Selective Synthesis of Secondary Amines by Pt Nanowire ... · (VARIAN CP-3800 GC, HP-5 capillary column, FID detector) and GC-MS (VARIAN 450-GC & VARIAN 240-GC) equipped with a CP8944

Supporting Information

Selective Synthesis of Secondary Amines by Pt Nanowire Catalyzed Reductive Amination of Aldehydes with Ammonia

Fenqiang Qi, Lei Hu, Shuanglong Lu,Xueqin Cao, Hongwei Gu*

General Experimental Procedures and Characterizations

Synthesis of Pt nanowires

Ultrathin Pt NWs were achieved by acidic etching of FePt NWs, which was synthesized according

to the procedure described by Wang et al.1 and Gu et al.2. 200 mg Pt(acac)2 and 20 mL oleylamine

(OAm) were mixed at room temperature under nitrogen atmosphere and this solution was heated to

120oC under stirring. This solution was kept at the temperature of 120oC for 20 minutes. 150μL

Fe(CO)5 was injected into the hot solution and then the temperature was gradually raised to 160 oC. The

reaction was kept at this temperature for half an hour without stirring. The black solution was then

cooled to room temperature and centrifuged in excess ethanol. The precipitate was redispersed in

ethanol and washed by ethanol for three times.

100 mg FePt NWs (in 20 mL methanol) were firstly treated by oxygen bubbling at 100°C, and 10

mL HCl/methanol (1:1) solution was added into the above suspension. The solution was heated and

stirred at 60°C for 1 hour, the resultant precipitates were obtained following 10 minutes of

centrifugation (3000 rpm). The dark solid was washed with ethanol for at least two times and stored in

ethanol.

Synthesis of Pt nanoparticles (NPs)3

Pt(acac)2 (100mg), octadecene (10 mL), oleic acid (OA) (1 mL), and oleylamine (OAm) (1 mL)

were mixed under stirring and bubbled by N2 for 5 minutes. The mixture was then heated to 65oC to

dissolve Pt(acac)2. The temperature was raised to about 180oC in 20 minutes. A solution of Fe(CO)5 in

hexane (0.1 mL, prepared by adding 0.1 mL Fe(CO)5 in 1 mL hexane under argon) was quickly injected

into the hot solution. The solution was further heated to 200oC and kept at this temperature for 1 hour

before it was cooled down to room temperature. 40 mL of isopropanol was added and then the

suspension was centrifuged to separate the NPs. The NPs were dispersed in 10 mL hexane and

precipitated out by adding ethanol. The process was repeated one more time to purify the NPs. The final

product was dispersed in 10 mL of ethanol for further use.

Electronic Supplementary Material (ESI) for Chemical CommunicationsThis journal is © The Royal Society of Chemistry 2012

Synthesis of Pt nanorods (NRs)2

Pt(acac)2 (200mg), sodium oleate (150mg) were added to oleylamine (OAm) (20 mL) under Ar and

stirring for about 5 minute. The mixture was then heated to 120oC for 15 min. As the solution turned

clear yellow, a drop of Fe(CO)5 (~0.005mL) was quickly injected into the hot solution. The solution

turned dark in color quickly. The temperature was further heated to 250oC and kept at this temperature

for 30 min before it was cooled down to room temperature. The sample was centrifuged in excess

isopropanol to separate the NRs. The NRs were dispersed in 10 mL toluene and precipitated out by

adding ethanol. The process was repeated one more time to purify the NRs. The final product was

dispersed in 10 mL of ethanol for further use.

Typical procedure for catalytic Symmetrical DBAs formation

Catalyst testing was carried out in a sealed tube. 1mmol aldehyde, 25% aqueous ammonia (150 μL)

and ethanol (2 mL) with 0.005 mmol Pt NW catalyst were added in the reaction tube and then sealed.

The reaction tube was thrice evacuated and flushed with hydrogen and took place at a certain

temperature under hydrogen atmosphere. Resulting product mixtures were analyzed by GC (VARIAN

CP-3800 GC, HP-5 capillary column, FID detector) and GC-MS (VARIAN 450-GC & VARIAN 240-

GC) equipped with a CP8944 capillary column (30 m × 0.25 mm).

Typical procedure for catalytic Unsymmetrical DBAs formation

Catalyst testing was carried out in a sealed tube. Two aldehydes (0.5 mmol), 25% aqueous

ammonia (150 μL) and ethanol (2 mL) with 0.005 mmol Pt NW catalyst were added in the reaction tube

and then sealed. The reaction tube was thrice evacuated and flushed with hydrogen and took place at a

certain temperature under hydrogen atmosphere. Resulting product mixtures were analyzed by GC

(VARIAN CP-3800 GC, HP-5 capillary column, FID detector) and GC-MS (VARIAN 450-GC &

VARIAN 240-GC) equipped with a CP8944 capillary column (30 m × 0.25 mm) and some amines were

purified by flash chromatography and characterized by 1HNMR and 13CNMR.


