Sciencemadness Discussion Board

Pentaerythritol from erythritol

darel - 16-6-2009 at 11:35

I am looking for a route to Pentaerythritol besides the acetaldehyde and formaldehyde combination. Would it be possible to synthesize Pentaerythritol from Erythritol?

hissingnoise - 16-6-2009 at 12:14

The short answer is no!
Erythritol contains 4 carbons, one fewer than pentaerythritol. . .
But the difference in performance between ETN and PETN is slight and erythritol can be nitrated by KNO3/H2SO4 mixtures, whereas PETN preparation requires strong, white HNO3.



[Edited on 16-6-2009 by hissingnoise]

Sauron - 16-6-2009 at 12:15

Well, no, and why would you think so> Because of the names?

And why would you want to if you could? Because it would be uneconomical if it could be done, but it cannot.

Pentaerythritol

C(CH2OH)4

Erythritol, ignoring the stereochemistry:

HO-CH2-CH(OH)-CH(OH)-CH2-OH

darel - 16-6-2009 at 12:43

I'm not asking to turn straight erythritol into Pentaerythritol. Just wondering if it can be done using erythritol as one of the reactants. I have a readily available supply of the stuff. It would be cheaper for me than the aldehyde route.

hissingnoise - 16-6-2009 at 12:50

Look darel, if you had a ready supply of glycerin would you look for its conversion to ethylene glycol?
ETN is an extremely powerful explosive. . .

Sauron - 16-6-2009 at 19:16

It's the wrong carbon skeleton.

You really seem hung up on names and pay no attention to structure.

Get a different hobby.

User - 17-6-2009 at 05:28

Quote: Originally posted by hissingnoise  
The short answer is no!
Erythritol contains 4 carbons, one fewer than pentaerythritol. . .
But the difference in performance between ETN and PETN is slight and erythritol can be nitrated by KNO3/H2SO4 mixtures, whereas PETN preparation requires strong, white HNO3.


Petn does not require high concentrations of HNO3 , only the yields suffer. The only thing that really maters is theamount of water in the mix which obviously can be altered.

Paddywhacker - 17-6-2009 at 09:49

Theoretically, almost anything can be turned into almost anything else on an industrial scale via partial combustion and carbon monoxide plus hydrogen to methanol and so on.

You can also do it biologically... convert the carbohydrate to biomass and use that as a feedstock.

But it isn't anything you can do with test-tubes and flasks in the chem lab.

Sauron - 17-6-2009 at 10:14

This is a stupid exercise in futility. On any scale it is hard to get cheaper than formalin and acetaldehyde. Instead the thread author wants to take a really unrelated (structurally) carbohydrate snd make pentaerythritol out of it, He might as well start with methane.

What is worse he is too lame to find out for himself that this is a brainless idea, and is inviting the forum to jump through hoops at his behest in quest of his magic process.

No thanks, fella. Try learning some chemistry so you won't waste our time like this.

[Edited on 17-6-2009 by Sauron]

Rich_Insane - 17-6-2009 at 11:22

You could not use erythritol as a reactant.

Look:



That's PE



That's erythritol

Pentaerythritol has no stereochemistry, and is far diffferent from erythritol. Erythritol is a sugar alcohol: It is derived from trees. The only similarities are that they are both polyols. Doing anything like this biologically is foolish. It either takes enormous amounts of time, or it costs thousands of dollars.

The Aldehyde process looks fairly simple, as all the precursors are quite easy to obtain. Calcium hydroxide, formaldehyde, and acetaldehyde. If you're that desperate, I believe Sigma sells 1 KG of PE for around $30.

[Edited on 17-6-2009 by Rich_Insane]

[Edited on 17-6-2009 by Rich_Insane]

kclo4 - 17-6-2009 at 13:22

If you find that you can not get acetaldehyde and formaldehyde or buy the one kilogram of PE, the aldehydes can be made with the partial oxidation of the corresponding alcohols, which are ethanol, and methanol.

Convert Erythritol to Pentaerythritol?

Siconic - 21-3-2010 at 08:25

Is it possible to convert erythritol to Pentaerythritol? Just a question, although it seems stupid since Pentaerythritol is obtained from condensation of acetaldehyde and formaldehyde. Just figured if there is a way it would be cheaper since erythritol is dirt cheap.

hissingnoise - 21-3-2010 at 09:00

Even if you could, which you can't, why would you want to?
There's very little to choose between ETN and PETN, performance-wise.


Bolt - 21-3-2010 at 10:05

That's not true: ETN is much, much more sensitive to shock than PETN. Also, eutectic mixtures will have different properties

hissingnoise - 21-3-2010 at 10:09

I said nothing about properties. . .

per.y.ohlin - 21-3-2010 at 10:14



They have a different carbon backbone. Just because they have a similar name does not mean they are chemically related.
EDIT: There is already a thread on this: http://www.sciencemadness.org/talk/viewthread.php?tid=12380

[Edited on 21-3-2010 by per.y.ohlin]

[Edited on 22-3-2010 by per.y.ohlin]

hissingnoise - 21-3-2010 at 10:21

Yeah, I did think I was repeating myself!