L//-Purine-2,6-diones

CN 3,7-dihydro-8-[(2-hydroxyethyl)methylamino]-l,3,7-trimethyl-l//-purine-2,6-dione... 

CN 7-[2-(diethylamino)ethyl]-3,7-dihydro-l,3-dimethyl-l//-purine-2,6-dione monohydrochloride... 

CnH 5N02 727-28- ) see Isoprenaline 7-[2-[2- (3,4-dihydroxyphenyl)-2-oxoethyl](phenylme-thy l)amino jcthy 11-3,7-dihydro-1,3-dimethyl-l//-purin-2,6-dione... 

Heteroxanthine l//-Purine-2,6-dione, 3,7-dihydro-7-methyl- Maleic acid 2-Butenedioic acid, (Z)-... 

Isocaffeine l//-Purine-2,6-dione,3,9-dihydro-l,3,9-trimethyl- Naphthalic acid 1,8-Naphthalenedicarboxylic acid... 

C - For powder diffraction data determination the key step is the generation of reliable trial structures for final refinement. The subject of the study reported here is the pharmaceutical material anhydrous theophylline (3,7-dihydro-1,3-dimethyl-l//-purine-2,6-dione), which contains both oxygen and nitrogen as possible hydrogen bond acceptor atoms. Solid-state NMR spectra of a commercial sample not only confirmed immediately that there was only one molecule in the crystallographic asymmetric unit but also produced distinctive and chemical shifts. 

In addition to several amides (asparagine, glntamine, urea), Doull et al. lists the imide 3,7-dihydro-l,3,7-trimethyl-l//-purine-2,6-dione (caffeine) among individual compounds used in cigarette manufacture by U.S. companies (1053). 

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