Table S1. Formation of Unsymmetrical dibenzylamines from an Equimolar Mixture of aldehydesa

Entry R1 R2 Yield(%)b

1 p-H p-Cl 57(55)

2 p-H p-CH3 61.7(59)

3 p-CH3 p-Cl 51.8(50)

4 p-OCH3 p-Cl 33.7(33) a Reaction conditions: aldehydes (0. 5 mmol), 25% aqueous ammonia (2 equiv) and ethanol (2 mL) at 80 °C ,1 bar H2 with 0.005 mmol Pt NW catalyst for 24 h; b GC yield.

Table S2. Upscaled process and results of dibenzylamine synthesis:

Benzaldehyde (g) Ethanol (mL) aqueous ammonia (mL) Pt NW(mmol) Yield(%)

2.12 40 3 0.1 91.6

10.6 200 15 0.5 90.8

Reaction conditions: All reactions were carried out at 80 °C, 1 bar H2 with Pt NW catalyst for 12 h; GC yield.

Fig. S1 EDX Analysis of FePt NWs. The Cu signal came from the copper grid on which the sample is supported.


Fig. S2 EDX Analysis of Pt NWs. The Cu signal came from the copper grid on which the sample is supported.

Fig. S3 TEM image of Pt nanowires

Fig. S4 TEM image of Pt nanowires after 6 cycles.


Fig. S5 Catalitic stabilities of Pt nanowire catalysts (reaction condition: benzaldehyde (1.0 mmol), 25% aqueous

ammonia (150 μL) and ethanol (2 mL) at 80 °C ,1 bar H2 with 0.005 mmol Pt catalyst; Yields of the product are

determined by GC.)

GC analysis of DBA formation:

Fig. S6 GC images of DBA formation.


NMR Analysis. 1H NMR and 13C NMR data were recorded at 400.0 and 100 MHz on a Varian Inova 400 spectrometer.

The 1H NMR and 13C NMR chemical shifts are reported relative to tetramethylsilane; the resonance of

the residual protons of the solvent was used as internal standard for 1H (m 2.5 d-DMSO) and all

deuterium solvent signals for 13C (m 45 d-DMSO). All measurements were carried out at 298 K.

Abbreviations used in the description of NMR data are as follows: s, singlet; d, dublet; m, multiplet.

1. dibenzylamine

The title compound was purified by flash chromatography (silica gel, acetic ether /light petroleum 1:10

and 1% triethylamine). The pure product was obtained as colorless powder in 90% yield. 1H NMR (400 MHz,d-DMSO, 25oC) d 7.36-7.30 (m, 8H), 7.24-7.21 (m, 2H), 3.68 (s, 4H). 13C NMR (100 MHz, d-DMSO, 25oC) d 146.2, 133.5, 133.3, 131.9, 57.6.

2. bis(4-methylbenzyl)amine


and 1% triethylamine). The pure product was obtained as colorless powder in 92% yield. 1H NMR (400 MHz,d-DMSO, 25oC) d 7.38-7.36 (d, 4H), 7.27-7.25 (d, 4H), 3.84(s, 4H), 2.43 (s, 6H). 13C NMR (100 MHz, d-DMSO, 25oC) d 146.6, 140.4, 134.0, 132.3, 50.8, 26.0.

3. bis(4-methoxybenzyl)amine


and 1% triethylamine). The pure product was obtained as colorless powder in 73% yield. 1H NMR (400 MHz,d-DMSO, 25oC) d 7.28-7.26 (d, 4H), 6.90-6.88 (d, 4H), 3.75(s, 6H), 3.68 (s, 4H). 13C NMR (100 MHz, d-DMSO, 25oC) d 163.1, 141.7, 133.5, 118.8, 60.3, 50.5.

4. bis(4-chlorobenzyl)amine


and 1% triethylamine). The pure product was obtained as colorless powder in 90% yield.


1H NMR (400 MHz,d-DMSO, 25oC) d 7.36-7.31 (m, 8H), 3.70(s, 4H). 13C NMR (100 MHz, d-DMSO, 25oC) d 145.1, 136.4, 135.1, 133.4, 56.7.

5. bis(4-bromobenzyl)amine


and 1% triethylamine). The pure product was obtained as colorless powder in 85% yield. 1H NMR (400 MHz,d-DMSO, 25oC) d 7.54-7.52 (d, 4H), 7.39-7.37 (d, 4H), 3.77(s, 4H). 13C NMR (100 MHz, d-DMSO, 25oC) d 137.4, 131.1, 130.8, 120.3, 50.5.

6. bis(2-phenylpropyl)amine


and 1% triethylamine). The pure product was obtained as colorless powder in 96% yield. 1H NMR (400 MHz,d-DMSO, 25oC) d 7.25-7.24 (d, 4H), 7.17 (s, 6H), 2.96-2.91 (m, 2H), 2.78-2.68 (m,

4H), 1.18-1.15 (m, 6H). 13C NMR (100 MHz, d-DMSO, 25oC) d 150.4, 133.7, 132.4, 131.6, 61.1, 43.7, 25.1.

7. diheptylamine

The title compound was purified by flash chromatography (silica gel, acetic ether /light petroleum 1:5).

