Talk:Caffeine

The Image

Pardon me for not keeping track, but what was the decision on images in wikipedia for things like molecule structures? I've just sent Larry a .png I created of the caffeine molecule, b/c the transcription on the main page looks so foreign to what I'm used to seeing--but I'm not a chemist, nor did I progress beyond CHM 2400.  :-) Should we create our own images, or handle it through ASCII art? The advantage of images would be that some vandal can't come in and change, say, an "H" to a "C" and slip it through. The disadvantage is that some professor can't come in and change, say, an "H" to a "C" and have it be duly noticed. Also, the images won't display in text browsers. Opinions? --KQ

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Without images, the web wouldn't be what it is; I say, go for the images.

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Yay! that's the quickest turnaround on any request for a new entry that *I've* ever made! MichaelTinkler, caffeine-addict

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That's because you're not the only caffeine addict here. :) -- Taw (who started Caffeine entry and is proud of it).

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KQ, a professor could still come in and make a note that the depiction isn't right, and someone could just then go fix it and repost it. Right?

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That's true I guess. The .png doesn't show up in IE 5.0 tho (or Opera 5.01), for some reason. It works in Photoshop, Irfanview, and NS 6.1. Any suggestions? Lee? Optimum format, preferences to toggle, etc.? --Koyaanis Qatsi

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What PNG? IE 5.0 should be fine (See, for example, http://www.libpng.org/pub/png/pngsuite.html to verify your browser). If you can give me a URL for the actual file you're talking about, I'll see if it is a correctly coded image file. --LDC

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The reason it doesn't show might be that there's no link in the article... --Magnus Manske

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Since I can't work out (from the discusion above) whether anybody has actually made an image, I went ahead and made one for my favourite molecule. BTW I'm not really a chemist so I used the ASCII structure as a reference, somebody else should check it. -- DrBob

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Anyhow, the Image works fine on Firefox. Now, if it were possible to have a graphics/ASCII images option... Erre 01:57, 9 Mar 2005 (UTC)

Leaving out carbons

I have made an image, which I emailed to Larry, but I did something wrong and it doesn't work in IE 5.0. I'll send it to LDC so he can point out what I've done wrong, but right now I'm at work and the image is at home. Thanks for making an image of your own, but the diagram leaves out the individual carbon atoms, and also has a shape different from how it's usually drawn, because it's based on the ASCII art, which is limited to pipes and slashes to indicate bonds. I'll send the image to LDC tonight when I get home. --Koyaanis Qatsi

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--> I AM a chem major, and yes, you traditionally leave out the carbons, occasionally on carbbohydrate chemistry an older notation is used where hydrogens are also omitted, biochemists use yet another notation, it's really quite confusing, but technically speaking, the chemical model is correct w/o the carbons, the methyl carbons however, are debatable

--- It was my impression that in schematic diagrams like this is was traditional to leave out the carbon atoms rather than clutter the diagram with what is otherwise obvious. Of course a more pictorial representation (such as a ray-traced picture with spherical atoms) has to leave them in. --LDC

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Well, it's been a long time since CHM, but the only atoms I remember leaving out were the hydrogen ones. Is it customary to leave out the carbons, too? Anyone? --KQ

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Well, I thought it was, which is why I left them out in the first place. I've certainly seen diagrams printed that way. But as I say, I'm not a chemist. -- DrBob

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I'm seeing it half and half on a google image search. Maybe a chemist can come explain to us laypeople.  :-) --KQ

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There are lots of carbons in lots of compounds. We leave them out as often as possible -BUT we know what we are talking about. That may not hold for a general audience. -A chemist.

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As a to-be-biochemist, it looks good to me. Definitely sufficient. --Magnus Manske

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I'm not a chemist, or looking to be one, and it definitely wouldn't have been clear to me. Who is your audience, anyway?

We can't teach all of chemistry in the caffeine article, don't you agree? Those who know what the image means (at least roughly;) will welcome it, and the others should take a chemistry class! The image is additional, it is not the central part of the article. But, if you (whoever you are) would like to start a "how to learn chemistry" wiki, go ahead, I will contribute when I have some time :) --Magnus Manske

I'm not sure I agree. I know what the image means, but I wouldn't have guessed that there were Carbons at the intersection of each 4 bonds without a letter there--though, with the C listed, I could tell you that the C stood for Carbon. Is it a stylistic matter (some of the images do show the C)? --KQ

In chemistry texts, carbon atoms in rings are left out more often than not, especially aromatic rings like benzene but other rings as well, and occasionally in straight chains. The only real exceptions are when you want to point out optical activity and when you want to make it really, really plain what is happening. I think it would be better to explain the convention somewhere than to try and put carbons in everywhere - consider what will happen with chlorophyll and heme.

For a practical example when to draw carbons, see [1] for aspirin drawn with and without carbon atoms. I think the initial remark was about "images of Lewis structures are too complicated for the unwashed masses", though. Or am I mistaken? --Magnus Manske

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That ring (the benzene ring) is, as they say, so common that it is usually drawn like that, but if you'll notice, the Carbons are still indicated in the attached molecule. --KQ

That's because the attachment is a straight chain, corresponding to the CH₃ groups here, where carbon are shown. It is fairly rare, though not unheard of in larger molecules, for carbons to be omitted in straight chains, since it isn't quite as clear how to replace them.

