Let's invent a new floor!

Recently I discovered this paper which attempts to build a better linoleum, as cross-linked epoxidized linseed oil:
https://www.sciencedirect.com/science/article/abs/pii/S09266... (carter2008.pdf)

Instead of the "natural" aerobic crosslinking of linolenic acid (by radical formation), Carter et al "forcibly" cross-link unsaturated fats by epoxidation followed by reaction with a diacid. This produced a stronger material with durability approaching that of polyvinyl chloride.

PVC had displaced linoleum due to its better properties and (eventually) lower cost, but it is probably the most toxic of the common polymers, because it is basically a bunch of alkyl chlorides. So it was interesting to see a mostly bio-based alternative.

However, the diacid cross-linker is bis-maleoyl dipropylene glycol:


This was preferable because it has a branched structure which lowers the melting point, and because the monoester of maleic acid has a reactive terminal COOH, due to the electron-withdrawing groups attached.

So the crosslinked ELO system was criticized in a master's thesis by some random Swede which actually makes a serious error in the results interpretation (someone will ask and I will explain), but does anyway raise a valid point about the crosslinker being derived from petrochemicals. The original paper actually acknowledged this problem, but the authors published no follow-ups.

Linseed oil is actually not the cheapest of the highly unsaturated oils (that is probably tung or walnut oil), but one of the nice things about linseed oil is that you can just buy epoxidized linseed oil, it's already an item of commerce, used for varnishes or something. In practice, various oils with high iodine value could be used.

Malonic anhydride is basically renewable. It is easily produced by the oxidation of furfural, which is one of the cheapest bio-derived chemicals coming from the distillation of sugars or polysaccharides. Of course, the home chemist is not going to oxidize furfural in a gas-phase process over a V2O5 catalyst -- they're going to distill malic acid, obviously.

It's the dipropylene glycol which is a sticking point. This is produced from propylene, which is not too easily had from biological sources -- usually, you can get C1 and C2 products from fermentation, a few C4, or you can use long-chain products that come directly from sugars.

But also, there's turpentine. Surprisingly, it can be farmed, by harvesting it from trees without killing the trees. Yields appear comparable to those for farming wood or vegetable oils. So I had the idea for a different diol coming from the ozonolysis of alpha-pinene:

and the corresponding crosslinker:

This is a little heavier than the dipropylene glycol version, but it is highly branched, so hopefully it is also a liquid.

The ozonolysis of alpha-pinene was investigated in the 1950s with a goal of producing a diacid (requiring dehomologation of the pendant methyl on the alkene), and investigators claimed up to 80% yield of the pinene ozonide, but worse conversion of this to the acid (termed "pinonic acid", from which I derive the name "pinodiol" for the diol):
https://pubs.acs.org/doi/pdf/10.1021/ie50548a034 (fisher1955.pdf)

However, we are interested in alcohols, and so we don't have to worry about side-reactions during oxidation. (The pinonic acid researchers also wanted to achieve oxidation without using additional hydrogen peroxide, which makes everything harder.) Instead we want to reduce the ozonide in situ, which is usually efficient. You or I would probably use borohydride (sousa1960.pdf) but industry would use hydrogen over Raney Ni:
https://www.sciencedirect.com/science/article/abs/pii/S00404...

Attachment: carter2008.pdf (811kB)
This file has been downloaded 179 times (original paper)

Attachment: fisher1955.pdf (560kB)
This file has been downloaded 164 times (pinonic acid by ozonolysis)

Attachment: sousa1960.pdf (484kB)
This file has been downloaded 192 times (borohydride reduction of ozonides)

You could always try some urushiol!

More seriously, a bit of searching awarded me a few possible diols/polyols that could be useful. The issue I found was that most of the low MW natural/naturally derived compounds have a melting point well above room temp. However, the secret to a workable polymer and cost-cutting may be to use more than one kind of diol. Here are some that I found:

• Ethylene glycol
  
• Propylene glycol
  
• Glycerin
  
• Isosorbide (from sugar or cellulose)
  
• 2,5-Bis(hydroxymethyl)furan (from sugar or cellulose)
  
• Pantoic acid
  
• Eucalyptol (after hydrolysis of ether)
  

I think this is a good idea to work on some cheap, naturally derived, nontoxic polymers. Be sure to keep us posted!

