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JOURNAL OFMOLECULARCATALYSISA CHEMICAL

Journal of Molecular Catalysis A: Chemical 98 ( 1995) 117-122

Surface active phosphines for catalysis under two-phase reactionconditions. P ( menthyl) [ ( CH 2) ,C,H,-p-SO,Na] 2 and the

hydroformylation of styreneTam Bartik , Hao Ding, Berit Bartik 2, Brian E. Hanson *

Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, USAReceived 30 May 1994: accepted 16 January 1995

bstract

The novel optically active phosphine, bis( 8-phenyloctyl) (Menth)phosphine, (Menth = lR,3R,4S( - )menthyl) is synthe-sized and sulfonated under mild conditions to yield the corresponding sulfonated phosphine, disodium bis-( 8-(pura-sulfonato-phenyl)octyl) (Menth)phosphine. The water soluble phosphine is used to generate an aqueous-methanol rhodium catalyst forthe hydroformylation of styrene. Th e catalyst shows high catalytic activity, bu t virtually no optical induction. Norma l to branchratios for the hydroformylation of styrene are in the range 0 .35 to 0.5. The catalytic data with TPPT S is given for comparison.TPPTS yields catalysts that are less active under two phase reaction conditions and slightly less selective for formation of 2-phenylpropanal.

A great deal of research interest has recentlyfocused on the development of water soluble tran-sition metal complexes as catalysts for the hydro-genation and hydroformylation of olefins [ l-91.In addition to the environmental benefits of waterbased processes, the ease of catalyst separationfrom water immiscible products provided by thesecomplexes may reduce the cost of commercialhomogeneous catalytic processes. With water sol-uble catalysts there is evidence that reactionoccurs in the aqueous phase [ 4,9]. For this reasonthe application of water soluble hydroformylationcatalysts has been limited to propylene, which hassufficient water solubility to provide good reaction

*Corresponding author. Research Group for Petrolchemistry of the Hungarian Academy

of Sciences (Veszprbm) FRG Research Fellow (Deutsche Forschungsgemeinschaft -

Bonn) 1991-1993

rates [ 21; reaction rates are low in a two phasesystem with higher olefins as the substrate.

Several approaches have been taken to increasethe reaction rate of a higher olefin with a watersoluble hydroformylation catalyst. For example,in those catalysts that contain TPPTS, trisodiumsalt of trisulfonated triphenylphosphine, thesodium ion may be replaced by a quatemaryammonium cation [ lo]. This allows the catalysisto be done in a homogeneous reaction environ-ment in a polar solvent such as an alcohol. Sur-factants have been added to two phase reactionmixtures in order to increase reaction rates [ 111.Another approach involves the immobilization ofwater soluble catalysts in a supported aqueousphase on a high surface area hydrophilic solid[ 121. These supported aqueous phase catalystshave proven very effective for the application of

1381-l 169/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved.SSDI1381-1169(95)00012-7


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118 T. Barti k et al. Journal of M olecular Cataly sisA: Chemical 98 1995) 117-I 22-I) p N 3 +01 3 ho-so p /N

PIdHCH2S0e.g.R = C H k 3I

Scheme 1.

water soluble catalysts to the hydroformylation ofhigher olefins.Another modification that retains the two

immiscible phases reaction format involves theuse of surface active phosphines [ 13,141.Although the mode of action in these systems isnot known at this time, it is clear that significantrate enhancements can be observed. For example,the tripyridylphosphine has been modified asshown in Eq. 1 to yield a sulfonated surface activephosphine, 1 [ 131 (Scheme 1) Rhodium com-plexes of 1 in the presence of excess phosphineare thought to form micelles.

Recently we reported the aqueous phase hydro-formylation of octene- 1 with rhodium complexesof trisulfonated tris ( ephenylalkyl) phosphines[ 141. The results show an increase in reaction rateas the alkyl chain length, and hence the surfaceactivity, increases.

