Supporting Information

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1 Supporting Information Robinson Annulation-directed Synthesis of Jet Fuel Ranged Alkylcyclohexanes from Biomass-derived Chemicals Yaxuan Jing, Qineng Xia, Junjian Xie, Xiaohui Liu, Yong Guo, Ji-jun Zou, and Yanqin Wang* Shanghai Key Laboratory of Functional Materials Chemistry and Research Institute of Industrial Catalysis, School of Chemistry and Molecular Engineering, East China University of Science of Technology, Meilong Road 13#, Shanghai 237, China. Key Laboratory for Green Chemical Technology of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 372, China * wangyanqin@ecust.edu.cn

2 Chemicals Pd(N 3 ) 2 aqueous solution was purchased from Heraeus Materials Technology Shanghai Co., Ltd. CoCl 2 6H 2, FeCl 3 6H 2 and NiCl 2 6H 2 were purchased from Aladdin Reagent Co., Ltd. Furfural and 2,4-pentanedione were purchased from shanghai Titan Technology Co., Ltd. All other chemicals were purchased from Sinopharm Chemical Reagent Co., Ltd. All purchased chemicals were of analytical grade and used without further purification. Method for preparation of mesoporous NbP 4 Mesoporous NbP 4 used here was synthesized at ph2 according to our previous report. 1 In a typical synthesis, 1.32 g (.1mol) of diammonium hydrogen phosphate was dissolved in ml water and then adjusted ph to 2 using phosphoric acid. With vigorous stirring, ml of.5 M niobium tartrate (ph=2) was added to the above solution. Then the mixed solution was dropped into the aqueous solution of cetyltrimethyl ammonium bromide (CTAB) which was previously prepared by dissolving 1. g of CTAB in 15 ml of distilled water. The ph value of the final solution was about 2. Afterwards, this mixture was stirred for additional 6 min at 35 C, and then the transparent solution was aged in a Teflon-lined autoclave for 24 h at 16 C. After cooled down, the solid was filtered, washed with distilled water and then dried at 5 C overnight. Finally, NbP 4 sample was obtained by calcination at 5 C for 5 h in air with a linear heating ramp of 1 C min -1 to remove organic species. 5%Pd/NbP 4 preparation 5%Pd/NbP 4 catalysts were prepared by incipient wetness impregnation of NbP 4 with the aqueous solution of Pd(N 3 ) 2. After impregnation, the catalysts were dried at 1 C for 12 h, followed by calcination in air at 5 C for 3 h with a linear heating ramp of 1 C min -1. Experimental Section The one-pot cyclization process of furfural and 2,4-pentanedione was performed in 5ml round-bottom flask. Typically, 2,4-pentanedione (5g), furfural (.1g), CoCl 2 6H 2 (.1g) and CaCl 2 (.1g) were transferred into the flask, which was then heated to a target temperature (8 to 1 C) and react for a period of time (4-28 h). After reaction, the reactor was quenched in an ice-water bath to stop the reaction immediately, then the liquid solution was separated from the solid catalyst by centrifugation and analyzed qualitatively by GC-MS (Agilent 789A-5975C) and quantitatively by GC-FID (Agilent 789) with undecane as the internal standard. The conversion of furfural was calculated by using the equation: furfural conversion [%] = (moles of furfural reacted) / (moles of starting furfural) 1%. The yield of C 1 was calculated by using the equation: C 1 yield [%] = (moles of C 1 produced) / (moles of starting furfural) 1%. The yield of C 15 was calculated by using the equation: C 15 yield [%] = [(moles of 1b produced) + (moles of 1c produced) + (moles of 1d produced)] / (moles of starting furfural) 1%. For the separation of one-pot cyclization products, 1ml of deionized water were put into the flask S1

