Sciencemadness Discussion Board

Making Pentaerythritol in home from easily available chemicals.

taniya.pinkpower1986 - 19-7-2010 at 20:09

Can anyone tell me ways by which Pentaerythritol can be produced in home?

mnick12 - 19-7-2010 at 20:15

You have not shown you have done any work, why should I help you? You could do some research on your own. And this should also be in beginnings.

But since your bound to find out anyway, pentaerythritol can be made by the condensation of 1mol of acetylaldehyde with 3mol of formaldehyde in the presence of a base usually CaCO3.

taniya.pinkpower1986 - 19-7-2010 at 20:16

Well I have this recipe with me

How to make Pentaerythritol
—————-

Prepare a solution of 800 g of paraformaldehyde and 165.5 mL of acetaldehyde in 5.5 L of water. Add to this solution 180 g of powdered calcium oxide in small portions with rapid stirring, a mechanical stirrer is advised. The rate of addition of the calcium oxide is adjusted such that the temperature of the solution rises to 50 C over a 30 minute period with the first portion. The addition of each subsequent portion should not be allowed to raise the temperature above 55 C. After the addition is complete, stirring is continued for 3 hours. The solution will become yellowish. After stirring, the solution is filtered to remove any contaminant particles, and the yellow filtrate is acidified with just enough hydrochloric acid to make it acid to litmus paper. It is recommended to decolorize the filtrate; add the decolorizer, stir for 5 minutes, and then filter again.
The colorless filtrate is now concentrated under reduced pressure until crystals begin to separate. Since it is rather inconvenient to run the entire lot, divide the solution into portions. The concentration can be done with a vacuum distillation setup. Using a 500-mL flask, add 200-300 mL of solution, when 40% of the water (80-120 mL) has boiled over, stop the distillation and add the next portion. Eventually you should have approximately 3 L of concentrated solution left. Heat this solution on a steam bath, while hot, suction filter it to remove any contamination. Any precipitated crystals that get caught on the filter can be washed through by wetting with steam.
The filtrate is now allowed to stand in a refrigerator overnight, whereupon the first crop of crystals will precipitate. These crystals are filtered to collect them. The filtrate is then boiled down to about 2 L, and again refrigerated overnight. A second crop of crystals will form; these can be filtered to collect them like before. The filtrate is now boiled down to about 1.2 L, refrigerated overnight, and the subsequent crystals are collected by filtration. The filtrate is finally boiled down to the consistency of syrup, refrigerated overnight, and the last crop of crystals is collected by filtration.
The combined crystals, which should weigh as much as 410-420 g, are recrystallized from an equal weight of hot water containing 10 mL of concentrated hydrochloric acid. This new solution can be decolorized, and then boiled down to obtain several additional crops of pure crystals. Discard the last 30-40 mL. The yield is about 55-57%.