Asymmetric hydroformylation is of importancedue to the potential for the enantioselective prep-aration of compounds of pharmaceutical interest[ 15-191. In this regard there has been somenotable success with rhodium complexes of che-lating chiral phosphites [ 18,191. Here we reportthe preparation of a surface active monodentatephosphine that bears a chiral menthyl moiety, andits use in the hydroformylation of styrene. Thecatalytic results are reported in aqueous methanolwhich is immiscible with styrene and the phen-ylpropanal hydroformylation products.

1 Experimental sectionAll reactions and analyses were carried out

under an argon atmosphere by standard Schlenktechniques. All solvents used in experiments werefreshly distilled under N2 to remove oxygen. Allchemicals were purchased from Aldrich and usedwithout further purification.

The high pressure hydroformylation reactionswere performed in 30 ml stainless steel reactionvessels equipped with high pressure gauges. Thetemperature of the catalytic reactions was con-trolled by an Omega CN 2000 temperature processcontroller and a silicon oil bath; n/b ratios andyields of the reactions were determined by gaschromatography on a Varian 3300 chromatographequipped with an HP 1 column (25 m X 0.32mm X 0.52 Frn) and FID detector; the carrier gaswas helium.

The enantiomeric excess (ee/%) of 2-phenyl-propanal was determined by optical rotation bycomparison with the reported rotation of 2-phen-ylpropanal [ 201.

Abbreviations:Menth = lR,3R,4S( - )menthyl. IR data; vs, verystrong; w, weak; NMR; s, singlet; d, doublet; t,triplet; q, quartet; quin, quintet; carbon numberingscheme:

10 11P c c c c c c c c 9 12

12345678 -0 14 13

Prepa ra t i o n o f l -B rom o -8 -pheny l oc t ane 2 ).1,8-Dibromooctane, 200 g (0.73 mol), and 200ml of diethyl ether were placed into a three-neckflask equipped with reflux condenser and equal-pressure dropping funnel. After the addition of200 ml of 1.8 M PhLi in cyclohexane the reactionwas heated at reflux for 24 h. Lithium bromidewas removed by filtration and the solvent removedby distillation. The resulting oil was vacuum dis-tilled, and the fractions were checked by GC. Thefraction collected at 160-165C and 3 Torr con-tained C6H5 CH2) sBr; yield, 22 g (23% based onPhLi). Colorless oil, bp (3 Torr): 160-165C.$: 1.5220. H NMR S ( CDC13) 1.21-1.49 (m,8H, C(3)&-C(6)H,), 1.6 (quin, Jnn=6.6 Hz,2H, C(7)&), 1.82 (quin, JHH=7.4 Hz, 2H,C(2)&), 2.59 (t, JHH=7.4 Hz, 2H, C(8)&),3.37 (t, Jnn=6.6 Hz, 2H, C(l)&), 7.03-7.40(m, 5H, C&Z,). 13CNMR S ( CDC13) 28.23 (s,C(4)H,),28.77 (s,C(5)H,),29.28 (s,C(3)H,),


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T. Bart ik et al. Journal of M olecular Cata ly sis A: Chemi cal 98 1995) 117-122 119

29.35 (s, C(6)H,), 31.50 (s, C(7)H2), 32.90 (s,C(2)H,), 33.94 (s, C(l)H,), 36.01 (s,C(8)H&jH,), 125.64 (s, C(U)H(C,H,)),128.30 (s, C( ll)H+C( 13)H(C,H,)), 128.43(s, C( lO)H+C( 14)H(C,H,)), 142.60 (s,C(8)H,C(9) (GH,) ). MS mlz:(M-H+) =268.

