S. Derkaoui et al. / Journal of Organometallic Chemistry 893 (2019) 52e60
53
Maghnite was placed in an Erlenmeyer flask together with 500 ml
of 1 M NaCl solution. The Maghnite/water mixture was stirred using
a magnetic stirrer until saturation was achieved over 24 h at room
temperature, the mineral was then washed with distilled water to
ꢀ
become chlorure free and then filtered and dried at 105 C. The
resulting activated bentonite catalyst was then stored in a her-
metically sealed container [21].
2.3. Synthesis and polymerization of methacrylamide monomer
(MAM)
Fig. 1. The schematic representation of reactivity of Acrylamide and Methacrylamide.
Synthesis of monomer was carried out by mixing 0.1 mol (10 ml)
þ
of ammonia with 1 g of clay catalyst Maghnite-H 0.25 M (10%),
after that, we added 0.1 mol (15 ml) of methacrylic anhydride (with
a molar ratio of 1:1 of methacrylic anhydride to ammonia) in bulk;
described in previous works in various solvents and initiators [13].
ꢀ
In water at 75 C using potassium persulfate as initiator [14] and in
ꢀ
ꢀ
the reaction mixture was cooled to 0e5 C using an ice bath during
water at 85 C using benzoyle peroxide as initiator rand their
ꢀ
1 h. After that, we filtered the solution recover the product (Scheme
). The product obtained was a white powder which when
copolymerization was studied [15] onto pectin in water at 70 C
1
using ammonium persulfate as initiator, and with methyl-
methacrylate in absolute ethanol using Azobisisobutyronitrile
recrystallized in a methanol-diethyl ether mixture. Yield: 85%.The
anionic polymerization of MAM was carried out in sealed tubes.
Each tube contains a mixture of 1 g of MAM, 10 ml of tetrahydro-
(
AIBN) as initiator [16]. The novelty of this work is to study the
anionic polymerization of methacrylamide initiated directly by a
þ
þ
furan THF and (0.15 g) 15% of Maghnite-Na . The mixtures were
montmorillonite clay, “Maghnite-Na ” a new green and recyclable
ꢀ
kept in an ice bath at 0 C and stirred with a magnetic stirrer under
catalyst. Initially, we have synthesized the monomer meth-
acrylamide by the condensation of ammonia with methacrylic
anhydride in bulk; and subsequently the polymerization of
monomer was carried out under suitable conditions in THF initi-
dry nitrogen for 2 h 30 min. The resulting polymer was precipitated
ꢀ
in methanol, washed for several times, dried at 40 C in vacuum and
weighed (yield ¼ 55%). (Scheme 2).
þ
ated by anionic catalyst “Maghnite-Na ”. This new non-toxic
3
. Results and discussion
initiator has been used successfully to prepare and study several
kinds of polymers [17,18].
We have developed a novel procedure to synthesize Meth-
acrylamide by using a heterogeneous silica catalyst that can effec-
tively catalyzed amide synthesis and anionic polymerization,
without production of toxic by-products. Montmorillonite have
both Brønsted and Lewis acid sites and when exchanged with
cations having a high charge density, as protons, produce highly
active catalysts for acid-catalyzed reactions. These exchanged
montmorillonite have been successfully used as catalysts for the
reactions of synthesis and polymerization of methacrylamide. The
chemical composition of montmorillonite clay “Maghnite” is re-
2
. Experimental section
2.1. Materials and methods
The chemicals and reagents used for the synthesis were ob-
tained from commercial sources and were used as received.
Methacrylic anhydride and Methanol were purchased from Sigma-
Aldrich; ammonia was obtained from Riedel-de-Haen. Raw-
Maghnite clay was obtained from ENOF Maghnia (Algeria). The
Maghnite-H (Mag-H ) was prepared as described by Belbachir
et al. [19]. X-ray diffraction (XRD) for MagH was performed on a
D8 Advanced Bruker AXSX-ray diffractometer. Fourier transforms
Infrared Spectroscopy (FT-IR) spectra were obtained between 400
and 4000 cm on an Alpha-PATR Bruker No 9501165. H and
Nuclear Magnetic Resonance (NMR) measurements were carried
out on a 300 MHz Bruker NMR Spectrometer equipped with a probe
BB05 mm, in CDCl
ported in Table 1. SiO
different catalysts with a low amount of Fe
2
and Al
2
O
3
are main components of the
, MgO and others. The
þ
þ
2 3
O
þ
bulk structures of the catalysts were analyzed by XRD.
The X-ray diffractogram of acidic and sodium montmorillonite
ꢀ ꢀ ꢀ
q from 7.0 to 6.8 and 5.8 , respec-
shows an offset of the angle 2
tively. Thus indicating the increase in the interlayer distance from
ꢁ1
1
13
C
1
2.52 Å to 15.56 Å for acidic clay and to 12.68 Å for sodium clay,
þ
confirming the intercalation of Na ions in the space initially
occupied by H ions [22] (Fig. 2).
3
Tetramethylsilane (TMS) was used as the in-
þ
ternal standard in these cases. TGA analysis was performed on a
PerkinElmer instrument STA 6000.
In (Fig. 3) FT-IR analysis results show the formation of the
Methacrylamide, The FT-IR spectrum of MAM exhibits two bands
ꢁ
1
ꢁ1
around 3376.12 and 3180.88 cm (broad), 607 and 550 cm which
2.2. Preparation of the catalysts
þ
þ
Maghnite-H and maghnite-Na were prepared according to
the process described by Belbachir et al. [20]. Raw-Maghnite (20 g)
was crushed for 20min using a prolabo ceramic balls grinder. It was
ꢀ
then dried for 2 h at 105 C. The raw Maghnite was placed in an
Erlenmeyer flask together with 500 ml of distilled water. The
Maghnite/water mixture was stirred using a magnetic stirrer and
combined with 0.25 M sulphuric acid solution, until saturation was
achieved over 2 days at room temperature. The mineral was then
washed with distilled water to become sulfate free and then dried
ꢀ
at 105 C. A barium nitrate test of the rinsing water residue is
needed to ensure that the sulfate is eliminated. The “Maghnite-
Na ” was prepared according to the following process:The raw-
Scheme 1. Schematic representation of the synthesis of methacrylamide (MAM)
catalyzed by Maghnite-H .
þ
þ