The pure product was obtained as colorless powder in 65% yield. 1H NMR (400 MHz,d-DMSO, 25oC) d 2.78 (s, 4H), 1.62(s, 4H), 1.24(s, 16H), 0.86-0.83(m,6H). 13C NMR (100 MHz, d-DMSO, 25oC) d 46.6, 31.0, 28.1, 26.0, 25.2, 21.9, 13.9.

8. bis((furan-2-yl)methyl)amine


and 1% triethylamine). The pure product was obtained as colorless powder in 71% yield. 1H NMR (400 MHz,d-DMSO, 25oC) d 7.71 (s, 2H), 6.56-6.55 (d, 2H), 6.49-6.47 (m, 2H), 4.13 (s, 4H). 13C NMR (100 MHz, d-DMSO, 25oC) d 147.7, 143.6, 110.9, 110.8, 42.2.


9. bis(1-phenylethyl)amine


and 1% triethylamine). The pure product was obtained as colorless powder in 50% yield. 1H NMR (400 MHz,d-DMSO, 25oC) d 7.40-7.38 (d, 4H), 7.33-7.29 (m, 4H), 7.22-7.18 (m, 2H), 4.04-

3.99 (m, 2H), 1.29-1.27 (d, 6H). 13C NMR (100 MHz, d-DMSO, 25oC) d 148.7, 128.0, 126.1, 125.7, 50.7, 39.7, 39.3, 38.9, 26.2.

10. N-(4-chlorobenzyl)(phenyl)methanamine


and 1% triethylamine). The pure product was obtained as colorless powder in 55% yield. 1H NMR (400 MHz,d-DMSO, 25oC) d 7.38-7.28 (m, 8H), 7.23-7.20 (m, 1H), 3.66(s, 4H). 13C NMR (100 MHz, d-DMSO, 25oC) d 146.0, 145.2, 136.4, 135.1, 133.5, 133.4, 133.3, 131.9, 57.5,

56.7.

11. N-(4-methylbenzyl)(phenyl)methanamine


and 1% triethylamine). The pure product was obtained as colorless powder in 59% yield. 1H NMR (400 MHz,d-DMSO, 25oC) d 7.37-7.30 (m, 4H), 7.25-7.23 (d, 3H), 7.13-7.11 (d, 2H), 3.69-

3.66 (d, 4H ), 3.07(s, 3H). 13C NMR (100 MHz, d-DMSO, 25oC) d 140.7, 137.6, 135.4, 128.6, 128.0, 127.9, 127.8, 126.5, 52.1,

51.9, 20.6.

12. N-(4-methylbenzyl)(4-chlorophenyl)methanamine


and 1% triethylamine). The pure product was obtained as colorless powder in 50% yield.


1H NMR (400 MHz,d-DMSO, 25oC) d 7.35 (s, 4H), 7.24-7.22 (d, 2H), 7.12-7.10 (d, 2H), 3.66-3.64 (d,

4H), 2.28 (s, 3H). 13C NMR (100 MHz, d-DMSO, 25oC) d 145.2, 142.9, 140.8, 136.5, 135.0, 134.0, 133.4, 133.3, 57.3,

56.8, 26.1.

13. N-(4-methoxybenzyl)(4-chlorophenyl)methanamine


and 1% triethylamine). The pure product was obtained as colorless powder in 33% yield. 1H NMR (400 MHz,d-DMSO, 25oC) d 7.35 (s, 4H), 7.25-7.23 (d, 2H), 6.88-6.86 (d, 2H), 3.72 (s, 3H),

3.64 (s, 2H), 3.59 (s, 2H). 13C NMR (100 MHz, d-DMSO, 25oC) d 163.4, 145.3, 138.0, 136.4, 135.1, 134.5, 133.4, 118.9, 60.4,

56.9, 56.6.

Reference [1] Wang, C.; Hou, Y. L.; Kim, J.; Sun, S. H. Angew. Chem. Int. Ed. 2007, 46, 6333.

[2] L. Hu, X. Q. Cao, D. H. Ge, H. Y. Hong, Z. Q. Guo, L. Chen, Z. Q. Guo, X. H. Sun, J. X. Tang, J. W. Zheng, J. M.

Lu and H. W. Gu, Chem. Eur. J. 2011, 17, 14283; M. Li, L. Hu, X. Q. Cao, H. Y. Hong, J. M. Lu and H. W. Gu, Chem. Eur. J. 2011, 17, 2763; L. Hu, X. Q. Cao, L. Chen, J. W. Zheng, J. M. Lu, X. H. Sun and H. W. Gu, Chem. Commun.

2012, 48, 3445; Z. Q. Guo, L. Hu, H. H. Yu, X. Q. Cao and H. W. Gu, RSC Adv. 2012, 2, 3477.

[3] Wang, C.; Daimon, H.; Onodera, T.; Koda, O.; Sun, S. Angew. Chem. Int. Ed. 2008, 47, 3588.


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Selective Synthesis of Secondary Amines by Pt Nanowire ... · (VARIAN CP-3800 GC, HP-5 capillary column, FID detector) and GC-MS (VARIAN 450-GC & VARIAN 240-GC) equipped with a CP8944