Hydration of α-pinenehomogenouscatalyzed by acidic polyether modified ammonium salt ionic liquid in “microreactor”

Lu Li†, Yue Liu†, Shi-Tao Yu†, Shi-Wei Liu†*, Cong-Xia Xie†‡, Fu-Sheng Liu†

†College of Chemical Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, Peoples Republic of China

†‡Key Laboratory of Eco-Chemical Engineering, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, Peoples Republic of China

1. Characterization of structure of Ionic liquid

[AC 1820]+[ H2PO4]-: FT-IR (KBr liquid film, cm−1):3389（-OH）, 2920（C-H）, 1460（C-H），1353（N-CH2，C-H）, 1249（P=O）, 1108（C-O-C）, 543（P-O）. 1H NMR ( D2O, 500 MHz):δ5.21（0.4H）, δ4.64（5.22H）, δ3.69~3.65（2.56H）, δ3.52（46.0H）, δ3.47~3.45（3.6H）, δ3.36~3.29（2.4H）, δ3.20~3.09（1.3H）, δ1.90~1.80（1.0H）, δ1.56（1.2H）, δ1.17~1.11（16.1H）, δ0.73~0.71（2.0H）. 13C NMR ( D2O, 500 MHz): δ130.05, δ71.76, δ64.23, δ60.32, δ53.96, δ52.76, δ31.88, δ29.76, δ29.36, δ29.04, δ27.03, δ26.29, δ23.07, δ22.58, δ13.91.

[AC 1820]+[HSO4]-: FT-IR (KBr liquid film, cm−1): 3473（-OH）, 2919（C-H）, 1460（C-H）, 1353（N-CH2，C-H）, 1247（S=O）, 1110（C-O-C）, 585（S-O）. 1H NMR (D2O, 500 MHz):δ8.04~8.00（0.4H）, δ5.21~5.15（1.0H）,δ4.65（23.7H）,δ4.17~3.10（27.9H）,δ1.93~1.80（2.4H）,δ1.57（4.1H）,δ1.18~1.11（53.6H）,δ0.73~0.71（6.8H）. 13C NMR ( D2O, 500 MHz):δ165.54, δ71.65,δ67.54,δ64.23,δ60.31,δ54.07,δ52.70,δ31.90,δ29.39,δ26.36,δ23.08,δ22.60,δ13.91。

[AC 1820]+[PTSA]-: FT-IR (KBr liquid film, cm−1): 3396（-OH）, 2920（C-H）, 1459（C-H），1353（N-CH2，C-H）, 1235（S=O）, 1112（C-O-C）, 593（S-O）. 1H NMR (D2O, 500 MHz):δ7.54~7.52（1.0H）, δ7.06~7.05（1.0H）, δ5.25~5.21（0.4H）,δ4.64（2.9H）,δ3.65（2.3H）,δ3.54~3.42（45.0H）,δ3.24（2.2H）, δ2.96（1.0H）,δ2.17（1.5H）,δ1.89~1.85（0.8H）,δ1.4（1.0H）,δ1.17（10.3H）,δ1.00（4.0H）, δ0.77~0.76（1.8H）. 13C NMR (D2O, 500 MHz):δ141.88, δ140.01, δ129.18,δ128.84,δ125.75,δ71.74,δ64.24,δ60.33,δ54.02,δ52.71,δ31.95,δ29.44,δ29.12,δ27.12, δ26.31,δ23.04,δ22.65,δ20.77,δ13.96.

[AC 1820]+[BF4]-: FT-IR (KBr liquid film, cm−1): 3455（-OH）, 2920（C-H）, 1459（C-H），1353（N-CH2，C-H）, 1248（B-F）, 1109（C-O-C）. 1H NMR (D2O, 500 MHz):δ4.64（4.3H）, δ3.76~3.70（2.3H）,δ3.64~3.50（35.6H）,δ3.50~3.49（3.0H）,δ3.39~3.22（2.5H）,δ3.10（1.0H）,δ1.96~1.87（0.2H）,δ1.58（1.0H）,δ1.20~1.14（15.0H）, δ0.76~0.73（1.7H）. 13C NMR (D2O, 500 MHz):δ71.77,δ64.16,δ60.35,δ52.81,δ31.94,δ29.62,δ22.62,δ13.89.

2. Determination of acidity and acid value

The acidity of ionic liquid wasdetermined by infrared spectrometry using pyridine as probe.Pyridine adsorbed at Lewis (L-Py)and Brφnsted (PyH+) acid exhibits bands at around ~1450 and ~1540 cm-1, respectively. The volume ratio of pyridine with ionic liquid was 1 : 3. The spectra were recorded using a Nicolet-510PFourier transform infrared spectrometerequipped with KBr windows,which resolution, scanning speed and wave number range, respectively,was 4 cm-1 , 0.2 cm/sand 400~4000cm-1,and determined by liquid membrane method under 20℃.

Determination of acid value of ionic liquid: Different concentrations of ionic liquid solution, 0.005 mol/L, 0.010 mol/L, 0.015 mol/L, 0.020 mol/L and 0.025 mol/L, were prepared. Ionic liquid solutionwas taken 10 ml in 100 ml tapered bottle, and then 2 drops of phenolphthalein indicator solutionwere addedinto. Then the solution titrated with 0.10mol/L potassium hydroxide water standard solution to pink. The blank experiments were done. The computation formula of acid value is as follows:

V1----the volume of potassium hydroxide standard solution consumpted by sample (mL)

V2----the volume of potassium hydroxide standard solution consumpted by blank (mL)
N----the molarity of potassium hydroxide standard solution (mol/L)

m----sample quality (g)

M----molarmass of potassium hydroxide (g/mol)

Table1 Acid value of ionic liquids

Concentration（mol/L） / Volume of KOH solution/10 mL ionic liquid
[AC 1820]+[ H2PO4]- / [AC1820]+[HSO4]-
0.005 / 1.00 / 1.06
0.010 / 2.02 / 2.05
0.015 / 3.15 / 3.10
0.020 / 4.20 / 4.10
0.025 / 5.24 / 5.12
Acid value(mg/g) / 93.1 / 93.9

3．Analysis of Hydration reaction products

Analysis of Hydration reaction products of Alpha pinene: Reaction products were identified using a GC-Mass spectrometer (TRACE GC/MS). The column usedwas an HP-5 capillary column with 50 m of length and 0.25 mm of internal diameter.The temperatures ofinjector and transference line were maintained constant at280℃.The initial temperature of the furnace wasmaintained at 80℃by 10min, then it was increased at rateof 20 ℃/min up to 280℃, and this temperature was maintained30 min. The carrier gas was N2. The samplesize was 0.1µm.

Fig. 1 Gas chromatograph of products of hydration of α–pinene

12.85-α–pinene;13.31-camphene;15.27-limonene ;16.60-terpinolene ; 17.15- fenchol;8- borneol;18.72-α-terpineol