November 27, 2024, 03:45:03 PM
Forum Rules: Read This Before Posting


Topic: Dehydration of Sucrose  (Read 4324 times)

0 Members and 2 Guests are viewing this topic.

grec08

  • Guest
Dehydration of Sucrose
« on: June 08, 2006, 03:48:37 PM »
This information is nowhere online, so any help would be greatly appreciated:

I am trying to recreate the second reaction seen here, which is the dehydration of sucrose by sulfuric acid with permanganate:
http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/MAIN/FORMC/PAGE1.HTM

I would like to perform this demonstration on a smaller scale to reduce the amount of fumes released. What concentrations, or how do I go about finding the concentrations, should be used of the sugar-water solution, the sulfuric acid, and the permanganate (I will be using potassium permanganate)? And, what respective volumes of these reactants should I use in order to perform the demonstration successfully, but produce fewer fumes? How do you know this!?  Thanks!

Offline constant thinker

  • mad scientist
  • Sr. Member
  • *****
  • Posts: 1275
  • Mole Snacks: +85/-45
  • Gender: Male
Re: Dehydration of Sucrose
« Reply #1 on: June 08, 2006, 05:56:04 PM »
I did something similar, but much more informally and without the permanganate. As far as the sugar-water concentration, I saturated around 125ml of water with sugar. I then added a few drops of 98% "concentrated" sulfuric acid. This worked just fine for me, but it will still produce steam, SO2, and I'm pretty sure with the heat that some of the sulfuric acid evaporated off also.

I would recommend either a fume hood or a well ventilated area. Test in small amounts first in a fume hood (or outside) so you know exactly what to expect. It really doesn't take much sulfuric acid to get this reaction going, especially if the sugar is dissolved. I also did this with just some dry sugar.

[Edit] I decided to put concentrated in quotes because it's somewhat of a relative term.
« Last Edit: June 08, 2006, 09:16:36 PM by constant thinker »
"The nine most terrifying words in the English language are, 'I'm from the government and I'm here to help.' " -Ronald Reagan

"I'm for anything that gets you through the night, be it prayer, tranquilizers, or a bottle of Jack Daniels." -Frank Sinatra

grec08

  • Guest
Re: Dehydration of Sucrose
« Reply #2 on: June 08, 2006, 06:09:28 PM »
Thank you!

Offline pantone159

  • Mole Herder
  • Chemist
  • Full Member
  • *
  • Posts: 492
  • Mole Snacks: +54/-6
  • Gender: Male
  • A mole of moles doesn't smell so nice...
    • Go Texas Soccer!!
Re: Dehydration of Sucrose
« Reply #3 on: June 08, 2006, 06:43:09 PM »
That looks like a pretty low concentration of permanganate, which is very strongly colored.  If you use too much, you won't have enough SO2 to reduce it all.  As far as the sulfuric acid, you want c. 98% 'concentrated' stuff.


Sponsored Links