clearly_not_atara
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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 143 times (original paper)
Attachment: fisher1955.pdf (560kB)
This file has been downloaded 136 times (pinonic acid by ozonolysis)
Attachment: sousa1960.pdf (484kB)
This file has been downloaded 146 times (borohydride reduction of ozonides)
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bnull
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Have you considered butanediol (choose an isomer)? It can be made by microbial fermentation of biomass.
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]
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clearly_not_atara
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You need a little more than that. Butanediol is probably long enough, but it's not branched, which means the corresponding bismaleate is likely a
solid. Usually you see lower melting points in open-chain branched hydrocarbons.
But turpentine is still the most expensive component of the process as I wrote it. So I definitely encourage more suggestions of possible diols.
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imidazole
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how about reducing lactic acid derivatives? that could be a way to make it. I can't think of many commercially available (renewable) branched
compounds, maybe partial carboxylation/oxidation of mixxed unsaturated fatty acids, esterfying/acetal/acetylating them, and then then splitting them
with ozone or something similar?
[Edited on 10-4-2025 by imidazole]
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chempyre235
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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]
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imidazole
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urushiol isn't as bad of a suggestion as you might initially think, given how lacquer is made, maybe other pinacols/phenols could be a source of
inspiration for the process
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clearly_not_atara
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Yeah I think urushiol is pretty interesting since the ortho-bonded aromatics are often low-melting. It also appears to be surprisingly abundant, in
that there is enough to be used to make things through traditional processes. The main obstacle might be its instability. If it can be obtained
directly in good quantities, it's perfect. Most of the urushi lacquer I see is pretty expensive, though.
Pantoic acid seems pretty nice but I don't know how abundant it is. I considered isosorbide and furan-2,5-dimethylol but they seem too rigid (cyclic).
The glycols are probably too light.
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] |
The suggestion of C4-fermentation gave me another idea. See, the aldol
dimerization of aldehydes gives branched compounds. As imidazole mentioned, branched compounds are not that widespread in nature. But
the aldol dimer of acetaldehyde is not really branched. The obvious next choice is butyraldehyde (as usual, C3 products are rare, except those derived
from glyceraldehyde). Apparently, biobutanol production is already approaching industry:
https://marinefuels.totalenergies.com/news/press-release/tot...
And the dimer of butyraldehyde leads to the highly branched alcohol 2-ethyl-1,3-hexanediol, or "etohexadiol", already an item of commerce (but at an
unfavorable price of about $10/kg) and a former insect repellent.
http://en.wikipedia.org/wiki/Etohexadiol
It is apparently not too prone to dehydration, since the original authors distilled it over an iodine catalyst to achieve this. The aldol addition
happens easily in the condensed phase:
https://www.sciencemadness.org/whisper/files.php?pid=700256&...
Dehydration is probably averted by reducing before distillation.
| Quote: | | 2-Methyl maleic acid (citraconic acid) could possibly be cheaper than normal maleate, as citraconic anhydride is obtained by dry distillation of
citric acid. |
Furfural is actually super cheap at the industrial scale (<~$1.5k/metric tonne) and it's easily produced from organic waste.
https://www.imarcgroup.com/furfural-pricing-report
https://en.wikipedia.org/wiki/Furfural
| Quote: | | Furfural is derived only from dried biomass. In addition to ethanol, acetic acid, and sugar, furfural is one of the oldest known organic chemicals
available readily purified from natural precursors. |
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imidazole
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I think Urushiol itself is a low supply / high demand product, but I was thinking in the ortho-bonded aromatics direction. I actually thought about
Acetaldehyde, but dropped it for the reason mentioned. I can actually say there has been a lot of reading about Cellulostic Butanol recently, and it
could become much more available.
Unrelated, but back in highschool I had this pie-in-the-sky idea to basically farm algae for biobutanol production, after a base treatment to
pre-treat the algae, and then use synthetic humic acids as a amine scavenger to bring ph back up and split the cellulose from the fatty acids, and
getting fertilizer, Butanol, and fatty acids, so I'm a huge fan of C-4 chemistry
I still think Lactic acid > Lactide > dipropylene glycol could be an interesting way to get the C-3 chemistry rolling, but I'm a fan of the way
things are going with aldols.
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chempyre235
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What about o-coumaric acid? It could be added to the copolymer as a UV-absorbing agent. It also has the ability to crosslink, and can be made from
hydrolysis of coumarin, which has several synthetic routes, and is found in a wide variety of plants.
Sporopollenins found in nature use p-coumarin and some other coumarin-based antioxidants for this purpose.
[Edited on 4/12/2025 by chempyre235]
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chempyre235
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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]
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clearly_not_atara
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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 mostly simply copied the chemistry that Carter had used! With one exception, where linear straight-chain dicarboxylic acids were used,
with a cure temperature of 160 C:
https://pubs.rsc.org/en/content/getauthorversionpdf/c5gc0091... (open access)
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...
Attachment: miller1993.pdf (668kB)
This file has been downloaded 125 times
[Edited on 17-4-2025 by clearly_not_atara]
[Edited on 17-4-2025 by clearly_not_atara]
Attachment: boquillon2000.pdf (199kB)
This file has been downloaded 112 times
[Edited on 17-4-2025 by clearly_not_atara]
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imidazole
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I was thinking catalytic hydrogenation and dehydration in one go, but from further research, it turns out you can go from lactic acid to propylene
glycol directly, without needing to first reduce it to an ester in decent yields, which might be easier than trying to dehydrate it in the first
place. (https://pmc.ncbi.nlm.nih.gov/articles/PMC5838540/)
| 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] |
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