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The bidentate phosphine ligand 1,2-bis(di-tert-butylphosphinomethyl)benzene (1,2-DTBPMB) has been reported over the years as being one of, if not the, best ligands for achieving the alkoxycarbonylation of various unsaturated compounds. Bonded to palladium, the ligand provides the basis for the first step in the commercial (Alpha) production of methyl methacrylate as well as very high selectivity to linear esters and acids from terminal or internal double bonds. The present review is an overview covering the literature dealing with the 1,2-DTBPMB ligand: from its first reference, its catalysis, including the alkoxycarbonylation reaction and its mechanism, its isomerization abilities including the highly selective isomerizing methoxycarbonylation, other reactions such as cross-coupling, recycling approaches, and the development of improved, modified ligands, in which some tert-butyl ligands are replaced by 2-pyridyl moieties and which show exceptional rates for carbonylation reactions at low temperatures.

Solvents have an enormous impact on yield and turnover of chemical reactions in complex media. There is, however, a lack of consistent model-based tools to a priori identify the appropriate solvent...

A reactive ionic liquid was successfully applied in the homogeneous ruthenium-catalyzed alcohol amination for the first time. Through detailed investigation of the phase behavior and the applicatio...

We present the development of catalytic auto-tandem reactions into continuous flow processes on the example of homogeneously catalyzed hydroaminomethylation (HAM, consisting of hydroformylation and...

For the first time, the successful application of the homogeneously catalyzed reductive amination in a thermomorphic multiphase system (TMS) and the first reported scale-up of this reaction into a ...

Over the past 20 years, thermomorphic multiphase systems (TMS) have been used as a versatile and elegant strategy for the recovery and recycling of homogeneous transition-metal catalysts, in both batch-scale experiments and continuously operated processes. TMS ensure a homogeneous reaction in a monophasic reaction mixture at reaction temperature and the recovery of the homogeneous transition-metal catalyst through liquid-liquid separation at a lower separation temperature. This is achieved by using at least two solvents, which have a highly temperature-sensitive miscibility gap. The suitability of commercially available solvents makes this approach highly interesting from an industrial point of view. For the first time, herein, all studies in the area of TMS are reviewed, with the aim of providing a concise and integral representation of this approach for homogeneous catalyst recovery. In addition to the discussion of examples from the literature, the thermodynamic fundamentals of the temperature-dependent miscibility of solvents are also presented. This review also gives key indicators to compare different TMS approaches, for instance. In this way, new solvent combinations and in-depth research, as well as improvements to existing approaches, can be addressed and promoted.

An alternative strategy for the Rh-catalysed hydroformylation of technical-grade methyl oleate in aqueous-media has been developed. This is achieved with the water-soluble Rh/NaTPPTS catalyst dissolved in a green polar phase consisting only of the safe and benign solvents water and 2-propanol. This approach allows to completely avoid the use of additional auxiliaries like surfactants, cyclodextrins, or other phase-transfer agents. Along with efficient immobilization and recycling of the catalyst, excellent chemo- (>96%) and regioselectivity (>98%) to the desired branched aldehyde products is achieved. Investigations on the composition- and temperature-dependent phase-behaviour of the multicomponent liquid system water/2-propanol/methyl oleate are carried out in order to optimise all reaction parameters. Beneficially, a pure nonpolar aldehyde product phase is obtained after reaction, containing only low amounts of 2-propanol (