Synthesis of bis( 8-phenyloctyl)menthyl phos-phine (3a). Bis ( 8-phenyloctyl) menthyl phos-phine was prepared from the reaction ofC6H5 CH2) ,MgBr and (Menth) PC& in ether[ 2 ] . After fractional crystallization from pentaneat - 80C the pure product is obtained as a col-orless oil in 45% yield upon warming to roomtemperature. Colorless oil, d (g/ml): 1.095.[(Y]: (CH &): -52.2. H NMR 6 (CDCl,):0.65-1.72 (m, 47H, 2X(C(l)&-C(:7)H,) +C,,,H,,(Menth)), 2.49 (t, &=8.1Hz,4H,C(8)UZ),7.15-7.22 (m, 10H,2XCa5).13C NMR S (CDC&): 11.02 (s,CI-I&H( Menth) ) , 14.17, 15.25 (s,(CH,)&H(Menth)), 26.72 (s br, C( l)H,P),27.51 (s br, C(2)H,C(l)H,P), 29.39 (m,C(3)H,-C(6)H,), 31.57 (s, C(7)H,), 36.08 (s,C(~)HK,HS), 45.07 (d, Jpcp=9.1 Hz,CI-IP(Menth)), 125.63 (s, C( 12)H(C,H,)),128.30 (s, C( 11+ 13)H(C,H,)), 128.42 (s,C(lO+ 14)H(C,H,)), 142.91 (s,C(8)H,C(9)(C,Hs)). P NMR S (CDCI,):-31.51 (s).

Synthesis of pg-disulfonated bis( 8-phenyloc-tyl) menthy lphosphin e (3b). The sulfonation ofbis ( 8-phenyloctyl) menthyl phosphine 3a) wascarried out in concentrated HzS04. Typically 5 g(8.5 mmol) of 3a was dissolved in portion in 20ml of concentrated H,SO, at room temperature.The sulfonation was complete after 2 h as deter-mined by H and 3P NMR and was quenched bythe slow addition of 20% NaOH at 0C. The vol-ume of the reaction solution was reduced to ca. 30ml and then 300 ml of methanol was added andthe mixture brought to reflux. After filtration thesolid was further extracted with 200 ml of 1O:lhot methanol/water. The extracts were combinedand reduced in volume to 50 ml. Addition of 250ml of acetone yielded p,p-disulfonated bis( 8-

phenyloctyl) menthyl phosphine in ca. 90%purity. Further purification was achieved byrecrystallization from ethanol. The yield of 3b was65% based on (Menth)P[ ( CHz)&H512. Whitecrystals, mp>300C. [cy]: (CH,OH): -31.5.H NMR 6 (D,O): 0.81-2.95 (m br, 51H,2X (CH,),+Menth), 6.91-7.15, 7.58-7.72 (m,8H, 2x&&). PNMR S (D,O): -31.60 (s).MS FAB (glycerol matrix) ml.21(M+H) + =753; 731, 689, 651, 315, 205, 137,115. (The FAB mass spectra show the molecularion plus a proton. The fragmentation processesgive peaks at ( + Naf -H+), (-Na++H+),and ( - S03Na +H ) . The cleavage of the men-thy1 group results in a (menthene - H+ ) fragment(137)).Preparation of trans- PdCl, (L = (Menth)P[(CH,) H5],) (4). The bis(phosphine)-palladium complexes of the nonsulfonated ligandswere prepared in chloroform at room temperaturefrom ( PhCN) ,PdC& by literature procedures[ 22,231. The purpose of the preparation of thiscompound was to estimate the steric size of thephosphine. The compound was isolated as an oiland thus was not subjected to analysis beyondrecording its 3P NMR spectrum. Only one signalwas observed consistent with formation of thetrans complex. P NMR 6 (CDC13): 14.18 (s).

Synthesis o f L,.Ni(CO),_, (L= (Menth)P[CH2)8C 5]2, y=l, 2) (5a, 56). The com-plexes LNi (CO) 3 and L2Ni ( CO) 2 were preparedfrom the nonsulfonated ligand in CH,Cl, follow-ing literature procedures [ 23-251. The complexeswere characterized by their infrared spectra in thecarbonyl region and by 3P NMR spectroscopy.Both of the nickel complexes 5a and 5b wereisolated as oils; the compounds, 5a and 5b couldbe isolated free from one another, as judged by3P NMR spectroscopy, but not free of solvent.The purpose of preparation of 5a was to estimatethe Tolman electronic parameter by infrared spec-troscopy. The purity of the complex was judgedto be sufficient for this purpose.

