SPECIFIC PROTONATION OF THE CARCINOGEN 7, 12-DIMETHYIBENZ [a]ANTHRACENE AND CHARGE LOCALIZATION IN THE a-COMPLEX

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In the class of the polycondensed aromatic hydrocarbons, the concept of localized charge in a {sigma}-complex, e.g., the carbonium ion formed by addition of a proton or other electrophile to an aromatic ring, has so far received experimental evidence only in the case of anthracene. The ultraviolet spectrum of this compound in sulfuric acid is similar to that of the benzhydryl cation. Ph{sub c}C{sup +}Me. This result implies the protonation of anthracene at one meso-carbon atom and the localization of the positive charge at the other. The {sigma}-complex of the potent carcinogen 7,12-dimethylbenz[a]anthracene (DMBA) in acidic medium offers another example ... continued below

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8 p.

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Cavalieri, Ercole & Calvin, Melvin. April 1, 1971.

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Description

In the class of the polycondensed aromatic hydrocarbons, the concept of localized charge in a {sigma}-complex, e.g., the carbonium ion formed by addition of a proton or other electrophile to an aromatic ring, has so far received experimental evidence only in the case of anthracene. The ultraviolet spectrum of this compound in sulfuric acid is similar to that of the benzhydryl cation. Ph{sub c}C{sup +}Me. This result implies the protonation of anthracene at one meso-carbon atom and the localization of the positive charge at the other. The {sigma}-complex of the potent carcinogen 7,12-dimethylbenz[a]anthracene (DMBA) in acidic medium offers another example of this type of charge localization. The determination of structure was achieved by comparing the NMR spectra of DMBA in neutral and acidic solvents. The ratio of the integrated intensities of the proton peaks in the spectrum of DMBA is, from right to left, 3:3:5:1:1:2:1. The assignment of the 7-CH{sub 3} ({sigma}3.00) and 12-CH{sub 3} ({sigma}3.29) resonances was made by comparison with the spectra of 7-methylbenz[a]anthracene (7-CH{sub 3}, {sigma}3.03) and 12-methylbenz[a]anthracene (12-CH{sub 3}, {sigma}3.32) under the same conditions. A good general correlation exists between the methyl chemical shifts of the twelve monosubstituted methylbenzanthrancenes and the corresponding aryl protons of benzanthracene.

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8 p.

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  • Report No.: UCRL--20650
  • Grant Number: DE-AC02-05CH11231
  • DOI: 10.2172/928502 | External Link
  • Office of Scientific & Technical Information Report Number: 928502
  • Archival Resource Key: ark:/67531/metadc898695

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • April 1, 1971

Added to The UNT Digital Library

  • Sept. 27, 2016, 1:39 a.m.

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  • Nov. 3, 2016, 8:01 p.m.

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Cavalieri, Ercole & Calvin, Melvin. SPECIFIC PROTONATION OF THE CARCINOGEN 7, 12-DIMETHYIBENZ [a]ANTHRACENE AND CHARGE LOCALIZATION IN THE a-COMPLEX, report, April 1, 1971; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc898695/: accessed December 17, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.