3 after one-pot cyclization reaction. Then, C 15, C 1 and 2,4-pentanedione were extracted from the flask by 3 * ml of dichloromethane. Finally the mixture of C 15 and C 1 were directly obtained by removing dichloromethane with rotary evaporation at 4 C and 2,4-pentanedione with rotary evaporation at 75 C. Dichloromethane and 2,4-pentanedione can be reused without further purification. The relatively pure C 15 and C 1 was purified by silica gel column chromatography and used as standards, the structure and purity were confirmed by 1 H NMR, 13 C NMR spectroscopy and mass spectrometry. The HD of the as-prepared products was conducted in a 5 ml Teflon-lined stainless-steel autoclave. Typically, (.2 g), Pd/NbP 4 (.1 g), and cyclohexane (6.46 g) were transferred into the autoclave. The reactor was then sealed, purged with H 2 for three times and charged to 4MPa H 2 pressure. The reaction was then carried out at 18 C and 4 MPa under magnetic stirring for 12 h. After the reaction, the autoclave was quenched in an ice water bath to room temperature. The liquid solution was separated from the solid catalyst by centrifugation and analyzed qualitatively by GC-MS (Agilent 789A-5975C) and quantitatively by GC-FID (Agilent 789) using octane as the internal standard. Here, we employed pure straight chain (C 1, C 11, C 13, C 15, C ) to replace targeted as standards, because pure targeted cannot be purchased or synthesized at present. The product yields were calculated by using the equation: yield [%] = (moles of carbon in product)/ (moles of carbon in C 15 ) 1%. Determination of freezing point Differential scanning calorimetry (DSC) was performed on a NETZSCH-DSC F3 Maia differential scanning calorimeter using hermetically sealed aluminum pans with a nitrogen flow of 5 ml/min. High purity indium was used to calibrate the calorimeter. Sample sizes were between 5-1 mg and the samples were ramped from -1 C to 5 C, down to -1 C and then back to 5 C, all at 1 C /min. S2

4 Figure S1: Mass spectrum of C 1 (1a). Figure S2: Mass spectrum of C 15 (1b). Figure S3: Mass spectrum of C 15 (1c). S3

5 Figure S4: Mass spectrum of C 15 (1d). Figure S5: 1 H (upper) and 13 C (down) NMR spectra of C 15 (1d). S4

6 C Figure S6: GC-MS trace of the one-pot cyclization products. Reaction conditions:.1 g of furfural, 5 g of 2,4-pentanedione,.1 g of CoCl 2 6H 2,.1 g of CaCl 2, 11 C, h. Conversion or yield (%) Conv. of furfural Yield of C 1 Yield of C Reaction temperature ( o C) Conversion or yield (%) Conv. of furfural Yield of C 1 Yield of C Reaction time (h) Figure S7. The one-pot cyclization process of furfural with 2,4-pentanedione with different reaction temperature for h (upper) and reaction time at 11 C (down). Reaction conditions:.1 g of furfural, 5 g of 2,4-pentanedione,.1 g of CoCl 2 6H 2,.1 g of CaCl 2. S5

7 1 Conversion or yield (%) Conv. of furfural Yield of C 15 Yield of C ,4-pentanedione/furfural mass ratio 1 Conversion or yield (%) Conv. of furfural Yield of C 15 Yield of C furfural/catalyst mass ratio 5 Figure S8. The one-pot cyclization process with different mass ratio of 2,4-pentandione to furfural (upper) and mass ratio of furfural to CoCl 2 6H 2 (down). Reaction conditions (upper):.1 g of furfural,.1 g of CoCl 2 6H 2,.1 g of CaCl 2, 11 C, h. Reaction conditions (down):5g 2,4-pentandione.1 g of furfural,.1 g of CaCl 2, 11 C, h. More detailed explanations for Figure 2 in main text Scheme S1 Reaction pathway for the production of jet fuel range branched. As we know, 2,4-pentanedione easily hydrolyzes to acetone and acetic acid, which may trigger the S6

