HAP-Pd(0): A highly efficient recyclable heterogeneous catalyst for the selective reduction of carbon-carbon double bond in ,-unsaturated ketones

Article abstract of DOI:10.1080/00397911.2011.605242

A recyclable heterogeneous hydroxyapatite-supported palladium(0) catalyst was prepared by a simple procedure and successfully applied for the selective reduction of carbon-carbon double bond in ,-unsaturated ketones using HCOONH4 as hydrogen transfer agen

Full text of DOI:10.1080/00397911.2011.605242

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HAP-Pd(0): A Highly Efficient Recyclable
Heterogeneous Catalyst for the Selective
Reduction of Carbon–Carbon Double
Bond in α,β-Unsaturated Ketones
Omkar Singh Chambyal a , Satya Paul a , Tahira Shamim a , Monika
Gupta a , Rajive Gupta a & André Loupy b
a Department of Chemistry, University of Jammu, Jammu, India
b Laboratoire des Reactions Sélectives sur Supports, Paris-South
University, Orsay, France
Accepted author version posted online: 13 Feb 2012.Version of
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To cite this article: Omkar Singh Chambyal, Satya Paul, Tahira Shamim, Monika Gupta, Rajive
Gupta & André Loupy (2013): HAP-Pd(0): A Highly Efficient Recyclable Heterogeneous Catalyst
for the Selective Reduction of Carbon–Carbon Double Bond in α,β-Unsaturated Ketones, Synthetic
Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,
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Synthetic Communications1, 43: 656–667, 2013
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2011.605242
HAP-Pd(0): A HIGHLY EFFICIENT RECYCLABLE
HETEROGENEOUS CATALYST FOR THE SELECTIVE
REDUCTION OF CARBON–CARBON DOUBLE BOND IN
a,b-UNSATURATED KETONES
Omkar Singh Chambyal,1 Satya Paul,1 Tahira Shamim,1
1
Monika Gupta, Rajive Gupta, and Andre Loupy
1
2
´
1Department of Chemistry, University of Jammu, Jammu, India
2
´
Laboratoire des Reactions Selectives sur Supports, Paris-South University,
Orsay, France
GRAPHICAL ABSTRACT
Abstract A recyclable heterogeneous hydroxyapatite-supported palladium(0) catalyst was
prepared by a simple procedure and successfully applied for the selective reduction of
carbon–carbon double bond in a,b-unsaturated ketones using HCOONH4 as hydrogen
transfer agent. The workup procedure is simple, and the catalyst could be recovered by
simple filtration and recycled for five consecutive runs without significant loss of activity.
Keywords HAP-Pd(0); heterogeneous catalysis; reductions; selectivity; a,b-unsaturated
ketones
INTRODUCTION
Hydrogenation is a most common reaction used in the synthesis of many
products across many industrial processes,[1,2] including the petrochemical, pharma-
ceutical, and food industries. Selective hydrogenation in organic synthesis is a great
challenge for chemists. Selective reduction[3–6] of carbon–carbon double bond in
a,b-unsaturated carbonyl compounds is a highly desirable organic transformation
because it leads to saturated carbonyl compounds, which have a wide range of appli-
cations in synthetic and pharmaceutical chemistry. The conventional hydrogenation
procedure, although it often offers selective reductions under mild conditions, gen-
erally requires a special setup and is always associated with the cautions of using
hydrogen gas. Moreover, heterogeneous and homogeneous catalytic transfer hydro-
genations have been used extensively in the reduction of a variety of functional
Received May 24, 2011.
Address correspondence to Satya Paul, Department of Chemistry, University of Jammu, Jammu
180 006, India. E-mail: paul7@rediffmail.com
656

