Sulfuric Acid-Catalyzed Conversion of Alkynes to Ketones in an Ionic Liquid Medium under Mild Reaction Conditions

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1 Sulfuric Acid-Catalyzed Conversion of Alkynes to Ketones in an Ionic Liquid Medium under Mild Reaction Conditions Wing-Leung Wong, Kam-Piu Ho, Lawrence Yoon Suk Lee, Kin-Ming Lam, Zhong-Yuan Zhou, Tak Hang Chan, and Kwok-Yin Wong* Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China * Corresponding author; bckywong@polyu.edu.hk; Fax: List of Contents: (1). Figure S1. X-ray structure of 1 (HSO 4 ) 2 (2). Table S1. Crystal data and structure refinement of 1 (HSO 4 ) 2 (3). Table S2. Bond angles and bond lengths of 1 (HSO 4 ) 2 (4). Experimental 4.1 Materials and Instrumentation 4.2 Synthetic Procedures 4.3 Procedures for Catalysis (5). Figure S2. ESI-Mass spectrum of ESI-Mass spectrum of 1 (HSO 4 ) 2 (6). Figure S3. High resolution mass spectrum of 1 ( HSO 4 ) 2 (7). Figure S4. (a) 1 H MR and (b) 13 C MR spectra of 1 (HSO 4 ) 2 1

2 1. X-ray structure of 1 (HSO 4 ) 2 : An ORTEP representation of 1 (HSO 4 ) 2 with 30% thermal ellipsoids. The crystal data can be obtained from the Cambridge Crystallographic Data Centre via (Deposition number: CCDC ) Figure S1. X-ray structure of 1 (HSO 4 ) 2. 2

3 2. Table S1. Crystal data and structure refinement of 1 (HSO 4 ) 2. Empirical formula (C 16 H 34 ).2(SO 4 H) Formula weight Temperature 296(2) K Wavelength Å Crystal system Monoclinic Space group P2(1)/n Unit cell dimensions a = (3) Å, = 90. b = (2) Å, = (2). c = (4) Å, = 90. Volume (5) Å 3 Z 2 Density (calculated) Mg/m 3 Absorption coefficient mm -1 F(000) 484 Crystal size 0.42 x 0.20 x 0.16 mm 3 Theta range for data collection 2.89 to Index ranges -12<=h<=12, -10<=k<=10, -17<=l<=16 Reflections collected Independent reflections 2335 [R(int) = ] Completeness to theta = % Absorption correction Semi-empirical from equivalents Max. and min. transmission and Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 2335 / 3 / 134 Goodness-of-fit on F Final R indices [I>2sigma(I)] R1 = , wr2 = R indices (all data) R1 = , wr2 = Largest diff. peak and hole and e.å -3 3

4 3. Table S2. Bond angles and bond lengths of 1 (HSO 4 ) 2 Bond angles [ ] C(8)-(1)-C(4) (11) C(8)-(1)-C(1) (11) C(4)-(1)-C(1) (11) C(8)-(1)-C(5) (11) C(4)-(1)-C(5) (11) C(1)-(1)-C(5) (10) (1)-C(1)-C(2) (12) (1)-C(1)-H(1A) C(2)-C(1)-H(1A) (1)-C(1)-H(1B) C(2)-C(1)-H(1B) H(1A)-C(1)-H(1B) C(1)-C(2)-C(3) (12) C(1)-C(2)-H(2A) C(3)-C(2)-H(2A) C(1)-C(2)-H(2B) C(3)-C(2)-H(2B) H(2A)-C(2)-H(2B) C(4)-C(3)-C(2) (13) C(4)-C(3)-H(3A) C(2)-C(3)-H(3A) C(4)-C(3)-H(3B) C(2)-C(3)-H(3B) H(3A)-C(3)-H(3B) (1)-C(4)-C(3) (12) (1)-C(4)-H(4A) C(3)-C(4)-H(4A) (1)-C(4)-H(4B) C(3)-C(4)-H(4B) H(4A)-C(4)-H(4B) (1)-C(5)-C(6) (12) (1)-C(5)-H(5A) C(6)-C(5)-H(5A) (1)-C(5)-H(5B) C(6)-C(5)-H(5B) H(5A)-C(5)-H(5B) C(5)-C(6)-C(7) (12) C(5)-C(6)-H(6A) C(7)-C(6)-H(6A) C(5)-C(6)-H(6B) C(7)-C(6)-H(6B) H(6A)-C(6)-H(6B) C(7)#1-C(7)-C(6) (15) C(7)#1-C(7)-H(7A) C(6)-C(7)-H(7A) C(7)#1-C(7)-H(7B) C(6)-C(7)-H(7B) H(7A)-C(7)-H(7B) (1)-C(8)-H(8A) (1)-C(8)-H(8B) H(8A)-C(8)-H(8B) (1)-C(8)-H(8C) H(8A)-C(8)-H(8C) H(8B)-C(8)-H(8C) O(1)-S(1)-O(4) (8) O(1)-S(1)-O(3) (8) O(4)-S(1)-O(3) (7) O(1)-S(1)-O(2) (7) O(4)-S(1)-O(2) (7) O(3)-S(1)-O(2) (6) S(1)-O(1)-H(1S)