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I work in the united states and I have never seen a carbon atom written in. I think that carbons should be unmarked to follow the precedent set by traditional publications. As for the masses reading the article, if they don't have a foundation that would enable them to understand the structure drawing system, the picture would probably be useless to them anyways.

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Here's the image KQ sent; I don't have any particular preference, but someone might.

http://www.piclab.com/images/caf.png

3D picture

1. Could the person who posted the 3D caffeine picture please shrink and crop it -- it's larger than my monitor!
2. Also, if you didn't use freeware to produce the caffeine model, you probably need to mention the name of the software (I know you do, if it's from Insight II, since I used to work at Accelrys when it was MSI). -- Marj Tiefert, Tuesday, April 2, 2002

I'll even do some of the work for you--I'll crop it and shrink, it when I get home tonight. But it still probably ought to be attributed. --LDC

I temporarily removed said picture (uploaded by Little_guru) from the article. For the curious, here it is again:

Why don't you use the public domain federally funded picture that you can find using "chemid" at http://chem.sis.nlm.nih.gov/chemidplus/chemidlite.jsp

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I think a 3d picture of caffeine (and indeed of all important molecules, especially water) are very desirable. They can be made easily with the free software RasMol: http://www.umass.edu/microbio/rasmol/ In order to render a molecule, you need a coordinate file; these are also widely available for free on many sites. AxelBoldt

types of structure representation

This is an important dicussion - it applies to a lot of molecular structures. The following are all useful methods for describing compounds:

• a registry number (there are many of these and they have no semantics)
• the molecular connection table (which atoms are connected to which). This is often a structured file but there are two common inline formats, SMILES and InChI. The latter is becoming very widely used and we recommend it for all Wikipedia chemistry where possible
• a 2D diagram. There is considerable flexibility in how this is drawn - are hydrogens to be included? Carbons? Should the molecule have a standard orientation? (For example I normally draw caffeine flipped about a vertical axis from the current picture and I suspect most people would, but it's not wrong.) The 2D diagram can usually be generated by machine from the connection table but it won't always be as aesthetic as the human ones but it will always be correct!
• 3D coordinates. These are obtained experimentally (e.g. by X-ray diffraction, by computation, or by model building. For some molecules (such as caffeine) there is only one possibility (apart from rotations about the N-CH3 bonds) but for many other molecules there are many conformations. 3D diagrams are great fun and if you can get the Jmol software running in some way (http://www.jmol.org) readers will love it.

(Peter Murray-Rust, http://wwmm.ch.cam.ac.uk)

You could, of course, become a Wikipedia editor and assist in this noble plan. It hope it was not you who left some grafitti on the page 16 minutes prior to your above message. JFW | T@lk 12:25, 5 December 2005 (UTC)

Greetings and thanks. I am very committed to the Wikipedia approach - it is mainly a question of time. One major project is to add InChIs to everything.

I am afraid it was me who added the graffiti! I thought that it was allowed to do this to demonstrate cleanup. But I won't do it again.

Best

P.

Toxicity

Tuxisuau - toxicity is measured using a measurement called LD50 (Lethal dose for 50% of a population), and so the use of the term half the population is actually correct. I am going to change back for now, but please feel free to add info to the discussion. Thanks Ddroar

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Ddroar - Ok, then u're right. But if u know about LD50, it will be better to add some reference to it (as u can see, i had no idea, so I invite u to write it) (Tuxisuau)

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With all due respect, an LD50 for caffeine of 10g / kg of body mass seems ridiculous. That would mean that 1/100th of your body mass would have to be caffeine to have a 50% chance of killing you! Several other sites I found seem to give values more like 75-150mg / kg of body mass, which seem much more reasonable. I don't have an authoritative source, but someone who does should look this up and put in the right value.

This site lists some values for mice and rats. Seems to be in the 50-300 mg/kg range, not sure if it's the same for humans, but 10g/kg seems way too high and these numbers are probably closer.

Toxicological Data: Oral rat LD50: 192 mg/kg. Investigated as a tumorigen, mutagen, reproductive effector. Reproductive Toxicity: May cause teratogenic effects. (doesn't mean I'd ever stop drinking espresso)

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Removed:

The cytochrome P450 system, which is responsible for breaking down caffeine, is not fully matured until about the age of 7 to 9 months (after birth). Indeed, the chemical half-life of caffeine in the infant's metabolism has been determined to be up to 120 hours, as opposed to the typical 3.5 to 10 hours in older children and adults. This means that continued exposition of unborn children and neonates to caffeine (e.g. through the placenta during pregnancy or through breast milk after birth) could lead to an accumulation of caffeine to toxic concentrations even at a moderate caffeine intake by the mother.