HAP-Pd(0)-CATALYZED REDUCTION OF C–C
657
Scheme 1. HAP-Pd0-catalyzed selective reduction of carbon–carbon double bond in a,b-unsaturated
ketones at 80 ꢀC.
groups.[7–9] Transition metals such as Pd, Rh, Pt, Ni, Cu, Ir, and Co and their
complexes are commonly used as catalysts for reductions.[10–15] Among these, pal-
ladium[16–19] is more advantageous with regard to reaction conditions, activity,
selectivity, and yields of final products. Most of the Pd-catalyzed selective reductions
have been reported in homogeneous media. For example, [(t-Bu2PH)Pd(P-t-Bu2)]2
was reported for the selective reduction of carbon–carbon double bond of a,b-
unsaturated ketones, aldehydes, sulfones, and phosphonates in good to excellent
yields.[20,21] Palladium-catalyzed selective reduction of a,b-unsaturated carbonyl
compounds has also been reported in the presence of triethylsilane in ethanol.[22]
Recently, heterogeneous catalysts[23–28] have emerged as more advantagous
over their homogeneous counterparts because of simplified recovery, recyclability,
and potential for incorporation in continuous reactors and microreactors. In this
context, some heterogeneous palladium catalysts have been developed for the selec-
tive reductions, such as the HCOONH4-Pd=C system for the reduction of various
functionalities[29] including heterocyclic ring in quinolines,[30] aryl ketones to alco-
hols,[31] benzyl glycosides,[32] dibenzyl uracils,[33] a,b-unsaturated nitroalkenes,[34]
cyclic a,b-unsaturated ketones,[35] aldehydes, sulfones, and phosphonates. Pd-
MCM-48, Pd=SiO2, and Pd=Al2O3 have been reported as effective catalysts for the
=
selective hydrogenation of conjugated and isolated C C of citral in supercritical
carbon dioxide[36] using H2 gas. Recently, polymer-supported palladium nanoparti-
cles[37] have shown excellent activity and selectivity for the hydrogenation of alkynes
and alkenes.
Herein, we describe the synthesis of a recyclable heterogeneous hydroxyapatite-
supported Pd(0) catalyst and its application for the selective reduction of
carbon–carbon double bond in a,b-unsaturated ketones using ammonium formate
as hydrogen transfer agent simply by stirring in acetonitrile at 80 ꢀC (Scheme 1).
RESULTS AND DISCUSSION
Hydroxyapatite used for the preparation of hydroxyapatite-supported Pd(0)
catalyst (HAP-Pd0) was prepared according to the literature procedure with slight
modification.[38] HAP-Pd0 was prepared by stirring a mixture of hydroxyapatite
and Pd(OAc)2 in ethanol for 3 h, followed by dropwise addition of hydrazine hydrate
(80%). To make the reaction medium completely heterogeneous, the catalyst was
conditioned by refluxing for 6 h in ethanol, toluene, and acetonitrile (each for 2 h)
to remove any physiosorbed palladium acetate. The conditioned catalyst was quite
stable and could be used for several days.
The characterization of HAP-Pd0 was done by X-ray diffraction (XRD),
atomic absorption spectrophotometry (AAS), scanning electron microscopy
(SEM) and transmission electron microscopy (TEM).

658
O. S. CHAMBYAL ET AL.
Powder XRD diffraction patterns of HAP-Pd0 (Fig. 1) exhibited three additional
reflections in addition to hydroxyapatite corresponding to 2h ¼ 39 ꢀ, 46 ꢀ, and 65 ꢀ,
which could be attributed to Pd(0) [Ref. Joint Committee on Powder Diffraction Stan-
dards (JCPDS) file: 46–1043]. The amount of the palladium supported on hydroxya-
patite was determined by AAS analysis and found to be 1.1 mmol=g.
The surface morphology and distribution of palladium in HAP-Pd0 were also
investigated using TEM and SEM. The TEM micrograph (Fig. 2a) shows the
distribution of palladium onto hydroxyapatite, and the average particle diameter
was about 20 nm. The SEM image (Fig. 3) indicates that the catalyst consists of
hydroxyapatite, possessing an empty space for adsorption of palladium
nanoparticles.
To test the activity of HAP-Pd0 as a completely heterogeneous catalyst for the
selective reduction of double bond in a,b-unsaturated ketones, 3-(4-methoxyphenyl)
-1-phenylprop-2-en-1-one was selected as the test substrate and the selective
reduction was carried out under different set of conditions with respect to different
solvents, temperatures, and molar ratios of HAP-Pd0 and ammonium formate. To
select the best solvent as far as selectivity is concerned, the reaction was carried
out in toluene, ethanol, water and acetonitrile. The results are summarized in
Table 1. It is clear that acetonitrile gave the best results. Further, to select the appro-
priate reaction temperature, the reaction was carried out at room temperature, 50,
and 80 ꢀC. We found that 80 ꢀC was the optimum reaction temperature. After carry-
ing out reactions with different molar ratios of the catalyst, 0.3 g equivalent to
0.33 mol% Pd gave the optimum results under mild conditions. For 1 mmol of
a,b-unsaturated ketone, 1.5 g of HCOONH4 was required. Thus, optimum con-
ditions selected are a,b-unsaturated ketone (1 mmol), HCOONH4 (1.5 g), HAP-Pd0
(0.3 g, 0.33 mol% Pd), acetonitrile (5 mL), and 80 ꢀC as the reaction temperature.
Figure 1. XRD diffraction patterns of HAP-Pd0.

