Hybrid materials composed of Ionic liquids & Heteropoly acids and their applications NCCR 5 th annual day July 30 th, 2011 G.S. Chinnama Naidu and Prof. G. Ranga Rao Dept. of Chemistry IIT Madras

Room temperature ionic liquids (RTILs) melt below 100 o C and form as ions 1 st RTIL ethyl ammonium nitrate e.g., pyridinium, imidazolium, alkyl phosphonium cations anions like halides, BF 4 -, PF 6 -, triflate melt below 100 o C and form as ions 1 st RTIL ethyl ammonium nitrate e.g., pyridinium, imidazolium, alkyl phosphonium cations anions like halides, BF 4 -, PF 6 -, triflate Applications solvents catalysis electrolytes separation extraction templates Applications solvents catalysis electrolytes separation extraction templates Properties non volatile non flammable high ionic conductivity thermally stable large electrochemical window more density Properties non volatile non flammable high ionic conductivity thermally stable large electrochemical window more density Py - pyridinium B - butyl Im - imidazolium BF 4 - tetrafluoro -borate Br – bromide M - methyl (BPy)Br (BMIm)Br(BMIm)BF 4 tetraethyl ammonium tetrafluoro borate

Heteropoly acids super solid acids polyoxometalates M-O octahedra basic unit e.g., Keggin XM 12 O 40 x-8 eg: H 3 PW 12 O 40.xH 2 O Dawson X 2 M 18 O 62 2x-16 eg: H 6 P 2 W 18 O 62.xH 2 O Lacunary XM 11 O 39 x-12 Applications homogeneous catalysis heterogeneous catalysis oxidation reactions acid catalyst salts of HPAs - catalysis Properties super acids Brønsted acidity multi e - redox transformations soluble in polar solvents KegginDawson

Hybrid materials containing of POM–based salts ILs Ionic liquid (aqu solution) HPA (aqu solution) Hybrid material (precipitate) + Characterization techniques Single crystal XRD & PXRD TGA shows thermal stability absence of water molecules FTIR electrostatic interactions UV-Vis DRS wavelength shift shows interactions Solid state NMR shift shows interaction between IL and POM Characterization techniques Single crystal XRD & PXRD TGA shows thermal stability absence of water molecules FTIR electrostatic interactions UV-Vis DRS wavelength shift shows interactions Solid state NMR shift shows interaction between IL and POM Applications organic conversions oxidation epoxidation of alkenes and cyclo alkenes acid catalysis esterification of polyols and polycarboxylic acids electrochemistry solid electrolytes ascorbic acid oxidation fast proton conductors Applications organic conversions oxidation epoxidation of alkenes and cyclo alkenes acid catalysis esterification of polyols and polycarboxylic acids electrochemistry solid electrolytes ascorbic acid oxidation fast proton conductors

Heteropolyanion-based ionic liquids Same method for following compounds [TEAPS] 3 PW 12 O 40 [PyPS] 3 PW 12 O 40 [MIMPS] 3 SiW 12 O 40 [MIMPS] 3 PMo 12 O 40 [TEA] 3 PW 12 O 40 [MIM] 3 PW 12 O 40 [Py] 3 PW 12 O 40 Same method for following compounds [TEAPS] 3 PW 12 O 40 [PyPS] 3 PW 12 O 40 [MIMPS] 3 SiW 12 O 40 [MIMPS] 3 PMo 12 O 40 [TEA] 3 PW 12 O 40 [MIM] 3 PW 12 O 40 [Py] 3 PW 12 O 40 PS propane sulfonate Py pyridinium TEA triethyl ammonium MIM methylimidazolium PS propane sulfonate Py pyridinium TEA triethyl ammonium MIM methylimidazolium Characterization 1 H, 13 C NMR FTIR ESIMS melting points Characterization 1 H, 13 C NMR FTIR ESIMS melting points Esterification of n-butanol and citric acid over (MIMPS) 3 (PW 12 O 40 ) a)before mixing b)during Rxn time c)before completion of Rxn d)after the Rxn Esterification of n-butanol and citric acid over (MIMPS) 3 (PW 12 O 40 ) a)before mixing b)during Rxn time c)before completion of Rxn d)after the Rxn (MIMPS) 3 (PW 12 O 40 ) (light brown colour) citric acid (white colour) n-butanol(colourless) (MIMPS) 3 (PW 12 O 40 ) Angew. Chem. Int. Ed., 2009, 48, 168 –171

Rxn induced self separation catalyst Catalytic activity of PS containing hybrids (MIMPS) 3 PW 12 O 40 > (PyPS) 3 PW 12 O 40 > (TEAPS) 3 PW 12 O 40 Hybrid material dissolved in water and polar solvents Its also dissolved in polyols and polycar -boxylic acids Rxn induced self separation catalyst Catalytic activity of PS containing hybrids (MIMPS) 3 PW 12 O 40 > (PyPS) 3 PW 12 O 40 > (TEAPS) 3 PW 12 O 40 Hybrid material dissolved in water and polar solvents Its also dissolved in polyols and polycar -boxylic acids b) n A :n B molar ratio of carboxylic acid and alchohol c) yield or selectivity of the ester Heterogenious rxns hybrid material insoluble monocarboxylic acid & alchohols runyield (%)selectivity (%) (MIMPS) 3 PW 12 O 40 catalyst recycling testof n-butanol and citric acid yield or selectivity depend upon tributyl citrate Various catalysts for citric acid and n-butanol esterification

