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Author: Subject: Pentaerythritol total synthesis
plante1999
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[*] posted on 14-7-2013 at 09:01
Pentaerythritol total synthesis


I'm currently working on a total, lab synthesis of pentaerythriol, for efficient preparation, ethanol and methanol would be better precursors, however, for the sake of a total synthesis from natural material, wood will be used in the final preparation.

_____________________________________

Alcohols preparation:

Methanol:

-Preparation of methanol from wood distillation.

Ethanol:

- Wood hydrolysis using HCl, and neutralisation of the glucose solution.

-Fermentation with yeast

-Distillation from the mixture


Aldehydes:

Formaldehyde:

- Heating methanol and air over silver beads, and pass the resulting gas in water to get formaldehyde solution.

Acetaldehyde:

-Ethanol dehydratation over phosphosphoric acid to make ethylene.

-Ethylene oxidation using Wacker chemistry, and pass the gas in water.

Pentaerythritol:

- NaOH Catalysed formaldehyde and acetaldehyde condensation.

-Crystallization to give approx 90%+ pentaerythritol.

-Nitration, and washing of the tetranitrate.

-Hydrolysis of the tetranitrate to 99.9%+ pentaerythriol.


____________________________________________


The results of each part will be reported in this thread, as well as the experimentations before each part.

At the moment, wacker chemistry, wood hydrolysis, and ethanol dehydratation have been attempted.



__________________________________

For scientific purpose, if a success is achieved, a total synthesis starting from carbon, and water should be attempted.

_________________________________________

Comments are welcomed.

Please comment if you find the experiments interesting, or possibly entertaining!

If one ask I can explain more in detail a certain part of the process.

[Edited on 14-7-2013 by plante1999]

[Edited on 15-7-2013 by plante1999]




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papaya
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[*] posted on 14-7-2013 at 12:40


One idea I have I'm not sure if it's real, but must be everyone have seen on youtube the catalytic oxidation of acetone vapors on sheet copper surface (self sustaining). Now, it's interesting to know what are the products of that reaction, because I believe these include methanal and ethanal and that's if true leading it into solution of Ca(OH)2 will condense them into PE , though yields are expected to be horrible I think, but simplicity...
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plante1999
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[*] posted on 14-7-2013 at 12:57


Yes, it produce a fraction of acetaldehyde, but mostly CO2 and water. the reaction is extremely inefficient in these condition. However, it is true that ethanol can be oxidized by air on various catalyst to acetaldehyde. However, the idea was to make a procedure that could all be done with normal/ground glass glassware.



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papaya
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[*] posted on 14-7-2013 at 13:26


If one could develop a real practical synthesis from available chemicals (not wood as it's too complicated, but acetone, alcohol, perhaps urotropin, etc.) with a decent yield that would be great.
Also plante how do you know aldehyde yield is only fraction and it mostly burns into CO2, are there some figures on that reaction?

[Edited on 14-7-2013 by papaya]
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plante1999
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[*] posted on 14-7-2013 at 13:37


Due to my personal knowledge in chemistry, the best production of acetaldehyde on copper is arround 400 Celsius, when the copper is at such high temp that it glow, it is over-oxidizing the acetone. Acetone is not selectively oxidized to acetaldehyde ether.

Making pentaerythritol in a few step reaction for common precursor is not easy, it need both acetaldehyde and formaldehyde. Of course it is possible to use Methanol and ethanol directly, but it does not enter in a total synthesis in my opinion.

The process I will be using use quite a bit of precious metals, and they are re-usable.

If, the process become popular, I'm pretty sure I could furnish a salt mix that you could dissolve to make 100ml of solution for the wacker catalyst, and some silver beads. each for about 15$, but one could buy all the material I will use and make it himself.

[Edited on 14-7-2013 by plante1999]




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elementcollector1
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[*] posted on 14-7-2013 at 13:44


How pure is the methanol from the destructive distillation of wood chips? I have plenty in my backyard to try something like this.



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plante1999
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[*] posted on 14-7-2013 at 14:05


Pretty pure, Enough for lab purpose, it need two distillation tough, the yield is about 3-7% weight of wood if I remember correctly, reference is Shreve second edition.



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[*] posted on 14-7-2013 at 15:06


What are you going to do with the pentaerythritol? Just curious since you mentioned plenty of times that you're not into energetic materials.
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plante1999
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[*] posted on 14-7-2013 at 15:15


Getting reputation on the EM part of SM, and maybe sell some if I make enough.



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[*] posted on 14-7-2013 at 22:40


I will be following this closely, each step you mentioned interests me especially deriving alcohols from wood chips.