HAP-Pd(0)-CATALYZED REDUCTION OF C–C
659
Figure 2. (a) TEM micrograph of HAP-Pd0. (b) TEM micrograph of HAP-Pd0 after the fifth run.
Figure 3. SEM image of HAP-Pd0.
Table 1. Effect of solvent on the HAP-Pd0-catalyzed reduction of
carbon–carbon double bond in a,b-unsaturated ketonesa
Entry
Solvent
Time (h)
Yield (%)b
1
2
3
4
Toluene
Water
6
6
6
6
40c
35c
50c
89
Ethanol
Acetonitrile
aReaction conditions: 3-(4-methoxyphenyl)-1-phenylprop-2-en-
1-one (1 mmol), HCOONH4 (1.5 g), HAP-Pd0(0.3 g, 0.33 mol%
Pd), solvent (5 mL) at 80 ꢀC.
bYield refers to separation based on column chromatography.
cThe rest being the starting materials.

660
O. S. CHAMBYAL ET AL.
To demonstrate the versatility of the catalytic process, different enones subsi-
tututed with electron-withdrawing and electron-donating groups were subjected to
reduction under the reaction conditions. All the substrate gave good results
(Table 2). It is pertinent to mention that no saturated or unsaturated alcohol was
detected, which clearly supports the high selectivity of the catalytic process. Further,
the developed protocol showed functional group tolerance for easily reducible
groups such as NO2 and CN (entries 11 and 12).
Table 2. HAP-Pd0-catalyzed selective reduction of carbon–carbon double bond in a,b-unsaturated
ketones using HCOONH4 in acetonitrile at 80 ꢀC
Entry
1
Substratea
Product
Time (h) Yield (%)b,c Mp=lit. mp (ꢀC)
7
87
68–70=68–69[39]
2
3
4
6
89
87
86
61–62=62–63[39]
66–67=67–68[40]
59–60=60–61[41]
6.5
6
5
6
7
8
9
6.5
7
90
83
86
90
85
38–39=37–39[39]
73–74=73–75[39]
54–55=53–54[39]
97–98=98–99[42]
81–82=82–83[41]
7.5
8
4.5
10
11
12
6
9
9
91
75
68
47–49=46–48[39]
65–66
90–91=91–92[43]
aThe reactions were carried out by stirring a mixture of a,b-unsaturated ketone (1 mmol), HCOONH4
(1.5 g), HAP-Pd0 (0.3 g, 0.33 mol% Pd), and acetonitrile (5 mL) at 80 ꢀC.
bYield refers to column chromatography yield.
cThe rest being the unreacted chalcones.

HAP-Pd(0)-CATALYZED REDUCTION OF C–C
661
Table 3. Comparison of different supported Pd catalysts for the selective
reduction of carbon–carbon double bond in a,b-unsaturated ketones
Entry
Catalystb
Time (h)
Yield (%)c
1
2
3
4
5
6
7
Pd=C
Pd=C
6
15
6
62
83d
53
Pd=SiO2
Pd=SiO2
Pd=Al2O3
Pd=Al2O3
HAP-Pd0
15
6
72d
58
15
6
78d
89
aReaction
conditions:
3-(4-methoxyphenyl)-1-phenylprop-2-en-1-one
(1 mmol), HCOONH4 (1.5 g), HAP-Pd0 (0.3 g, 0.33 mol% Pd), acetonitrile
(5 mL) at 80 ꢀC.
bPd=C, Pd=SiO2, and Pd=Al2O3 were prepared by a procedure similar to
that described for HAP-Pd0. An amount of the catalyst equivalent to
0.33 mol% Pd was taken for the test reaction.
cYield refers to column chromatography yield, the rest being the starting
materials.
dYield refers to maximum yield after 15 h. After this no further conversion
was observed.
To compare the activity of HAP-Pd0 over Pd=SiO2, Pd=Al2O3, and Pd=
charcoal, selective reduction of 3-(4-methoxyphenyl)-1-phenylprop-2-en-1-one was
attempted using HCOONH4 in acetonitrile at 80 ꢀC (Table 3). Pd-HAP0 was found
to be more active, though similar selectivity was observed.
In the case of heterogeneous catalysts, deactivation and recyclability are impor-
tant issues that need to be addressed. For reductions, this becomes more important.
Figure 4. Recyclability of HAP-Pd0 for the selective reduction of carbon–carbon double bond in
3-(4-methoxyphenyl)-1-phenylprop-2-en-1-one (1 mmol) using HCOONH4 (1.5 g), HAP-Pd0 (0.3 g,
0.33 mol% Pd), acetonitrile (5 mL) at 80 ꢀC for 6 h.