International audience; Hydroaminomethylation (HAM) is a highly efficient homogeneously catalyzed autotandem reaction converting alkenes into valuable amine products with water being the only coproduct. This work reports for the first time the scale-up of the highly regioselective HAM of 1-decene with diethylamine for a potential continuous process application in a green and sustainable aqueous biphasic medium. The catalytic system Rh/SulfoXantphos and randomly methylated β-cyclodextrin (RAME-β-CD) were herein dissolved in the plain aqueous phase. The addition of cyclodextrins as a green mass transfer agent remarkably increases the reaction rate as well as the selectivity toward linear amines, but they can also support solid content precipitation in this reaction system due to up-scaling effects. Therefore, parameters such as catalyst concentration, organic volume fraction, cyclodextrin concentration, and recyclability were investigated regarding the stability and activity of the system. Especially the organic volume fraction had a decisive influence on solid content precipitation. High regio- and chemoselectivities of 35 and 82%, respectively, at nearly full conversion were achieved toward the linear product amine. The catalytic system was further recycled in batch and scaled up into a 2100 mL autoclave without loss in activity and selectivity. Finally, a continuous process concept was proposed for an extensive investigation regarding long-term stability of the catalytic system.

For the first time, randomly methylated β-cyclodextrin was applied as the mass transfer agent in a continuous process. Considering the example of the Rh-catalyzed hydroformylation of 1-decene, process development was shown, where cyclodextrin was used together with a catalyst system that was continuously recovered and recycled using an aqueous biphasic system. In initial experiments, water-soluble and commercially available Rh/TPPTS and Rh/sulfoxantphos catalyst systems were scaled up from 50 ml into 1000 ml high-pressure autoclave systems to demonstrate their scalability. Both these systems were compared, and they afforded excellent chemoselectivity (>99%) toward the desired linear aldehyde product. In particular, higher regioselectivity (up to 31) was achieved for the Rh/sulfoxantphos system. Investigations regarding the long-term stability of the mass transfer agent and both catalyst systems were carried out in a continuously operated miniplant process. It was shown that the process could be successfully operated under the steady state for over 200 h with chemoselectivity of >97% toward the desired aldehyde product. Simultaneously, extremely low Rh leaching (total: 0.59%) was observed over the entire period of 200 h.

Aldoxime synthesis directly starting from alkenes was successfully achieved through the combination of hydroformylation and subsequent condensation of the aldehyde intermediate with aqueous hydroxylamine in a one-pot process. The metal complex Rh(acac)(CO)(2) and the water-soluble ligand sulfoxantphos were used as the catalyst system, providing high regioselectivities in the initial hydroformylation. A mixture of water and 1-butanol was used as an environmentally benign solvent system, ensuring sufficient contact of the aqueous catalyst phase and the organic substrate phase. The reaction conditions were systematically optimised by Design of Experiments (DoE) using 1-octene as a model substrate. A yield of 85% of the desired linear, terminal aldoxime ((E/Z)-nonanal oxime) at 95% regioselectivity was achieved. Other terminal alkenes were also converted successfully under the optimised conditions to the corresponding linear aldoximes, including renewable substrates. Differences of the reaction rate have been investigated by recording the gas consumption, whereby turnover frequencies (TOFs) >2000 h(-1) were observed for 4-vinylcyclohexene and styrene, respectively. The high potential of aldoximes as platform intermediates was shown by their subsequent transformation into the corresponding linear nitriles using aldoxime dehydratases as biocatalysts. The overall reaction sequence thus allows for a straightforward synthesis of linear nitriles from alkenes with water being the only by-product, which formally represents an anti-Markovnikov hydrocyanation of readily available 1-alkenes.

The palladium-catalysed carboxytelomerisation of a branched 1,3-diene with alcohols is herein presented. By applying the renewable β-myrcene as a model substrate, access to highly branched industrially relevant C21-esters in a 100% atom economical way is thereby established. Based on a detailed investigation on the influence of different monophosphine ligands, the Tolman angle was determined to be a crucial factor for high chemoselectivity towards the desired ester products. Additionally, through a comprehensive design of experiments (DoE), significant reaction parameters were identified leading to optimised reaction conditions for methanol as the nucleophile. Finally, the generality of these optimised reaction conditions was proven by applying eight different alcohols yielding highly branched esters with yields of up to 99% and excellent chemoselectivities.