(Menth)P[(CH,)8C6HS]2Ni(C0)3 5a). IR(cm-, CH,Cl,) v(C0): 2059.57 (w), 1980.47(vs). 3PNMR 6 (CD&l,): 21.57 (s).


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I. Bartik et al. /Journal of Molecular Catalysis A: Chemical 98 (I 995 I 17-122 121

PRI CH,),C,H,-p-SO,Nal2/Rh acafHCO), = 3 IM) 1Rb aca~NC0)~ + PRI CH,~C6H,-p-SO,NnlZ

tI 0

Ill

0 I

0.6+ n/b

04

0.2

02468 IO 12 14 16lime h)

fb) 9yrene hyd rotiirmylatmn

IO0 TPPWRh acac) CO)2 = 3/l

t

1.0

0

02468 IO 12 I4 16fm~e h)

Fig. 1. (a) Yield of aldehydes and n/h ratio as a function of time inthe two phase hydroformylation of styrene with Rh( acac) ( CO)z and3h at a P/Rh ratio of 3. Styrene/Rh=XO; 120C. 14 atm CO:H*,1:1. (b) Yield of aldehydes and n/b ratio as a function of time inthe two phase hydroformylation of styrene with Rh( acac) (CO), andTPPTSataPkhratioof3. Styrene/Rh=SlO; 120C. 14atmCO:H2,1:l.

Reaction selectivity is indicated in Figs. 1 and2 only as the n/b ratio. The possibility exists w iththe menthyl phosphine, 3b that optical inductionin the formation of 2-phenylpropanal may lead tothe preferential formation of one enantiomer.Thus the optical purity of the products was inves-tigated. Unfortunately no significant enantiomericexcess was observed by optical rotation in any ofthe reactions with 3b as the ligand.

3. DiscussionThe initial turnover frequencies, as estimated

from the initial slopes in Figs. la and lb, are 245

80 -0X

60 -06+ n/h

41, +--- -----_..__ ___-_+_

I I 2 1 4 5 6 1 8 9 IOURh

W Slyrene bydmformyladonIN?- Rb acacXCO)> + TPPTS

80 -

u .,,,....,,,.,,,,,,..rIJ I 2 -i 4 5 6 7 8 9 1

URhFig. 2. a. Yield of aldehydes and n/b ratio as a function of ligand torhodium ratio at a constant reaction time of 2 h with catalysts derivedfrom Rh(acac)(CO), and 3b Styrene/Rh=500; 12OC, 14 atmCO:H2, 1:l. (b) Yield of aldehydes and n/b ratio as a function ofligand to rhodium ratio at a constant reaction time of 8 h with catalystsderived from Rh( acac) (CO), and TPPTS. Styrene/Rh = 500;120C 14 atm CO:H2, 1:l.

mol aldehyde (mol - Rh) h - and 100 mol alde-hyde (mol - Rh) h - I for ligand 2 and TPPTSrespectively at a L/Rh ratio of 3. W hile a differ-ence in rate may be expected between a trialkyl-phosphine and a triarylphosphine for the rhodiumcatalyzed hydroform ylation of olefins it can beargued that the higher rate is expected for the latter[ 2 11. In the comparison above, the more surfaceactive phosphine, 3b shows the higher rate, inspite of the fact that it is a trialkylphosphine.

The mech anism for the increase in rate is notclear at this time. It was argued that those sulfo-nated tripyridyl phosphines with a long alkylchain, 1 form micelles and thus show increasedreaction rates over their nonsulfonated analogs[ 141. In addition to increased reaction rates evi-dence for micelle formation was argued based onthe increased solubility of water insoluble com-pounds in the reaction medium . W hen the aque-


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122 T. Bart ik et al. Journal of M olecular Cata ly sis A: Chemical 98 1995) 117-122

ous/nonaqueous mixtures form stable emulsionsthe reaction rates decreased dramatically [ 141. Inthe example presented here after reaction thenonaqueous and aqueous phases rapidly separateand the color associated with rhodium complexformation is exclusively in the aqueous phase. Noevidence for the formation of an emulsion wasobserved. In favor of some degree of phosphineaggregation in the aqueous phase for 3b is the factthat the water insoluble dye Orange-OT dissolvesin dilute aqueous solutions of 3b [ 271. Studiesare in progress to measure directly the degree ofaggregation of this phosphine and related surfaceactive phosphines in aqueous solution.

