[Penguinone]

Question:Give mechanistic reasoning for the following observations: CH₃  +  excess CH₂O --> [OH- H2O] C(CH2OH)₄
Attempt see below:

NB:I am particularly stuck on getting the last hydroxyl group to work.

Any help will be greatly appreciated.

[Penguinone]

Maybe the last hydroxyl group is made by a crossed Cannizzaro reaction with formaldehyde?

[AlphaScent]

Cannizzaro makes sense, but would not give desired product.  Would give the trihydroxyl carboxylic acid and methanol.

Are you sure its not the acid is to certainty the tetrahydroxyl moiety you are looking for Penguinone?

Cannizzaro is also classically a disproportionation, this is not. 

[clarkstill]

Penguinone is right Alpha, you're doing the Cannizzaro the wrong way round... if you use formaldehyde as the source of hydride to reduce the final tri(hydroxymethyl) acetaldehyde, you get the correct product.

[AlphaScent]

AHHHHHHHHH, so you are saying the formaldehyde is the source of the hydride and a hydroxyl would be kicked out?

[AlphaScent]

I was wrong.  It would be a crossed Cannizzaro reaction.  The formaldehyde is the reductant, oxidized to sodium formate (formic acid upon work-up) and the correspnding alcohol. 

Good Stuff.