662
O. S. CHAMBYAL ET AL.
Thus, a series of five consecutive runs for the reduction of 3-(4-methoxyphenyl)-
1-phenylprop-2-en-1-one under the reaction conditions for 6 h were carried out with
the same catalyst. The results are represented in Fig. 4, which demonstrate that the
catalyst is highly stable under the reaction conditions, though catalytic activity drops
very little after every use. The drop in activity might not be due to the leaching of
palladium because the amount of Pd before and after the fifth use remains almost
the same (determined by AAS analysis). The TEM micrographs of the catalyst after
the fifth run did not show any loss of uniformity in distribution of Pd over HAP
(Fig. 2b). The structural changes on the surface of hydroxyapatite may be respon-
sible for the slight loss of catalytic activity.
CONCLUSION
In conclusion, we have developed a mild and highly efficient method for the
selective reduction of carbon–carbon double bond in a,b-unsaturated ketones
without affecting the carbonyl group using HAP-Pd0 and ammonium formate in
acetonitrile at 80 ꢀC. Moreover, the catalyst is highly stable and hence recyclable
under the reaction conditions.
EXPERIMENTAL
All melting points were determined on a Perfit melting-point apparatus and are
1
uncorrected. H NMR spectra were recorded on a Brucker DPX-200 NMR spec-
trometer (200 MHz) in CDCl3 using tetramethylsilane (TMS) as an internal stan-
dard, and infrared (IR) spectra were recorded on a Perkin-Elmer FTIR
spectrophotometer using KBr discs. Mass spectral data was recorded on Bruker
Esquire 3000 (ESI), whereas thermal analysis was carried out on a DTG-60
Shimadzu thermal analyzer with heating rate of 10 ꢀC=min. SEM images were
recorded using a Jeol T-300 scanning electron microscope, and TEM images were
recorded on H7500 Hitachi. Pd content was determined on GBC Avanta-M atomic
absorption spectrometer manufactured by GBC Scientific. The catalyst was stirred in
diluted. HNO3 for 10 h, and the resulting filtrate was subjected to AAS analysis.
Preparation of Hydroxyapatite-Supported Palladium(0) [HAP-Pd0]
Hydroxyapatite was prepared by stirring a solution of diammonium hydrogen
phosphate (8 g) in double-distilled water (250 mL) at pH 12 and calcium nitrate
[Ca(NO3)2.4H2O] (25 g) in double-distilled water (150 mL) for 10 min. The suspen-
sion was then further stirred for 4 h at 115 ꢀC, and the solid was filtered off, washed
with double-distilled water (500 mL), and then dried in the oven at 95 ꢀC for 5 h. The
oven-dried hydroxyapatite was calcined in air at 750 ꢀC for 30 min before use.
HAP-Pd0 was prepared by stirring a mixture of hydroxyapatite (3 g) and Pd(OAc)2
(0.05 g) in ethanol (25 mL) at room temperature for 2 h, followed by addition of
hydrazine hydrate (80%, 1.5 mL) dropwise over a period of 20 min. It was further
stirred at room temperature for 7 h. The color of the catalyst changed to dark grey,
which indicated that Pd(II) was reduced to Pd(0). HAP-Pd(0) was filtered off and
washed with ethanol (10 mL) and acetone (3 ꢁ 20 mL). To remove any physiosorbed

