Nano copper ferrite: A reusable catalyst for the synthesis of β, γ -unsaturated ketones

Article abstract of DOI:10.1007/s12039-012-0258-9

Copper ferrite nano material as reusable heterogeneous initiator in the synthesis of β, γ - unsaturated ketones and allylation to acid chlorides are presented. The reaction of allylichalides with various acid chlorides is achieved in the presence of coppe

Full text of DOI:10.1007/s12039-012-0258-9

c
J. Chem. Sci. Vol. 124, No. 3, May 2012, pp. 639–645. ꢀ Indian Academy of Sciences.
Nano copper ferrite: A reusable catalyst for the synthesis
of β, γ -unsaturated ketones
Y L N MURTHYa,∗, B S DIWAKARa, B GOVINDHa, K NAGALAKSHMIa,
I V KASI VISWANATHb and RAJENDRA SINGHc
aOrganic Research Labs, Department of Organic Chemistry, Andhra University, Visakhapatnam 530 003, India
bDepartment of Chemistry, K L University, Greenfields Vaddeswaram, Guntur 522 502, India
cDefence Research and Development Organization (ER&IPR), Rajaji Marg, New Delhi 110 011, India
e-mail: murthyyln@gmail.com
MS received 24 April 2011; revised 9 November 2011; accepted 20 December 2012
Abstract. Copper ferrite nano material as reusable heterogeneous initiator in the synthesis of β, γ -
unsaturated ketones and allylation to acid chlorides are presented. The reaction of allylichalides with various
acid chlorides is achieved in the presence of copper ferrite nano powders at room temperature in tetrahydro-
furan (THF). The present method is first of its kind in the synthesis of title compounds without any additive/
co-catalyst. The nano catalyst is easily recovered and its reusability is recorded.
Keywords. Nano copper ferrite; heterogeneous initiator; allylation; β, γ -unsaturated ketones; reusability.
1. Introduction
more economic and environmentally benign. Here in,
we report nano copper ferrite as a reusable catalyst,
for the allylation of acid chlorides with shorter reaction
times (than reported) in good to moderate yields. The
general synthetic scheme is presented in scheme 1.
Despite the advantages of homogeneous metal catalysts,
difficulties in recovering the catalyst from the reaction
mixture severely inhibit their use in industry. Heteroge-
neous catalysis results in easy separation and recycling
of catalyst. Recent reports reveal that magnetic nano-
particles are efficient catalysts and they can be easily
separated from reaction mixture.1 The high surface area
to volume ratio of metal oxide nanoparticle is mainly res-
ponsible for their catalytic performance.2 Copper ferrite
nano material is one such reusable catalyst which shows
profound catalytic activity in organic synthesis.3
β, γ -Unsaturated ketones are versatile synthons in
the synthesis of natural products.4 In general acylation
of olefins produces β, γ -unsaturated ketones, but α, β-
unsaturated ketones may also be generated.5 The syn-
thesis is complicated by a tendency towards prototropic
rearrangement producing conjugated α, β-unsaturated
ketones.6 Allyl ketones are prepared by the reaction
of various allylic organometallics7 with acyl halides
but these reactions are of limited applications. Cad-
mium8, zinc9 and indium10 are some of the transition
metal powders reported earlier to synthesize these β,
γ -unsaturated ketones but the processes employed are
tedious and time taking. Thus it is clearly evident that
the need for the development of new and flexible pro-
tocols is required in such a way that they should be
2. Synthetic procedures
2.1 Preparation of the nano catalyst
The catalyst was synthesized by citrate gel precur-
sor method.11 Copper (II) nitrate and iron (III) nitrate
were taken in stoichiometric proportions and minimum
amount of deionized water was added to produce clear
cationic solution. Citric acid solution was then prepared
in stoichiometric ratio. Aqueous solutions with 1:1
molar ratio of metal ion solutions were mixed and citric
acid was added in equimolar ratio to the above mixed
metal ion solution. pH was adjusted to 7 by adding
ammonia solution. The aqueous mixture was kept for
stirring to form a highly viscous gel. The gel was then
heated gradually up to 90◦C to evolve reddish brown
gases and became dried gel which was finally treated at
350◦C for 1 h to observe whether the dry gel burnt out
in self propagating manner to form loose powder. The
finely powdered particles were calcinated at 600◦C. The
powder was then characterized.
2.2 General synthesis of β, γ -unsaturated ketone 3a
In a typical procedure, allyl bromide (1 mmol) in abso-
lute THF (5 ml) was added to a stirring suspension of
∗For correspondence
639