PXRD pattern of a) PWA and b)(BMIM) 3 PW 12 O P MAS NMR of a) PWA and b)(BMIM) 3 PW 12 O 40 UV Vis DRS of a) PWA b) (BMIM)Br and c )(BMIM) 3 PW 12 O 40 loss of water molecules and replacement of protons by BMIM cations 2θ = 9.4º intense peak - layered structure loss of water molecules and replacement of protons by BMIM cations 2θ = 9.4º intense peak - layered structure downfield shift - interactions of BMIM and POM downfield shift - interactions of BMIM and POM 220, 260 and 310 nm charge transfer transitions in Keggin units 311 nm to 295 nm - intermolecular electrinoc transitions 220, 260 and 310 nm charge transfer transitions in Keggin units 311 nm to 295 nm - intermolecular electrinoc transitions Br - J. Chem. Sci., 2008, 120 (6), 587–594 Investigation of hybrid material prepared by IL and polyoxometalate anion

FTIR spectra of a) BMIMBr and b) (BMIM) 3 PW 12 O 40 Near IR spectra of a) PWA and b) (BMIM) 3 PW 12 O 40 Splitting of alkyl and Im C—H stretching Absence of overtone and combination bands absence of water molecules in hybrid material acid strength is less compare to PWA better catalytic activity reusable primary Keggin structure cm -1 range P-O bend.596 cm -1 W-Oe-W stretch.815 cm -1 W-Oc-W stretch.891 cm -1 W-O terminal stretch. 987 cm -1 P-O stretch.1083 cm -1 J. Chem. Sci., 2008, 120 (6), 587–594

(bmim)PF 6 (bmim) 3 (PW 12 O 40 ) (bmim)Cl substrate0.8 mmol H2O2H2O2 1.2 mmol catalyst2.4 µmol solvent1 ml solventyield (%)selec- tivity TON (bmim)PF (bmim)[(CF 3 S O 2 ) 2 N] (bmim)BF 4 trace12<1 CH 3 CN1773 CH 3 OHtrace401 CH 2 Cl 2 trace751 substrateproductyield (%) selec- tivity TON cis-cyclooctenecyclooctene oxide cyclohexenecyclohexene oxide octene1,2-epoxyoctane trans-2-octenetrans-2,3- epoxyoctane methyl-2- heptene 2-methyl-2,3- epoxyheptane epoxidation of cyclooctene in different solvents epoxidation of cyclooctene in different solvents epoxidation of different alkenes in (bmim)PF 6 New J. Chem., 2008, 32, 283–289 A role of IL as an activator for efficient olefin epoxidation catalyzed by polyoxometalate

Time-dependent 31 P NMR spectra at 50 °C: (A) [bmim] 3 PW 12 O 40 reacted with 50 equivalents of H 2 O 2 in a mixed solvent (MeCN– [bmim][PF 6 ] (1:1)); (B) [C 5 H 5 N(CH 2 ) 15 CH 3 ] 3 PW 12 O 40 reacted with H 2 O 2 in MeCN; (C) [bmim] 3 PW 12 O 40 reacted with H 2 O 2 in MeCN. Rxn time: (a) 0 min; (b) 15 min; (c) 30 min; (d) 45 min; (e) 90 min. Rxn time after the addition of substrate cis-cyclooctene: (f) 0 min; (g) 10 min. Case A peak for PW 12 O (-14.4 ppm) 15 min 4.1 (Venturello complex), & ppm (peroxo intermediates) 30 min 4.1, 14.4 ppm [PO 4 {W(O)(O) 2 } 4 ] 3- alkene addition loss of 4.1 ppm peak Venturello complex is active species Case A peak for PW 12 O (-14.4 ppm) 15 min 4.1 (Venturello complex), & ppm (peroxo intermediates) 30 min 4.1, 14.4 ppm [PO 4 {W(O)(O) 2 } 4 ] 3- alkene addition loss of 4.1 ppm peak Venturello complex is active species Case B peak for PW 12 O (-13.8 ppm) 45 min 1.3 ppm weak peak alkene addition no change in intensity of peaks - no active species Case B peak for PW 12 O (-13.8 ppm) 45 min 1.3 ppm weak peak alkene addition no change in intensity of peaks - no active species Case C peak for PW 12 O (-14.0 ppm) no excess peaks after adding H 2 O 2 Case C peak for PW 12 O (-14.0 ppm) no excess peaks after adding H 2 O 2 Effect of [bmim][PF6] in mixed solvents (MeCN and IL) on the epoxidation of cis-cyclooctene at 60 °C for 1 h total mass balance(%) yield (%) substrate (%) pure MeCN no Rxn 10% IL 50% cyclooctene epoxidized 30% IL cyclooctene dissapears for epoxidation mixed solvent system (bmim)PF 6 accelerate the Rxn pure MeCN no Rxn 10% IL 50% cyclooctene epoxidized 30% IL cyclooctene dissapears for epoxidation mixed solvent system (bmim)PF 6 accelerate the Rxn New J. Chem., 2008, 32, 283–289 Venturello complex

Conclusions:  MIMPS) 3 (PW 12 O 40 ) good catalyst for esterfication Rxn induced self seperation catalyst Recyclable catalyst  (bmim) 3 PW 12 O 40 hybrid material characterization by using different techniques  (bmim)PF 6 is active solvent for epoxidation  Rxn kinetics studied by time dependent 31 P MAS-NMR  epoxidation studied in mixed solvents Conclusions:  MIMPS) 3 (PW 12 O 40 ) good catalyst for esterfication Rxn induced self seperation catalyst Recyclable catalyst  (bmim) 3 PW 12 O 40 hybrid material characterization by using different techniques  (bmim)PF 6 is active solvent for epoxidation  Rxn kinetics studied by time dependent 31 P MAS-NMR  epoxidation studied in mixed solvents