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appetsbud
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[*] posted on 25-10-2008 at 09:10
Practical coursework


I'm about to begin my A level practical chemistry coursework, and i'm in the process of deciding what to investigate. I would rather investigate some sort of organic procedure but it has to generate some sort of numbers which i can use to create graphs and other such things.

i was just wondering if anyone here could give me some inspiration?

and please don't tell me to make aspirin from salicylic acid :P

oh, and as an amateur home chemist, this also gives me an opportunity to experiment with chemicals i might not be able to buy down the local pharmacy. any thoughts?
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kclo4
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[*] posted on 25-10-2008 at 11:41


There really are so many things you could do, especially when it comes to organics. I don't really know exactly what they are wanting you to do, since I don't have your class, but I'll make an attempt to suggest something you might want to do :P

The first thing I thought of, although perhaps not the most exciting and probably not the best, you could test for the best acid catalyst to produce 1,3,5-trimethylbenzene via the condensation of acetone. This could be done with different acids such as phosphoric , hydrochloric, Sulfuric, and them at different concentrations even.
Reflux each for a certain amount of time with all the needed controls, neutralize them and then extract the trimethylbenzene via distillation or something like that.

Strong Bases might also work for this? NaOH vs KOH vs others. I don't know, I think it would probably lead to another condensation product.

Of course the problem with that is there are going to be a LOT of weird byproducts and side reactions, but I think after it was nuetralized, you could distill them at different factions producing relativily pure trimethlybenzene. It boils at 164.7 °C 1,3,5-Trimethylbenzene is also called mesitylene http://en.wikipedia.org/wiki/Mesitylene


Or you could make aspirin from salicylic acid :P
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chemoleo
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[*] posted on 25-10-2008 at 16:31


If you like inorg chemistry, have access to a spectrophotometer, cuvettes etc., you could do a beautiful little project on interhalogens - do spectral analysis, and perhaps even some specific reactions with interhalogens.
I made a start of it, generating iodine bromide, IBr, see
https://sciencemadness.org/talk/viewthread.php?tid=9690&...

Perhaps tht sounds interesting to you.
Interesting chemicals accessible for sure!




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[*] posted on 26-10-2008 at 08:13


Actually, it is pleasant that you want realy to investigate smth new, not like most other chemistry students:) (and it is understandable - otherwise you would not have been registered here)
So, concerning organics, there are realy many things you could do.
I dont have any suggestions now, because most of my ideas are related to rather narrow fields of organics, that may be not interesting to you(and not acceptable by your scientific advisors)..
Also, if you're searching for something new to investigate (for example things, that can not be found in literature) you should be aware that ill luck may come easily, and you'll have no results to submit.
So better if you have some definetly workable idea (for results) and another - for your own curiouity (and practical use for all forum :D )
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[*] posted on 29-10-2008 at 10:32


i came up with something that i might investigate, i was thinking possibly investigating the amounts of the chemical that is responsible for all the hype about chocolate's connection with love; phenethylamine.

I would probably go about it by attempting to extract it from pure cacao powder or some other chocolate product, then putting it through some sort of apt chromatography (hopefully thin layer) and comparing it with a known source.

i think pea is legal to buy as i have seen it advertised as a bodybuilding supplement (http://www.bodybuilding.com/store/uniq/pea.html)

or i could make it from phenylalanine for extra browny points :)

Extraction would have to be worked on, but off the top of my head i would say something along the lines of :
addition of some sort of some alkaline solution, to release the PEA in its free base form (assuming it is in some salt form in chocolate). vacuum filter to remove solids and facilitate extraction process, wash filter cake etc... i don't have the data of PEA's solubility in different solvents but i presume there would be a preferred solvent that would extract it and little else, possibly methanol or acetone. extract using a separatory funnel and wash with water (PEA is relatively insoluble in water) , possible slightly basic to remove acidic impurities..(?) then fractionally distill, or just evaporate off the solvent to attain a reasonably pure product. recrystalize using ether!!

if i can find out more about the solubilitys i would do the initial extraction of the solid mass with large amounts of a relatively bad solvent, then extract that with a better solvent to concentrate it, as hopefully the PEA would migrate. this would be to reduce the amount of solvent that i would have to evaporate off.

i could also titrate the freebase (cause everyone loves titrations!!!) to check purity for extra extra browny points :D

of course all of this is theoretical so far, and i have been unable to find any references quoting the PEA content in chocolate, i guess there's always a first time..?!
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theobromacacao
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[*] posted on 29-10-2008 at 13:27