This is pharmacokinetic nonsense. Even if there were no foetal metabolism, the caffeine level would not rise above the level in the maternal blood. As the mother metabolises caffeine, the foetal caffeine would diffuse back across the placenta. bignoter

Yerba Mate

Ok, I just looked up "mateine" in response to the claim that yerba mate doesn't have caffeine, but a similar chemical compound called "mateine." I found 132 results in google, most of them in fringe or alternative publications. I'd feel much better about it if we had some backing from a recognized authority, such as a peer-reviewed scientific journal. Koyaanis Qatsi, Monday, April 1, 2002

it does not have it... i just checked all the 4 diff. types of mate packages i found at home now; they have all the other things like potassium content specified; no caffeine... as far as you won't find the mate in your supermarket i suppose you wont find the non-recognised articles either. try some of these: http://www.lasmarias.com.ar/ilayerba_nut.htm http://www.yerbamate.co.uk/pages/page10.htm Zisa

I will find mate in my supermarket, and my package (Yogi Green tea mate) says it contains 44mg caffeine per cup. The Yogie mint mate says "7.5 mg" per cup, so I'm guessing that mate itself has at least 7.5 mg caffeine, as it's commonly understood. Thanks for the links though. Koyaanis Qatsi, Monday, April 1, 2002

okay... the mates i have found here i have bought in uk, italy and argentina and in none of these packets i have found any mgs or mentions of caffeine, instead e.x. taragui mate has specified its kcals, proteines, lipides, glucidos, fibers, pantonine acids, riboflavine, potasium, magnesium and other minerals. Zisa btw, 'green tea mate' is partly green tea and partly yerba or pure mate?

Partly green tea and partly mate. But the green tea mate' (w/ 7.5mg caffeine [or mateine]) has no other caffeine-containing ingredient. I think LDC, below, is on to somethine when he suggests we let scientists come to a conclusion on it, then just report what they determine. cheers, Koyaanis Qatsi

I changed the Yerba Mate page; for this page, though, I think it's fine to just leave out any mention of mate. It's not really critical to describing caffeine as such, and it avoids having to change the article when later research finally decides the question. -- Lee Daniel Crocker

That sounds like a good approach. Koyaanis Qatsi

I have taken a somewhat less drastic approach in this spirit (removing claims I can't substantiate, but leaving reference to mate). btw the non-mention of caffeine on the packaging doesn't mean anything; tea and coffee aren't required to mention it either (at least in Canada and the US), since they're not products to which it's been added as a food ingredient. toh

I have taken a more direct approach regarding mateine - all the claims that mateine is not caffeine are based on bunk science. Avoiding mentioning it now to avoid having to change the article later presumes that later research will prove mateine is not caffeine. Starting with that assumption, if mateine *is* caffeine, what is sufficient 'later research' to let the result be mentioned? Better to stick with current knowledge for now, and let later results deal with themselves. I understand that many people have different experiences with yerba maté than with coffee, but that doesn't mean that it's a lack of caffeine. There are plenty of other chemicals in coffee and yerba maté, any of which could significantly change how it interacts with our bodies. --Matthew Weigel

How does it work?

How and why does caffeine stimulate the nervous system? AxelBoldt

Content chart controversy

I think the caffeine content numbers will mislead a lot of lazy readers and will help others a lot less than they easily could. For readers to correctly compare the different caffeine sources, they need to know the content per serving, not content per arbitrary unit. So for regular coffee I think we should state the content "mg per 8-ounce cup" ( or really to use consistent units I think it should be "mg per 250 mL serving" ). Espresso is more potent, but a shot is only 50mL, so the caffeine content should be stated in "mg per 50 mL shot." Incidentally, even for readers who are inclined to calculate serving content themselves, some of the numbers are perfectly useless, because "ounce" could mean either weight or volume in the context of cofee, and "coffee" could mean either liquid or beans in the context of the unqualified word, "ounce." 168... 17:55, 21 Oct 2003 (UTC)

The listed caffeine content for yerba maté is absurd in this table; if it were 200mg/oz then I doubt I'd be able to feel my face as I write this. Maté's caffeine content is similar to black or oolong tea (relatively high in terms of mg/g of dried leaf, but lower than coffee in the beverage as variously prepared). Perhaps the writer confused the dry content with that of the beverage, or perhaps it's just that "more mate marketing misinformation means major money".

I am removing mate from the table until a verifiable figure can be found.

- toh

Another possible link

Would a link to http://www.erowid.org/chemicals/caffeine/caffeine.shtml be appropriate?

Copyright issue

Much of the Metabolism & Toxicology section seems to be taken from http://www.drowning.com/caffeine.html. Isn't that a copyright violation?

It probably is, unless both are copied from a US government (FDA, CDC, whatever) work. Pakaran. 14:06, 14 Oct 2004 (UTC)

It is from the DSM IV, which is copyright (but possibly fair use) the American Psychiatric Association. JFW | T@lk 14:48, 14 Oct 2004 (UTC)

The APA is very protective of its copyright. We could probably get away with quoting small parts of it, but if each of our articles on a subject in the DSM quotes from the relevant section, that could quickly add up to a problematic amount of total quoting. --Delirium 08:49, Nov 20, 2004 (UTC)

Should we really be copy and pasting unattributed paragraphs from one of the bottom links? (See the whole thing about 'caffeine intoxication')

Caffeine content of Espresso vs. regular coffee

According to some sources, Espresso is the form of coffee with the least amount of caffeine, the explanation being that when making an Espresso, the water comes into contact with the coffee powder only a very short time.

For example, The Economist (admittedly no scientific publication) writes:

(...) it [Espresso] contains less caffeine than almost any other form of prepared coffee.