Now to make the reagents that will be used in pentaerythritol production

How to make Acetaldehyde
———————————
Place 260 mL of 23% sulfuric acid in a 1500-mL Florence flask. Connect an addition funnel to the flask, and set it up for vacuum distillation with a 500-mL receiving flask. The receiving flask should be immersed in a salt-ice bath to cool the distillate when it comes over. Although a setup for vacuum distillation is used, it is not necessary to apply a vacuum; the vacuum adapter merely provides a means of equalizing pressure. Prepare a solution of 100 g of sodium dichromate in 200 mL of water and 127 mL of ethyl alcohol. Factor in the amount of water that is already in the ethyl alcohol when making the solution, i.e. 100 mL of 95% alcohol has 5 mL of water in it already. Place this solution in the addition funnel, position the stem of the funnel so that it is about 3 cm above the surface of the acid. Heat the acid until it just begins to boil, then add the mixture in the funnel in a steady stream to the acid. It will not be necessary to heat the flask during the addition because it will generate its own heat. The heat will be sufficient to distill over the acetaldehyde along some alcohol and waste acetal. If acetaldehyde vapors begin to escape from the flask, regulate the distillation by decreasing the amount of dichromate solution being added. If the reaction flask does not boil on its own, gently heat it for a short time until boiling begins.
The crude acetaldehyde thus obtained is difficult to distill from the alcohol and acetal mixed with it. It is therefore converted to aldehyde-ammonia, then back to pure aldehyde. Place the crude acetaldehyde in a Florence flask of suitable volume to contain no more than two thirds of the liquid. Attach a reflux condenser to the flask. Fill the condenser jacket with 30 C water. It is only necessary to have the warm water in the jacket, not flowing. Stop up the lower connecter to prevent water from leaking out. To the top of the condenser, attach a glass tube connected to a wash bottle filled with 50 mL of ether. This wash bottle is then connected to another wash bottle filled with 50 mL of ether. After all connections have been made, the crude aldehyde is heated to a gentle boil for 5-10 minutes. The ether will absorb the acetaldehyde as it boils off. If the ether begins to rise up into the connecting tube from the condenser to the wash bottle, increase the heating. Combine the ether into a 150-mL beaker immersed in a salt-ice bath. Bubble dry ammonia gas into the ether through a funnel or wide tube immersed near the bottom of the beaker. Add ammonia until the ethereal solution smells strongly of ammonia. After about an hour, pure ammonia-aldehyde should have separated out. Scrape the crystals from the beaker and collect them by suction filtration. Wash the crystals with a small amount of ether, and allow them to dry in a desiccator. The yield is about 30 g.
To obtain pure acetaldehyde, dissolve 10 g of aldehyde-ammonia in 10 mL of water in a 50-mL Florence flask. Add 28 mL of cold 29% sulfuric acid to the flask and set it up for simple distillation. Heat the flask on a water bath to distill over the aldehyde. Place the receiving flask in a salt-ice bath to cool the volatile acetaldehyde.
Acetaldehyde is extremely volatile and cannot be stored satisfactorily unless it is refrigerated or sealed in glass ampoules (not just capped), therefore it is necessary to prepare acetaldehyde each time it is needed. There is, however, an easier solution. A quick and easy way to store acetaldehyde is to polymerize it to paraldehyde, which can be handled and stored easily, then depolymerize when you need to use it. Now you can make a larger amount without worry.
To polymerize acetaldehyde for storage, place it in a dry test tube and cautiously add 1 drop of concentrated sulfuric acid per 2 mL of acetaldehyde in the tube. Mix thoroughly, the polymerization will begin to take place. Some gentle warming can hasten the reaction. After some minutes add 3-4 mL of water per 2 mL of acetaldehyde, an insoluble precipitate of paraldehyde will form. As an aside, technically paraldehyde is a controlled substance. It is a sedative and a hypnotic drug useable by prescription only.
To depolymerize paraldehyde back into acetaldehyde, place the paraldehyde into a round-bottom 200-mL Florence flask. Add 4-5 drops of concentrated sulfuric acid for every 20 g (20 mL) of paraldehyde in the flask. Set the flask up for fractional distillation, use glass in the fractionating column. Use a 125-mL Erlenmeyer flask as the receiver; keep it cool by immersing in an ice water (but not salt-ice) bath. Place a loose plug of cotton into the Erlenmeyer flask to help reduce evaporation loss; it must be loose. Care must be taken to prevent the cotton from coming into contact with the distillate. After setting up, heat the flask gently. The temperature of the distillate must not be allowed to rise above 35 C as it will only repolymerize. The acetaldehyde is now ready for use.

Production of Paraformaldehyde.

To polymerize formaldehyde , place it in a dry test tube and cautiously add 1 drop of concentrated sulfuric acid per 2 mL of formaldehyde in the tube. Mix thoroughly, the polymerization will begin to take place. Some gentle warming can hasten the reaction. After some minutes add 3-4 mL of water per 2 mL of formaldehyde, an insoluble precipitate of paraformaldehyde will form.



taniya.pinkpower1986 - 19-7-2010 at 20:43

Quote: Originally posted by mnick12  
You have not shown you have done any work, why should I help you? You could do some research on your own. And this should also be in beginnings.

But since your bound to find out anyway, pentaerythritol can be made by the condensation of 1mol of acetylaldehyde with 3mol of formaldehyde in the presence of a base usually CaCO3.



If things were that easy I won't have bothered anyone.Perhaps you should read the name of the topic carefully I said "easily available chemicals" as far as my knowledge goes Acetaldehyde is restricted,that is why I am trying to make pentaerythritol from scratch which also includes making acetaldehyde and paraformaldehyde which we will be using in making pentaerythritol in later stage.And yes I have searched this forum before posting I am not that lazy.IF ANYONE HAS ANY BRIGHT IDEA TO MAKE PENTAERYTHRITOL PLEASE SAY IT
Any ways here is a patient to make pentaerythritol


Attachment: Synthesis-of-Pentaerythritol-Patent.pdf (280kB)
This file has been downloaded 1660 times

[Edited on 20-7-2010 by taniya.pinkpower1986]

devongrrl - 20-7-2010 at 02:32

You may have problems then.