As a rough figure, chocolate contains approx. 10mg per 100g fresh weight (Food: The Chemistry of Its Components, 3rd ed., T.P. Coultate, p268). Am sure I also had some more figures regarding chocolate compounds, but damned if I can find them! If I do find them I'll post them here. Good luck with your project!
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[*] posted on 29-10-2008 at 14:29


thanks for that^^ any chance if you could tell me whether that data is for the PEA content of fresh cocoa beans or ground cocoa or even cocoa butter? chocolate itself is pretty vague. i think i plan on using cocoa solids, crushed. post fermentation and whatnot.

after a wee search i found an old thread on the same subject: https://sciencemadness.org/talk/viewthread.php?fid=15&ti...

it helps a bit, but there is some contradicting information about, this msds says that PEA is only very slightly soluble in water, but soluble in solvents such ash methanol, octanol, acetone and ether-

http://www.sciencelab.com/xMSDS-Phenethylamine-9927690

however this next msds and the posts in the previous SM thread claim PEA is soluble in water.

http://www.jtbaker.com/msds/englishhtml/p1872.htm

im disinclined to believe the first one, as i am aware of science labs bad reputation as a source...
However... in the previous thread it is mentioned to convert to the hydrochloride salt first, this would surely have a different solubility in things...

does anyone have any more solid information on the solubility of PEA and its' salts? or just any help in general?
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[*] posted on 30-10-2008 at 04:43


i have come up with a few possible extraction routes, i thought i would post them here for hope of some possible correcting if they are drastically wrong.

Warning! long postage...
METHOD 1

here I am taking the second msds to be true (second msds said that PEA is soluble in water), in that it PEA will be soluble in water. As all the data a have is for the pure PEA free base and not its salts, I will try and deal with it in that form, as then I will have more reliable information on its properties.

1. Create alkaline solution, place in beaker. There should be roughly double liquid to cocoa powder weight, maybe even more due to the fact that PEA may be only very slightly soluble in water.
2. Pulverise cocoa to a fine powder, if not already ground. And slowly add to your alkaline solution with stirring. Hopefully if the PEA is in salt form in the organic material, adding to an alkaline solution should release it as the free base form.
3. Vacuum filter the whole mishmash, and wash the filter cake with warm water a few times, add the washings to the filtrate. Hopefully this alkaline solution should contain any PEA contained in the cocoa.
4. As NaOH is insoluble in organic solvents, as Is water… I will then extract the solution with a suitable organic solvent, ether would be ideal if it weren’t for its excessive volatility. Most likely I will use acetone. Wash with dH2O a few times then decant organic phase into rbf.

METHOD 2

For this method I will use this statement as the basis of the reaction: “Converting insoluble amines into hydrochlorides is a common way to make them water- and acid-soluble.” (5) although I do not have any direct data for the salts of PEA I will attempt to treat it as any other salt. This method takes into account the first msds, saying that PEA is only very slightly soluble in water.

1. Create an acidic solution with either HCl or H2SO4, to create the hydrochloride or the sulfate salt of PEA respectively.
2. Add the ground cocoa slowly with stirring, warm slightly to facilitate the dissolution process. Leave for a suitable amount of time for the PEA to convert to the salt form and dissolve.
3. Vacuum filter the mix, wash the filter cake and dispose of the solids.( or repeat the extraction to make sure all PEA is extracted, this step applies to the last method also).
4. Add an excess of concentrated ammonia, this will neutralize the whole mess, and release the PEA in its free base, water insoluble form.
5. Extract this with a suitable solvent, ether or acetone etc… this should leave you with a solution of PEA in an organic solvent. Wash this with water a few times. This theoretically leaves you in the same position as four in the last method. Purification I think should be the same.

