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The selective hydrogenation of functionalized nitroaromatics poses a major challenge from both academic as well as industrial viewpoints. As part of the CHEM21 initiative (www.chem21.eu), we are interested in highly selective, catalytic hydrogenations of halogenated nitroaromatics. Initially, the catalytic reduction of 1-iodo-4-nitrobenzene to 4-iodoaniline served as a model system to investigate commercial heterogeneous catalysts. After determining optimal hydrogenation conditions and profiling performances of the best catalysts, hydrogenations were transferred from batch to continuous flow. Finally, the optimized flow conditions were applied to transformations which represent important steps in the syntheses of the active pharmaceutical ingredients clofazimine and vismodegib.

The temporal evolution of Pt nanoparticle formation in ethylene glycol solution from H(2)PtCl(6)·6H(2)O at 90 °C for different molar ratios of NaOH to Pt (84, 6.5, and 2) in the presence or absence of poly(N-vinyl-2-pyrrolidone) (PVP) as protecting agent was followed in situ by small-angle X-ray scattering (SAXS). The SAXS profiles were analyzed regarding particle size and size distribution using the Guinier approximation and the indirect Fourier transform technique (IFT). The NaOH to Pt ratio has an influence on the integral nanoparticle formation rate as well as on the metal reduction rate and the ratio of nucleation to growth reactions. The fastest nanoparticle formation rate was observed for the NaOH/Pt ratio of 6.5. The obtained results indicate that the differences in the particle formation rate might be due to differences in the reduction rate of the formed Pt complexes. In alkaline reaction media (NaOH/Pt = 84 or 6.5), small nanoparticles with a relatively narrow size distribution were formed. Therefore, it is assumed that for these NaOH/Pt ratios the particle formation is dominated by nucleation reactions. Additionally, the in situ studies point out that nanoparticles prepared at the NaOH/Pt ratio of 84 do not grow further after attaining a certain particle size. For a NaOH to Pt ratio of 2, that means in acidic medium, particle formation should be dominated by growing processes and, therefore, larger particles are formed accompanied by a broader particle size distribution. The influence of PVP on the nanoparticle formation rate is relatively low. However, in acidic medium, the presence of PVP is necessary in order to protect the formed nanoparticles from irreversible aggregation reactions.

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Ozonolysis of acetic acid 1-vinyl-hexyl ester was carried out in a falling film microreactor in a continuous fashion. The influence of reaction variables (e.g., olefin concentration, ozone initial partial pressure, gas velocity, temperature and liquid flow rate) on the product formation in the liquid phase was studied over a wide range of operating conditions. Based on the obtained results, a formal reaction scheme for the ozonolysis of acetic acid 1-vinyl-hexyl ester is suggested. The acetic acid 1-formyl-hexyl ester and the corresponding carbonyl oxide are the main products of the cleavage of the primary formed ozonide. The secondary ozonide acetic acid 1-[1,2,4]trioxolan-3-yl-hexyl ester is formed by consecutive reaction of the acetic acid 1-formyl-hexyl ester and the carbonyl oxide.

The previously unknown heteropolyoxometalates [gamma-SiO(4)W(10)O(32)(OH)Cr(2)(OOCR)(2)(OH(2))(2)](5-) (R = H, CH(3)) have been prepared by the reaction of [gamma-SiO(4)W(10)O(32)](8-) with [Cr(OH(2))(6)](3+) in formate or acetate buffer solution. Isolation of these new Cr(III)-substituted polyoxometalates was accomplished both as Cs(+) salts and as the Bu(4)N(+) salt for the acetate-containing anion. The compounds were characterized by elemental analysis, UV/vis, IR, and ESR spectroscopy, and cyclic voltammetry. The single-crystal X-ray structural analysis of (Bu(4)N)(3)H(2)[gamma-SiO(4)W(10)O(32)(OH)Cr(2)(OOCCH(3))(2)(OH(2))(2)].3H(2)O [P2(1)2(1)2(1); a = 17.608(12), b = 20.992(13), c = 24.464(11) Å; Z = 4; R = 0.057 for 6549 observed independent reflections] reveals that the two corner-linked CrO(6) octahedra are additionally bridged by two acetate groups, demonstrating the relationship to the well-studied oxo-centered trinuclear carboxylato complexes of Cr(III).