Palladium-catalyzed hydroesterification of olefins with isosorbide in standard and Brønsted acidic ionic liquids

Palladium-catalyzed hydroesterification of olefins with isosorbide in standard and Brønsted acidic ionic liquids

    Palladium-catalyzed hydroesterification of olefins with isosorbide in standard and Brønsted acidic ionic liquids J´erˆome Boulanger, ...

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    Palladium-catalyzed hydroesterification of olefins with isosorbide in standard and Brønsted acidic ionic liquids J´erˆome Boulanger, Adeline Seingeot, Bastien L´eger, Romain Pruvost, Mathias Ibert, Andr´e Mortreux, Thomas Chenal, Mathieu Sauthier, Anne Ponchel, Eric Monflier PII: DOI: Reference:

S1566-7367(15)00235-6 doi: 10.1016/j.catcom.2015.06.008 CATCOM 4357

To appear in:

Catalysis Communications

Received date: Revised date: Accepted date:

26 April 2015 10 June 2015 11 June 2015

Please cite this article as: J´erˆ ome Boulanger, Adeline Seingeot, Bastien L´eger, Romain Pruvost, Mathias Ibert, Andr´e Mortreux, Thomas Chenal, Mathieu Sauthier, Anne Ponchel, Eric Monflier, Palladium-catalyzed hydroesterification of olefins with isosorbide in standard and Brønsted acidic ionic liquids, Catalysis Communications (2015), doi: 10.1016/j.catcom.2015.06.008

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ACCEPTED MANUSCRIPT Palladium-catalyzed hydroesterification of olefins with isosorbide in standard and Brønsted acidic ionic liquids

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Jérôme Boulanger, a Adeline Seingeot,a Bastien Léger,a Romain Pruvost,b Mathias Ibert,c André Mortreux,b Thomas Chenal,b Mathieu Sauthier,b Anne Ponchela and Eric Monflier*a Université d’Artois, Unité de Catalyse et de Chimie du Solide (UCCS), UMR 8181, Faculté des

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Sciences Jean Perrin, Rue Jean Souvraz, SP 18, F-62307 Lens Cedex, France.

Université de Lille, Unité de Catalyse et de Chimie du Solide (UCCS),UMR 8181, ENSCL, Bât C7,

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59650 Villeneuve D’Ascq, France.

Roquette Frères, 1 rue de la Haute Loge F-62136 Lestrem, France.

* Corresponding author e-mail: [email protected]

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Abstract:

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The palladium catalyzed hydroesterification of 1-octene with isosorbide was studied in standard and Brønsted acidic ionic liquids as reaction media. High conversions and

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selectivities towards the targeted isosorbide diesters have been achieved by using a catalytic system composed of Pd(OAc)2 and trisulfonated triphenylphosphine dissolved

in 1-(4-

sulfonic acid)-butyl-3-methylimidazolium tosylate. The catalytic phase can be reused several

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times without any significant decrease in activity and selectivity.

Keywords: Hydroesterification · Isosorbide · Palladium · Ionic liquids · Biphasic catalysis

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Graphical abstract:

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Pd / TPPTS

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Ionic liquid

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Introduction

Due to their unique and specific chemical and physical properties, ionic liquids (IL) have been successfully used these last years to develop practical, convenient and recyclable catalytic

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systems [1]. Indeed, charged transition-metal complexes can be efficiently immobilized into

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these media and severe mass transfer limitations can be avoided due to the partial solubility of many organic substrates in ILs. [2] The hydroesterification in ILs has been the focus of

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numerous studies. This reaction is mainly catalyzed by palladium complexes in the presence of strong protic acids and allows to obtain in an single step a wide range of esters from readily

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available and low cost derivatives such as CO, olefins and alcohols.[3] The first results were reported by Monteiro et al. in 1998.[4] The Pd-catalyzed hydroesterification of styrene derivatives was performed in the presence of [BMI][BF4] under mild experimental conditions. A few years later, Shaughnessy et al. reported that catalytic activities of the (Ph3P)2PdCl2 precatalyst during the hydroesterification of styrene derivatives depended on the nature of the

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ILs.[5] Some experiments have been made by the same team in order to recycle the IL containing the catalytic active species. A loss of activity was observed from the third run despite the addition of PPh3 ligand at the end of each run. The leaching of the catalyst was

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also observed by Kollar et al. during the hydroesterification of styrene in the presence of palladium complexes stabilized by mono- or diphosphines.[6,7,8] Recently, Mecking et al.