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plante1999
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[*] posted on 15-7-2013 at 03:22


If one want pictures for some part which I did not put picture, please ask, and I will re do this part to be able to take pictures.

Take note that I do NOT recommend to use the same apparatus as I use most of the time, due to my lack of equipment, I will very often go with an improvised apparatus that is more dangerous, and give less yield. The procedures are writen with the equipment it would be preferable do be done in.

Wood hydrolysis:
__________________________________

Material:

-Glass rod

-2x 500 ml beacker

- stand & clamps

- Wire gauze & ring

-Funnel & Fast filter (coffee filter)

-Burner & fuel
Reagents:

-31% HCl technical grade

- wood shaving, or dust

- Sodium bicarbonate

_______________________________-

Procedure:

in the beaker, 100 g of wood dust or shaving is placed, hardwood is preferable, but softwood works too. 200 ml of tap water is added and 5 ml of hydrochloric acid. Mix with the glass rod. It should be a paste at this part of the experiment. Put the beaker with the paste over an alcohol burner, and slowly heat the paste to boiling temperature. Keep the paste boiling until the mixture becomes very fluid, which take about 25 minutes. Then, filter the mixture in a new 500 ml beaker. A brown mess will be left in the filter, but the filtrate will be a slight yellow color. This solution is a solution of glucose and various contaminant, as well as hydrochloric acid. Slowly add some sodium bicarbonate to the filtrate until neutral, or that it stops fizzling.

The product in the filtrate contains quite a bit of lignin, and it is justified to dry it and keep it for the methanol preparation.

This solution can be used to grow yeast, or various micro-organism on, it is essentially glucose plus nutriments.
____________________________________________

Explanation:

Wood is mostly made of cellulose and lignin. The former is a long polymer made of glucose linked with ester bonds. The Later is a phenolic type polymer, that essentially is not decomposable, in nature, it turn to what we call black earth when wood decompose.

The hydrolysis of the ester bonds to glucose unite proceed in water, but is catalyzed by acids, or bases. Cellulose is not soluble in water and lignin is not too, but glucose is, as such a filtration is a good purification procedure.


[Edited on 15-7-2013 by plante1999]




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[*] posted on 15-7-2013 at 13:09


about the thing where you react the ethanol to get acetaldehyde

http://answers.yahoo.com/question/index?qid=20101108080201AA...

Na2Cr2O7 and K2Cr2O7 can be made by electrolysis of steel in conc. HCl
thereafter neutralization with NaHCO3
thereafter collection of the Cr(OH)3
thereafter reacting with NaClO by boiling it
thereafter boiling the whole thing down
thereafter adding HCl to form the dichromate

NaCl can be avoided as a massive impurity, if you care to use H2O2 instead, which is abit slower and not as cheap




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
http://www.trimen.pl/witek/calculators/stezenia.html
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plante1999
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[*] posted on 15-7-2013 at 18:22


Dichromate will indeed make acetaldehyde with ethanol, but in a fraction of it, due to its very strong oxidizing power. It will yield a lot of acetic acid. By experience, as I already made 100g of pure dichromate from stainless steel, dichromate production is a pain in the ass, and yield from the reaction will be low.

You can read about users results in the acetaldehyde thread if I remember correctly.




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papaya
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[*] posted on 16-7-2013 at 00:59


Perhaps one could oxidize ethanol electrolytically in solution (I remember the strong odor of ethanal when I unintentionally did this). If it's possible in alkaline solution then nickel can serve as a wear resistant anode.
edit: I just got an idea - what if one takes ethanol, methanol, water and lye, mix them and pass a current through solution (small perhaps). Could methanal and ethanal condense into penta in situ and if the latter is insoluble the phase separation will prevent it from further reactions on electrodes?

[Edited on 16-7-2013 by papaya]
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plante1999
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[*] posted on 16-7-2013 at 03:41


In water, I doubt the main product will be aldehydes, but acid. However, I would not doubt it is possible to make them using an intermediate catalyst oxidant, probably in another medium than water.

http://www.sciencedirect.com/science/article/pii/00134686648...

http://jes.ecsdl.org/content/92/1/335.abstract

http://www.ncbi.nlm.nih.gov/pubmed/22337651




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[*] posted on 16-7-2013 at 03:55


Couldn't you render alcohol conductive just by dissolving NaOH in it ? :O
What about the second idea?
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plante1999
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[*] posted on 16-7-2013 at 18:55


Yes, up to a certain point were only alkoloxide would be left. The oxidation power at an anode is too strong to left a sugar alcohol in solution. Pretty sure it would be oxidized badly.



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