Quantitative Correlation of Physical and Chemical Properties with Chemical Structure: Utility for Prediction

Rational approaches, design strategies, structure activity relationship and mechanistic insights for anticancer hybrids

A 36-step synthesis was carried out in automated synthesizers to provide a synthetic key intermediate of taxol. A key step involved a microwave-assisted alkylation reaction to construct the ABC ring system from an AC precursor. Subsequent formation of the D ring afforded baccatin III, a well-known precursor of taxol.

A formal total synthesis of taxol aided by an automated synthesizer.

An improved model for the prediction of ignition quality of hydrocarbon fuels has been developed using 1H nuclear magnetic resonance (NMR) spectroscopy and multiple linear regression (MLR) modeling. Cetane number (CN) and derived cetane number (DCN) of 71 pure hydrocarbons and 54 hydrocarbon blends were utilized as a data set to study the relationship between ignition quality and molecular structure. CN and DCN are functional equivalents and collectively referred to as D/CN, herein. The effect of molecular weight and weight percent of structural parameters such as paraffinic CH3 groups, paraffinic CH2 groups, paraffinic CH groups, olefinic CH–CH2 groups, naphthenic CH–CH2 groups, and aromatic C–CH groups on D/CN was studied. A particular emphasis on the effect of branching (i.e., methyl substitution) on the D/CN was studied, and a new parameter denoted as the branching index (BI) was introduced to quantify this effect. A new formula was developed to calculate the BI of hydrocarbon fuels using 1H NMR spect...

Predicting Fuel Ignition Quality Using 1H NMR Spectroscopy and Multiple Linear Regression

The assessment of the ignition quality of a wide range of oxygenated hydrocarbons is one key challenge in the identification of novel molecular entities qualifying as biofuels or biofuel blend components derived from oxygen-rich lignocellulosic feedstocks. The present contribution summarizes the results from a comprehensive experimental screening campaign targeting a diverse set of pure-component oxygenated hydrocarbon fuels and their ignition characteristics in an ASTM D6890 Ignition Quality Tester (IQT). This constant-volume combustion chamber experiment has been chosen because of its rapid screening potential. The unique collection of data is utilized for group contribution modeling with the aim of unraveling relationships between the ignition delay observed in IQT experiments and the fuel’s molecular structure. We propose a simple, yet predictive, estimator for the derived cetane number of pure oxygenated hydrocarbons covering acyclic and cyclic, branched and straight, saturated and unsaturated hydroc...

A Novel Group Contribution Method for the Prediction of the Derived Cetane Number of Oxygenated Hydrocarbons

The review describes the syntheses and probable biologically active conformations of taxol, a natural antitumor agent, and systematizes published data on the structure-activity relations in the series of taxol analogs.

Taxol: Synthesis, bioactive conformations, and structure-activity relationships in its analogs

The QSPR problem for cetane numbers of hydrocarbons, a key property of oil fuels, was considered for the first time. Based on the approach developed, calculations have been carried out and relations derived for prediction of the cetane numbers of alkanes and cycloalkanes. Results of cetane number calculations for 180 unknown and non studied hydrocarbons are presented.

Cetane numbers of hydrocarbons: calculations using optimal topological indices

A new method proposed for solving QSPR tasks is based on transition from numerical values to topological equivalents (TEs) of physicochemical properties of chemical compounds. The TEs are unambiguously related to corresponding properties; for n-alkanes, they are linear functions of the number, n, of carbon atoms. Since the TE depends only on the corresponding physicochemical parameter, it can be calculated for any hydrocarbon using the same relationships as those known for n-alkanes. The optimal topological index (OTI) constructed using the chemical structure matrix for TEs usually has a much smaller basis compared to the topological index obtained by analogous procedure for the physicochemical property. An algorithm for modeling of physicochemical properties using the TEs was developed and evaluated taking the octane numbers of alkanes and cycloalkanes as examples.

Octane numbers (ONs) of hydrocarbons: a QSPR study using optimal topological indices for the topological equivalents of the ONs

Optimal topological indices for particular physicochemical properties can be designed using the chemical structure matrix. Taking the alkane boiling points as examples, the extrapolation properties of some well-known topological indices were compared with those of the optimal topological indices designed ad hoc. The advantages of the new indices are shown.

Ad hoc optimal topological indices for QSPR

On the basis of the octane-number topological equivalents (TEs) constructed earlier by the inverse function method, related to the octane numbers by a biunique function, and linearly dependent on the number of carbon atoms n for n-alkanes, the octane numbers of alkenes have been simulated with the use of optimal topological indices. The models obtained suggest the maximum attainable (within linear QSPR approaches) accuracy of calculation, which exceeds by a few orders of magnitude that of previously known procedures. The octane numbers are predicted for 68 alkenes that have not been characterized experimentally.

A. N. Ryzhov

Papers

Taxol: Synthesis, bioactive conformations, and structure-activity relationships in its analogs

Cetane numbers of hydrocarbons: calculations using optimal topological indices

Octane numbers (ONs) of hydrocarbons: a QSPR study using optimal topological indices for the topological equivalents of the ONs

Ad hoc optimal topological indices for QSPR

Modeling the octane numbers of alkenes by the inverse function method