See Espresso coffee (The Economist)

• I agree with the anon above. The National Geographic [2] article on caffeine stated that espresso has around 40mg per ounce, not 100mg. I am going off of memory as I do not have a subscription, but it seems what whomever posted the espresso content was making things up. Espresso is a darker bean, roasted longer (which reduced caffeine content) and it contains less water, which reduces caffeine content due to the fact that it is barely water soluble (which is why we need to heat our water for coffee and tea).

• Also, I am skeptical of most of these caffeine content figures, there are no sources cited.

Reid 20:34, 7 February 2006 (UTC)

The article cites robusta. This variety has more caffeine than the most common variety used for taste: arabica. Thus, the amount given might be OK. Jclerman 22:00, 7 February 2006 (UTC)

Robusta is not by any means used in all types of espresso, and then only as a minority portion of a blend (mainly as a crema-enhancer). Arabica remains by far the main element; most of the blends I've seen appear to have no better than perhaps a 1/6 ratio of Robusta to Arabica.

100 mg per shot is a gross exaggeration. There are plenty of reliable sources out there to verify the 40mg per ounce fact.

Caffeine and chocolate

Are we sure we're not confusing chocolate's caffeine content with its theobromine content? Theobromine is the primary stimulant, and its caffeine content is much less. - Gilgamesh 23:29, 26 Oct 2004 (UTC)

"The Biochemist, (Apr/May 1993, p 15) did chemical composition tests where they specifically distinguished between Caffeine and Theobromine. They found regularly up to 1.3% by weight Theobromine in Chocolate. They also found other pharmacologically active compounds including up to 2.20% Phenylethylamine up to 1.54% Tele- methylhistamine and occasionally up to 5.82% Serotonin. They could not detect any Caffeine at all."

[3] and many more pages tell this inevitable truth. No caffeine in chocolate unless added afterwards. Maybe you ought to correct this like has been done for the foreign versions of this page?

Maybe some day someone will explain the difference between "could not detect" and "does not contain" to you. Until then, I hope you will enjoy this link. No one disputes that theobromine and tryptophan (I'm not sure whether cocoa contains actual serotonine) are more important constituents of cocoa than caffeine. BTW, the page you have cited also repeats the "Yerba Maté has no caffeine" myth claiming that "mateine" was a stereoisomer of caffeine (see the article for details why this is bunk). Aragorn2 18:49, 18 December 2005 (UTC)

Shirt

Do you wikipedians mind if I include a link to the
Caffeine Shirt (http://www.thinkgeek.com/tshirts/generic/2891/)
and the Caffeine Keychain (http://www.thinkgeek.com/gadgets/lights/6a43/)
in the External Links part?

I don't see how those products give any further encyclopedic information on Caffeine, so I'd advise against it. - Mpnolan 04:07, 21 Dec 2004 (UTC)

One More Hydrogen

Is there a hydrogen atom missing in the diagram? I only count nine but the chemical formula says ten. It appears to me that it should bond to the carbon on the left hand side that only shows three bonds. 20:25, 14 Nov 2004 (UTC)

Isn't there some kind of organic chem convention where you can omit obvious hydrogens? Pakaran (ark a pan) 20:31, 14 Nov 2004 (UTC)

Thanks for clearing that up. I didn't know for sure. I would show the hydrogen for clarity, but I'm not a chemist, so it is probably alright the way it is. Thanks again. 21:03, 14 Nov 2004 (UTC)

Yes, there is one hydrogen atom present but not shown at the tip of the five-membered ring. This is omitted to simplifiy the drawing of the structure. Since each carbon has four bonds, any carbon atom that shows less than four bonds is bonded to enough hydrogen atoms so it will be using four bonds. 29 Jan 2006

Caffeine content of Green Tea, etc.

<Jun-Dai 21:41, 30 Dec 2004 (UTC)>Doesn't the caffeine content of green tea vary wildly with the type of green tea in question (e.g., sencha vs. gyokuro-cha)? Why aren't any sources being credited for these data?</Jun-Dai>

Anecdote about coffee plant with little caffeine

Assuming that the information is accurate, the data I removed (compare my revision to 08:05, 15 Feb 2005) about a coffee plant in Ethiopia which contains very little caffeine should be moved to the coffee and/or coffee plant article (if such an article exists, as it should).

The passage is useful information, but requires significant rework to the writing style. I'm unsure of its accuracy.

Source of caffeine in soft drinks?

Is the caffeine added to fizzy drinks chemically synthesized? Extracted from vegetable sources (guarana? coffee? what?)?

It's 'waste' from coffee decaffeination. Cacycle 23:01, 15 Mar 2005 (UTC)

units

Units

If anyone's got time, the section on concentrations could do with editing so that the SI are the primary units, with other units in parentheses.

I second that - having a mix of different non-SI units makes it hard to compare the caffeine doses -- anon

Caffeine regulation in Canada

I don't know where this fact belongs, and I don't have a reliable reference, but as I understand it, in Canada there are restrictions on what drinks can contain caffeine - you can't add it to clear pops or juices, only colas. Canadian Mountain Dew has no caffeine. This is being circumvented by adding guarana... --Andrew 15:41, Apr 24, 2005 (UTC)

Of course, Guarana actually CONTAINS caffeine itself, but via loopholes in both Canada and the U.S., it doesn't need to be labeled as caffeine per se because it's within the guarana, a natural substance, as opposed to being in the form of pure caffeine powder, which is what's normally added to soft drinks. So guarana Mountain Dew will actually have caffeine, but consumers won't be told this.