HAP-Pd(0)-CATALYZED REDUCTION OF C–C
663
Pd(OAc)2, the catalyst was conditioned by refluxing for 6 h respectively in ethanol,
toluene, and acetonitrile, each for 2 h. Finally, the HAP-Pd(0) was dried in the oven
at 95 ꢀC for 5 h and stored in a desiccator.
General Procedure for the Selective Reduction of Carbon–Carbon
Bond in a,b-Unsaturated Ketones Using HAP-Pd(0)
Acetonitrile (5 mL) was added to a mixture of a,b-unsaturated ketone
(1 mmol), ammonium formate (1.5 g), and HAP-Pd0 (0.3 g, 0.33 mol% Pd), and the
reaction mixture was stirred at 80 ꢀC for an appropriate time (monitored by
thin-layer chromatography, TLC). After completion of the reaction, the reaction
mixture was cooled to room temperature and filtered. The residue was washed with
acetonitrile (2 ꢁ 10 mL). The organic solvent was removed under reduced pressure,
and product was obtained after passing through column of silica gel and elution with
EtOAc–petroleum ether (1:9). The residue was again washed with deionized water
(200 mL) followed by acetonitrile (3 ꢁ 10 mL) and dried at 100 ꢀC for 2 h. It can
be used further for carrying out the reactions.
Spectral Data of Compounds
1,3-Diphenylpropan-1-one (Entry 1). IR (KBr, nmax cmꢂ1): 2933 (aliphatic
1
=
CH2 stretch), 1681 (C O stretch); H NMR (200 MHz, CDCl3): d 2.98 (t, 2H, CH2),
3.33 (t, 2H, CH2), 7.20–7.55 (m, 10H, Harom); m=z: 210 (Mþ). Anal. calcd. for
C15H14O: C, 85.71; H, 6.66; O, 7.61. Found: C, 85.70; H, 6.60; O, 7.60.
3-(4-Methoxyphenyl)-1-phenylpropan-1-one (Entry 2). IR (KBr, nmax
cmꢂ1): 2943 (aliphatic CH2 stretch), 1687 (C O stretch); 1H NMR (200 MHz,
=
CDCl3): d 2.94 (t, 2H, CH2), 3.33 (t, 2H, CH2), 3.95 (s, 3H, OCH3), 6.91 (d, 2H,
Harom), 7.12–7.85 (m, 7H, Harom); m=z: 240 (Mþ). Anal. calcd. for C16H16O2:
C, 79.79; H, 6.71; O, 13.32. Found: C, 79.93; H, 6.72; O, 13.29.
1-(4-Bromophenyl)-3-(4-methoxyphenyl)propan-1-one (Entry 3). IR
(KBr, vmax cmꢂ1): 2999 (aliphatic CH2 stretch), 1682 (C O stretch); 1H NMR
=
(200 MHz, CDCl3): d 3.01 (t, 2H, CH2), 3.34 (t, 2H, CH2), 3.87 (s, 3H, OCH3),
6.85 (d, 2H, Harom), 7.20–7.55 (m, 4H, Harom), 7.95 (d, 2H, Harom); m=z: 318
(Mþ), 320 (M þ 2). Anal. calcd. for C16H15BrO2: C, 60.21; H, 4.74; O, 10.02. Found:
C, 60.20; H, 4.72; O, 10.04.
1-(4-Chlorophenyl)-3-(4-methoxyphenyl)propan-1-one (Entry 4). IR
(KBr, nmax cmꢂ1): 2934 (aliphatic CH2 stretch), 1680 (C O stretch); 1H NMR
=
(200 MHz, CDCl3): d 3.04 (t, 2H, CH2), 3.38 (t, 2H, CH2), 3.92 (s, 3H, OCH3),
6.95 (d, 2H, Harom), 7.25–7.68 (m, 4H, Harom), 7.97 (d, 2H, Harom); m=z: 274
(Mþ), 276 (M þ 2). Anal. calcd. for C16H15ClO2: C, 69.95; H, 5.50; O, 11.65. Found:
C, 69.93; H, 5.49; O, 11.62.
1-(4-Fluorophenyl)-3-phenylpropan-1-one (Entry 5). IR (KBr, vmax cmꢂ1):
1
=
2990 (aliphatic CH2 stretch), 1668 (C O stretch); H NMR (200 MHz, CDCl3): d
3.08 (t, 2H, CH2), 3.30 (t, 2H, CH2), 7.19–7.78 (m, 7H, Harom), 7.99 (d, 2H, Harom);