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investigated the hydroesterification of ethylene with cellulose in [BMI][MeSO3] and managed to synthesize cellulose propionate with a degree of substitution of 1-2.[9] The Pd-catalyzed

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hydroesterification of various olefins can also be performed in Brønsted acidic ionic liquids (BAILs). The synthesis of these compounds was first reported by Davies et al. in 2002 [10]. In this case, the addition of a strong acid was not necessary as the IL acts as an acid promoter and a reaction medium. Several BAILs with different acidic scales were employed as acid promoters to achieve the hydroesterification of styrene or 1-hexene with various alcohols in the presence of a catalytic system composed of palladium and triphenylphosphine.[11] The best results were obtained with BAILs exhibiting a Hammett acidity function less than -0.11. Unfortunately, addition of fresh PPh3 phosphine at the end of the reaction was necessary to recycle the catalytic system and maintain the activity and selectivity of the catalyst. The methoxycarbonylation of ethylene in BAILs was investigated by Riisager et al.[12] The catalytic system composed of palladium and 1,2-bis(di-tert-butylphosphinomethyl)benzene was found to be very active and can be reused up to 15 times without apparent loss of catalytic activity or selectivity. The pre-formation of the catalytic species before the

ACCEPTED MANUSCRIPT introduction of carbon monoxide appeared to be a crucial point to avoid the formation of Pdblack. Interestingly, the same team has also reported that the palladium catalyzed methoxycarbonylation of ethylene can be achieved in the presence of zwitterions, which allow

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to decrease the amounts of acid promoter without loss of activity.[13]

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We report herein the Pd-catalyzed hydroesterification of 1-octene with isosorbide in ILs (Schemes 1 and 2). The hydroesterification of 1-octene as model olefin with isosorbide can

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potentially lead to the formation of several possible molecules: the monoesters 3a and 3b and the diesters 4. The number of possible isomers is multiplied by the possible combinations of linear and branched structure of the aliphatic chains formed as a consequence of the

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hydroesterification reaction.[14] This reaction has never been investigated in ILs media and is of great interest as alternative pathways are needed to access isosorbide diesters. Indeed, these compounds which are used as alternative plasticizers to phtalates are classically obtained from the reaction with acyl chlorides or esterification with carboxylic acids.[15] The influence of different parameters such as the nature of the IL and the phosphine will be

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studied. Finally, the recyclability of the best catalytic system will be discussed.

Experimental

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2.

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Insert Schemes 1 and 2.

In a typical hydroesterification experiment, the catalyst Pd(OAc)2 (0.04 mmol), the phosphine ligand (0.64 mmol), the Brønsted acidic ionic liquid (2.0 g) and isosorbide (10.26 mmol) were introduced in a 70 mL stainless steel autoclave, which was purged by vacuum/dry nitrogen. 1octene (25.66 mmol) was purged by nitrogen flow and transferred in the autoclave. The reactor was pressurized with carbon monoxide (40 atm), heated at 110°C and magnetically stirred for 20 h. After the reaction, the system was cooled and the excess of carbon monoxide was vented. The crude was diluted by addition of diethyl ether (2 mL) and analyzed by GC.

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Results and discussion

The first experiments were carried out as previously reported in homogeneous medium for the

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hydroesterification of 1-octene with isosorbide, excepted that 2.0 g of IL was added to the

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Insert Table 1

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reaction medium in the place of dioxane.[13] The catalytic results are summarized in table 1.

Although the isosorbide conversions and diesters selectivities obtained in standard ILs were

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lower than those obtained in dioxane, these first experiments clearly demonstrate that the catalytic reaction can be performed in the presence of IL (Compare entries 2-4 with 1). The nature of the counter anion of the IL affected the conversions and selectivities. The best results were obtained in [BMI][PF6] with an isosorbide conversion of 81 % and a diesters selectivity of 87 %. When [BMI][BF4] or [BMI][p-TsO] was used as IL, the diesters

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selectivities were notably decreased and an important amount of 1-octene was isomerized in the presence of [BMI][BF4]. No conversion was observed when the reaction was performed

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without p-toluenesulfonic acid (PTSA), confirming that the presence of a strong acid promoter is required to achieve the hydroesterification (Entry 5). Entries 6 to 10 indicate

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however that addition of PTSA in the medium can be avoided by using BAILs having a SO3H group in the cation structure (Scheme 2). Conversions and selectivities were very dependent

