CO conversion covers a wide range of possible application areas from fuels to bulk and commodity chemicals and even to specialty products with biological activity such as pharmaceuticals. In the present review, we discuss selected examples in these areas in a combined analysis of the state-of-the-art of synthetic methodologies and processes with their life cycle assessment. Thereby, we attempted to assess the potential to reduce the environmental footprint in these application fields relative to the current petrochemical value chain. This analysis and discussion differs significantly from a viewpoint on CO utilization as a measure for global CO mitigation. Whereas the latter focuses on reducing the end-of-pipe problem "CO emissions" from todays' industries, the approach taken here tries to identify opportunities by exploiting a novel feedstock that avoids the utilization of fossil resource in transition toward more sustainable future production. Thus, the motivation to develop CO-based chemistry does not depend primarily on the absolute amount of CO emissions that can be remediated by a single technology. Rather, CO-based chemistry is stimulated by the significance of the relative improvement in carbon balance and other critical factors defining the environmental impact of chemical production in all relevant sectors in accord with the principles of green chemistry.

The hydrogenation of CO2 to methanol using a recyclable molecular organometallic catalyst in the absence of an alcohol additive is demonstrated for the first time.

The synthesis of dimethoxymethane (DMM) by a multistep reaction of methanol with carbon dioxide and molecular hydrogen is reported. Using the molecular catalyst [Ru(triphos)(tmm)] in combination with the Lewis acid Al(OTf)3 resulted in a versatile catalytic system for the synthesis of various dialkoxymethane ethers. This new catalytic reaction provides the first synthetic example for the selective conversion of carbon dioxide and hydrogen into a formaldehyde oxidation level, thus opening access to new molecular structures using this important C1 source.

The use of the well-defined [Ru(triphos)(tmm)] catalyst, CO2 as C1 source, and H2 as reducing agent enabled the reductive methylation of isolated imines, as well as the direct coupling of amines with aldehydes and the subsequent reductive methylation of the in situ formed imines. The method, which afforded the corresponding N-methyl amines in very good to excellent yields, was also used for the preparation of the antifungal agent butenafine in one step with no apparent waste, thus increasing the atom efficiency of its synthesis.

The synthesis of dimethoxymethane (DMM) by am ultistep reaction of methanol with carbon dioxide and molecular hydrogen is reported. Using the molecular catalyst [Ru(triphos)(tmm)] in combination with the Lewis acid Al(OTf) 3 resulted in av ersatile catalytic system for the synthesis of various dialkoxymethane ethers.This new catalytic reaction provides the first synthetic example for the selective conversion of carbon dioxide and hydrogen into af ormaldehyde oxidation level, thus opening access to new molecular structures using this important C 1 source.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under http://dx.

The synthesis of trimethylamine (TMA) through am ulticomponent combination of ammonia with carbon dioxide and molecular hydrogenb yu sing ah omogeneous ruthenium catalyst was explored. The use of [Ru(triphos)(tmm)] [triphos: 1,1,1-tris-(diphenylphosphinomethyl)ethane, tmm:t rimethylenem ethane] together with aluminumt rifluoromethanesulfonatea s ac o-catalyst resulted in high ammonia conversion and excellent selectivity for TMA in organic solvents. Aqueous solutions of ammonium chloride were methylated almost quantitatively to the corresponding hydrochloride salt (i.e.,T MA·HCl) in ab iphasic solvent system by using the same Ru complex without the need for any co-catalyst.Methylamines, the simplest members of the aliphatic amine family,r epresent highly importanta nd versatile intermediates within the chemical supply chain. The industrial significance of methylamines is reflected by aw orldwide annual production larger than 1.3 10 6 tw ith ag rowing rate of 3.5% per annum. [1] These basic chemicals are generally used as valuable buildingb locks for the synthesis of solvents, surfactants, ionexchange resins, and synthetic fibers, as well as agrochemical and pharmaceutical products. [2] Methylamines are prepared on industrials cale by the exothermicr eactiono fa mmonia (NH 3 )a nd methanol( CH 3 OH) with an amorphous silica-alumina catalyst in fixed-bed reactors at 390-430 8C( Scheme 1A). The composite equilibria within the reaction network result in complex product mixtures, and the three possible methylamines (mono-, di-, and trimethylamine:M MA, DMA andT MA) are generally produced with moderate selectivity for the individual product, largely controlled by the NH 3 /CH 3 OH feed ratio. [2, 3] Moreover,M MA, DMA, TMA, and NH 3 form an azeotropic mixture, and the use of zeolite-based catalysts in combinationw ith methanol results in dimethyl ether (DME) as an additional byproduct. [4] Consequently,t he downstream purificationp rocess is laboriousa nd requiresatrain of four to five distillationcolumns, which finally results in integrated production plants at economy of scale. [2a, 5] The synthesis of the ammonium chlorides is typically achieved in as ubsequents tep (Scheme 1B).Herein, we report anovel catalytic approach for the selective synthesis of trimethylaminea nd its hydrochloride by using carbon dioxide (CO 2 )a sarenewable C 1 building block fort he formation of the three methyl groups on ammonia in the presence of molecular hydrogen. [6] In previousw ork from our group, aw ell-defined and highly versatile [Ru(triphos)(tmm)] [triphos:1 ,1,1-tris(diphenylphosphinomethyl)ethane,t mm:t rimethylene methane] catalystw as developed for the hydrogenation of CO 2 to methanola nd the utilizationo fC O 2 and H 2 for the N-methylation of primary ands econdary amines. [7] On the basis of these investigations, the directt riple N-methylation of NH 3 (Scheme 1C)orNH 4 Cl (Scheme 1D)byusing acombination of CO 2 and H 2 was targeted.In the mid-1990s, the group of Baiker worked on this challenging transformation and d...

The use of the well-defined [Ru(triphos)(tmm)] catalyst, CO 2 as C 1 source, and H 2 as reducing agent enabled the reductive methylation of isolated imines, as well as the direct coupling of amines with aldehydes and the subsequent reductive methylation of the in situ formed imines. The method, which afforded the corresponding N-methyl amines in very good to excellent yields, was also used for the preparation of the antifungal agent butenafine in one step with no apparent waste, thus increasing the atom efficiency of its synthesis.

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