Nonaromatic C-H groups

Most of the variation between the spectra of Figures 3 and 4 occurs below 1250 cm. 1. Above this frequency all the spectra are strongly similar in pattern, and some of these similarities extend to the spectra of Figure 2. Common to all the spectra is the intense absorption from nonaromatic C-H groups with... 

Growth of the 1700 cm.-1 band is accompanied by reduction in the intensity of all absorptions associated with nonaromatic C-H groups. Currently held views are that aliphatic structures are destroyed during the oxidation of coal, and the changes in absorption pattern support this. 

In the spectrum of resinite from lignite there is also some loss of nonaromatic C-H groups that is shown particularly in the region below approximately 1250 cm. 1. The absorption at 1700 cm."1 becomes less sharp and widens on the low frequency side as oxidation proceeds. A distinct kink in the trace does develop at 1600 cm. 1, and it will be interesting to establish if broadening of the absorption band continues with prolonged oxidation and whether or not a separate band may eventually arise at the lower frequency. For com-... 

Gsj = value from Table 2-344 for C—H group j bonded to at least one functional group or atom Ctk = value from Table 2-345 for functional group k Nr = number of nonaromatic rings Ncr= number of —CH2— groups in nonaromatic ring(s) required to form cyclic paraffin of same ring size(s)... 

On the basis of initial H NMR studies and theoretical calculations. the bicyclo[3.1.0]hexenyl cation 41 was described as a potentially homoantiaromatic species that possessed the cyclic conjugated 47r-electron system represented by 41a. However. later theoretical studies of 41 and experimental studies of long-lived ions including 41, the cyclohexadienyl cation 41c. s and methylated derivatives such as 41h J were interpreted as indicating the ion was nonaromatic. The allylic ion 41 was reported to be stabilized by electron donation from the two external C—C bonds of the cyclopropyl group and not the Ci—C3 bond. A related example... 

Cyclization with the participation of hydroigrl groups or double bonds equivalent to them with aromatic rings is used in the syntheses of estrogens (aromatic ring A Schemes 49, 84, 88) or intermediates for the production of nonaromatic steroids (aromatic ring C Scheme 51). On the basis of the cyclization of a model tricyclic carbinol (81) under the action of 90% sulfuric acid, it was shown that when R = Me the formation of a cyclo-pentanophenanthrene derivative (83) takes place predominantly, while when R = H the spirane derivative (85) is the main product. This was explained by the comparative stabilities of the intermediate carbonium ions (82) and (84). When R = H, the tertiaiy carbonium ion (84) leading to the spirane (84) is more stable, and when R = Me the formation of the isomeric tertiary ion (82) is possible, and this cyclizes to the product (83) [55] (Scheme 88). 

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