• In fact, Mountain Dew Energy, sold in Canada, contains caffeine as a medical ingrediant, listed as such - the regulartions about this sort of thing are a little looser than they used to be. WilyD 22:37, 1 March 2006 (UTC)

Guarana is a bright red berry similar in size and shape to a cranberry, the outside fruit of the berry contains little if any caffeine, this is used in carbonated drinks like Anarcticas Guarana and Coca-cola's Kuat. The seed is where the main caffeine concentration is found, it is sold in a highly potent powder form.

Toxicity =

Too much caffeine can lead to caffeine intoxication. The symptoms of this disorder are restlessness, nervousness, excitement, insomnia, flushed face, diuresis, gastrointestinal complaints, even hallucinations. They can occur in some people after as little as 250 mg per day.

I'm very sceptical to the claim that 250 mg can cause hallucinations in anyone. Is there any source for it ?

Considering that an *average* Finn consumes 400-500 mg of caffeine per day (from ~0.5l of coffee) I find that claim ludicrous.

As for the other claims, calling those symptoms "caffeine intoxication" doesn't seem appropriate. They're mostly organism's natural reaction to stress, and the caffeine is supposed to induce them, in intensity depending on dosage. The article could be a little more balanced. Taw 01:22, 24 May 2005 (UTC)

-- It should be considered that caffeine tollerance develops very quickly. 250mg given to a small person with no caffeine tollerance could cause very drastic effects. I've seen people given as little as 300mg become wrecks, because they have no tolerance, while I have used 1200mg or more in the course of a day without apparent ill effect. I would LOVE to see some mathematical formulae that represent the PERCIEVED dose of caffeine, given adaptation to exposure. I would imagine that hallucinations are a result of VERY high doeses possibly combined with sensitivity to caffeine. In my experience, nervousness, irritability, lack of coordination, and gastointestinal complaints are most common. Again, all of this is annecdotal, but does provide some reference to the 250mg figure.

haha...Pull the other one. 250 mg can't under any *normal* circumstance induce hallucinations unless you're suffering from extreme oversensitivity and extremely low BMI. That's 3 cups of coffee for chrissakes - Sure I've seen people with little to no normal caffeine intake drink energy drinks, coffee or consume caffeine pills and the only symptoms I've witnessed are slight overanxiety, sweating along with what you called gastrointestinal complaints aka gas. I find this article with its links extremely biased...I'd dispute its neutrality if I only knew how :P

Purpose

What is the purpose/properties of putting/allowing caffeine in soft drinks and other beverages (assuming we're not talking about an Energy Drink or something else promoted as a stimulant)? Does decaffeined soda taste different than its counterpart? What is the justification for not having more decaffeinated beverages?

Depression

No mention of caffeine's links with depressive illness.

Because this isn't a pseudoscience wiki. -- Zantastik talk 08:05, 15 Jun 2005 (UTC)

Another great and dismissive Wikipedian reply. There exists mountain of evidence linking heavy caffeine consumption with depression. A 2 second google search would have shown you that. Rotten

If you're referring to the potential for caffeine to cause adverse effects, like insomnia, it's covered towards the end of the article. Otherwise, I agree with Zantastik. (pops open a mountain dew, sings a happy song) - Jersyko talk 12:30, Jun 15, 2005 (UTC)

Caffeine is the root of all evil, didn't you know? JFW | T@lk 06:37, 25 July 2005 (UTC)

Inaccuracies with Caffeine in Tea

"This article states that green tea has less caffeine than does black tea, while black tea is nothing but green tea that has been subjected to a process of oxidization. If someone disagrees, then tell me why I'm wrong and reinsert the material that I'm about to remove."

Reply to Zantastik: The fermenting process (withering, rolling, allowing oxidation) results in the leaves turning darker and more of the juices created by the process ending up on the outside of the leaves. Then, the leaves are blasted. So, black tea, which is fermented, DOES result in higher caffeine levels than green & white tea, which are unfermented. I think what leads to the higher levels is more of the juices dried onto the outside of the leaves.

-- Zantastik talk 08:03, 15 Jun 2005 (UTC)

Why the imperial units?

...which are incomprehensible to those used to metric units especially when they're used with SI derivative units. I'd propose some unit cleaning & internationalizing for the article, eg. I have no idea what the following means: ~2 shots of espresso from robusta beans (2 floz) (what is floz? what is a shot in this context?)....Remember that the readers are a global crowd.

    "Floz " is a typo for "fl oz," or "fluid ounce." A British fluid ounce is 28.413 ml (found on http://convert.french-property.co.uk/); American fluid ounces are very slightly different, but I think they are also approximately 28.4 ml.140.247.131.116 20:31, 4 January 2006 (UTC)

The article also doesn't even begin to cover the positive effects of caffeine. Infact the article is heavily biased towards caffeine is teh evil substance while it has many positive effects to the human body.