8 side reaction. We guess that the yield of C 15 may increase by removing water, which come from crystalline water in CoCl 2 6H 2, commercial 2,4-pentanedione and generated in the one-pot cyclization process. Therefore, we added anhydrous calcium chloride to remove water during the reaction (Figure 2 in main text). As expected, compared with the result without CaCl 2, the existence of CaCl 2 had a notable improvement on the yield of C 15, from 7.4 to 89.8%, indicating CaCl 2 can absorb water to prevent the hydrolysis of 2,4-pentanedione. In contrast, C 15 were not obtained when only CaCl 2 was involved, indicating that CaCl 2 does not have ability to catalyze the one-pot cyclization process, however, a large amount of C 1 (77.5%) were obtained. To determine whether CaC l2 has catalytic activity for aldol condensation of furfural with 2,4-pentanedione, we tested the aldol condensation of furfural with 2,4-pentanedione without CaC l2 and CoCl 2 6H 2, interestingly enough, the yield of C 1 also reached 73.7%, indicating the aldol condensation can be carried out without any catalysts. It may be because 2,4-pentanedione, which is a typical β-dicarbonyl compound, possesses very active α-h atom and reaction conditions (11 C, h) were enough to overcome energy barrier of the aldol condensation. Therefore, the jet fuel range branched C 1 can be produced through catalyst-free aldol condensation of furfural with 2,4-pentanedione, followed the total hydrodeoxygenation (scheme S1). As we know, branched can be added to jet fuel to decrease the freezing point, so C 1 can be directly blended into jet fuel without hydroisomerization. Specifically, the synthetic route is short and the aldol reaction has no use for any catalysts. To further confirm the role of CaCl 2 and eliminate influence of the interactions of CaCl 2 with CoCl 2 6H 2, 2,4-pentanedione was pre-treated with CaCl 2 to remove the water originated from non-pretreated 2,4-pentanedione, then the one-pot cyclization process of pre-treated 2,4-pentanedione with furfural was triggered over CoCl 2 6H 2 without CaCl 2 and 83.8% yield of C 15 was achieved, higher than that (7.4%) with non-pretreated 2,4-pentanedione without CaCl 2, which can eliminate influence of the interactions of CaCl 2 with CoCl 2 6H 2, lower than that (89.8%) with CaCl 2 co-added during reaction, this may originate the influence of crystalline water in CoCl 2 6H 2 and the water generated in the one-pot cyclization process. These results indicate it is better to add CaCl 2 as desiccant during the reaction. Considering that the aldol condensation of furfural with 2,4-pentanedione can be carried out without any catalysts at a relatively higher conditions (Figure S9), we conducted the aldol condensation at a slightly lower conditions (5 C, 2h) to prove catalysis of CoCl2 6H2 to the aldol condensation of furfural with 2,4-pentanedione. As shown in table S1, furfural cannot react with 2,4-pentanedione without catalysts at 5 C for 2h. In contrast, C1 were obtained in the presence of CoCl2 6H2, indicating CoCl2 6H2 has the catalytic performance for the aldol condensation of furfural with 2,4-pentanedione. We also investigated the mechanism of Robinson annulation and the details are presented in the Supporting Information. Table S1. The catalysis of CoCl 2 6H 2 to the aldol condensation of furfural with 2,4-pentanedione. Catalyst Conversion [%] furfural Yield [%] C 1 Yield [%] C 15 CoCl 2 6H No CoCl 2 6H Reaction conditions:.1 g of furfural, 5 g of 2,4-pentanedione,.1 g of catalyst,.1 g of CaCl 2, 5 C, 2h. S7

