Methylene group, fragment values

Table 2.5 lists the additive values for representative fragments/and structural factors F. As an example, the infinite dilution distribution ratio of C2H5 C(0)0C2H5, ethyl propionate, between 1-octanol and water is obtained as follows. The carboxylate group contributes -1.49 to log P, each ethyl group contributes 0.89 -H 0.66 - 0.12 = 1.43 (for the methyl and methylene groups and... 

Note the very low value of Sj in PHTHB. This could be explained by the fact that in the hexamethylene chain, the central part contains a total of two methylene groups after exclusion of the methylene groups whose motion is limited by the mesogenic fragment (two on each side). Such a short fi gment cannot form an ordered sequence. In the case of PDTHB, the central part is the (-CH2-)5 fragment, and it can assume a stretched conformation. 

Fragmentation of the betaines 180, R = Me, Et, -Pr, i-Pr R = Cl, NOj, CN, has been shown to proceed by intramolecular splacement of the o-substituent of the iV-aryl group and formation of the tetracyclic systems 181 as shown in Scheme 2. The subsequent breakdown pattern shown in Scheme 2 was observed for 181, R = T and 181, R = M-Pr, but not for 181, R = Me, where elimination of methylene would be necessary compounds 180, R = Me, R = NOj R = CN, underwent fragmentation by loss of CHjN from the tetracyclic species 181, R = Me. In all, seven different compounds were examined in this study and the differences noted in their fragmentation patterns assigned to the relative ease of elimination of Cl, NO2, or CN. All the compounds showed prominent ions at mie values corresponding to C7H4N+ and... 

From the UV spectrum it became apparent that a conjugated hetero-annular diene comparable with that of buxamine-E and buxaminol-E (cf. Vol. IX, p. 405) is involved. The IR spectra showed the amide bands and the PMR spectra revealed the presence of three tertiary and one secondary C-methyl, one dimethylamino group, one primary alcohol, a proton adjacent to the secondary alcohol, and one amidic and two methylene protons. Moreover, 226 displayed signals of two methyls of the isobutyramide side chain whereas 227 showed benzamide substitution. The measured values are in accordance with the mass-spectrometric fragmentation pattern. 

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