640
Y L N Murthy et al.
1a-j
3a-j
= Copper ferrite nano particle.
R = (a)C6H5 (b)2-ClC6H4 (c)2-Br,5-F,C6H3 (d)2-Br,5-F,C6H3, (e)Furanyl (f)5-Phenyl,3-Methyl,4-
,
Isoxazolyl, (g)5-(2,5-dichloro)Phenyl,3-Methyl,4Isoxazolyl, (h)(CH3)3C-, (i)C11H23- (j)C15H31-,
Scheme 1. Synthesis of β, γ -unsaturated ketone using allyl bromide.
copper nano ferrite (10 mol%) and stirring was continu- 1058 (C-O-N); 1HNMR (90 MHz, CDCl3/TMS): 8.18–
ed for 30 min at room temperature. Benzoyl chloride 8.22 (m, ArH), 3.67 (d, 2H), 6.29 (m, 1H), 4.96–5.04
(1 mmol) was then added in THF (10 ml) to the reac- (d/d, 2H), 2.49 (s, 3H); 13CNMR (22.5 MHz, CDCl3/
tion mixture and then the reaction was continued for a TMS):174.9, 62.16, 160.53, 132.88, 131.09, 129.15,
certain period of time as required for completion (moni- 128.38, 126.87, 109.92, 42.30, 12.82.
tored by TLC). The reaction mixture was then filtered to
separate the catalyst and the filtrate was quenched with
a few drops of water and the product was extracted with
dichloromethane and the solvent was removed under
reduced pressure. Further purification was attained by
2.2e 1-(3-(2,6-Dichlorophenyl)-5-methylisoxzol-4-yl)
but-3-en-1-one (table 4 entry 7) 3g: IR (υmax, KBr
Pellet in cm− 1): 1712 (-C=O), 1637(-C=C-), 3060
(=C-H), 1645 (C=N), 1069 (C-O-N), 717 (C-Cl);1HNMR
column chromatography, a colourless crystalline com-
(90 MHz, CDCl3/TMS): 7.78–8.34 (m, ArH), 3.97 (d,
pound was formed and recrystalized from ethanol. The
2H), 6.48 (m, 1H), 4.23–4.54 (d/d, 2H), 2.57 (s,3H);
pure compound was then characterized. Spectral data of
13CNMR (22.5 MHz, CDCl3/TMS): 175.74, 162.12,
selected compounds are given below.
158.67, 134.65, 131.97, 128.10, 109.93, 42.29, 12.80.
2.2a 1-Phenyl but-3-en-1-one (table 4 entry 1)3a:12 IR
2.2f 1, 4-Diphnyl-but– 3- en-1 one (table 4 entry 11)
(υmax, KBr Pellet in cm−1): 1701 (-C=O), 1669 (-C=C-),
4a:13 IR (υmax, KBr Pellet in cm−1): 1450, 1598,
1
3009 (=C-H); HNMR (90 MHz, CDCl3/TMS): 7.25–