Resource-efficient bis-hydroaminomethylation of the castor oil derived renewables methyl 10-undecenoate and 10-undecene-1-ol with piperazine furnished linear, bifunctional molecules. A structured and sustainable path towards a novel polyester from these monomers was developed. Key to success was the selective crystallization of the linear product directly from the crude reaction mixture in >98 % purity. Additionally, with this methodology, the homogeneous Rh catalyst was retained in the supernatant and was successfully recycled. Finally, polycondensation yielded a novel piperazine-linked polyester.

An efficient protocol was developed to prepare a series of dialkylpiperazines via Rh-catalyzed bis-hydroaminomethylation of linear aliphatic alkenes with piperazine. The well-known Rh/Biphephos catalytic system was applied, yielding the desired dialkylpiperazines within six tandem catalytic steps, already at low catalyst loadings of 0.1 mol%. For the model alkene 1-octene, good yields and linearities of 80% and 77:23, respectively, were achieved under optimized conditions. Influences on the catalytic system regarding n/iso ratio, possible side reactions and the reaction path are discussed on the basis of yield vs. time plots and parameter optimization. With the developed general protocol, other linear, functionalized and branched substrates were effectively transformed to the corresponding linear N,N-disubstituted piperazines.

The orthoester Johnson–Claisen rearrangement of allyl alcohol with triethyl orthoacetate for the synthesis of ethyl 4-pentenoate has been optimized, in order to allow for a selective and efficient subsequent alkoxycarbonylation using formates in an atom efficient manner. Diethyl adipate was successfully yielded in up to 89% applying very low orthoester excess, formic acid and mild reaction conditions in an innovative, one-pot procedure.

Hydroformylation of alkenes for the production of aldehydes is one of the most important homogeneously catalyzed reactions on an industrial scale. Mostly, these processes are based on expensive rhodium as the catalyst metal. In this contribution, we present for the first time the successful application of ruthenium as a cheaper alternative metal in a continuously operated miniplant. In the reaction of 1-octene, ex situ extraction of the oxo-products is conducted using the nonpolar solvent iso-octane, while the catalyst is retained in a polar DMF phase. After optimizing the reaction conditions on a batch scale, the recycling of the ruthenium catalyst was realized over a period of 90 h in a fully automated miniplant setup.

A new tandem catalytic process was designed and developed as a tool for the direct conversion of the widely available feedstock 2,7-octadienol into an α,ω-diester. This innovative auto-tandem catalysis is atom efficient and consists of three consecutive palladium-catalysed reactions: ether formation, ether carbonylation and alkoxycarbonylation. By using the design of experiments (DoE) approach, significant parameters were determined and the yield of the desired α,ω-diester was optimised. Model substrates allowed deeper insight into the progress of the reaction to be gained and, as a result, the reaction sequence was uncovered. Furthermore, by simply applying other ligands, a different reaction path was followed, allowing other, new tandem catalytic sequences to be explored and enabling new compounds to be obtained.

Oleochemicals are used in the chemical industry in numerous processes and applications, having the largest share among all other renewable resources. Besides the well-known transformations performed at the carboxylic moiety of the alkyl chain, many natural occurring fatty compounds offer a further opportunity for refinement, that is: catalytic functionalization of the CC double bond. In the present review, the authors describe the mission of the scientific work that is performed at the chair of Technical Chemistry at the TU Dortmund towards selective and atom economic functionalization of oleochemicals. Special emphasis lays on homogenous transition metal catalysis towards potential applications of the resulting products and their continuous production in miniplant scale. The given examples are discussed in the context of the work of other groups and summarize recent developments in the field of addition and fission reactions of oleochemicals. The Mission of Addition and Fission—The functionalization of oleochemicals using homogeneous transition metal catalysis is a very elegant way for producing valuable chemicals via many possible pathways. In this review, recent contributions to e.g. addition or cleavage reactions by Behr's group at the TU Dortmund are presented and discussed in the context of relevant literature, highlighting their significance in this important field of oleochemistry.