PURIFICATION

1. Set up for fractional distillation or vacuum evaporation depending on desire to retain solvent. Actually, probably fractional distillation. Distil out the solvent (acetone Bp= 56.53C (3)) and remove that fraction, crank up the temperature and the next fraction should be PEA at 196C (1), however there are likely to be impurities, slowly take the temperature up, if anything comes over to the receiving flask, hold the temperature and collect all of that fraction, replace receiving flask and continue, this allows for attainment of other impurities that may be of interest. Keep going until you reach the 196C area and collect the PEA!
2. If 196C is considered too high a temperature to work safely and accurately (likely) distil off everything up to, say 150C, then whack on a vacuum and distil over the remaining substance. This will only be a viable option if PEA is known to be the highest fraction extracted. Most likely it will be.
3. Another possible option would be to create the hydrochloride (or similar) salt form of PEA, this would be done by adding hydrochloric acid to the solution. There is a possibility that the salt form would not be soluble in the organic solvent, causing it to precipitate out (yay!). Otherwise create the salt form, after having vacuum evaporated the majority, say half, of the solvent, then slowly evaporate down the solvent in a crystallizing basin, and await crystals!
4. If step 5 or 6 was followed rather than 7, create a salt form of the PEA as described in 7 and continue for re-crystallization. Warm up some ether, only slightly!! (ether Bp =34.6C (4)) on second thoughts, don’t warm. Actually, don’t even use ether as it is likely that the salt form wont be soluble in it. Use water. So warm water, as hot solvent holds more solute that cold, and dissolve PEA.HCl in it. Use as little water as possible. Whack in fridge and crystals should precipitate out when cooled, maybe even put in freezer for a wee bit. Not too long, we don’t want ice.
5. Vacuum filter your crystals and boom! should be done!

well, these are my possible extraction routes, purity testing would be TLC, Titration, and simply smelling to see if the characteristic ammoniacal smell is there in the free base.

what you thinks?

should i have posted this in a new topic? a wee bit ot as it's no longer discussion of possible projects, but hey...

peace!
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Ozonelabs
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[*] posted on 1-11-2008 at 12:56


We feel it fair to warn you;

1.) Acetone is miscible with water, how you planning to sep off the organic solvent layer if you use acetone?
2.) Sodium Hydroxide IS soluble in many Organic solvents (MeOH, EtOH etc.)
3.) You wont JUST get the Phenethylamine out of chocolate, there are other organic molecules that you would extract making workup troublesome (caffeine etc.)
4.) Phenethylamine is illegal.
5.) Phenethylamine would be subject to Monoamine Oxidase in the body... hence it couldn't act in the brain to cause the 'love' feeling. You are refering, I believe to the class of compounds 'Phenethylamines' of which certain compounds (MDMA etc.) are a part of.
6.) You would need rather concentrated acids to form the amine salts for your second route, I KNOW that such concentrated acids are not available for pupil use in schools as per CLEAPSS guidelines.

You do have the basic understanding, but it needs to develop further.




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appetsbud
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[*] posted on 2-11-2008 at 05:59


thanks, this will prevent me spending too much time on what could turn out to be an unfruitful exercise. im still going to try and see if this is hypothetically replying to your points.

1.) ahh, how silly of me, i should have researched a little bit further, but still, perhaps ether? or another non polar solvent. this would also solve problem 2...
2.) NaOH is insoluble in ether and other non polar solvents.
3.) i understand that, and i don't neccesarily need 100% pure PEA, as its impurities would allow more fore me to write about, if everything went perfectly i would be left with very little to talk about.
4.) damn. that pretty much scuppers my plans. ill have a little search to make sure that you are talking about the restrictions of my country (UK) rather than another, and maybe ask my teacher also.
5.) i already understood this, i wasn't planning on creating it for human consumption, i figured i could come to some conclusion based on the amounts of PEA and its pharmacological attributes to debase this theory. (side note, i have seen claims that chocolate also contains MAOI's, shocker!)
6.) bleh, although i have used concentrated acids in my school (sulphuric for gas density laws in physics, even), you might be right. Again i will have to check.

i'm sure ether would not be the only option as a solvent, and due to its notoriety i would probably have to use something else. ill just have a look through the merck at school :p
ahh well, thanks for the reply!


*edit* i have found some supplements on ebay.co.uk containing PEA,

http://cgi.ebay.co.uk/Nutrex-Lipo-6x_W0QQitemZ200269055599QQ...

either this should be reported, or, yay!
plus i find it hard to believe that they can make something that people munch down everyday illegal.

[Edited on 2-11-2008 by appetsbud]
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[*] posted on 2-11-2008 at 06:37


Pleasure.

DCM would work as a solvent. Then again- CLEAPSS may have chlorinated solvent restrictions...

We are based in the U.K.- The legality of Phenethylamine compounds is rather clear cut.

Conc H2SO4 is one thing, it doesnt fume. Conc HCl does. Alot.

If you would like any advice feel free to contact us by e-mail.




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