You'd need to get hold of potassium dichromate & sulphuric acid to synthesise the ethanal and if you can't get that then forget it.

hissingnoise - 20-7-2010 at 03:44

Ethanal can be prepared by bubbling C2H2 (from calcium carbide) in sulphuric acid containing a mercury catalyst. . .
This hydrolysis was widely used for ethanal at one time.

It's so unusual and interesting to hear girls talk about the synthesis of HEs. . .

bbartlog - 20-7-2010 at 05:48

There's an extensive thread on the topic of home synthesis of acetaldehyde, see: http://www.sciencemadness.org/talk/viewthread.php?tid=55#pid... (and actually there are other older threads with additional information). Although some people have had success it seems like a really satisfactory method remains to be found, which is interesting given the number of possible approaches...

rrkss - 20-7-2010 at 06:46

The heated CuO catalyst method for oxidation looks promising. I'm not a big fan of dichromates in a home laboratory since hexavalent chromium can do some nasty things and is tough to legally dispose of.

JohnWW - 20-7-2010 at 11:09

What do you want to use pentaerythitol for? I suppose you could react it with HNO3 to get the tetranitrate (PETN), which is an high explosive, comparable to sucrose octanitrate and cellulose nitrate.

It is also used to make pentaerythritol tetraacrylate, for making a type of acrylic polymer. Derivatives of pentaerythritol are components of alkyd resins, varnishes, PVC stabilizers, tall oil esters, and olefin antioxidants. Halogen-free pentaerythritol esters are also environmentally friendly alternative to conventional electrical transformer fluids, being both readily biodegradable and non-hazardous in water, as well as having high dielectric constants, low volatility, and high flash points.

See, for further info including synthesis, http://en.wikipedia.org/wiki/Pentaerythritol .
Further syntheses and info are given in:
http://www.orgsyn.org/orgsyn/pdfs/CV1P0425.pdf
http://www.chemplan.com/chemplan_demo/sample_reports/Pentaer...
http://www.perstorppolyols.com/upload/pds_allyl_pentaerythri...
http://hasyweb.desy.de/science/annual_reports/2006_report/pa...
http://www.inchem.org/documents/sids/sids/115775.pdf

Re PETN:
http://chppm-www.apgea.army.mil/erawg/tox/files/WTA%28PETN%2...

Also, because it is a neoprene derivative in which the four methyl groups each have an H replaced by -OH, it has properties similar to glycerol, except for much higher melting and boiling points and lower solubility in water. It would probably taste sweet, like glycerol and other polyols, but it would probably be too toxic to use as a sweetener.

[Edited on 20-7-10 by JohnWW]

quicksilver - 21-7-2010 at 06:10

As a cautionary note I'd like to interject that synthesized pentaerythitol is often found wanting for PETN. A great deal of information exists as to the need for a "higher purity level" of pentaerythitol in PETN mfg. The common 30 gal barrels of pentaerythitol used in the vinyl & paint industries produce a very low quality product and are NOT used in explosive manufacture. Very often this is what is sold off at non-chemical supply formats wherein pentaerythitol has been occasionally sold.
To save someone from a great deal of work with that synthesis I really do advise a degree of caution. Commonly, in Germany they use what they term "pentaerythitol-M" (reagent grade) exclusively. I'm fairly certain that a search of that term will illustrate more & the demands of mfg in the USA. The result is generally a great deal of lower nitrations (PEN) as well as poor yields even with 1.51 acid.

Jimmymajesty - 22-7-2010 at 09:03

Acetaldehyde can be made at home without taking a shower of hexavalent chromium or mercury. All you need is a little investment, unfortunately gas phase catalytic processes cannot be reproduced with PE tubing and such.

I can make 100g acetaldehyde/day, see the acetaldehyde thread for details.

I think even in vogel, there is a description of a catalytic process to make butanal.

The hard part of the synth is the acetaldehyde, If you have something that you think acetaldehyde, or you have relatively contaminated acetaldehyde, you will only get char, the same thing when you pour ccH2SO4 to sugar, then dilut it with water.