8.4(ArH, m), 3.89 (2H, d), 5.82–6.09 (1H, m), 5.09–
5.39 (2H, d/d);13C NMR (22.5 MHz, CDCl3/TMS)
δ171.94, 133.77, 130.2,129.4, 128.41,105.07, 42.28.
1679, 3062; 1HNMR (90 MHz, CDCl3/TMS): 3.89 (2H,
br S), 5.82–6.09 (1H, m), 5.09–5.39 (1H, d/d), 7.25–8.4
(ArH,m); 13C NMR (22.5 MHz, CDCl3/TMS): δ171.94,
133.77, 130.2, 129.4, 128.41,105.07, 42.28
2.2b 1-(2-Chloro phenyl) but-3-en-1-one (table 4 entry
2) 3b: IR (υmax, KBr Pellet in cm−1): 1715 (-C=O),
1680 (-C=C-), 3071 (=C-H), 776 (C-Cl);1 HNMR (90 MHz,
CDCl3/TMS): δ7.41–7.93 (m, ArH), 3.33 (d, 2H), 4.76–
5.10 (m, 1H), 4.22 (d/d, 2H); 13CNMR (22.5 MHz, CDCl3/
TMS): δ166.69, 132.55, 131.94, 131.6, 130.73, 127.20,
36.74.
2.2g 1-(2-Chloro phenyl)-4-phenyl-but-3-en-1-one
(table 4 entry 12)4b: IR (υmax, CHCl3 in cm− 1): 725,
1249, 1445, 1593, 1714, 3040; 1HNMR (90 MHz, CDCl3/
TMS): 3.53 (2H, br S), 6.33–6.53 (1H, m), 5.11 (1H,
d/d), 7.32–7.83 (ArH, m);13C NMR (22.5 MHz, CDCl3/
TMS): 165.00, 132.98, 132.87, 132.01, 130.84, 130.51,
130.00, 129.4, 128.00, 127.13, 126.18, 125.54, 44.87.
2.2c 1-(Furan-2-yl) but-3-en-1-one (table 4 entry 5)
3e: IR (υmax, KBr Pellet in cm− 1): 1717 (-C=O), 1648
2.2h 1-Furan-2yl-4-phenyl-but-3en-1-one (table 4 entry
13)4c: IR (υmax, CHCl3 in cm− 1): 1014, 1116, 1473,
1581, 1701, 2877, 3016; 1HNMR (90 MHz, CDCl3/TMS):
3.85 (2H, br S), 6.08 (1H, m), 6.26–6.41 (1H, dd), 6.53–
6.71 (3H, m), 7.31–7.67 (ArH, m); 13C NMR (22.5 MHz,
CDCl3 /TMS): 160.34, 146.09, 144.07, 135.41, 133.51,
1238.08, 126.16, 124.38, 118.91, 111.16, 44.87
1
(-C=C-), 3127 (=C-H), 1077 (C-O-C); HNMR (90 MHz,
CDCl3/TMS): δ7.53, 7.33, 6.78 (m, 3H), 3.6 (d, 2H), 6.57–
6.55 (m, 1H), 4.365.22 (d/d, 2H); 13CNMR (22.5 MHz,
CDCl3/TMS): δ178.28, 162.32, 147.19, 143.92, 119.39,
112.21111.82, 27.67.
2.2d 1-(5-Methyl-3-phenyisoxazol-4-yl) but-3-en-1-one
(table 4 entry 6) 3f :10 IR (υmax, KBr Pellet in cm−1): 1719 2.2i 2-Methyl-6-phenyl-hex-5-en-3-one (table 4 entry
(-C=O), 1599 (-C=C-), 3108 (=C-H), 1678 (C=N), 14)4d: IR (υmax, CHCl3 in cm− 1): 1438, 1593, 1724,

