Recent Applications of Pd-Catalyzed Suzuki-Miyaura and Buchwald-Hartwig Couplings in Pharmaceutical Process Chemistry.

Cross coupling reactions have changed the way complex molecules are synthesized. In particular, Suzuki-Miyaura and Buchwald-Hartwig amination reactions have given opportunities to elegantly make pharmaceutical ingredients. Indeed, these reactions are forefront at both the stages of drug development, medicinal chemistry, and process chemistry. On one hand, these reactions have given medicinal chemists a tool to derivatize the core molecule to arrive at scaffold rapidly. On the other hand, these cross couplings have offered the process chemists a smart tool to synthesize the development candidates safely, quickly, and efficiently. Generally, the application of cross coupling reactions is broad, and this review will specifically focus on their real (pharma) world applications in large scale synthesis those appeared in last two years.

Catalytic Fast Pyrolysis of Lignocellulosic Biomass to Benzene, Toluene, and Xylenes

Catalytic Fast Pyrolysis is a rapid method to depolymerize lignocellulose to its constituent components of hemicellulose, cellulose, and lignin. The pyrolysis reaction in absence of oxygen occurs at a very high heating rate to a targeted temperature of 400 to 600 °C for very short residence time. Vapors which are not condensed and are then contacted with a catalyst that is efficient to deoxygenate and aromatize the pyrolyzed biomass. One class of highly valuable material that is produced is a mixture of benzene, toluene, and xylenes. From this mixture, para-xylene is extracted for further upgrading to polyethylene terephthalate, a commodity polyester which has a demand in excess of 80 million tonnes/year. Addressed within this review is the catalytic fast pyrolysis, catalysts examined, process chemistry, challenges, and investigation of solutions.

An Overall Furnace Model for the Silicomanganese Process

Controlling and optimizing smelting processes in submerged-arc furnaces are complicated by the limited amount of information available regarding the internal conditions. Computer models can help to bridge this knowledge gap. Due to the process complexity, computer models are commonly restricted to electrical conditions, thermal conditions, or chemical reactions, for instance. We have developed an overall model for a pilot-scale silicomanganese furnace that simultaneously considers electrical and thermal conditions, process chemistry, and flow of solid and liquid substances. To the best of our knowledge, this is the first comprehensive silicomanganese furnace model. The model has been compared to experimental data. Using information about the inner state of the furnace provided by the model, we are able to predict and explain an increase in temperature during over-coking as well as changes in the product compositions.

Quantum-chemical modeling of the processes of cadmium sulfide and cadmium selenide films synthesis in aqueous solutions

The quantum-chemical modeling of the synthesis process chemistry of CdS and CdSe in aqueos solutions was carried out. For that reason, the CdS synthesis simulation was carried out through the formation of Cd(II) complex forms with the trisodium citrate and ammonium hydroxide. At the CdSe synthesis, the sodium selenosulfate with and without trisodium citrate was used. It was established that this process passes through several intermediate stages with the transitional reactive complexes formation. On the basis of obtained data, the energy stages diagrams are constructed and the comparison of CdS and CdSe synthesis processes with various complexing agents has been carried out. The CdS and CdSe films were obtained by chemical synthesis method from an aqueous solution of cadmium salt, complexing and chalcogenizing agents. X-ray phase analysis confirmed the formation of desired compounds, which was predicted by modeling.

Structure of Plasma (re)Polymerized Polylactic Acid Films Fabricated by Plasma-Assisted Vapour Thermal Deposition

Plasma polymer films typically consist of very short fragments of the precursor molecules. That rather limits the applicability of most plasma polymerisation/plasma-enhanced chemical vapour deposition (PECVD) processes in cases where retention of longer molecular structures is desirable. Plasma-assisted vapour thermal deposition (PAVTD) circumvents this limitation by using a classical bulk polymer as a high molecular weight “precursor”. As a model polymer in this study, polylactic acid (PLA) has been used. The resulting PLA-like films were characterised mostly by X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) spectroscopy. The molecular structure of the films was found to be tunable in a broad range: from the structures very similar to bulk PLA polymer to structures that are more typical for films prepared using PECVD. In all cases, PLA-like groups are at least partially preserved. A simplified model of the PAVTD process chemistry was proposed and found to describe well the observed composition of the films. The structure of the PLA-like films demonstrates the ability of plasma-assisted vapour thermal deposition to bridge the typical gap between the classical and plasma polymers.