Here are few example links for the positive effects: http://www.newscientist.com/article.ns?id=dn3619 http://www.medicalpost.com/mpcontent/article.jsp?content=/content/EXTRACT/RAWART/3623/23A.html http://www.cosic.org/coffee-and-health/alzheimers-disease http://www.abc.net.au/rn/talks/8.30/helthrpt/stories/s30640.htm http://www.indianpediatrics.net/dec-99/99-dec-20.htm http://www.faqs.org/faqs/caffeine-faq/

Stereochemistry of Caffeine

The article mentions, However, this is impossible; caffeine is an achiral molecule with no chiral centers, and therefore has no stereoisomers.. If I understand the phrasing correctly that caffeine is achiral because it has no chiral centers, then that's contradicted by the article on chirality which states, It is also possible for a molecule to be chiral without any specific chiral centers in the molecule. The articles on axial_chirality and planar_chirality support that notion, as well. Can someone verify the article's assertion from scientific sources like a peer-reviewed journal article or review on caffeine? - Gyan 02:36:10, 2005-09-04 (UTC)

Take a look at the caffeine molecule. It's obvious that there are no chiral centers - all tetravalent atoms (i.e. carbon atoms) have at least one double bond or two identical neighbors. There are no chiral axes either: The only potential chiral axis is between the two central carbon atoms which share a double bond. The ligands of those carbon atoms, however, cannot be inverted without altering the molecule's connectivity. As for potential planar chirality - the caffeine molecule is pretty much planar, so that makes no sense at all. If the achirality of this simple molecule is still disputed, however, I challenge people to come up with a depiction of an actual stereoisomer (e.g. "mateine" or "guaranine"), then we can discuss whether that's actually structurally identical and exhibits a different configuration -- there's simply a limit on how much the burden of proof should be allowed to shift in this debate. Aragorn2 20:14, 18 December 2005 (UTC)

Caffeine as an appetite suppressant?

This is a somewhat uninformed question - but I notice that whenever I drink coffee in the morning (9,10am) I'm not hungry again until dinner time. I have a constant feeling of fullness, yet I know caffeine speeds up one's metabolism. Is this an effect of caffeine, the particular coffee, or maybe the cream perhaps (I don't use sugar)?

Also, what causes "the shakes"? Is it just the musculo-nervous system over-wired from the caffeine, or something else? Are the shakes from caffeine the same shakes from low blood sugar?

USP?

What is USP, mentioned in the image text? United States Pharmacopoeia?

Melting / boiling points ?

1. Melting point: 238 °C
2. Boiling point: 178 °C (sublimes)

Isnt it meant to be the other way round ? When i did Chem things normally melted and then boiled? --2mcm^Gespräch 20:10, 26 October 2005 (UTC)

Actually, you got it right on the head. Under normal conditions, most things do melt before they boil. But caffeine, under most conditions, sublimes- it goes directly from a solid to a gas without any liquid phase. If you worked with iodine, the same thing probably happened. Dry ice is another example- it's carbon dioxide that goes directly from a solid to a gas without an intermediate stage. Even water can be coaxed into doing this- in fact, most any substance can. --2tothe4 23:22, 27 October 2005 (UTC)

Solubility/ boiling and melting points

Anyone know if caffeine is soluble in ethanol or other solvent and if so how soluble it is? The other thing is, I answered about the subliming buisness above, but under what conditions does caffeine melt instead of sublime? I'm assuming it has something to do with pressure, in which case this pressure should be indicated in the article. --2tothe4 23:25, 27 October 2005 (UTC)

As a general rule, the more the volume changes during a reaction, the more that reaction is affected by pressure (see Phase diagram). So bp is expected to be highly pressure-dependent while melting is reasonably independent of pressure. If P is not known, a reported bp value is pretty useless. However, there are standards that may be implied. DMacks 09:07, 15 February 2006 (UTC)

I actually found part of it... I found it's insoluble in ethanol(on the godawful slow online CRC, at http://www.hbcpnetbase.com/ ) But no luck on the melting conditions yet. --2tothe4 23:42, 27 October 2005 (UTC)

Usage in Pain Relief Pills

How is caffeine used as a pain relief enhancer in medicines like Exedrine? 153.104.16.114 01:50, 11 November 2005 (UTC)

It might be related to the action of caffeine on the adenosine receptors which mediate(s) antinociception, thus helping with the analgesia of muscle and bone. Hence, it might work alone, without aspirin or acetaminophen (paracetamol) in the formulation. Don't consider this medical advice, just my unproven hypothesis. Jclerman 03:10, 11 November 2005 (UTC)

I have read that caffeine has no documented enhancing effects when used with pain relievers. However, this article states ""There is no evidence that caffeine relieves pain, but it can enhance the effects of aspirin, possibly by lifting a person's mood," says Michael Weintraub, M.D., director of FDA's Office of OTC Drug Evaluation." PrometheusX303 13:39, 15 January 2006 (UTC)

It is also useful to consider that caffeine withdrawl is a very common cause of headaches, so to add it to pain relief pills is a fair method of covering bases. Of course, that's speculation, and is not appropriate for the article proper. – ClockworkSoul 16:22, 16 January 2006 (UTC)

Caffeine Chemistry

As an organic chemistry student, I'm finding the drug page on caffeine to be inadequate. Is someone willing to write an organic compound article, following that format (see dichloromethane)? I don't do much of this sort of thing, but if someone were to write Caffeine_(chemistry) or whatever the standard would be, I think it would be helpful. --horsedreamer 18:36, 16 November 2005 (UTC)

Well, with your credentials you should certainly be able to make a start! JFW | T@lk 20:46, 16 November 2005 (UTC)

Check the page how: how's that look? – ClockworkSoul 19:30, 2 January 2006 (UTC)

