Need a lead on alkyl acrylate monomers - they are like fucking rocking horse shit - or hen's teeth - rare as fuck in any decent amount here nowadays (I swear to god they used to be available)...

Alternatively, anyone got anything on the oxidation of acrolein or the dehydration of lactic acid? Not a patent requiring 15 fucking metal catalysts and a gas phase reaction, something I can do in the garage with fuck all equipment preferably...

The only thing I can find requires Cobalt (yeah, good fuckin' go) or Manganese acetylacetonates (which I suspect is the acetoacetate but I ain't looked that closely)...

Sort this one out and we have routes to everything without chemical supply companies being involved, propionic, lactic & acrylic....

See US patent 2341339. Acrolein can be converted to acrylic acid or acrylic ester using a simple vanadium catalyst and oxygen gas at atmospheric pressure and low temperature. Acrolein is nasty but easy to prepare, and one-pot ester formation is very attractive. I wonder if this same scheme might be also be used for conversion of cinnamaldehyde to cinnamic acid or its esters.

Like you I have been trying to find some less-than-horrible way to convert lactic acid or lactate esters to acrylic acid or esters. Ethyl lactate is now cheaply and widely available in the USA as a solvent for use in painting, so it would be ideal to find some conversion for it. The best known process is high temperature gas phase catalytic dehydration of acetylated alkyl lactate. This is certainly an industrial-only process if only because of its heavy demand for acetic anhydride. Later inventors have managed to bypass acetylation, but still require high temperatures. If you were feeling ambitious US patent 2859240 might be a good starting point.

It is not clear to me whether the inconvenience of a high temperature gas phase reaction is worse than that of using acrolein.

PMMA no doubt will depolymerize beautifully, if you want a methacrylate.

I am a bit skeptical about depolymerization of sodium polyacrylate or polyacrylic acid.

If you look at the first article posted, figures 2 and 3, the sharpest acrylic acid production peaks are below 225 C. There's a second peak at higher temperatures, but they are much lower and broader, plus indeterminate intermediate-molecular-weight products are much more prominent at those higher temperatures, so you certainly don't want to increase the heat in hopes of getting further acrylic acid.

If you also look at the % mass loss plots, you'll see that little mass is lost below 225 C. By eyeball I'd estimate less than 10%. And a non-negligible part of that mass is being lost as water and acetone, which should be easy enough to separate but also doesn't help yield any.

Again as a ballpark estimate I'd guess you can get about 5 weight percent of acrylic acid, mixed with water and acetone, based on your starting quantity of polyacrylic acid. So you start out with 200 grams of polyacrylic acid in hopes of getting 10 grams of acrylic acid monomer. That might be ok just on economics, because the starting material is cheap, but if you've ever done pyrolysis before you know what a bitch heat transfer and cleanup are. You have to get the whole mass of material up to 225 C or thereabouts without overheating material near the walls of your vessel (else you'll get those nasty complex products) and without underheating material near the center (because then your yield will be even lower).

Then you have to charge a fresh vessel (or, god forbid, CLEAN IT if you're not using disposable vessels) and start again to get the next 10 grams. Scale it up to do more per batch? Good luck! Heat transfer becomes harder the larger the vessel and the batch.

Looking this over, it sounds a little more negative than I intended. I just think that this depolymerization is in a different league from that of polystyrene or PMMA, which are lovely to work with because they yield only one major product and you don't have to worry about maintaining a narrow temperature range.

I got in on this thread late, but I wanted to make a few remarks. It is true that alkylacrylates depolymerize easily, due to the alkyl group facilitating scission of carbon backbone, much the same as ripping a perforated piece of paper vs an intact piece of paper.

Lactic acid dehydrates poorly, if at all, under acid conditions, which is paradoxical considering that it is a secondary alcohol. The primary alcohol dehydrates much more readily. The best I can come up with as far as OTC syntheses of acrylates involves nitrosating beta-alanine to give 3-hydroxypropanoic acid, and dehydrating and esterifying this in one step w/ methanol and concentrated H2SO4. I can produce some patents in support of this, but I must search for them.

can't you just buy methylacrylate?
it's a pretty common chemical.

polyalkylacrylates depolymerize poorly, because radicals are captured by tertiary C-H producing inactive tertiary radicals (that can't react further). polymethylmethacrylate in this case does not form a tertiary radical, and polystyrene's tertiary radical is having practically same stability as benzylic, thats why it seems to not be formed much, or easily cleaved back into benzylic and alkene