Interesting uses of caffein?

Hi, i have just been given a rather (10yr) old botle of caffein (50g in total).
Are there any intersting uses for this? possible (somehow) make malonic acid and diethylurea from it?
Thanks,

P.s. I dont plan on consuming any, it has been in the lab too long

Because of large amounts of no-caffeine coffee production, caffeine became very cheap - price is less than 40 american dollars per 1 kg (guaranteed quality). In 25 kg bags even cheaper, heh. Of course made in People's Republic of China
A little out of topic informations, just by the way.....

[Edited on 11-11-2009 by kmno4]

Uhm, yeah well i did use PA grade caffeine a couple of times (on myself that is).
It was from a new bottle we received in the lab, so no dirty spatula's.
It is a interesting use for caffeine .
Did some dose calculations and decided that 800mg would be acceptable, equivalent of quite some coffee.
I suspended it in water a thrown it down my throat.
After about half an hour it started working and it wasnt by far a good feeling.
Very shaky nervous feeling that kept hanging for about 4 hours before it started wearing off.
I will never do this again, actually i hate it.
Still sometimes when i drink coffee i get a bit of the same feeling, it triggers some sort of reminding and it isnt nice.

I am not really into doing drugs, i see it as some sort of experiment.

800mg Pro plus pills contain 25mg each!!! you fucked up your calculations!!!

Iam a heavy coffee drinker
Let me be clear that the dose was rather high, i am aware of that.

Quote: Originally posted by Picric-A

800mg !!!

Good god! I'd prolly be having a total freak out

Thats like 10 cans of Redbull

The last time I drank 4 espressso shots to stay up all night finishing a problem set, I ended up so jittery that I became less productive. Then I stared at the ceiling for 6 hours as I tried to sleep when I finished the homework

[Edited on 11/12/2009 by Saerynide]

Quote: Originally posted by Picric-A

800mg Pro plus pills contain 25mg each!!! you fucked up your calculations!!!

Some time ago I came across a paper by E. Fischer (1) describing the products of the reaction between caffeine and potassium chlorate in hydrochloric acid. The products are 1,3-dimethylalloxan and methylurea but 8-chlorocaffeine is produced in copious amounts as an intermediate product. The process sounded relatively easy and the product interesting so I tried it twice, as detailed below. These experiments could have been posted into several threads but I am posting them here because Nicodem posted a number of highly interesting reference above and it would be a pity for them to "get lost".

The significance of dimethylalloxan is that it condenses with hydroxylamine to give dimethylvioluric acid an interesting reagent for alkaline earth metals. While 8-chlorocaffeine was not isolated I think it could be easily by simply reducing the amount to chlorate used. I hope these prelimenary experiments prompt other to have a go and with more success

In E Fischer's paper he isolated the dimethylalloxan as the sparingly soluble partial reduction product amalinic acid (tetramethylalloxantin) and then re-oxidises it to the alloxan derivative with nitric acid though commenting that dichromate had been used by others.

Experiments;
Attempted direct synthesis of 1,3-dimethylvioluric acid from Caffeine:
14.977g of caffeine were dissolved in 21ml of 30% hydrochloric acid and 45ml of water by warming gently to 50°C and then commencing the addition of 5.700g sodium chlorate. The sodium chlorate was added in small portions over a period of about 1 hr at such a rate that the temperature was maintained close to 50-55°C. Occasionally the temperature would rise suddenly to close to 70°C after several small additions of sodium chlorate, there appears to be an induction period or temperature and slow addition is essential. A cold water bath was required on several occasion to check the temperature rise. Over cooling to below 50° stalls the reaction.

Fig 1 After the addition of a little chlorate the solution turns yellow.

The solution quickly becomes yellow and an exothermic reaction set in. After a short time the solution turns cloudy and then a precipitate of 8-chlorocaffeine starts to form as a cream yellow solid. After the addition of about half of the sodium chlorate the reaction mixture becomes a porridge like slurry of chlorocaffeine. With continued addition the chlorocaffeine slowly re-dissolves and eventually gives a clear yellow solution.

Fig 2 Chlorate addition half way much chlorocaffeine precipitates.

Fig 3 Chlorate addition complete giving a clear yellow solution.

Rather than isolate the dimethylalloxan by reduction to tetramethylalloxantin as described by Fischer I decided to try and precipitate the dimethylalloxan as the the oxime (dimethylvioluric acid) by the direct addition of hydroxylamine solution. The reaction mixture was first treated with 10% sodium metabisulphite solution until it no longer smelt of chlorine and then the acid was partially neutralised by adding 20ml of 40% NaOH solution to give a pH of about 4.5. 20ml of 25% hydroxylamine solution, roughly a twofold molar excess (from ice cold hydroxylammonium chloride and sodium hydroxide solutions mixed externally) were added. The solution immediately acquired a raspberry red colouration indicating the formation of a violuric acid derivative (violuric acid is colourless but gives a red colouration with sodium ions). The solution was cooled in the fridge overnight but no crystals formed.

The reaction solution was vacuum evaporated to slightly less than half its original volume and cooled. The evaporation caused the red colour to fade to a pale orange but after 24 hours only a little salt had crystallised in small cubes. Repeated evaporation to half volume again resulted in a pale orange syrup and much white crystalline solid but after filtering and washing with alcohol proved to be merely salt. The filtrate refused to crystallize even when mixed with a little ice cold alcohol or water and tested with barium acetate failed to give a coloured crystalline precipitate nor did it give an intense blue colour with ferrous sulphate. These reactions seem to indicate that the violuric acid derivative had been totally decomposed.