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on the nature of counter anion of BAILs. The best results were obtained in the presence of [BSMI][p-TsO]. In this case, both the conversion and selectivity were very similar to those obtained in homogeneous medium (Compare entry 10 with 1). When the PPh3/Pd molar ratio was decreased to 8, no significant modification of the catalytic results was observed (Entry 11). However, it should be highlighted that the presence of PPh3 is crucial to observe the formation of isosorbide diesters. Indeed, the reaction gave only an isomeric octene mixture when no PPh3 was added to the reaction mixture (Entry 12). Finally, it must be pointed out that the nature of IL does not influence the l/b ratio. Indeed, this ratio was found to be equal to 3 whatever the IL used.

As these preliminary experiments have proved that [BSMI][p-TsO] was the best BAILs to perform the hydroesterification of 1-octene with isosorbide, ICP-AES measurements were performed at the end of the reaction on the organic layer composed of octenes, monoesters

ACCEPTED MANUSCRIPT and diesters. The amount of palladium in this organic phase was found to be 209 ppm, indicating that 22 % of the initial amount of palladium was in the organic phase. This result is in agreement with the results reported in the literature [5-8] and can undoubtedly be attributed

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to the marked hydrophobic character of PPh3 ligand. To solve this problem, the use of ionic

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ligands such as the sodium salts of sulfonated mono and bidentate arylphosphines have been considered. These ligands are expected to have a higher affinity for the IL than PPh3 due to

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their ionic nature. The catalytic results are summarized in table 2.

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Insert table 2

The results obtained with the sodium salt of trisulfonated triphenylphosphine ligand (TPPTS) were close to those obtained with the PPh3 ligand. For instance, the 1-octene and isosorbide

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conversions were found to be 69 % and 79 %, respectively, with TPPTS, vs. 73 % and 85 % with PPh3 (Compare entry 2 with 1). Furthermore, the reaction medium rapidly separated into two clear phases at the end of the reaction (See ESI) and no trace of palladium could be

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detected in the organic phase, i.e., below the detection limit (1 ppm). The ability of the TPPTS ligand to efficiently immobilize the catalytic species into [BSMI][p-TsO] was also confirmed

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by performing recycling experiments. The catalytic phase could be reused in three consecutive runs without a significant drop in conversions or selectivities (Entries 3 to 5).

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Supplementary experiments were performed with lower amounts of palladium, TPPTS or [BSMI][p-TsO] (Entries 6-8). No notable decrease in the conversions and selectivities was observed when the amounts of TPPTS or [BSMI][p-TsO] were decreased by 2 or 2.5, respectively (Entries 6 and 8). In contrast, a decrease in the palladium content led to lower conversions and diester selectivity (Entry 7). A catalytic test was also performed by using a mixture of [BSMI][p-TsO] and BSMI zwitterion as solvent (Entry 9). Indeed, it has been recently reported that the presence of zwitterions can contribute to stabilize transition states and active catalytic Pd intermediates in the hydroesterification reaction.[13] Unfortunately, an important decrease in the conversions and diester selectivity was observed in this solvent. (Compare entries 8 and 9). The results obtained with bidentate ligands such as 9,9-dimethyl2,7-disulfonato-4,5-bis(diphenylphosphino)xanthene (sulfonated xantphos) and 1,4-bis[bis(msulfonatophenyl)phosphine]butane (DPPBTS) were rather disappointing. An important decreases in isosorbide conversion and diester selectivity were observed with these

ACCEPTED MANUSCRIPT diphosphines (Entries 10 and 11), which could not be avoided by using a pre-formed catalyst (Entry 12). Nevertheless, the ratio of linear isomers to branched isomers could be notably increased with these bidentate phosphines and especially with the DPPBTS ligand. The good

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results obtained with the TPPTS ligand in [BSMI][p-TsO] prompted us to evaluate another

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SO3H-functionalized BAILs. N-(4-sulfonic acid) butyl triethylammonium tosylate [SBTA][pTsO] was chosen as the acidity of this BAILs was comparable to that of [BSMI][p-TsO]. As shown in entry 13, hydroesterification can be performed in this BAIL but the selectivities

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were lower. Moreover, a decrease in the catalytic activity was clearly observed during the recycling experiments (Entries 14-16). These results strongly suggest that the nature of the

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cation of BAILs contributes to stabilize the catalytic species. The different solvation patterns of TPPTS in the employed solvents could be at the origin of this phenomenon.