9 1 L n Co 4 L L L n-1 Co 1a L n-1 Co 2a 6 5 Scheme S2. Proposed reaction mechanism of the Co(II)-catalyzed Michael addition of C 1 with 2,4-pentanedione. Robinson annulation is actually a tandem reaction of Michael addition and intramolecular aldol condensation. It is clearly 2a contains four equivalent carbonyl groups which can trigger easily intramolecular aldol condensation in the presence of Lewis acid. To understand the reaction mechanism of Co(II)-catalyzed Michael addition of 1a with 2,4-pentanedione, we presented a proposed reaction mechanism based on previous report in Scheme S2. 2 Firstly, the chelate ligand 4 is formed by the coordination of donor 1 to the metal center and particularly stabilized by Π-delocalisation. Then the acceptor 1a of Michael addition is proposed to coordinate at a vacant site to form species 5 by ligand exchange. The function of the centre metal is not only to hold the acceptor 1a in proximity to donor 1, but also activated acceptor 1a by its Lewis acidity. Subsequently, the complex 5 undergoes the nucleophilic conjugate addition to form new C-C bond, which affords the intermediate 6. Finally, the product 2a is liberated from the species 6 and the chelate ligand 4 is regenerated by ligand exchange. In conclusion, CoCl 2 6H 2 has the catalytic performance for each reaction (aldol condensation and Robinson annulation) in the one-pot cyclization process. Figure S9: GC-MS trace of the HD products of C 15. Reaction conditions: C 15 (.2 g), cyclohexane (6.46 g), Pd/NbP 4 (.1 g), 4 MPa H 2, 18 C, 12 h. S8

10 Figure S1: Mass spectrum of C 15. Figure S11: Mass spectrum of C 11. Figure S12: Mass spectrum of C 13. S9

11 Main route Scheme S3. Possible pathways for the main C-C cracking product formation during HD of C 15. Figure S13: Mass spectrum of C 1. Figure S14: Mass spectrum of C. S1

12 1 8 Yield(%) 6 4 C C 11 C 15 C 1 C 13 Condition A Condition B Figure S15. The product distribution of the under different reaction conditions of the one-pot cyclization process. Condition A:.1 g of furfural, 5 g of 2,4-pentanedione,.1 g of catalyst,.1 g of CaCl 2, 11 C, h. Condition B:.1 g of furfural, 5 g of 2,4-pentanedione,.1 g of catalyst,.1 g of CaCl 2, 14 C, 36 h. Reaction conditions of HD: C 15 (.2 g), cyclohexane (6.46 g), Pd/NbP4 (.1 g), 4 MPa H 2, 19 C 12 h. Scheme S4. Proposed reaction pathway for the HD of C 15 into C 15 alkylcyclohexanes We tried to investigate the HD pathway by time course, however, due to varieties and complex configurations of the intermediates, they cannot be separated by GC-MS, so we cannot provide time curve of HD reaction. However, our group has long-term experience on S11

13 Nbx-based catalysts in the hydrodeoxygenation of furan-derived adducts to liquid. Based on our previous reports 3-5 and approximate results observed from GC-MS, we proposed a reaction pathway for Pd/NbP 4 -catalyzed HD and present in Scheme S4. According to our previous experience, 3 the sequence of the Pd/NbP 4 -catalyzed HD reaction of furan-derived adducts was as follows: 1) hydrogenation of unsaturated bonds (exocyclic C=C double bond, furan ring and C= double bond), 2) dehydration/hydrogenation of the hydroxy groups, 3) tetrahydrofuran-ring-opening reaction, and 4) dehydration/hydrogenation of the hydroxy group caused tetrahydrofuran-ring-opening reaction. Specifically, the hydrogenation selectivity of the unsaturated bonds decreased as follows: exocyclic C=C double bond>furan ring>c= double bond. 5 Therefore, the hydrogenation reactivity of 1 decreased as follows: exocyclic C=C double bond (from 1 to 2) >furan ring (from 2 to 3) >C= double bond (from 3 to 4). Then the hydrogenolysis of the hydroxy group 4 was carried out by acid-catalyzed dehydration and palladium-catalyzed hydrogenation. With the opening of the tetrahydrofuran ring (catalyzed by Nbx species) of 5, the hydroxy group 6 were generated. Finally, 7 was obtained by dehydration/hydrogenation of the hydroxy group 6. Yield (%) C C 13 C 11 C 1 C Reaction temperature ( o C) Yield (%) C C 13 C 11 C 1 C Initial H 2 pressure (MPa) Figure S16. Results of HD of C 15 under various reaction temperature at 4 MPa H 2 (left) and initial H 2 pressure at 18 C (right). Reaction conditions: C 15 (.2 g), cyclohexane (6.46 g), Pd/NbP 4 (.1 g), 12 h. The total HD of C 15 was carried out at different temperatures from 16 to C over Pd/NbP 4 catalyst. Analysis of HD products showed that reaction temperature had a strong influence on the rates of the removal of unsaturation and oxygen, as well as the degree of C-C cleavage. Lower temperatures (<18 C) resulted in slow rates of the removal of unsaturation and oxygen, but higher temperatures (>18 C) promoted C-C cleavage. Therefore, 18 C is a proper temperature for the total HD. Compared to the temperature, the influence of initial H 2 pressure on the yields of C 15 alkylcyclohexanes was small. The yield of C 15 alkylcyclohexanes increases from 52.9 to 64.1 % as H 2 pressure from 3 to 4 MPa, but further increase did not affect the yield of C 15 alkylcyclohexanes, implying 4 MPa is an optimal H 2 pressure for the HD reaction. S12