5 Bond lengths [Å] (1)-C(8) (17) (1)-C(4) (18) (1)-C(1) (16) (1)-C(5) (16) C(1)-C(2) 1.515(2) C(1)-H(1A) C(1)-H(1B) C(2)-C(3) 1.523(2) C(2)-H(2A) C(2)-H(2B) C(3)-C(4) 1.508(2) C(3)-H(3A) C(3)-H(3B) C(4)-H(4A) C(4)-H(4B) C(5)-C(6) 1.522(2) C(5)-H(5A) C(5)-H(5B) C(6)-C(7) (18) C(6)-H(6A) C(6)-H(6B) C(7)-C(7)# (3) C(7)-H(7A) C(7)-H(7B) C(8)-H(8A) C(8)-H(8B) C(8)-H(8C) S(1)-O(1) (12) S(1)-O(4) (11) S(1)-O(3) (12) S(1)-O(2) (11) O(1)-H(1S)

6 4. Experimental 4.1 Materials and Instrumentation All chemicals were purchased from Aldrich or Acros Organic. All the solvents were of analytical reagent grade and used without further purification. A Hewlett-Packard 8900 GC-MS and GC-FID equipped with EC-1 or EC-WAX columns (Alltech Associates, Inc.) were used to identify the reaction products and to determine the reaction yield. 1 H and 13 C MR spectra were recorded on a Bruker DPX-400 MHz MR spectrometer. Tetradecane was used as an internal standard in the quantitative GC-FID and GC-MS measurements. 4.2 Synthetic Procedures (A) Preparation of 1 (Br) 2 : 1,6-dibromohexane (15.4 ml, 0.1 mol) was added to 1-methylpyrrolidine (22.9 ml, 0.22 mol) in 50 ml acetonitrile with caution. The mixture was gently heated to reflux under argon for 24 h. White solids of 1 (Br) 2 were precipitated out upon the cooling down to the room temperature. THF was added to complete the precipitation of the product. Following the decant of solvent, the product was washed thoroughly with THF and dried under vacuum to afford 1 (Br) 2 as a white solid with 99 % yield. 1 H MR (400 MHz D 2 O): δ (m, 4H), (m, 4H), 2.25 (s, 8H), 3.09 (s, 6H), (m, 4H), (m, 8H); ESI-MS m/z: [M 2+ ] = 127, [M -Br - ] + = 333, 335. (B) Preparation of 1 (HSO 4 ) 2 : The 1 (Br) 2 (16.6g, 40 mmol) and Ag 2 O (13.9 g, 60 mmol) were added into a round-bottomed flask containing 150 ml water. The mixture was stirred for 24 h and the precipitates of AgBr were filtered out and recycled. The filtrates, 1 (OH) 2, were neutralized by slow addition of concentrated sulfuric acid (4.5 ml, 84 mmol; 95 % - 98 %, ACS Grade). The insoluble brown solid was filtered out. After drying, 1 (HSO 4 ) 2 was obtained as a white hygroscopic solid with 99 % yield; ESI-MS m/z: [M 2+ ] = 127, [M -HSO - 4 ] + = 351; m. p. = 184 C. (C) Preparation of 1 (HSO 4 ) 2 crystals for the X-ray crystallographic analysis: 1 (HSO 4 ) 2 (0.1 g) was dissolved in a hot solution of absolute ethanol. After coolong, dry acetone was vapor diffused slowly into the solution at room temperature under closed conditions. Transparent crystals suitable for X-ray crystallography analysis were obtained. Caution: the compound is very sensitive to and readily absorbs moisture from air. The detailed crystal data for 1 (HSO 4 ) 2 are available at the Cambridge Crystallographic Data Centre (Deposition number: CCDC ). 6

7 4.3 Procedures for catalysis (A) General procedures for alkyne hydration in ionic liquid: 1 (HSO 4 ) 2 (3.1 g, 7 mmol), H 2 SO 4 (430 µl, 8 mmol), H 2 O (36 µl, 2 mmol), and phenylacetylene (110 µl, 1 mmol) were added to a 25 ml round-bottomed flask. The reaction mixture was vigorously stirred at 40 C for 30 min, and then extracted with pentane (4 x 10 ml). The collected organic layers were combined and dried over sodium sulfate. The solution was concentrated by rotary evaporation and the yield was determined by GC with an internal standard. (B) Recycling studies of 1 (HSO 4 ) 2 -H 2 SO 4 medium for the hydration of phenylacetylene: The initial hydration reaction of phenylacetylene was carried out similar to that described in the general procedures. After each experiment had been completed, the resulting product, acetophenone, was extracted with pentane for the determination of reaction yield. The residual pentane was removed under vacuum, and the reaction mixture of 1 (HSO 4 ) 2 -H 2 SO 4 was reused for the next run. To the recycled 1 (HSO 4 ) 2 -H 2 SO 4, only H 2 O (36 µl, 2 mmol) and phenylacetylene (110 µl, 1 mmol) were added, and the next cycle was carried out under the same conditions. 7

8 m/z (calc.) = HSO 4 - m/z (calc.) = Figure S2. ESI-Mass spectrum of 1 (HSO 4 ) 2 8

9 (a) For C 16 H 34 2 : Measured M.W [M] 2+ = Theoretical M.W [M] 2+ = Mass Error = -2.4 ppm (b) HSO 4 - For C 16 H 35 2 O 4 S : Measured M.W [M] + = Theoretical M.W [M] + = Mass Error = 2.5 ppm 6. Figure S3. High resolution mass spectrum of 1 ( HSO 4 ) 2 : (a) For [C 16 H 34 2 ] 2+, and (b) For [C 16 H 35 2 O 4 S] + 9

10 (a) 6H 8H 4H 8H 4H 4H (b) 7. Figure S4. (a) 1 H MR and (b) 13 C MR spectra of 1 (HSO 4 ) 2 in D 2 O 10