Synthesis of β, γ -unsaturated ketones
3020; 1HNMR (90 MHz, CDCl3/TMS): 1.13–1.21 (6H,
641
Table 2. Reusability of nano catalyst.
d), 2.13–2.55 (1H, m), 3.85(2H, br S), 6.16 (1H, m),
6.26–6.41 (1H, dd), 6.26–6.54 (1H, dd), 6.54–6.71
(ArH, m), 7.30–7.38 (ArH, m); 13CNMR (22.5 MHz,
CDCl3/TMS): 181.64, 135.63, 133.81, 128.33, 127.94,
126.39, 125.00, 124.3, 45.07, 31.98, 23.18, 21.75, 18.47.
S.No
Catalyst recoverya(%)
Yeildb(%)
1
2
3
4
—
97
86
80
95
89
82
78
aCatalyst recovered by membrane filtration and washed with
diethyl ether and then by distilled water
3. Results and discussions
bYields compared to isolated products
In a typical experiment, allylhalide and acid chloride
were mixed in the presence of catalytic amount of cop-
per nano ferrite in stoichiometric portions using tetrahy-
drofuran as solvent and stirred at room temperature. The
completion of the reaction was monitored by thin-layer
chromatographic technique (n-hexane and ethyl acetate
as elute). In our initial efforts to optimize the reaction
condition, we screened various solvents like tetrahy-
drofuran, diethylether, dichloromethane and acetoni-
trile for this reaction. We found the reaction was effi-
cient in tetrahydrofuran compared to the other solvents
tested. The results are listed in table 1. From table 1, it is
clearly evident that a significant decrease in yields and
longer reaction times are noted for the solvents other
than THF, whereas in the presence of tetrahydrofuran
the yields are promising and shorter reaction times are
noted.
After completion of the reaction, the catalyst was
recovered by magnetization and washed with diethyl
ether and the recovered catalyst was reused for few
more cycles. During washing with the solvent, it was
clearly evident that there was no leaching of catalyst
and was confirmed by performing the reaction with the
filtrate. Atomic absorption spectroscopy was employed
to determine the copper content of copper ferrite nano
particles and it was found to be 27.3%. The leaching of
metal after three cycles was found to be 0.156%. From
our investigations, we observe that nano catalyst shows
excellent to good reactivity with promising yields even
for the next three cycles in the same reaction. Since,
there was no observable loss in the yield percentage; the
further reusability of nano catalyst was not needed. The
results are listed in table 2.
From table 3, it is noticed that in some reactions
the catalyst needs co-catalysts/additives. Some reac-
tions need the acidic/basic workup to get the product.
But here in this nano sized copper ferrite catalyst; there
is no need of additives, ligands, co-catalysts and no
need of activation for its reusability. The notable advan-
tages of this method are (i) lesser reaction times and (ii)
reusability than the earlier reported methods.
The allyl bromide and cinnamyl chloride reacted
with a wide variety of 10 acid chlorides under the
above optimized conditions and the results are sum-
marized in table 4. From the table 4, it is observed
that when the reaction proceeded with aliphatic long
chain acid chlorides, the formation of allyl ketone was
not found. It appears that neither electronic effects,
nor steric effects are important factors in acylation
of allyl halides by nano catalyst. All the acylation
reactions proceed with allylic rearrangement,14 so that
the double bond was removed from the conjuga-
tion. The mechanism, in which electrophillic attack of
nano ferrite occurs at the γ carbon atom of allylic
moiety, generated in situ, will react with the acyl
halides resulting in the title compounds. The forma-
tion of stable allyl ketone is confirmed by IR and
1
NMR spectral studies. In HNMR spectra, the chemi-
cal shift at δ 4.01–5.39, as doublet of doublet, con-
firms the presence of formation of stable olefinic
bond. This indicates that allylation takes place at car-
bonyl carbon without any prototropic rearrangement.
Table 3. Reaction times by different catalysts for the ally-
lation of acid chlorides.
S.No
Catalyst
Time*(h)
Table 1. Allylation of acid chlorides under different sol-
vent systems.
15
1
2
3
4
5
6
Ni(Cod)2
Zn9
15
3
3
3
2
S.No
Catalyst
Solvent
Time(h) Yield*
Cd8
In10
1
2
3
4
CuFe2O4
CuFe2O4
CuFe2O4 Dichloromethane
CuFe2O4 MeCN
THF
(C2H5)2O
1.5
3.5
6
95
78
63
BuSnCl2+Additive16
CuFe2O4
1.5
12
trace
*Reaction times related to the synthesis of allyl phenyl
ketone
*Isolated yields

