoquinone reduction needs some water too, since DMF is dipolar-APROTIC. Besides nobody has posted a DMF Wacker with reduced water yet. Everybody just used the literature numbers for H2O/DMF 1/7 or whatever they are, nobody tried to reduce the water to the bare minimum yet. It might run much faster with reduced water content, or slow water addition during the reaction.
And at least in my corner of the world the tech grade MeOH and IPA I bought were close to reagent grade purity, but I used barreled stuff from a chem supplier (still cheapest grade available) not some OTC source. But I still doubt that they contain 1% water. Purity statements on the label are usually guaranteed minimum purities, don't take them too literally thinking when it says it's 99% the it must be exactly 99% pure. That purity also depends on how it was determined, GC for example can't detect H2O. When I buy tech grade MeOH there will be EtOH in it, along with formaldehyde, acetone, other alcohols etc, making up that missing 1%.