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Conclusion

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As a summary, it can be stated that the hydroesterification of olefins with isosorbide can be successfully carried out in standard and Brønsted acidic ILs. The use of ionic ligands such as

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the trisulfonated triphenylphosphine is essential to immobilize the catalytic system in the ionic liquid phase. The best results in terms of activity, selectivity and recyclability were

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obtained using a catalytic system composed of Pd(OAc)2 and trisulfonated triphenylphosphine dissolved in 1-methyl-3-(butyl-4-sulfonic acid) imidazolium tosylate. This system allowed to

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reuse the catalyst without addition of phosphine at the end of each recycling and to avoid the supplementary addition of strong acids into the reaction medium. These features are essential for possible future industrial exploration. Acknowledgements We are grateful to the ANR for the financial support dedicated to the project ISOSORB-CO (2010–006–01). Roquette Frères is gratefully acknowledged for providing pure samples of isosorbide. Isosorbide is part of the BIOHUB program (http://www.biohub.fr).

References [1] P. Wasserscheid, W. Klein, Angew. Chem. Int. Edit. 39 (2000) 3772-3789. [2] H. Olivier-Bourbigou, L. Magna, D. Morvan Appl. Catal. A : Gen. 373 (2010) 1-56. [3] A. Brennführer, H. Neumann, M. Beller, ChemCatChem (2009) 1, 28-41. [4] D. Zim, R.F. de Souza, J. Dupont, A.L. Monteiro, Tetrahedron Lett. 39 (1998) 7071-7074.

ACCEPTED MANUSCRIPT [5] M.A. Klingshirn, R.D. Rogers, K.H. Shaughnessy, J. Organomet. Chem. 690 (2005) 36203626. [6] G. Rangits, L. Kollar, J. Mol. Catal. A. Chem. 242 (2005) 156-160.

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[7] A. Balazs, C. Benedek, S. Torös, J. Mol. Catal. A: Chem. 244 (2006) 105-109.

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[8] G. Rangits, L. Kollar, J. Mol. Catal. A: Chem. 246 (2006) 59-64.

[9] A. Osichow, S. Mecking, Chem. Commun. 46 (2010) 4980-4981.

Am. Chem. Soc. 124 (2002) 5962-5963.

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[10] A.C. Cole, J.L. Jensen, I. Ntai, K.L.T. Tran, K.J. Weaver, D.C. Forbes, J.H. Davis, J.

[11] J. Yang, H. Zhou, X. Lu, Y. Yuan, Catal. Commun. 11 (2010) 1200-1204.

Chem. 16 (2014) 161-166.

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[12] E.J. García-Suárez, S.G. Khokarale, O.N. van Buu, R. Fehrmann, A. Riisager, Green

[13] S.G. Khokarale, E.J. García-Suárez, J. Xiong, U.V. Mentzel, R. Fehrmann, A. Riisager Catal. Commun. 44 (2014) 73-75.

[14] R. Pruvost, J. Boulanger, B. Léger, A. Ponchel, E. Monflier, M. Ibert, A. Mortreux, T.

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Chenal, M. Sauthier, ChemSusChem 7 (2014) 7 3157-3163.

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[15] M. Rose, R. Palkovits, ChemSusChem 5 (2012) 167-176.

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Scheme 1. Hydroesterification of 1-octene with isosorbide.

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Scheme 2. Structures of synthesized ILs

ACCEPTED MANUSCRIPT Table 1. The hydroesterification of 1-octene with isosorbide in the presence of different ionic liquids.a

d e

Isosorbide conversion (%) 97 81 75 71 <1 40 <1 77 64 85 79 <1

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75 61 61 47 <1 41 16 67 43 73 72 12

Isomerization selectivity (%) 5 3 23 <1 <1 49 99 15 <1 6 7 99

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10 10 10 10 -

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[BMI][PF6] [BMI][BF4] [BMI][p-TsO] [BMI][p-TsO] [BSMI][HSO4] [BSMI][CH3COO] [BSMI][NTf2] [BSMI][Cl] [BSMI][p-TsO] [BSMI][p-TsO] [BSMI][p-TsO]

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1c 2 3 4 5 6 7 8 9 10 11d 12e

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Ionic Liquid

1-octene conversion (%)