642
Y L N Murthy et al.
Table 4. Synthesis of allyl ketones using copper ferrite nano particles.
S.No
1
R-COCI
Allyl halide
Product
Time(h)
1.5
Yield(%)
95
O
Br
[15]
3a
1a
Cl
Cl
O
2
3
4
-do-
-do-
-do-
2.3
2.0
3.0
86
84
81
1b
1c
1d
3b
O
F
F
Br
Br
3c
O
MeO
MeO
Br
Br
3d
O
5
6
-do-
-do-
2.5
3.0
75
82
O
O
1e
3e
O
C6H5
C6H5
N
N
O
O
[10]
O
1f
C6H3(2,5-Cl)
3f
(Cl-5,2)C6H3
N
O
N
O
7
8
-do-
-do-
3.5
3.0
80
75
3g
1g
O
C(CH3)3
C(CH3)3
3h
1h
9
H23C11
1i
C15H31
1j
-do-
-do-
NR
10
NR

Synthesis of β, γ -unsaturated ketones
643
Table 4. (continued)
S.No
R-COCI
Allyl halide
Product
Time(h)
Yield(%)
O
Cl
11
2.0
81
80
2a
Cl
[16]
4a
Cl
O
12
-do-
2.5
4b
O
2b
O
13
14
-do-
-do-
2.5
3.0
75
72
O
2c
4c
O
(H3C)2HC
(CH3)2CH
2d
4d
*Yields compared to isolated products and characterized by IR and NMR studies compared with authentic samples
NR: No reaction
From 13CNMR data the chemical shift for carbonyl in scheme 2. The reaction was done under above said
carbon is observed at 162–175 ppm and 132.5– optimized conditions. The results are listed in table 4.
143.92 ppm corresponds to the β carbon and chemi-
XRD studies were carried out to the above nano fer-
cal shift at 105.07–111.82 ppm for the γ carbon. This rite and XRD spectrum is presented in figure 1. From
indicates the tolerance to the double bond. The results the XRD data, it is observed that the copper ferrites
with allyl bromide encouraged us to extend the reaction are spinal crystals. From the XRD data, the size of the
with cinnamyl chloride. The synthetic route is presented copper ferrite particles is calculated by using sheerer
2a – d
4a – d
= Copper ferrite nano particle
R = (a)C6H5, (b)2-ClC6H4, (c)Furanyl, (d)-CH(CH3 2
)
Scheme 2. Synthesis of β, γ -unsaturated ketone using cinnamyl chlorides.

644
Y L N Murthy et al.
formulae and particle size is found to be 20 nm. This
shows that the synthesized powder has nano size crys-
talline. The scanning electron microscope studies are
carried out on the copper ferrite sample at 600◦C, and it
is presented in figure 2. The TEM image was recorded
and presented in figure 3. The lump size with irregu-
lar morphology was observed and it was found at
400 μm at 600◦C. From the above study, we observed
less number of pores with smaller lump size, resulting
fine grained microstructure with respect to ferrites.
Figure 1. XRD spectrum of CuFe2O4 at 600◦C.
4. Conclusions
In conclusion, we report here for the first time an
efficient protocol in the synthesis of β, γ -unsaturated
ketones using copper ferrite nano material. The notable
advantages are less expensive, heterogeneous reusable
catalyst; mild reaction conditions, high yields of pro-
ducts, shorter reaction times, no isomerization during
the reaction and easy workup.
Acknowledgements
The authors are thankful to Defence Research and
Development Organization (DRDO), New Delhi for
providing financial assistance. The authors are also
grateful to the Committee On Strengthening Infrastruc-
ture for Science & Technology (COSIST) Labs, Andhra
University for providing spectral data.
Figure 2. SEM image CuFe2O4.
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