History section needs improvement

I believe "the first documented use of caffeine in a beverage for its pharmacological effect" was by Buddhist monks, of the sect best known as Zen (Chan in Mandarin Chinese; Son/Seon in Korean). Zen made it to Japan in the 12th century, meaning it was in Korea and China even earlier. However, I don't know the dates for the history of green tea use within Zen Buddhism. Anybody else know? Squidley 07:29, 17 November 2005 (UTC)

"4 to 20 mg/floz ... (40 to 170 mg/5 floz)"

Inconsistent arithmetic. Please check for correct figures. Jclerman 04:29, 22 November 2005 (UTC)

A little bit help with spiders

I'm doing a biology project on drugged spiders' web patterns. This article has only one sentence about it and actually the resources are limited. I was just asking if you could add some more about that, or advice me a source, etc. Thanks for your time. --Quinlan Vos 19:58, 27 November 2005 (UTC)

Will this message ever get attention? I really need some info from chem students. Thank you for your time again. --Quinlan Vos 01:46, 18 January 2006 (UTC)

Heyy.. Dude, spiders are like really far out. I mean, like drugs are too.. but spiders are just whoa. you know? yeaah.

• Though this is a talk page, try and stay on subject please... The PA 17:58, 27 January 2006 (UTC)

Caffeine extraction

About solubility, I'm a college student and I did a lab consisting of the extraction of caffeine from Red Bull. I have my entire protocol I could summarise for this page to point out that though it isn't difficult, it requires some time and a good amount of equipement for it to be done. I posted a sumamry about the extraction on the french page, go see it and tell me if it makes sense (it should, because I did that in my lab and it worked).

We used chloroform to get the caffeine out of the drink so it should be a nice organic solvant, though to what extent...

I was thinking something along these lines:

"It is very difficult to know the exact amount of caffeine in a particular drink that is not automatically prepared. The ammount of caffeine in a single serving of coffee varies considerably due to many variables. Concentration can vary from bean to bean within a given bush; prepration of the raw bean will affect concentration, as well as multiple variables involved in brewing.

To extract caffeine takes some time (about two hours) and requires chemicals unavailable for everyday use and a nice system of distillation and sublimation. To extract caffeine, one must take the beverage one wants to extract the caffeine from and mix it with a solvent with a finer affiliation to the caffeine and a different density. Chloroform is known to possess both these properties.

Caffeine will go in the solvent it is the most soluble in, and it is more soluble in chloroform than water. Using a separating funnel, one should take about 30 ml of chloroform and 200 ml of the beverage one wants to extract the caffeine from and agitate for about two minutes. The bottom phase will be the chloroform and the caffeine, so one will keep this phase. Repeating this step about five times should ensure extraction of most of the caffeine.

The next step is a distillation using a standard distillation column where one gets rid of most of the chloroform. Finally, one has to sublimate the caffeine under vacuum."

Does that fit with the objective of this article? The PA 01:47, 8 December 2005 (UTC)

• Comment I think that's a great nugget of info to include in the article. It's well-written and I can only think of a few suggestions. You might consider reducing the use of "you" (there's a grammatical word for this that I can't immediately recall) in favor of "one" or some other workaround. Change "The amount of caffeine in, say, a cup of coffee, varies a lot, even if it is made by the same person the same way every day" to something like "The ammount of caffiene in a single serving of coffee varies considerably due to many variables. Concentration can vary from bean to bean within a given bush; prepration of the raw bean will affect concentration, as well as multiple variables involved in brewing." My version isn't that great; I'm just suggesting a more encyclopedia-like and less conversational voice. Jasmol 03:31, 8 December 2005 (UTC)
• It's nice, I like it! I'll edit my above post to your ideas and wait around just a couple days more to decide where to put it and wait for more feedback.
  The PA 04:30, 8 December 2005 (UTC)
• I'll put it in the article and see what happens, as it's not getting a lot of attention this way.
  The PA 01:16, 12 December 2005 (UTC)

Long term effects

It would be nice if there was more on the long term effect of regular caffiene use in this article.

• Well there is the part about caffeine addiction on the article which I find interesting and concerns this subject. The PA 05:25, 29 December 2005 (UTC)

The spider web picture

It seems to have an anti-caffeine agenda to me. Yes, technically it is a neutral fact, but IMO it is obviously meant to imply that caffeine has analogous adverse effects on the human mind. For this, it is actually a very weak argument, because a spiders nervous system is clearly very different from a humans (and they were probably given extremely high doses anyway). Yet, the picture seem quite convincing at first glance and some casual readers will probably consider it good "evidence" for the above-mentioned conclusion (people like analogies).

Thus, I find the picture highly misleading and vote for its removal (or maybe move it to a page about spiders or differences of drug effects between species, where it would be more on-topic than here). If you want to argue that caffeine has negative effects on human cognition, fine, but please do so explicitly and not in such an unfair way.

Sorry for the rant, maybe I'm overreacting. I guess that I'm just a little tired of this kind of "reasoning".