14 3 25 Intensity (a.u.) Frequency(%) <2 2.1~ ~3. 3.1~ ~4. 4.1~ ~5. Pd particle diameter(nm) > Temperature ( o C) Figure 17. H 2 -TPR profile of 5 wt% Pd/NbP 4 and typical TEM images of Pd/NbP 4 as well as their particle-size distributions. The sharp peak at -15 C in H 2 -TPR can be attributed to the reduction of Pd. The sharp peak at such low temperature indicates that the Pd particles are well dispersed and the size of Pd is very small, which is in well accordance with the TEM images. Therefore, Pd/NbP 4 can be reduced in situ HD reaction. The broad peak at about C can be attributed to the hydrogen absorption on metal Pd and the negative peak at about 56 C can be assigned to the dehydrogenation peak. We noticed that the integral areas of the broad peak at C and negative peak at 56 C are substantial equal. S13

15 9 8 7 Yield (%) C C 13 C 11 C 1 C Run number 4 5 Figure S18. Recyclability test of Pd/NbP 4 for HD of C 15. Reaction conditions: C 15 (.2 g), cyclohexane (6.46 g), Pd/NbP 4 (.1 g), 18 C, 4 MPa H 2, 12 h. The recyclability of Pd/NbP 4 for HD was performed at 18 C, 4 MPa H 2 for 12 h and the results are shown in Figure S18. After each reaction cycle, the catalyst was first separated from the liquid phase by centrifugation, washed with ethanol, and then dried at 323 K for 12 h for the next run. The Pd/NbP 4 catalyst shows a high reusability for the HD reaction. Reference 1. Zhang, Y.; Wang, J. J.; Ren, J. W.; Liu, X. H.; Li, X. C.; Xia, Y. J.; Lu, G. Z.; Wang, Y. Q., Mesoporous niobium phosphate: an excellent solid acid for the dehydration of fructose to 5-hydroxymethylfurfural in water. Catalysis Science & Technology 12, 2 (12), Pelzer, S.; Kauf, T.; van Wullen, C.; Christoffers, J., Catalysis of the Michael reaction by iron(iii): calculations, mechanistic insights and experimental consequences. Journal of rganometallic Chemistry 3, 684 (1-2), Xia, Q. N.; Cuan, Q.; Liu, X. H.; Gong, X. Q.; Lu, G. Z.; Wang, Y. Q., Pd/NbP(4) multifunctional catalyst for the direct production of liquid from aldol adducts of furans. Angewandte Chemie 14, 53 (37), Xia, Q. N.; Chen, Z. J.; Shao, Y.; Gong, X. Q.; Wang, H. F.; Liu, X. H.; Parker, S. F.; Han, X.; Yang, S. H.; Wang, Y. Q., Direct hydrodeoxygenation of raw woody biomass into liquid. Nature communications 16, 7, Gu, M. Y.; Xia, Q. N.; Liu, X. H.; Guo, Y.; Wang, Y. Q., Synthesis of Renewable Lubricant Alkanes from Biomass-Derived Platform Chemicals. ChemSusChem 17, 1 (), S14