Hydrogen benchmarking

Among the few systems that can be solved exactly are the particle in a onedimensional box, the hydrogen atom, and the hydrogen molecule ion Hj. Although of limited interest chemically, these systems are part of the foundation of the quantum mechanics we wish to apply to atomic and molecular theory. They also serve as benchmarks for the approximate methods we will use to treat larger systems. 

The cyclohexene hydrogenation is a well-studied process especially in conventional trickle-bed reactors (see original citations in [11,12]) and thus serves well as a model reaction. In particular, flow-pattern maps were derived and kinetics were determined. In addition, mass transfer can be analysed quantitatively for new reactor concepts and processing conditions, as overall mass transfer coefficients were determined and energy dissipations are known. In lieu of benchmarking micro-reactor performance to that of conventional equipment such as trickle-bed reactors, such a knowledge base facilitates proper, reliable and detailed comparison. 

Benchmarking to pure liquid-phase hydrogenation - use of hydrogen donors... 

Trisubstituted Alkenes. With very few exceptions, trisubstituted alkenes that are exposed to Brpnsted acids and organosilicon hydrides rapidly undergo ionic hydrogenations to give reduced products in high yields. This is best illustrated by the broad variety of reaction conditions under which the benchmark compound 1-methylcyclohexene is reduced to methylcyclohexane.134 146,192 202 203 207-210 214 234 When 1-methylcyclohexene is reduced with one equivalent of deuterated triethylsilane and two equivalents of trifluoroacetic acid at 50°, methylcyclohexane-... 

Much of the microscopic information that has been obtained about defect complexes that include hydrogen has come from IR absorption and Raman techniques. For example, simply assigning a vibrational feature for a hydrogen-shallow impurity complex shows directly that the passivation of the impurity is due to complex formation and not compensation alone, either by a level associated with a possibly isolated H atom or by lattice damage introduced by the hydrogenation process. The vibrational band provides a fingerprint for an H-related complex, which allows its chemical reactions or thermal stability to be studied. Further, the vibrational characteristics provide a benchmark for theory many groups now routinely calculate vibrational frequencies for the structures they have determined. 

It transpires that most classes of monodentate ligands include members that are able to induce high enantioselectivity in the hydrogenation of the two benchmark substrates 52 a and 53 a. It is not clear whether their corresponding acids 52b and 53 b have been studied or, alternatively, if the authors decided not to include (disappointing) ee-values. For phosphoramidite MonoPhos (29 a), however, the ee-values are invariably excellent. Overall, the TOFs range from 50 to 170 IT1, but have not been optimized in most cases. Unfortunately, with one exception [87], the hydrogenation of dehydroamino esters in which R1 is a (functionalized) alkyl substituent has not been studied, probably because of their difficult accessibility. 

Nevertheless, there remains a plethora of substrates that have not yet been studied using the monodentate ligand approach. In the application of asymmetric hydrogenation, it is very important to go beyond the benchmark substrates, and several studies have already shown that the scope of enantioselective hydrogenation might be much broader than was originally assumed. 

Most recently, a catalyst system based on PEG-modified phosphine ligands was reported to allow for a highly effective C02-induced separation procedure. In this case, the scC02 was used only at the separation stage to precipitate the catalyst and extract the products. The hydrogenation of styrene to ethyl benzene was used as a benchmark reaction, and it was shown that the catalytic active species could be recovered and not only re-used for another hydrogenation but also be subjected as a cartridge to a series of different transformations [43]. 

The reaction of ammonia and hydrogen chloride in the gas phase has been the subject of several studies in the last 30 years [56-65], The interest in this system is mainly that it represents a simple model for proton transfer reactions, which are important for many chemical and biological processes. Moreover, in the field of atmospheric sciences, this reaction has been considered as a prototype system for investigation of particle formation from volatile species [66,67], Finally, it is the reaction chosen as a benchmark on the ability, of quantum chemical computer simulations, to realistically simulate a chemical process, its reaction path and, eventually, its kinetics. 

Based on the analysis of the potentials and the economics of hydrogen corridors from neighbouring countries and a cost comparison with domestic hydrogen production in the EU25, which is used as a benchmark, the following conclusions can be drawn ... 

The PACE-T(H2) model analyses the world economy based on the GTAPinGAMS structure (Rutherford, 1998). It incorporates top-down benchmark data in the form of social accounting matrices to which the model is calibrated. The main data source for the calibration of national and international commodity flows is the GTAP5 database (GTAP, 2002). The trade shares of hydrogen and conventional cars are taken from the sector Motor vehicles and parts of the GTAP database. 

We mentioned above that the interaction between carboxylic and carboxylate groups constitutes a benchmark system for the investigation of the relationship between topology and charge carried by the components. In the case of inter-anion hydrogen bonding interactions on mono-deprotonated poly-... 

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