Comment: I agree that the picture should in no way be used as evidence for the argument that caffeine is highly dangerous and/or destructive. However, I think it is a rather interesting bit of information and should remain. I've seen two other similar pictures, where the spiders were on LSD and marijuana (not both at the same time). The LSD web was even more geometrically perfect than the average spider web, and the marijuana web was loosely constructed and unfinished. It would be foolish to speculate from these pictures that caffeine is destructive to thought and organizational thinking or that LSD enhances performance. Here is one of many links that has pictures of various drug-induced webs: http://www.trinity.edu/jdunn/spiderdrugs.htm

There is no claim or insinuation that caffeine is highly dangerous, and considering that plant caffeine serves as an insect deterrant, the reason for its effect on arthropods is clear. The article makes no such claims about humans, however. – ClockworkSoul 15:12, 26 January 2006 (UTC)

Major rewrite/reformat

I was very bold, and went ahead and spent four hours reformatting this entire article. Overall, very little was removed (except a bit on caffeine chirality that I thought was too technical), but a great deal of reorganization and copyediting took place. One major flaw of this article was one that most major articles can claim after a period of time: an accumlation of minor one-line edits that contribute to an overall awkwardness to the article. I hope that I haven't offended anybody with my changes, but please keep in mind that I put a vast amount of thought and effort into it. Ironically, I didn't enjoy any caffeine at all while I did this work. – ClockworkSoul 02:07, 31 December 2005 (UTC)

Re: "No caffeine, http://www.mrkland.com/fun/xocoatl/caffeine.htm"

This is in response to this edit, with the comment "No caffeine, http://www.mrkland.com/fun/xocoatl/caffeine.htm". Your post prompted me to do a detailed search on the claim (I want everything to be accurate as possible), and I found the following results:

• The cited web page has a "science page", which cites "Biochemist, Apr/May 1993, p 15. copyright of Royal Society of Chemistry website 2000" as its source. However, no such journal as "Biochemist" exists.
• I found a few journals with similar names, though: Biochemistry, Bioconjugate Chemistry, and Biomacromolecules. Searching the entire year of 1993 turns up two articles that mentioned caffeine in the article body, and none that mentioned both caffeine and chocolate.
• A quick PubMed search however, finds quite a number of articles that mention finding caffeine in both cocao and chocolate in the small quantities mentioned in the caffeine article. [4] [5] [6] [7]
• Other sources confim this, including the International Cocoa Organization and the International Food Information Council.

ClockworkSoul 23:14, 3 January 2006 (UTC)

Claim about an "energizing drink"

The article currently contains the following sentence:

"In addition, Arabica coffee, which is widely regarded as the highest quality of commercially produced coffee, contains less caffeine content than the Robusta variety, which is normally used in instant coffee or is combined with arabica to produce a flavorful yet highly energizing coffee drink"

It seems to claim special "energizing" qualities for a drink made from both arabica and robusta. This sounds rather like quack science. I can think of two possibilities:

1) the article previously contained a brand name of some energy drink containing both types of coffee bean, and that the brand name has been removed to leave a rather misleading sentence.

or

2) someone genuinely believes that a mixture of the two coffees has this special property... for which there seems to be no evidence whatsoever.

Either way, I think the phrase "yet highly energizing" has got to go.

I'll wait for a second opinion before going ahead, but if anyone else agrees please go ahead and make the change.

• I'm with you. At the very least, it's POV. I'm removing it now. – ClockworkSoul 22:25, 21 January 2006 (UTC)

I don't think it's meant to claim that the combination has a special property; rather, it is simply stating, in a rather strange way, that combining the two beans combines the properties of both. ie, the flavour of arabica and the high caffeine of robusta. More often I think the two are combined for the cheapness and high yield of the robusta, rather than the caffeine. 57.66.51.165 14:28, 1 March 2006 (UTC)

"The caffeine is generally obtained..."

Comment about a paragraph that perhaps needs correction: It is my understanding that one of the reasons that determines which source of caffeine is used (natural -extracted- or artificial -synthesized-) is the respective country regulations, i.e., whether they require to use only natural products in the drinks. Some manufacturers of soft drinks used to obtain "forensic" carbon isotope analysis on batches of caffeine in order to decide whether to use them in their drinks. Jclerman 17:22, 28 January 2006 (UTC)

• If you can find a source for that, it would be a welcome addition/correction to the article. – ClockworkSoul 16:13, 29 January 2006 (UTC)
  • I'll try to find something. My unpublished source is my witnesing it while I did research in a radiocarbon dating lab in Europe. Jclerman 22:06, 9 February 2006 (UTC)
  • There should be a paper somewhere. I'll do a bit of searching, too. – ClockworkSoul 01:14, 10 February 2006 (UTC)

the cocoa article

Can someone go over to cocoa and write about its chemical composition? it seems the caffeine article has more information on it that its own article. --Fs 11:31, 17 March 2006 (UTC)

A Strange report of Caffeine Addiction

Report by China Central TV

It seemed that in some places in Shanxi, China, people are abusing caffeine in a way not dissimliar to heroin; they even "chase the dragon" and there are illegal labs synthesizing caffeine from theophylline since the former is a controled substance in China yet the latter isn't.

Should it be added to this article? — Preceding unsigned comment added by Samuel Curtis (talk • contribs)

• The article is unavailable now, but I'm personally skeptical of articles posted on any tightly-controlled state-operated media, especially when it has do do with a substance that is banned. This smells of propaganda to me, and I would prefer that we wait for a less potentially biased source. – ClockworkSoul 20:51, 19 March 2006 (UTC)