Sciencemadness Discussion Board

Create propane2ol from Glucose - How to??

krokoko001 - 10-11-2008 at 03:45

Well at first I must admit that I created my account is only for finding a good answer for my question...
My probem is, I had to make isopropyl acetate from glucose. It is quite easy to create acetate, but I wonder how a Sr Hi Schoolboy can create isopropyl... My mates either crack buthane or hexane to create propene... But I think cracking sucks - you exploit hexane from the Middle East and "Crack!" - you had everything- it's just like hacking. Others at higher grades told me to ask (faithfully) Mr.Kobell and Mr.Wurtz, but I dont think it worths such divine reactions. I have imagined several imaginative ways:
C6H12O6»C2H5OH»C2H4C2H5CN»C2H5COOH»C3H8. I'm not sure about the last reaction, it surely needs hydrogen and Nickel but... I'm not sure.
My problem is that I know no more than 3 ways to lengthen the carbon string - Dimerize(?) and trimerize(?) Acetylene, dimerize drinking alcohol, and +HCN. So when it's time to synthesis something with an odd number of carbon atoms I must use HCN (rather toxic.. I don't like it) and what I get is always a carboxylic...
Can anybody suggest me a way other than what I listed to create that darnned ester??
BTW this is for fun: You got Acetylene, and are to give me PropaneDioic (Did I called it right, I mean HOOC-CH2-COOH). What reactions would you do and more important, HOWMANY?
Please notice that the problems above is purely chemistic. I don't care who sells acetylene for money and go buy dioic.And, before posting, I must admit I'm a non-English speaker. If that doesn't have a meaning, what I meant was my country does not speak English (but not all of them lol)

Foss_Jeane - 20-11-2008 at 18:22

Your best bet for this would be fermentation. Chaim Weisman did work along those lines in the 1930s -- '40s. IIRC, he produced isopropanol along with butanols and acetone. Might want to look into that.

Other possibilities are from propene, or by reducing acetone (electorlytic reduction in partitioned cell? Wolf-Kishner or Clemmensen reductions take acetone all the way to propane).

Nicodem - 20-11-2008 at 23:33

A fermentation process of glucose using the Saccharomyces cerevisiae fungi gives ethanol.
An oxidation of ethanol with air in the fermentation process with the Acetobacter genus of bacteria gives acetic acid.
Acetic acid can be transformed into acetone by numerous processes, but the most school-book version would be by preparing the calcium salt and thermolyse it. This gives numerous products, from which acetone can be distilled. An alternative would be using the thermolysis of acetic acid directly over ThO2.
Acetone can be reduced to isopropanol by various methods, hydrogenation representing the cheapest (a suitable catalyst needs to be used, for example nickel based catalysts, copper chromite, etc.).
Isopropanol can be esterified with acetic acid by the Fischer esterification method.

PS: Homework and other school exercises go to the Beginnings section where I'm moving this.

bquirky - 21-11-2008 at 03:03

Gday,

Not strongly related to the thread topic .. but

Would it be possible to add Hydrogen to a organic compound with an electrolytic process ?

I have attempted to electrolise Ethanol with a small amount of sodium hydroxide solution and it changed into a bright orange substance with a stench so fowl as to cause an instant headache ! and smelt like ants from a distance.. formic acid perhaps?

It evaporated into a thick paste and then deep orange crystals.

It obviously changed into a different substance but is it possible to do this in a more controlled fashion to synthisise other useful products? ethanol is cheap and OTC not many people talk about that kind of synthesis..


any ideas ?

not_important - 21-11-2008 at 08:20

Electrolytic reductions are well known, electrolytic oxidations less common but can be done. Choice of conditions is important, especially the electrodes - one reduction worked well with electrodes made from rolled lead sheet but not when the electrodes were directly cast from the same lead.

Nicodem looks to have a good mostly synthetic chem route, Foss_Jeane the fewest steps and a well documented process.

If you start with glycerol instead of glucose, you can get 1,3-dichloro-2-hydroxy-propane by treating glycerol in acetic acid with HCl. Don't remember if you can get away with strong aqueous HCl or need to use the gas, it's in patent lit and shows up in some other references. That can be taken to your target using one of several different reductions.

Foss_Jeane - 21-11-2008 at 11:09

Quote:
Originally posted by bquirky

Would it be possible to add Hydrogen to a organic compound with an electrolytic process ?


Yes. Works great, and can be used to reduce lots of different things. You can get chloroform from CCl4 by reducing with acid, a copper cathode, and a partitioned cell. Amines from nitro compounds, phenyl hydrazines from the diazo compound, etc.

Electrolytic oxidizations are also done, as in chlorinations, or, for example, oxidizing iso-eugenol into vanillin.
Quote:
Originally posted by bquirky

I have attempted to electrolise Ethanol with a small amount of sodium hydroxide solution and it changed into a bright orange substance with a stench so fowl as to cause an instant headache ! and smelt like ants from a distance.. formic acid perhaps?


You want to do that in an acidic environment. Acetaldehyde polymerizes in basic environments, which is probably what you got there, depending on how pure the ethanol was initially. You can electrolytically oxidize ethanol to acetaldehyde and acetic acid. Voltage control is critical for max yields of acetaldehyde, and temperature control if acetic acid is the desired compound since you need to keep the acetaldehyde in solution.

Partitioned cells are a good idea to keep anode products away from the cathode and vice versa. Also, be well aware that these oxidizations will also produce CO, and you need to be aware of that. CO isn't good for you.

497 - 21-11-2008 at 11:31

Quote:

You can get chloroform from CCl4 by reducing with acid


Could you then get CH2Cl2 by reduction of CHCl3? That would be interesting.

Foss_Jeane - 22-11-2008 at 14:03

Quote:
Originally posted by 497
Could you then get CH2Cl2 by reduction of CHCl3? That would be interesting.


Of course you can. It's that the more chlorines you remove, the more difficult it gets to remove more. So you'd need a cathode with a higher overvoltage, such as Hg, Pb, Pb-Hg. These reductions take place in an acidic environment in a partitioned cell.