Talk:Caffeine

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Caffeine is a former featured article. Please see the links under Article milestones below for its original nomination page (for older articles, check the nomination archive) and why it was removed.

This article appeared on Wikipedia's Main Page as Today's featured article on September 16, 2006.

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Date	Process	Result
January 22, 2006	Featured article candidate	Not promoted
August 20, 2006	Peer review	Reviewed
September 7, 2006	Featured article candidate	Promoted
December 9, 2011	Featured article review	Demoted
Current status: Former featured article

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Self-assembly of Caffeine

Caffeine is known to exist in different polymorphic form. It has been shown that an anhydrous form of caffeine can undergo supramolecular self-assembly leading to gelation in alcoholic solvents including ethanol at very low concentration (1). This might bring some new application of caffeine in materials science.

(1) Nonappa; Kolehmainen, E. Caffeine as a Gelator. Gels 2016, 2, 9. — Preceding unsigned comment added by Nonappa (talk • contribs) 17:40, 3 March 2016 (UTC)[reply]

Are you proposing this be added to the "Research" section? Sizeofint (talk) 19:18, 3 March 2016 (UTC)[reply]

Review

... of risks and benefits for neurological disease doi:10.1136/practneurol-2015-001162 JFW | T@lk 22:44, 16 March 2016 (UTC)[reply]

Semi-protected edit request on 8 August 2016

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In the Physical and chemical properties, the line "It is weakly basic (pKa = ~0.6) requiring strong acid to protonate it.[138]" is incorrect, I would suggest changing it to:

"It is weakly basic (pKb = ~0.6) requiring strong acid to protonate it.[138]" and not referencing the book but the paper directly (see below).

The pKa value for caffeine is around 14:

https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma-Aldrich/Product_Information_Sheet/c0750pis.pdf

I followed the citation 138 and in the book "Harry G. Brittain; Richard J. Prankerd (2007). Profiles of Drug Substances, Excipients and Related Methodology, volume 33: Critical Compilation of pKa Values for Pharmaceutical Substances. Academic Press. p. 15. ISBN 0-12-260833-X. Retrieved 15 January 2014." on the page 106 values of pKa for caffeine are indeed -0.13 and 0.18 - this is also incorrect, thus it would suggest that caffeine is an acid comparable in strengt to e.g. TFA. The table on the page 106 points out to the paper by ROBERT L. BENOIT AND MONIQUE FRECHEIT "Protonation of hypoxanthine, guanine, xanthine, and caffeine". In the paper, it were the pKb values that were measured not pKa (as stated in the last line of the abstract).

212.87.10.2 (talk) 12:54, 8 August 2016 (UTC)[reply]

I did a CTRL-F in that paper [1] and I'm not seeing where it has the 0.6 figure. Sizeofint (talk) 17:27, 8 August 2016 (UTC)[reply]

Not done: Like Sizeofint I cannot find anything in the article to support that change. The sheet does say the pKa is 14, but there's nothing about 0.6 in the pdf and there's no "pKb" either. EvergreenFir (talk) 01:02, 9 August 2016 (UTC)[reply]

Contradiction

In the lead, it says caffeine may be used to treat pulmonary dysplasia of prematurity and prevent apnoea of prematurity, then in the next section that it is used to treat or prevent pulmonary dysplasia of prematurity and treat, but not prevent, apnoea of prematurity. Which is correct? At least I try (talk) 03:03, 21 August 2016 (UTC)[reply]

I think the article is correct, fixed the lead. Sizeofint (talk) 04:09, 21 August 2016 (UTC)[reply]

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assorted problems

Addiction - some degree of aversion may actually occur, which? (with?) people preferring placebo Effects of genetics - and beta-1 and beta-2 play roles - beta-1 & beta-2 should be fully identified here (rather than in a following sentence). people with the heterozygote? (heterozygous?) ADR beta-2 Beta 2- (is it beta-2, beta2, or beta 2? - be consistent) adrenoceptors are receptors that regulate glycogenolysis, secret? insulin (insulin secretion,?) and intramusculatly transport? (intramuscular transport of? - I doubt the receptor transports insulin or glucose itself) glucose Arg389 homozygotes? (homozygous?) subjects altered norepinephrine (an adrenoceptor agonist) neurotransmission contribute? (contributes?) to Biosynthesis - The text describes chemical synthesis, not biosynthesis. Figure - lab synthesis - where does the nitroso (NO) group come from? Analogs - have also been elucidated? (identified?). Products - and inhalation? (inhalants?). Caffeine content in select food and drugs - 12 fl. oz. Coca-Cola Classic is listed as 34 mg and 96 mg/L but the same size Guarana Antarctica is given as 30 mg (less) and 100 mg/L (more - inconsistent). 69.72.92.65 (talk) 06:36, 6 February 2017 (UTC)[reply]