Dimethylphenanthrene

Dimethyl hydrogen phosphite 1,4 Dimethylphenanthrene Dimethyl sulfate... 

Sinsheimer JE, Giri AK, Hooberman BH, et al. 1991. Mutagenicity in Salmonella and sister chromatid exchange in mice for 1,4-dimethylphenanthrenes 1,3-,2,4-dimethylphenanthrenses and... 

Figure 1.4 Two-dimensional plot of HPLC (log /J and GC (log Iq) retention indexes (1) naphthalene (2) 2-methylnaphthalene (3) 2,3-dimethylnaphthalene (4) 2,3,6-trimethyl-naphthalene (5) biphenyl (6) fluorene (7) dibenzothiophen (8) phenanthrene (9) 2-methylphenanthrene (10) 3,6-dimethylphenanthrene (11) benzo[a]fluorene (12) chrysene (data replotted from reference (31)).

The molecules most profitably studied in connection with purely steric isotope effects have been isotopically substituted biphenyl derivatives. Mislow et al. (1964) reported the first more or less clearcut example of this kind in the isotope effect in the configurational inversion of optically active 9,10-dihydro-4,5-dimethylphenanthrene (7), for which an isotopic rate ratio ( d/ h) of 1-17 at 295-2°K in benzene solution was determined. The detailed conformation of the transition state is not certain in this case, as it involves the mutual passage of two methyl groups, and thus it is difficult to compare the experimental results with... 

Inhibition of tumorigenicity by peri methyl substitution. The methylated PAH shown are less tumorigenic than other methyl isomers in the same series or than their parent compounds. References 5,12-dimethylchrysene (14) 4,9-dimethylphenanthrene... 

Dimethyl-1 -pentene 4.4- Dimethyl-1 -pentene 2.4- Dimethyl-2-pentene cis-4,4-Dimethyl-2-pentene frara-4,4-Dimethyl-2-pentene 2,7-Dimethylphenanthrene 4,5 -Dimethy lphenanthrene 9,10-Dimethylphenanthrene 2,3-Dimethylphenol 21.02... 

The authors succeeded in preparing (20-25) a series of long-lived carbocations bearing vinyl and related groups in the p-position to the carbocationic center (la-d, 3). Their structures were confirmed by and 13C NMR spectroscopy. These cations can be considered as a-complexes of C-centered electrophilic agents, namely vinyl and methyl-substituted vinyl cations derived from 9,10-dimethylphenanthrene and 1,2-dimethylacenaphthylene, respectively. Quite naturally, they had not been prepared by electrophilic vinyl-... 

Garrigues, P, Radke, M., Druez, O., Willsch, H., and Bellocq, J., Reversed-phase liquid chromatographic retention behaviour of dimethylphenanthrene isomers, J. Chromatogn, 473, 207, 1989. 

The unsigned average deviation between calculated and experimental energies is 0.36 kcal/mol for a collection of 35 benzenoid molecules. This result does not include 7,12-dimethylbenz[a]anthracene (36) the discrepancy of 16 kcal/mol between theory and experiment is in all likelyhood due in part to an error in the latter. Although certainly real, steric interactions involving the methyl group in position 12 are probably not so severe as to cause a destabilization exceeding that found in 1,8-dimethylnaphthalene and 4,5-dimethylphenanthrene—molecules that are discussed further below. 

Example 14.4 4,5-Dimethylphenanthrene. Using the C NMR spectrum measured by Stothers et al. [275], we deduce A/// = 36.8 kcal/mol assuming planarity. Closely neighboring methyl groups that are separated by five bonds in the molecular skeleton, however, result in chiral nonplanar conformations [276]. Modeling, where appropriate, the CC bonds on those described for biphenyl and m-stHbene, one predicts A/// = 47.8 for the nonplanar form, in acceptable accord with the reported value [248], 46.26 + 1.46 kcal/mol, a result that is self-explanatory. 

Phenanthrene, fluoranthene, and pyrene—the three abundant parent PAHs identified by GC—were confirmed by MS. The major GC peaks between phenanthrene and fluoranthene were characterized as methyl- and dimethylphenanthrene/anthracene. Four compounds, each having a nominal mass of 192 amu were dejected. Small fragment ions at masses corresponding to (M-l), (M-27)+ and M", were detected. A general feature of these spectra was loss of a methyl group from the parent ion. The spectral features are characteristic of dimethyl or ethylphenanthrene/anthracene. 

Epoxidation of aromatic hydrocarbons is an important method for the preparation of arene oxides. m-Chloroperbenzoic acid (MCPBA) is used in a two-phase system that involves treating the hydrocarbon with a large excess ( 10-fold) of MCPBA in methylene chloride-aqueous sodium bicarbonate at room temperature. The yields are moderate (10-60%). Because the arene oxides are sensitive to acids, the presence of sodium bicarbonate buffer is necessary. A number of K-region (see Section VII for a definition) epoxides like phenanthrene 9,10-oxide (1, 59%), 9,10-dimethylphenanthrene 9,10-oxide (2,40%), 9-phenylphenanthrene 9,10-epoxide (3,50%), pyrene 4,5-oxide (4, 14%), and chrysene 4,5-oxide (5,9%) have been prepared by this method.9... 

Also, 9,10-dimethylphenanthrene (199) on oxidation with Cr(V)-phen-anthroline complex has been shown to give l0,10-dimethyl-9-phenanthrone (200).121... 

Phenanthrene (7), the smallest member of the helicene series, is planar in its neutral state and shows aromatic character. Reducing the compound with lithium affords a highly paratropic dianion34 (72 ) that, according to calculations, is not planar35. It is possible to twist the sp2 framework of phenanthrene by its alkylation at the 4- and 5-positions36, i.e. in 4,5-dimethylphenanthrene (8), 2,4,5,7-tetramethylphenanthrene (9) and 2,4-di-ferf-butyl-5,7-dimethylphenanthrene (10). When these systems are reduced with lithium metal, three... 

Decahydro-4a,Sb-dimethylphenanthrene (3). This very air-sensitive hydrophen-anthrene nucleus is obtained by a [2 -I- 2 -I- 2] cycloaddition of enediync (1) mediated by CpCo(CO),. This cyclization is noteworthy because it involves cyclization of a tetra-... 

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