Isomers, chemical

Fig. 12.3 Minimum Wiener-index principle Wiener Index is able to select compact isomers, chemically stable...

More than 400 chemical compounds have been identified in marijuana. Approximately 60 of these are unique to the cannabis plant, substances called cannabinoids. Of the cannabinoids, a group of isomers (chemically similar substances) called tetrahydro-cannabinols (THC) are thought to be the most psychoactive. These are Ai-THC (also called A9-THC) and A6-THC (also called A8-THC). Other cannabinoids include cannabidiolic acid (CBDA), cannabidiol (CBD), and cannabinol (CBN). Their role in marijuana intoxication is less well understood. The amount of THC produced depends on the strain of cannabis and on environmental factors such as growth, harvest, and storage conditions. 

Isomers Chemical compounds having the same formula, but different three-dimensional structures. 

Isomer Chemical compounds with the same molecular weight and atomic composition but differing molecular structure (e.g., n-pentane and 2-methylbutane). 

L. H. Hall and L. B. Kier TABLE 1. Index values for heptane isomers Chemical graph... 

Fong, Y. Y., Abdullah, A. Z., Ahmad, A. L., Bhatia, S. (2008). Review—development of functionalized zeolite membrane and its potential role as reactor combined separator for para-xylene production from xylene isomers. Chemical Engineering Journal, 139, 172-193. 

Fowler, P. W., Zerbetto, F. (1995b). Charging and equilibration of fullerene isomers. Chemical Physics Letters, 243(1-2), 36-41. 

Raghavachari, K. (1992). Ground state of C84 Two almost isoenergetic isomers. Chemical Physics Letters, 190(5), 397-400. 

Tagmatarchis, N., Arcon, D., Prato, M., 8c Shinohara, H. (2002). Production, isolation and structural characterization of [92]fullerene isomers. Chemical Communications, 2002(24), 2992-2993. 

Zheng, G. S., Irle, S., 8c Morokuma, K. (2005). Performance of the DFTB method in comparison to DFT and semiempirical methods for geometries and energies Of C20-C86 fullerene isomers. Chemical Physics Letters, 412(1-3), 210-216. 

Fig. 14 Representative direct enantiomeric separations of brivanib and its isomers on different CSPs (a) polysaccharide Chiralcel OD-H (coated ceUulose carbamate), (b) Chiralpak 1C (3,5-dichlorophenylcarbamate of cellulose, immobilized on 5-(jtm silica), (c) Chirobiotic V2 (vancomycin), (d) Cyclobond RSP (cyclodextrin), (e) ChiroSil SCA (-) (crown ether), and (f) Sumichiral OA-4800 (Pirkle) column. Peak identification 1, (SR)-, 2, (RS) 3, (RR)-, 4, (S5) 5, positional isomer , chemical impurity (adapted from [150])...

The shift due to Coulomb interactions is of the order of 10 of the transition energy. The value of the shift for every nuclear level depends on the chemical state of the atom. This is characterized by the IV (0)l s parameter which is the electron density at the nucleus in the absorber (a) or in the source (s). In a Mossbauer spectrum this part of the full electrostatic interaction manifests itself as the isomer (chemical) shift d between the centre of gravity of the... 

Consecutive Registry Numbers are awarded to each new substance registered in the CAS Registry database. Although they contain no inherent information about the chemical composition or structure of the substance, they represent a unique identification tag for each substance and its stereo chemical descriptor. E.g. different CAS Registry Numbers are assigned to isomers, chemicals marked with isotopes or ions with different valences. It is important to know that unspecific chemicals also have a unique number ... 

The characteristic shift of the center of the Mossbauer spectrum from zero velocity is called the isomer (chemical) shift and reflects the differences in electronic environment of Fe in source and absorber. When there is a quadrupole splitting of the I = 3/2 14.4 keV level, a two-line spectrum results. Six lines are found when there is no quadrupole interaction and when either an external magnetic field is applied or a hyperfine interaction exists, thai produces an effective field at the nucleus. Relaxation effects and the different charge states of Fe lead to a wide variety of spectra which have been analyzed (Cammack et al, 1977). 

Wright, R. H. Odor and molecular vibration Optical isomers. Chemical Senses and Flavour 3, 35—37(1978). 

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