Ionic liquid structure-induced effects on organic reactions.

Understanding the ways in which the constituents of ionic liquids, i.e. the type of cation, its substitution, and the type of anion chosen, interact with reactants is prerequisite to deliberately designing an ionic liquid solvent with optimum performance.

Switchable selectivity during oxidation of anilines in a ball mill.

A solvent-free method for the direct oxidation of anilines to the corresponding azo and azoxy homocoupling products by using a planetary ball mill was developed. Various oxidants and grinding auxiliaries were tested and a variety of substituted anilines were investigated. It was possible to form chemoselectively either azo, azoxy, or the nitro compounds from reaction of aromatic anilines.

An alternative solvent-free synthesis of nopinone under ball-milling conditions: Investigation of reaction parameters.

A new method for the oxidative cleavage of β-pinene (1) yielding nopinone (2) with potassium permanganate as oxidant under solvent-free conditions was established. The reaction was performed in a conventional ball mill with use of a grinding auxiliary. The auxiliary has the ability to sorb liquid reactants such as 1 on its surface to make liquid(s) accessible for mechanical impact.

Solvent-free and time-efficient Suzuki-Miyaura reaction in a ball mill: the solid reagent system KF-Al(2)O(3) under inspection.

Although a plethora of synthetic procedures mediated by KF-loaded aluminas is available in the literature, there is almost no data concerning the influence of parameters such as alumina modification or KF-loading on experimental results. Hence, the Pd-catalyzed, solvent-free Suzuki-Miyaura reaction was chosen as model reaction to investigate the effect of the above mentioned parameters on the results of coupling reactions. The results from ball milling experiments led to the conclusion that self-prepared and commercially available KF-Al₂O ₃differ in water content.

Fate of monoterpenes in near-critical water and supercritical alcohols assisted by microwave irradiation.

The rearrangement of alpha- and beta-pinene was studied under microwave irradiation in near-critical water and supercritical lower aliphatic alcohols, with the aim of identifying the pathway of alpha- and beta-pinene isomerization. Generally, two pathways occur, pyrolysis on the one and acidolysis on the other hand, whereby acidolysis is predominant in the case of near-critical water and the second pathway is favored for experiments employing supercritical alcohols. The different behavior of these two structurally related solvents is attributed to the increased availability of protons if water is heated to 270 degrees C and 80 bar, thus enhancing the autoprotolysis of water.

A practical approach for ambient-pressure hydrogenations using Pd on porous glass.

A Pd on porous glass catalyst system was used in the liquid-phase hydrogenation of terpenoid substrates with dihydrogen at room temperature and atmospheric pressure. A multitude of substances were hydrogenated selectively with yields of 90-100 %. In all experiments, only C--C, C--N, and N--N double bonds were hydrogenated.

Mechanistic and kinetic insights into the thermally induced rearrangement of alpha-pinene.

The thermal rearrangement of alpha-pinene (1) is interesting from mechanistic as well as kinetic point of view. Carrier gas pyrolyses with 1 and its acyclic isomers ocimene (2) and alloocimene (3) were performed to investigate the thermal network of these hydrocarbons. Kinetic analysis of the major reaction steps allows for a deeper insight in the reaction mechanism.

Pd on porous glass: a versatile and easily recyclable catalyst for Suzuki and Heck reactions.

The catalytic activity of Pd supported on porous glass was studied for both Suzuki and Heck reactions under aerobic conditions, with particular focus on the Suzuki coupling. The reactions were carried out in water under microwave irradiation. The effects of the catalyst preparation process (calcination time and temperature), as well as the base, substrate, and boron compound used on the coupling reaction were investigated in relation to the reusability of the catalyst.

Thermal isomerization of (+)-cis- and (-)-trans-pinane leading to (-)-beta-citronellene and (+)-isocitronellene.

Catalyzed and uncatalyzed rearrangement reactions of terpenoids play a major role in laboratory and industrial-scale synthesis of fine chemicals. Herein, we present our results on the thermally induced isomerization of pinane (1). Investigation of the thermal behavior of (+)-cis- (1 a) and (-)-trans-pinane (1 b) in a flow-type reactor reveals significant differences in both reactivity and selectivity concerning the formation of (-)-beta-citronellene (2) and (+)-isocitronellene (3) as main products.

Kinetic model for the thermal rearrangement of cis- and trans-pinane.

On the basis of pyrolysis experiments with cis-pinane ( 1a), trans-pinane ( 1b), beta-citronellene ( 2), and isocitronellene ( 3), rate constants and activation parameters for the thermal rearrangement of the title compounds were calculated. Combining these with experimental parameters (residence time) allows for the kinetic modeling of the thermal rearrangement of 1a, 1b, 2, and 3. The chosen model of competitive first-order reactions describes the thermal behavior of the title compounds in a very good manner over a wide temperature range.

UV-spectroscopic quantitative determination of non-aromatic amines in ionic liquids.

In the last decade, ionic liquids have shown great promise in a plethora of applications. Nevertheless, little attention has been paid to the characterization of the purity of these fluids, which ultimately lead to non-reproducible data in the literature. Derivatization with carbon disulfide is used to quantitatively determine primary and secondary non-aromatic amines (detection limit: 0.