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1,3,7-Trimethyluric acid, also referred to as trimethyluric acid and 8-oxy-caffeine, is a purine alkaloid that is produced in some plants and occurs as a minor metabolite of caffeine in humans. [1] The enzymes that metabolize caffeine into 1,3,7-trimethyluric acid in humans include CYP1A2 , CYP2E1 , CYP2C8 , CYP2C9 , and CYP3A4 .
Xanthine (/ ˈ z æ n θ iː n / or / ˈ z æ n θ aɪ n /, from Ancient Greek ξανθός xanthós ' yellow ' for its yellowish-white appearance; archaically xanthic acid; systematic name 3,7-dihydropurine-2,6-dione) is a purine base found in most human body tissues and fluids, as well as in other organisms. [2]
For example, the three isomers of xylene CH 3 C 6 H 4 CH 3, commonly the ortho-, meta-, and para-forms, are 1,2-dimethylbenzene, 1,3-dimethylbenzene, and 1,4-dimethylbenzene. The cyclic structures can also be treated as functional groups themselves, in which case they take the prefix "cyclo alkyl -" (e.g. "cyclohexyl-") or for benzene, "phenyl-".
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A multiple choice question, with days of the week as potential answers. Multiple choice (MC), [1] objective response or MCQ(for multiple choice question) is a form of an objective assessment in which respondents are asked to select only the correct answer from the choices offered as a list.
[1] [2] [3] Aspirin Still a Bayer trademark name for acetylsalicylic acid in about 80 countries, including Canada and many countries in Europe, but declared generic in the U.S. [4] Catseye Originally a trademark for a specific type of retroreflective road safety installation. [5] The IP belong to Reflecting Roadstuds Ltd. and was registered by ...
[2] [3] There is a well-known myth about the word quiz that says that in 1791, a Dublin theatre owner named Richard Daly made a bet that he could introduce a word into the language within 24 hours. He then went out and hired a group of street children to write the word "quiz", which was a nonsense word, on walls around the city of Dublin.
A classic example for favoring the keto form can be seen in the equilibrium between vinyl alcohol and acetaldehyde (K = [enol]/[keto] ≈ 3 × 10 −7). In 1,3-diketones, such as acetylacetone (2,4-pentanedione), the enol form is more favored. The acid-catalyzed conversion of an enol to the keto form proceeds by proton transfer from O to carbon.