A simple procedure for the separation of the catalytically important phosphabicyclononane isomers

Downing, Joanne H.; Gee, Victoria; Pringle, Paul G.

doi:10.1039/a703204h

Cited by 22 publications

(14 citation statements)

References 4 publications

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“…The difference in chemical properties of the [3.3.1] and [4.2.1] isomers as noted before was exploited to separate a mixture of 9-H-9-phosphabicyclo[3.3.1]nonane and 9-H-9-phosphabicyclo[4.2.1]nonane by a sequence of hydrophosphination/dehydrophosphination reactions [43]. Furthermore the difference in coordinating ability has been used to separate the isomers by selectively coordinating the [3.3.1] isomer by the addition of a metal to a solution containing both isomers [44,45].…”

Section: Resultsmentioning

confidence: 99%

Steric and electronic properties in bicyclic phosphines. Crystal and molecular structures of Se=Phoban-Q (Q=C2, C3Ph, Cy and Ph)

Bungu

Otto

2007

Journal of Organometallic Chemistry

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Section: Resultsmentioning

confidence: 99%

Steric and electronic properties in bicyclic phosphines. Crystal and molecular structures of Se=Phoban-Q (Q=C2, C3Ph, Cy and Ph)

Bungu

Otto

2007

Journal of Organometallic Chemistry

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“…[7] Ligands derived from the pure isomers show significant differences in their catalytic properties.…”

Section: Communicationsmentioning

confidence: 99%

Separation of Phobane Isomers by Selective Protonation

Eberhard

Carrington-Smith

Drent

et al. 2005

Advanced Synthesis & Catalysis

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Abstract:The industrially important mixture of symand asym-phobanes are separated efficiently by selective protonation of the sym isomer with hydrochloric acid; carbonylation catalysts generated from diphosphanes derived from the separated isomers have quite different activities and product selectivities.Keywords: basicity; hydrocarbonylation; palladium; phosphanes; separation Phobane is a mixture of the sym-and asym-bicyclic secondary phosphines, 9-phosphabicyclo[3.3.1]nonane (1) and 9-phosphabicyclo[4.2.1]nonane (2), formed by the reaction of PH 3 with 1,5-cyclooctadiene [Eq. (1)].[1]The ratio of the isomers in phobane batches varies from ca. 2 : 1 to 3 : 2. ð1ÞDerivatives of 1 and 2 have been known for almost 40 years [1] and have important applications in catalysis, [2 -4] particularly in Co-based hydroformylation of long-chain alkenes.[2] It is known [5] that 1 is more nucleophilic than 2 and it would therefore be expected that phobane-derived ligands would show different coordination chemistry. [4,5] In fact, we have recently shown that the new diphosphine o-C 6 H 4 {CH 2 P(C 8 H 14 )} 2 derived from 1, containing the "bisbi" backbone, forms mononuclear trans chelates with rhodium(I), nickel(II), palladium(II), and platinum(II).[6] Mixtures of isomeric phobanes are used because an economic separation has not been available. [7] We report here a simple, commercially viable [8,9] procedure for the separation of 1 and 2.Scheme 1 illustrates the method of separation. Both phosphines 1 and 2 readily dissolve in concentrated acids but we observed that 1 is significantly more basic than 2. Thus dropwise addition of concentrated HCl to a 1 M solution of 1 and 2 in ether led to selective extraction of 1. 31P{ 1 H} NMR spectroscopy showed that the ethereal phase contained exclusively 2 and the aqueous phase contained a 7 : 1 mixture of protonated 1 and 2. Ether extraction of the aqueous phase gave 2 in > 99% purity. Addition of NaOH to the aqueous phase and extraction of the liberated 1 into ether gave 1 in 78% yield and > 98% purity after sublimation. This selective protonation procedure is forgiving in the sense that too much or too little acid can easily be corrected as the separation is based on reversible equilibria. The separation is conveniently carried out on 30 -40 g scales (see Experimental Section) and has been carried out on a 175 g scale.When 1 Figs. 1 and 2). Both complexes have approximate C 2 symmetry with the PH bonds essentially perpendicular to the coordination plane and in mutually anti orientations.The structure of [PtCl 2 (2) 2 ] shows that the preferred phobane configuration in 2 has the hydrogen atom on P syn to the five-membered ring. A comparison of the COMMUNICATIONS

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“…Compound 1 is derived from the addition of a primary phosphine across cycloocta-1,5-diene, but two regioisomers can be formed and these are relatively difficult to separate. 5 In this paper, we report some studies of a cobalt system modified with a phosphine formally derived in a similar way, but from (R)-(ϩ)-limonene. Detailed results of the use of this ligand in cobalt catalysed hydroformylation reactions have been patented 6 and a recent publication reports that the chain length of the alkyl group on phosphorus has a marked effect on the activity and selectivity of the hydroformylation reaction.…”

Section: Introductionmentioning

confidence: 99%