Sciencemadness Discussion Board

Experimental Organic Compound

bereal511 - 14-11-2006 at 22:35

I'm doing a project on the dropping concentrations of an organic compound under certain conditions. But I'm having a problem trying to find a suitable organic compound for part of the experiment. It should fall under these conditions:

- relatively cheap
- easily obtainable (does not need licenses, industrial orders, or bulk orders)
- low volatibility (where if you were to leave it in the sun for a week, only a fraction would have evaporated)
- easily indicatable (sp.) using techniques that are relatively cheap and accessible
- does not readily react with metal oxides
- soluble in water
- preferably does not chemically rape plastic, but if it does, no problem


Thanks for any input, I really appreciate it.

[Edited on 15-11-2006 by bereal511]

DDTea - 15-11-2006 at 10:26

How about Ethylene or Propylene Glycol (Antifreezes)? The only problem is they come premixed with water; however, they meet all your criteria. Their boiling points are quite high, and they are nice and oily and it's about the time of year where you'll find them all over shelves of K-Mart or even the right part of a grocery store.

They are soluble in water, will not react with plastics... The only issue I can think of is indicating. There are several reactions that can be done with alcohols; one of which is oxidation to an acid.

Maybe you could do your indication step each day by taking a sample from your "master liquid," adding a predetermined amount of Potassium Permanganate (another over the counter oxidizer found in hardware stores; strong enough to oxidize an alcohol all the way to a carboxylic acid), and then using pH paper to get a rough estimate over time? But then this would only work if it's being done in water..and if it's being done in water, the water would probably evaporate off long before the Ethylene/Propylene glycol, leading to an *increasing* concentration of the organic compound over time..

Just my stab at the problem; anyone else want to try?

bereal511 - 15-11-2006 at 15:09

Evaporation of water isn't so much of an issue mainly because I'll be adding equal amounts of water that is loss to evaporation over the period of the experiment.

The antifreeze idea sounds pretty good with the potassium permangante. I just hope that I can either 1.) purify the antifreeze enough to use in the experiment or 2.) find a supplier of propylene glycol. Price isn't so much of an issue, I just don't want to be dishing out hundreds of dollars for a few liters of the stuff.

Tacho - 16-11-2006 at 02:25

A compound with a phenol group would be very easily detected using ferric chloride, easily found in electronics shops as etching solution for printec circuits. The reaction is sensitive and yields a very visible color change or precipitate.

Eugenol becomes a water-soluble phenolate in alkaline solutions, but I don't know if the phenolate reacts with ferric chloride in the same way.

Phenol itself is water soluble to a certain extent. But I think it's volatile and not very recomendable healthwise.

Can't think of any other easy to find phenol right now. Anyone?

DrP - 16-11-2006 at 03:09

Quote:

- relatively cheap
- easily obtainable (does not need licenses, industrial orders, or bulk orders)
- low volatibility (where if you were to leave it in the sun for a week, only a fraction would have evaporated)
- easily indicatable (sp.) using techniques that are relatively cheap and accessible
- does not readily react with metal oxides
- soluble in water
- preferably does not chemically rape plastic, but if it does, no problem


Sugar / Urea / Urea phoshpate (Are water soluable solids)

Tacho - 16-11-2006 at 03:46

Hydroquinone is a water-soluble phenol and also a reducing agent that has many easy indicating reactions. Some (at least one from Kodak) photo developers have a high hydroquinone content.

Tacho - 16-11-2006 at 15:54

I just tested eugenol dissolved in alkaline water (with NaOH) and it gives a dense precipitate when ferric chloride is added.

DDTea - 20-11-2006 at 00:01

How exact do your measurements have to be for this project? What I mean is, to what extent is this quantitative vs. qualitative; because measuring varying concentrations of a compound in solution over time based on color or pH will require at least mildly involved calculations...and the proper equipment, needless to say.

This will only be amplified if you do an intermittent reaction such that you *can* take measurements (introduce more human error)

So you might want to consider another factor: "easiness"--which chemical and measurement technique makes your life easier.

Elawr - 20-11-2006 at 01:44

Glycerol .

bereal511 - 20-11-2006 at 10:53

Hmmm, I'll take your point into account Samosa. The exactness of the project can be varied on my part. Ideally, I'd like to be able to measure the organic compound quantitatively, but if it cannot be done with potentially large errors, then it probably wouldn't be worth the trouble.

I'm working on this in a high school laboratory setting and I currently have $500 at my disposal. It'd probably be best just to do a simple indication step to show that the organic compound is still present within the mother liquor until its concentration reaches 0.

And Elawr, I also thought of glycerol as a potential candidate, but I'm having trouble thinking of a way to measure its concentration in water. Care to elaborate?