[Edit]: It may help to do some reading on natural stable biopolymers, like sporopollenin.

I also just found that the product of eucalyptol hydrolysis is called terpin, and can also be derived from geraniol or linalool by action with dilute H₂SO₄, according to Wikipedia.

I had another thought as well. 2-Methyl maleic acid (citraconic acid) could possibly be cheaper than normal maleate, as citraconic anhydride is obtained by dry distillation of citric acid. It is also a liquid at room temperature and dehydrates spontaneously, possibly facilitating easier esterification.

[Edited on 4/11/2025 by chempyre235]

[Edited on 4/11/2025 by chempyre235]

[Edited on 4/11/2025 by chempyre235]

Quote: Originally posted by bnull

Edit: Oops, forgot the review: Abhishek R. Varma, Bhushan S. Shrirame, Sunil K. Maity, Deepti Agrawal, Naglis Malys, Leonardo Rios-Solis, Gopalakrishnan Kumar, Vinod Kumar. Recent advances in fermentative production of C4 diols and their chemo-catalytic upgrading to high-value chemicals[J]. Chinese Journal of Catalysis, 2023, 52: 99-126. [Edited on 9-4-2025 by bnull]

Quote: Originally posted by clearly_not_atara

Pantoic acid seems pretty nice but I don't know how abundant it is.

Apparently, pantoic acid is a biosynthetic intermediate in the process that produces vitamin B5 (pantothenic acid). This process is already exploited by bioengineers to yield isobutanol.

I don't have access, but I did find an article from Springer that covers this.
https://link.springer.com/article/10.1007/BF00182178

PubChem entry for pantolactone:
https://pubchem.ncbi.nlm.nih.gov/compound/989

Also, here is the Wikipedia page on a-ketoisovaleric acid, the precursor to pantoic acid.
https://en.wikipedia.org/wiki/Ketoisovaleric_acid

Perhaps another synthetic route to the lactone could be had by using a furan derivative as the starting ingredient.



@clearly_not_atara, what do you think of the possibility of terpin?




[Edited on 4/14/2025 by chempyre235]

Quote: Originally posted by clearly_not_atara

chempyre: miller1993, attached. But this appears to be a conventional chemical synthesis, not a fermentation. I really wanted some better guide to what I should hope for out of a diol. So I searched through the citations of Carter et al's original paper. However, they all simply copied the chemistry that Carter had used! This is an interesting example of the dysfunction of modern scientific research: it is just easier to get funding and support if you are doing something repetitive. I can't find anyone testing other crosslinkers, even just substituting the diol. So I found the PhD thesis that the paper was based on: https://openresearch.surrey.ac.uk/esploro/outputs/doctoral/T... But here the only alternatives listed are all cyclic anhydrides. They don't work well, obviously, since the maleic chemistry was the signature advancement. And there is no explanation for why the anhydride was used in one case and the diacid in the other, though the original report using the anhydrides may tell us something: https://www.sciencedirect.com/science/article/abs/pii/S00323... (boquillon2000, attached) The essential requirement is: the bis-maleoyl ester diacid -- what I am tempted to call a "bimaleate" by analogy to a bicarbonate -- must be a liquid. It is also good for it to be "flexible", though we are not sure what that means; maybe a glycol or catechol is already flexible enough because of the bimaleate pattern. In general, branched motifs and cis-oriented double bonds lower the mp of a compound, while cyclic structures and trans-oriented double bonds raise it. This is a very rough guide. Based on this, I like etohexadiol, and neopentyl glycol (neé pantoic acid). So: is the bimaleate of etohexadiol a liquid at room temperature? What about that of the other alcohols? Quote: I still think Lactic acid > Lactide > dipropylene glycol I have a hard time imagining how lactide is reduced to dipropylene glycol? In fact, reducing esters to ethers is very tricky. I did find one example which used NaBH4 + BF3 in mixed solvents: https://pubs.acs.org/doi/pdf/10.1021/jo01053a054 This is a little too advanced... [Edited on 17-4-2025 by clearly_not_atara] [Edited on 17-4-2025 by clearly_not_atara]