3a + 3b selectivity (%) 8 13 30 36 <1 78 <1 23 35 6 7 <1

4 selectivity (%)

l/b ratiob

92 87 70 64 <1 22 <1 77 65 94 93 <1

75/25 75/25 75/25 75/25 75/25 75/25 75/25 75/25 75/25 -

Experimental conditions: [Pd(OAc)2] = 0.04 mmol (1 eq.), PPh3 = 0.64 mmol (16 eq.), PTSA = 0.41 mmol (10 eq.), Isosorbide = 10.26 mmol) (257 eq.), 1-octene = 25.66 mmol (642 eq.), Ionic liquid = 2.0 g, T = 110°C, 40 bar CO, 900 rpm, reaction time = 20 h. Ratio of linear isomers to branched isomers determined by GC-FID after saponification of the crude mixture of esters. Catalytic test was carried out in 1,4-dioxane PPh3/Pd molar ratio : 8. Experiment performed without PPh3.

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Entry

PTSA/Pd molar ratio

ACCEPTED MANUSCRIPT Table 2. The hydroesterification of isosorbide with 1-octene in the presence of different phosphines.a

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a b c d e f g h

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[BSMI][p-TsO]

11 12k 13 14l 15m 16o

[BSMI][p-TsO] [BSMI][p-TsO] [SBTA][p-TsO] [SBTA][p-TsO] [SBTA][p-TsO] [SBTA][p-TsO]

TPPTS Sulfonated xantphos DPPBTS DPPBTS TPPTS TPPTS TPPTS TPPTS

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28 41 90 71 67 3

28 44 65 48 44 3

75/25 75/25 75/25 75/25 75/25 75/25 75/25 75/25

Pd content in the organic phase (ppm) 204 <1 <1 <1 <1 -g -g -g

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85/15

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53 48 55 60 57 67

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90/10 90/10 75/25 75/25 75/25 -

-g -g -g -g -g -g

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4 selectivity (%) 94 89 82 84 76 87 46 82

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PPh3 TPPTS TPPTS TPPTS TPPTS TPPTS TPPTS TPPTS

3a + 3b selectivity (%) 6 11 18 16 24 13 54 18

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[BSMI][p-TsO] [BSMI][p-TsO] [BSMI][p-TsO] [BSMI][p-TsO] [BSMI][p-TsO] [BSMI][p-TsO] [BSMI][p-TsO] [BSMI][p-TsO] [BSMI][pTsO]/BSMI

Isosorbide conversion (%) 85 79 81 80 74 80 64 81

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1-octene Isomerization conversion selectivity (%) (%) 73 6 69 11 59 23 60 22 52 15 72 13 50 10 67 13

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Phosphine

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BAIL

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Entry

l/b ratiob

Experimental conditions: [Pd(OAc)2] = 0.04 mmol (1eq.), P atom = 0.64 mmol (16 eq.), Isosorbide = 10.26 mmol) (257 eq.), 1-octene = 25.66 mmol (642 eq.), BAIL = 2.0 g, T = 110°C, 40 atm CO, 900 rpm, reaction time = 20 h. Ratio of linear isomers to branched isomers determined by GC-FID after saponification of the crude mixture of esters. Performed with the catalytic phase recovered from entry 2. Performed with the catalytic phase recovered from entry 3. Performed with the catalytic phase recovered from entry 4. TPPTS = 0.32 mmol. Not determined. [Pd(OAc)2] = 0.02 mmol, TPPTS = 0.32 mmol.

ACCEPTED MANUSCRIPT [BSMI][p-TsO] = 0.8 g Mixture of [BSMI][p-TsO] (0.8 g) and BSMI (1.2g) Performed with a pre-formed catalyst: Pd(OAc)2 (0.04 mmol) and DPPBTS ligand (0.32 mmol) were heated to 80°C under nitrogen atmosphere during 2 h in a mixture of [BSMI[p-TsO] (2.0 g) and isosorbide (1.5 g) before catalysis. l Performed with the catalytic phase recovered from entry 13. m Performed with the catalytic phase recovered from entry 14. o Performed with the catalytic phase recovered from entry 15.

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Highlights Standard and Brønsted acidic ionic liquids (BAILs) can serve as solvent.



Isosorbide conversions up to 85 % with a chemoselectivity in diesters of 90 % are obtained.



The immobilization of the catalyst in the BAIL can only be achieved with ionic ligands.



Trisulfonated triphenylphosphine allows to recycle the catalytic system.

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