In other cases you will obtain the following syrup after the synthesis, and drying:)

penta.JPG - 36kB

Rich_Insane - 22-7-2010 at 09:47

Well, I suppose you could request a "small" sample from a company.... One guy from China offered me a 1 kg sample, but he wanted $50.

Formaldehyde shouldn't be too hard to get.... Acetaldehyde is a liquid (though it is volatile), it shouldn't be too hard to obtain perhaps a few liters. Honestly, if you want to make HEs like PETN from pentaerythritol, I would discourage using synthesized PE unless you've got a really nice setup and you can at least do a GC to verify purity or something. Sigma Aldrich sells 1 kg for $30 last time I checked, and considering how high-grade that stuff is, finding other sources shouldn't be very difficult. Of course there is the issue of finding out if they will ship to a residential address.....

If you really must make it yourself, then you could use ethylene and oxygen (2:1 ratio of ethylene to oxygen). Acetylene could be purchased as well, but really, who wants to mess with mercury catalysts?

shadow31 - 15-2-2013 at 14:37

What is a decolorizer, in the pentaerythritol making process is said to use decolorizer but what substance is this ?

Mailinmypocket - 15-2-2013 at 14:41

Quote: Originally posted by shadow31  
What is a decolorizer, in the pentaerythritol making process is said to use decolorizer but what substance is this ?


It is essentially activated charcoal, look on google for decolorizing charcoal

zed - 20-2-2013 at 18:08

Acetaldehyde restricted? Why?

chemrox - 21-3-2016 at 18:16

Quote: Originally posted by taniya.pinkpower1986  

To polymerize acetaldehyde for storage, place it in a dry test tube and cautiously add 1 drop of concentrated sulfuric acid per 2 mL of acetaldehyde in the tube. Mix thoroughly, the polymerization will begin to take place. Some gentle warming can hasten the reaction. After some minutes add 3-4 mL of water per 2 mL of acetaldehyde, an insoluble precipitate of paraldehyde will form.

I need some paraldehyde for a mycology colorimetric reagent. Does anyone know if this actually works? I tried it once and with no result but my acetaldhyde was not fresh.

Daffodile - 21-3-2016 at 20:25

Quote: Originally posted by chemrox  
Quote: Originally posted by taniya.pinkpower1986  

To polymerize acetaldehyde for storage, place it in a dry test tube and cautiously add 1 drop of concentrated sulfuric acid per 2 mL of acetaldehyde in the tube. Mix thoroughly, the polymerization will begin to take place. Some gentle warming can hasten the reaction. After some minutes add 3-4 mL of water per 2 mL of acetaldehyde, an insoluble precipitate of paraldehyde will form.

I need some paraldehyde for a mycology colorimetric reagent. Does anyone know if this actually works? I tried it once and with no result but my acetaldhyde was not fresh.


I tried it and it didn't work. I don't know why though... At the time my stuff was fresh af, although maybe ethanol contamination prevented a successful precipitation.

EDIT: By 'fresh af' I mean like 50 to 100 seconds after being collected by distillation.

[Edited on 22-3-2016 by Daffodile]

Daffodile - 23-3-2016 at 16:08

Okay so I tried making formaldehyde by refluxing Methanol with a red hot copper catalyst. The stuff smelled like formalin, although I wouldn't be surprised if some formic acid was produced. I tried to polymerize the formalin in solution by adding a few drops of Sulfuric acid to the product, but nothing precipitated. Can somebody please try the same thing with their better quality formalin just to see if it works?

According to the patents I checked, the synth works all the same with unpolymerized formalin, except slightly less well. Not a huge deal here, but it bugs me that I can't make it work. Also tried making some formalin from Hexamine, but it was so wierd, there was enough formic acid also produced to make my whole thing a waste of time.

EDIT: I think my lack of precipitate may have been because the solvent was Methanol, and a lot of it. The paraformaldehyde could have just dissolved in it, without precipitating. Its still not nice though that NO precipitate was collected, so it'd be nice for someone else to try the polymerization as well.

[Edited on 24-3-2016 by Daffodile]

hissingnoise - 24-3-2016 at 02:26

I notice ebay still has pentaerythritol, but for how much longer, one must wonder?

macckone - 25-3-2016 at 20:23

Pentaerythritol is a poor candidate for restriction. Glycerin and other nitratable substances are ready substitutes.