A journey into amide and alkylamine synthesis from CO

International audienceNitrogen containing molecules are essential for life. They are also key products in the chemical industry and areproduced at the megaton scale. Among these compounds, amides and alkylamines are of particular importance.Amides are indeed among the most ubiquitous functions in living systems and form important materials (nylon,hydrogels, etc.), solvents, or pharmaceutics. An analysis carried out by the three leading pharmaceuticalcompanies in 2006, revealed that amide bonds formation was used in the synthesis of 65% of the drugscandidates.Classically, amide compounds are synthesized from the reaction of an activated carboxylic acid derivative with anamine but traditional methods prove expensive with a poor atom economy. An appealing alternative wouldconsist in promoting the direct carbonylation of an amine with CO. During the last decade, a handful of catalystswere shown to facilitate the carbonylation of tertiary amines. However, they require harsh conditions (> 30 bar, >190°C), and use of precious and/or toxic metal (palladium, rhodium or cobalt). In this context, we have designed the first system able to promote the carbonylation of amines to amides with iron catalysts. Low valent iron carbonyl complexes, in combination with a promotor (MeI) and a Lewis acid, favor the carbonylation of a variety of aromatic and aliphatic amines at low CO pressures (P < 8bar

Experimental and numerical simulation of scour at bridge abutment provided with different arrangements of collars

In this paper, the effects of different widths and lengths of collar around bridge abutment on local scour depth are studied numerically and experimentally. Numerical simulation of scour hole evolution at bridge abutment is more convenient than the experimental modeling, because the computational cost and time have significantly decreased. The numerical model solves 3-D Navier–Stokes equations and bed load conservation equation. The k–ε turbulence model is used to solve the Reynolds-stress term. The simulated results are verified using the laboratory experiments. In addition, the multiple linear regressions are applied to correlate the maximum local scour depth with the other independent parameters. It was found that the relative length of collar 0.73 around bridge abutment reduces the maximum scour depth by 69% compared to no-collar case. Moreover, the results of 3-D numerical model and regression models agree well with the experimental data

Indirect synthesis of methyl and alkylamines from CO2

International audienceIn the past few years C02 has been investigated as a Cl building block for the synthesis of a variety of chemicals and especially methylamines. 1 However due to the inertness of CO 2 , the methylation of amines re~.Juire either the use of activated hydrides (silanes/boranes) whose by-products are not recyc1able, or the use oflarge excess ofH 2 yie1ding poor faradaic efficiencies. On the other hand, great improvements have been made for the 2-e1ectron reduction of CO 2 to CO or HCOO-offering convenient platforms for the indirect synthesis of chemicals form C02. 2 However to the best of our knowledge, neither HCOO-nor CO has been reported for the synthesis of methyl or alkylamines. We therefore report the first ruthenium catalyzed synthesis of methylamines using HCOOH as the unique source of carbon and hydrogen. 3 Thanks to a theoretical and experimental approach,4 we were able to achieve quantitative yield for the methylation of amines. If the use of HCOOH is lin;üted to the synthesis of methylamines, we also deve10ped the synthesis of alkylamines via the homologation of amines, using CO as a building block. 5 Amines bearing an alkyl chain of up to 5 carbons were synthetized from the corresponding methylamines in one pot thanks to a cobalt catalyst

Investigating the effect of curved shape of bridge abutment provided with collar on local scour, experimentally and numerically

Scour around bridge supports such as abutments can result in structural collapse and loss of life and property, so there is a need to control and minimize the local scour depth. In this paper, numerical and experimental studies were carried out to investigate the effect of different relative radii of the bridge abutment provided with collar on local scour depth. A 3-D numerical model is developed to simulate the scour at bridge abutment using SSIIM program. This model solves 3-D Navier–Stokes equations and a bed load conservation equation. The k–ε turbulence model is used to solve the Reynolds-stress term. It was found the curvature shape of bridge abutment provided with collar could share to reduce the local scour depth by more 95%. In addition, the results of simulation models agree well with the experimental data

Experimental and theoretical investigations of scour at bridge abutment

Numerical and experimental studies were carried out to investigate the effect of different contraction ratios and entrance angles of bridge abutment on local scour depth. A 3-D numerical model is developed to simulate the scour at bridge abutment. This model solves 3-D Navier–Stokes equations and a bed load conservation equation. The k−ε turbulence model is used to solve the Reynolds-stress term. In addition, the model verification is made by comparing the computed results with existing experimental data. The results show the ability of the numerical model to simulate local scouring at bridge abutments for different contraction ratios and entrance angles of abutment with high accuracy. The determination coefficient and mean relative absolute error, in average, are 0.95 and, 0.12, respectively

Experimental and numerical simulation of scour at bridge abutment provided with different arrangements of collars

In this paper, the effects of different widths and lengths of collar around bridge abutment on local scour depth are studied numerically and experimentally. Numerical simulation of scour hole evolution at bridge abutment is more convenient than the experimental modeling, because the computational cost and time have significantly decreased. The numerical model solves 3-D Navier–Stokes equations and bed load conservation equation. The k–ε turbulence model is used to solve the Reynolds-stress term. The simulated results are verified using the laboratory experiments. In addition, the multiple linear regressions are applied to correlate the maximum local scour depth with the other independent parameters. It was found that the relative length of collar 0.73 around bridge abutment reduces the maximum scour depth by 69% compared to no-collar case. Moreover, the results of 3-D numerical model and regression models agree well with the experimental data

A two-level evolutionary algorithm for solving the petrol station replenishment problem with periodicity constraints and service choice

This paper addresses the petrol station replenishment problem with periodicity constraints and introduces the frequency service choice as a decision variable. We present a mathematical optimization model for the problem and we develop first a simple heuristic method that is able to handle the complexity of the problem and then two metaheuristic approaches based on a novel two-level evolutionary algorithm. The first level deals with the periodicity and frequency selection of the visits to the petrol stations. The second level of evolution assigns the stations to the tank-trucks such that the total traveled distance is minimized. The effectiveness of the proposed approaches has been tested by means of a comprehensive experimental study by using first a set of randomly generated test cases and then a real-life problem. © 2018, Springer Science+Business Media, LLC, part of Springer Nature