664
O. S. CHAMBYAL ET AL.
m=z: 228 (Mþ). Anal. calcd. for C15H13FO: C, 78.93; H, 5.74; O, 7.01. Found: C,
78.90; H, 5.72; O, 7.00.
3-(4-Chlorophenyl)-1-phenylpropan-1-one (Entry 6). IR (KBr, vmax cmꢂ1):
1
=
2967 (aliphatic CH2 stretch), 1683 (C O stretch); H NMR (200 MHz, CDCl3): d 3.12
(t, 2H, CH2), 3.37 (t, 2H, CH2), 7.08–7.78 (m, 7H, Harom), 8.03 (d, 2H,Harom); m=z:
244 (Mþ), 246 (M þ 2). Anal. calcd. for C15H13OCl: C, 73.61; H, 5.31; O, 6.54. Found:
C, 73.58; H, 5.28; O, 6.50.
1-(4-Chlorophenyl)-3-phenylpropan-1-one (Entry 7). IR (KBr, vmax cmꢂ1):
1
=
2957 (aliphatic CH2 stretch), 1677 (C O stretch); H NMR (200 MHz, CDCl3): d 3.12
(t, 2H, CH2), 3.37 (t, 2H, CH2), 7.08–7.78 (m, 7H, Harom), 8.03 (d, 2H, Harom); m=z:
244 (Mþ), 246 (M þ 2). Anal. calcd. for C15H13OCl: C, 73.61; H, 5.31; O, 6.54. Found:
C, 73.59; H, 5.29; O, 6.56.
1-(4-Bromophenyl)-3-phenylpropan-1-one (Entry 8). IR (KBr,
vmax cmꢂ1): 2982 (aliphatic CH2 stretch), 1668 (C O stretch); 1H NMR
=
(200 MHz, CDCl3): d 3.05 (t, 2H, CH2), 3.29 (t, 2H, CH2), 7.16–7.73 (m, 7H,
Harom), 7.97 (d, 2H, Harom); m=z: 288 (Mþ), 290 (M þ 2). Anal. calcd. for
C15H13OBr: C, 62.50; H, 4.51; O, 5.55. Found: C, 62.48; H, 4.48; O, 5.52.
1,3-Bis(4-chlorophenyl)propan-1-one (Entry 9). IR (KBr, vmax cmꢂ1):
1
=
2955 (aliphatic CH2 stretch), 1672 (C O stretch); H NMR (200 MHz, CDCl3): d
3.00 (t, 2H, CH2), 3.27 (t, 2H, CH2), 7.08–7.98 (m, 8H, Harom); m=z: 278 (Mþ),
280 (M þ 2). Anal. calcd. for C15H12OCl2: C, 75.00; H, 5.00; O, 6.66. Found: C,
74.98; H, 4.97; O, 6.68.
1-(4-Chlorophenyl)-3-(4-fluorophenyl)propan-1-one (Entry 10). IR (KBr,
1
vmax cmꢂ1): 2964 (aliphatic CH2 stretch), 1650 (C O stretch); H NMR (200 MHz,
=
CDCl3): d 3.02 (t, 2H, CH2), 3.33 (t, 2H, CH2), 7.25 (d, 2H, Harom), 7.42–7.85 (m,
4H, Harom), 8.01 (d, 2H, Harom); m=z: 261 (Mþ), 263 (M þ 2). Anal. calcd. for
C15H12OClF: C, 68.80; H, 4.58; O, 6.11. Found: C, 68.84; H,4.59; O, 6.10.
1-(4-Chlorophenyl)-3-(4-nitrophenyl)propan-1-one (Entry 11). IR (KBr,
vmax cmꢂ1): 2974 (aliphatic CH2 stretch), 1670 (C O stretch); 1H NMR
=
(200 MHz, CDCl3): d 3.12 (t, 2H, CH2), 3.39 (t, 2H, CH2), 7.28–7.37 (d, 2H, Harom),
7.68–7.75 (m, 2H, Harom), 7.99–8.10 (d, 2H, Harom), 8.26–8.34 (d, 2H, Harom);
m=z: 289 (Mþ), 291 (M þ 2). Anal. calcd. for C15H12O3ClN: C, 62.17; H, 4.15; O,
16.58; N, 4.83. Found: C, 62.19; H, 4.16; O, 16.59; N, 4.84.
Benzylmalononitrile (Entry 12). IR (KBr, vmax cmꢂ1): 2986 (aliphatic CH2
1
stretch), 2255 (CN stretch); H NMR (200 MHz, CDCl3): d 3.18 (d, 2H, CH2), 3.76
(t, 1H, CH), 7.12–7.37 (m, 5H, Harom); m=z: 156 (Mþ). Anal. calcd. for C10H8N2: C,
76.92; H, 5.13; N, 17.95. Found: C, 76.93; H, 5.11; N, 17.92.
ACKNOWLEDGMENTS
We are grateful to Sophisticated Analytical Instrumentation Facility (SAIF),
Punjab University, Chandigarh, for the SEM, TEM, and XRD and the Head, Institute
Instrumentation Centre, Indian Institute of Technology, Roorkee, for AAS analysis.

HAP-Pd(0)-CATALYZED REDUCTION OF C–C
665
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