Mass spectra phenanthrenes

Besides a parent ion, the mass spectra of benzo- and dibenzothiepins show the corresponding naphthalene or phenanthrene radical cations as the base peak.2-16 The mass spectra of 1-benzo-thiepin 1-oxides and 1,1-dioxides show the same naphthalene radical cation, formed by loss of sulfur monoxide or sulfur dioxide, respectively.14 In contrast, in the mass spectrum of 2,7-di-terf-butylthiepin peaks resulting from the loss of sulfur are not found.17... 

A fairly similar material has been obtained in an FTT synthesis extended over 6 months (Hayatsu et al., 1977). Upon pyrolysis, it gave a mass spectrum resembling that of the Murchison polymer (Fig. 9). The spectrum shows mainly benzene, naphthalene, and their alkyl derivatives, as well as alkyl-indanes, fluorene, anthra-cene/phenanthrene, alkenes, alkanes, and alkylphenols (Hayatsu et al., 1977). This material has not been studied by the more informative, gentle oxidation methods. 

The flash vacuum pyrolysis and the mass spectrometric fragmentation of a series of five methyl substituted phenanthrenes were correlated with each other in a quaUtatively predictable way.i ) The major thermochemical products for these compounds generally corresponded to one of the five most intense fragment ions in the compound s electron impact mass spectrum. The importance of products which corresponded to ions with high appearance potentials increased with increasing temperature in the thermolysis system. 

The results for thermolysis and electron impact induced fragmentation of 4-methyl-phenanthrene, 37, are representative of the series studied by Dougherty, Bertorello and BertoreUo.i ) The major singly charged ions in the mass spectrum of 37 are illustrated in Eq. (26). 

Pyrolysis of 37 at 750 °C returned 50 % of the starting material and gave the products illustrated in Eq. (27). The virtual absence of a peak at m e 178 in the mass spectrum of 37 which would correspond to the phenanthrene... 

Treatment of phenanthrene with diazomethane yields a product JJ for which mass spectrometry indicates a molecular weight of 192. The infrared spectrum of JJ resembles that of 9,10-dihydrophenanthrene its nmr spectrum shows two signals of one proton each at 8 -0.12 and 8 1.48. 

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