Some quick notes on the preparation of lead(IV)-acetate

Lead(IV)-acetate is a useful oxidant in both inorganic and organic chemistry, me being interested in it to use in a Kochi-Decarboxylation in particular to make iodocubane (I‘ve actually already done this reaction and it worked beautifully, once I have the NMR I‘ll post its preparation in my cubane thread).

It’s preparation is achieved by simple reaction of lead(II,IV)-oxide with glacial acetic acid with acetic anhydride added to react with the water produced to prevent hydrolysis of the acetate (https://onlinelibrary.wiley.com/doi/10.1002/9780470132326.ch...).

(Only work with lead if you have a proper way to dispose of heavy metal waste)
A 250 ml wide-neck erlenmeyer flask, containing a 3,5 cm cylindrical stirbar and an internal thermometer, was charged with 108 g of glacial acetic acid and 36 g of acetic anhydride (353 mmol). With good stirring 60 g of lead(II,IV)-oxide (87,5 mmol) (Note 1) were added in spatulas gradually at a rate so the powder doesn’t cake up, and the resulting orange suspension warmed on the hotplate to a temperature of 60 °C (Note 2) until all the orange color had disappeared, taking a couple minutes, resulting in a pinkish suspension of the product. Things were left to cool over night (Note 3), collected by vacuum filtration on a 10 cm Büchner funnel, washed with some glacial acetic acid and a little bit of n-pentane (Note 4), and finally dried under vacuum. From this 25,3 g (62,5% yield, 77,3% lit.) of light pink needles were collected, quickly turning a brown color on exposure to humid air, and are therefore stored under argon.

Note 1: It seems logical to assume that using lead(IV)-oxide directly should equally work in this preparation, however when attempting this the mixture had to be heated to 100 °C for a couple of days to achieve completion of the reaction resulting in a gel like precipitate which was impossible to filter.
Note 2: In the procedure the heating is described as optional as the addition is described to already be exothermic, I however never noticed an increase of more than 5 °C.
Note 3: When things were filtered just shortly after reaching room temperature the precipitate partly had a gel-like consistency, causing the filtration to be a lot slower and a whole lot more annoying.
Note 4: By passing chlorine through the mother liquors the byproduct lead(II)-acetate could be oxidized to more lead(IV)-acetate, as I got more then sufficient material for my immediate applications and it’s best prepared fresh to avoid hydrolysis I didn’t bother doing that though.


Fig.1: Suspension of the lead(II,IV)-oxide


Fig.2: The collected product