The preparation was repeated using twice the original quantity of caffeine and using the hydrogen sulphide reduction of E Fischer to recover the dimethylalloxan as the sparingly soluble tetramethylalloxantin.

2) 29.960g of caffeine were dissolved in 42ml of 30% hydrochloric acid and 90ml of water by warming to 50°C and then adding slowly in small portions at a time 11.56g of sodium chlorate. The addition took just over an hour. The reaction is rather exothermic and difficult to control even with a cold water bath at hand. Cooling the reaction mixture too quickly or harshly tended to stall the reaction and the reaction vessel had to be return to the hot plate which tended to cause the reaction to run away with the temperature sometimes rising as high as 77°C.

As before after the addition of about half of the chlorate the reaction mixture became a thick slurry of chlorocaffeine which dissolved slowly on further addition of sodium chlorate. Once the addition was complete and a clear yellow solution was obtained 10% sodium metabisulphite solution was added until the solution no longer gave a blue colour with starch-iodide paper.

Hydrogen sulphide was then passed through the solution using an inverted funnel that just touched the surface of the liquid to prevent suck-back. The gas generator was charged with 24g of coarsely crushed ferrous sulphide and the dropping funnel with 35ml of 30% hydrochloric acid. The gas was washed by passing through a washing bottle containing just enough water to cover the bottom of the inlet tube. The rate of acid addition was adjusted to give about 1 bubble of H2S per second at the wash bottle and the apparatus left to run until the acid was exhausted. The pale yellow crust that formed around the base of the funnel was broken away every 10-15 minutes but stirring or swirling the beaker.

Fig 4 The hydrogen sulphide gassing set-up.

When gas production had practically ceased the equipment was dismantled and the precipitate recovered by filtration at the pump and washed with copious amounts of cold water practically odourless. The yield of dried product was 9.76g and is clearly a mixture of sulphur and a granular white material.

Fig 5 White precipitate of sulphur and alloxantin derivative.

Fischer states that the crude material was recrystallized from a large volume of water but gives no clear guidance as the quantity require. So 400ml of water was chosen as a starting volume and after simmering the raw product in this volume of water for 10 minutes only a little finely dispersed sulphur appeared to remain undissolved. Some of the sulphur was very fine so a little (0.25g) of decolourizing carbon was added and the solution filtered hot. On cooling a crop of small equant shiny crystals formed. These were recovered by filtration and washed with a little cold water and dried. The filtrate was evaporated on a water bath the 100ml and cooled but only a trace of additional tetramethylalloxantin formed, this was recovered, washed and dried as before. The combined yield was 1.37g which is a very poor yield but little further material could be obtained from the second filtrate. The amount of sulphur-charcoal mixture on the filter seemed rather too small to account for the large loss during recrystallization.

Discussion: The first experiment probably failed because I failed to completely neutralise the hydrochloric acid present and the hydroxylamine was simply converted back to the hydrochloride and so the process may be worth another try using complete neutralisation before adding the hydroxylamine. A more reliable method of ensuring that all of the chlorine/chlorine dioxide had been destroyed may also help.

The overall yield is stated by Fischer to be about 60% with reasonable care but in the second experiment my yield was only about 6% depending on the nature of the hydrate. There are several places where loss may have occurred, the most obvious is the difficulty in controlling the temperature during the initial oxidation. It is worth noting that Nightingale (2) in the preparation of alloxantin from uric acid by the same method stress the need for accurate temperature control and that for larger quantities the oxidation stage should be carried out on batched of 15g of uric acid.

A further possible loss may have occurred during the hydrogen sulphide reduction. In the preparation of alloxantin form alloxan (3) Tipson describes a method where the solution of alloxan is divided in two and one half exhaustively reduced with hydrogen sulphide to dialluric acid and then the two solution mixed together. The alloxan and dialluric acid react to give alloxantin. My calculation carried out after the reduction suggest that only 3g of hydrogen sulphide are require even if the yield of oxidation product, dimethylalloxan was quantitative, this is equivalent to about 8g of commercial ferrous sulphide. So I used roughly a threefold theoretical excess and given that the yield of oxidation was probably much less than theory the excess may have been significantly larger although a little undissolved ferrous sulphide did remain in the gas generator. The rationale behind the large excess of hydrogen sulphide was to compensate for the small amount actually absorbed by the reaction mixture but in the event, and much to my surprise, absorption was almost total. It is possible therefore that almost all of the dimethylalloxan was reduced to the likely more soluble dimethyldialluric acid. In future preparation of this type a much smaller amount of hydrogen sulphide will be used or the solution will be divided and only half exhaustively reduced as recommended by Tipson.

Although the weight of crude alloxantin-sulphur mixture is not reported, it would appear looking at the preparation of Nightingale that a much smaller volume of water could have been used for the recrystallization, probably only 100ml or so.

1) Fischer E., Ueber Caffein, theobromin, xanthin und guanin; Leibig’s Ann. d. Chem. u. Pharm; v215 p253 (1882)
2) D. Nightingale Org Synth Col Vol 3 p42
3) R. S. Tipson Org Synth Col Vol 4 p25