A quantitative structure-activity relationship (QSAR) model is presented in which both the independent and dependent (response) variables are derived from density functional theory (DFT) calculations on a large set of 14-electron complexes, LCl(2)Ru=CH(2), with different dative ligands, L. The multivariate model thus correlates the properties of the 14-electron complexes with a calculated measure of activity, with modest computational cost, and reproduces the experimental order of activity for the Grubbs ruthenium catalysts for olefin metathesis. The accuracy and applicability of the model is to a large extent due to the use of highly specific geometric and electronic molecular descriptors which establish a direct connection between activity and chemically meaningful donor ligand properties. The ligands that most efficiently promote catalytic activity are those that stabilize the high-oxidation state (+4) metallacyclobutane intermediate relative to the ruthenium-carbene structures dominating the rest of the reaction pathway. Stabilization of the intermediate is ensured, among others, through ligand-to-metal sigma donation, whereas metal-to-ligand pi back-donation destabilizes the intermediate and lowers catalytic activity. A bulky dative ligand drives the reaction toward the less sterically congested metallacyclobutane species and thus contributes to catalytic activity. The multivariate model and the high-level descriptors furthermore provide practical handles for catalyst development as exemplified by the suggestion of several new donor ligands predicted to give more active and functional group tolerant ruthenium-based catalysts. The present strategy holds great promise for broader screenings of olefin metathesis catalysts as well as for development of homogeneous transition metal catalysts in general.

The oxidation of lignosulfonates (LS) to vanillin by persulphate, oxygen, and a variety of catalytic systems has been investigated. Cobalt and copper catalysts appeared to be the most effective in the oxidation by oxygen. An investigation where multivariate mathematical and statistical design and modelling have been used for the process optimisation has led to the development of a multivariate mathematical model which describes the oxidation process with high predictive capacity. By using this model, an increase of the vanillin yield from 4.1% of the current procedure to 7.2% is obtained, this corresponding to 75% relative improvement of the yield.

New methods of free-radical perfluoroalkylation of aromatics and alkenes are reported. n-C(4)F(9)I has been utilized as source of C(4)F(9)(*) radical through iodine abstraction by phenyl or methyl radical. The reaction with alkenes, carried out in the presence of catalytic amount of Cu(OAc)(2), leads to substitution by a mechanism substantially identical to the aromatic substitution and not to the usual chain addition of perfluoroalkyl group and iodine atom to the double bond. This has allowed to measure for the first time the absolute rate constants and the partial rate factors for the homolytic aromatic perfluoroalkylation by competition kinetics. The C(4)F(9)(*) radical shows a clear-cut electrophilic character in the aromatic substitution, as already reported for the addition to alkenes, but the low regio- and chemoselectivities suggest that the polar effect is not the main factor in determining the high reactivity of perfluoroalkyl radicals toward aromatics (10(5)-10(6) M(-1) s(-1), 2-3 orders of magnitude more reactive than alkyl radicals). The enthalpic factor, related to the involved bond energies, appears to be the major cause of the increased reactivity. The polar effect is considered as related more to the polarizability than to the polarity of a radical (the sigma-perfluoroalkyl radicals are considered less polarizable and hence less sensitive to polar effects than pi-radicals).

Evidences concerning a novel free-radical mechanism for the oxidation of alkanes by aromatic peracids are reported. The mechanism involves hydrogen abstraction from the OH group of peracids by an aroyloxyl radical; the acylperoxyl radical thus generated is responsible for the selective oxidation. The reaction is affected by the presence of oxygen and it is inhibited by TEMPO and by solvents forming hydrogen bonds with peracids. A more simple and effective synthetic procedure has been developed, on the basis of the autoxidation of aliphatic and aromatic aldehydes in the presence of alkanes. It is also shown that the previously reported inertness of alcohols toward peracids must be ascribed to solvent effects, due to the formation of hydrogen bonds; in suitable solvents alcohol oxidation smoothly occurs.

This is a general overview of some first-, second-and thirdgeneration fine chemicals with origins from the lignin oxidation process. The synthetic organic processes of these substances are presented as well as several applications for the synthesis of a variety of pharmaceutical chemicals.