Although the phosphine is chiral no opticalinduction is observed in 2-phenylpropanal. Thisis not surprising in that monodentate chiral phos-phines generally perform poorly in asymmetrichydroformylation [ 281.

AcknowledgementsWe thank NSF (CTS-9101846) for support of

this work. Berit Bartik gratefully acknowledges afellowship from the Deutsche Forschungsgemein-schaft ( 199 l-93).

References[ l W.A. Herrmann and C.W. Kohlpaintner, Angew. Chem., bit.

Ed. Engl., 32 (1993) 1524.[2] E.G. Kuntz, CHEMTECH, 17 (1987) 570.[ 31 A. Benyei and F. Jo6, J. Mol. Catal., 58 (1990) 151.

[4] A.F. Borowski, D.J. Cole-Hamilton and G. Wilkinson, Nouv,J. Chem., 2 (1978) 137.

[51 P. Kalck, P. Escaffre, F. Serein-Spirau, A. Thorez, B. Besson,Y. Colleuille and R Perron, New J. Chem., 12 ( 1988) 687.

[6] A. Abatjoglou, US Pat. 5.196.596 (1993).[7] M.K. Markiewicz and M.C. Baird, Inorg. Chim. Acta, 113

(1986) 95.[ 81 C. Larpent, F. Brise-Le Menn and H. Patin, New J. Chem., 15(1991) 361.[91 LT. Horvath, Catal. Lett., 6 ( 1990) 43.

[lo] E. Kuntz, US Pat. 4,248,802 ( 1981).[ 111 Y. Dror and J. Manassen J. Mol. Catal., 2 (1977) 219[ 121 (a) J. P Arhancet, M.E. Davis and B.E. Hanson, J. Catal., 129

( 1991) 94; (b) J. P Arhancet, M.E. Davis and B.E. Hanson,J. Catal., 129 (1991) 100.

[ 131 B. Fell and G. Pagadogianakis, J. Mol. Catal., 66 ( 1991) 143.[ 141 T. Bartik, B. Bartik and BE. Hanson, J. Mol Catal., 88 ( 1994)

43.[ 151 I. T&h, B.E. Hanson and I. Guo, Organometallics, 12 (1993)

848-852.[ 161 G. Parrinello and J.K. Stille, J. Am. Chem. Sot., 109 (1987)7122.[ 171 L. Kollar, J. Bakos, I T&h and B. Heil, J. Organomet. Chem.,

370 ( 1989) 257.[ 181 J.E. Babin and G.T. Whiteker, World Pat. WO93103839,

(1993)[ 191 G.D. Cuny and S.L. Buchwald, J. Am. Chem. Sot., (1993)

114 2066.[20] G. Consiglio, P. Pino, L. Flowers and C.K. Pittman, J. Chem.

Sot., Chem. Commun., (1983) 612.[21] G.M. Kosolapoff and L. Maier, Organic Phosphorus

Compounds, Vol. 1, Wiley-Interscience, New York, 1972.[22] T. Hayashi, M. Konishi and M. Kumada, Tetrahedron Lett.,

(1979) 1871.[23] T. Bartik, B. Bartik, B.E. Hanson, I. Guo and I. Toth,

Organometallics, 12 (1993) 164.[24] W. Strohmeir and F.J. Muller, Chem. Ber., 100 (1967) 2812.[25] C.A. Tolman, Chem. Rev., 77 (1977) 313.[26] T. Bartik and T. Himmler, I. Organomet. Chem., 293 ( 1985)

343.[27] A.W. Adamson, Physical Chemistry of Surfaces, 5th Ed.,

Wiley Interscience, p. 509.[28] H.B. Kagan, in G. Wilkinson, F.G.A. Stone and E.W. Abel,

(Eds. ) , Comprehensive Organometallic Chemistry, PergamonPress, London, 1980, Chap. 53.

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