ISSN:
0894-3230
Keywords:
Organic Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The Multifunctional Autocorrelation Method (MAM) derived from the autocorrelation method of Moreau et al. was used to calculate molar volumes for 300 linear or branched alkanes from C6 to C11 and 104 oxygenated compounds including 40 alcohols, 30 ethers and 34 ketones. Components Ci of a MAM connectivity vector were compared with several topological descriptors. MAM descriptors were generally more efficient than topological descriptors but good regressions were obtained for alkanes only when more than two components Ci were used. An excellent regression was obtained with four components (C0 to C4): \documentclass{article}\pagestyle{empty}\begin{document}$$ V_{\rm m} = 4 \cdot 45C_0 + 6 \cdot 44C_1 - 3 \cdot 33C_2 + 0 \cdot 46C_4 + 52 \cdot 9{\rm (}n = 300,r = 0 \cdot 999,s = 0 \cdot 81) $$\end{document} Models obtained using descriptors based on connectivity were good enough for many practical purposes. However, to derive models adapted to estimate molar volumes for alkanes, an autocorrelation vector V based on Van der Waals volumes (as given by Bondi) was considered. The best equation obtained again includes three components: \documentclass{article}\pagestyle{empty}\begin{document}$$ V_{\rm m} = 1 \cdot 750V_0 - 0 \cdot 123V_3 - 0 \cdot 037V_4 + 17 \cdot 97{\rm (}n = 300,r = 0 \cdot 999,s = 0 \cdot 85) $$\end{document} To extend the use of MAM to compounds containing heteroatoms, a set of alcohols, ketones and ethers, were each functional group represents a different interaction type, was considered. Chemical families were first studied individually, then the total set was considered. The components of an autocorrelation vector V based on Van der Waals volumes were used as molecular descriptors. Oxygenated compounds are correctly described by only one component V0. The correlation coefficient is 0·993 for all the chemical families studied, and the standard error of the estimate is low (s = 2·56). Comparison of standard errors of the estimate for Wiener's indices (s = 17·38) and autocorrelation components (s = 3·95), for all chemical families, shows that components of MAM are more efficient as molecular descriptors. The quality of regression equations was not significantly changed when 104 oxygenated compounds and 141 alkanes were studied in a global set.
Additional Material:
7 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/poc.610061008
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