A.H. Chowdhury et al.
Molecular Catalysis 450 (2018) 46–54
2 3
formic anhydride [34], chloral [35], KF-Al O formic acid (FA)-DCC
[
36] or EDCI [37], activated formic esters [38], ammonium formate
39], and formic acid in polyethylene glycol [40], aq. 85% formic acid
, FeCl , AlCl , NiCl and sulfonic acid
supported hydroxyapatite encapsulated γ-Fe has been reported as
[
with ZnO [41]. Recently, ZnCl
2
3
3
2
2 3
O
efficient catalysts [42] for the N-formylation reaction. However, toxi-
city of the reaction systems, high reaction time and temperatures, poor
chemical stability, formation of side products are the major drawbacks
for these reactions. Further, FA used as reagent for this N-formylation
reaction can be synthesized very efficiently through the photo/elec-
2
trochemical reduction or catalytic hydrogenation of CO [43]. Thus, FA
is a sustainable reagent for the N-formylation reaction.
In recent years, functionalized porous nanomaterials are frequently
employed as adsorbents [44,45] and catalysts [46–48] due to their
large surface area-to-volume ratio and abundance of both surface acid
and base sites [49]. Since the synthesis of MgO based nanomaterial is
very simple and economical, exploring its catalytic potential using CO
or HCO H as a reagent can be very useful as far as sustainability of the
2
2
catalytic process is concerned [50]. Thus, here we report the MgO based
nanomaterial through a simple precipitation method and explored its
catalytic activity for the synthesis of organic cyclic carbonates through
2
CO fixation reaction on a wide range of epoxides under ambient re-
action conditions. This MgO nanomaterial also catalyzes the N-for-
mylation of various types of amines with formic acid as reagent with
excellent product yields at room temperature.
2. Experimental
2.1. Materials
Magnesium nitrate hexahydrate [Mg(NO
3
)
2
,6H
2
O], ammonium
SO ), sodium
)were purchased from Merck, India. Commercial
hydroxide (NH
4
OH, 25% aqueous), sodium sulfate (Na
2
4
bicarbonate (NaHCO
3
available MgO, all epoxides, amines, formic acid (98%) and solvents
were purchased from Sigma-Aldrich. All reagents and solvents were
distilled through standard process and dried before use. Deionized (DI)
water was used for all the experiments wherever needed.
2.2. Synthesis of MgO nanomaterial
The magnesium oxide nanomaterial was synthesized from the
aqueous magnesium nitrate solution through ammonia precipitation
method. 0.01 mol aqueous solution of magnesium nitrate hexahydrate
was taken in a round bottom flask and a calculated amount of an
aqueous ammonium hydroxide solution was added to the magnesium
nitrate solution dropwise under continuous stirring at room tempera-
4
ture. The NH OH to Mg mole ratio was maintained at 6:1. A white
precipitate was obtained. Then the bottle was closed tightly and the
mixture was stirred magnetically at 65 °C for 5 h. After 5 h, the heating
was stopped and the mixture was stirred slowly for the next 18 h at
room temperature. The precipitate was then collected by centrifugation
followed by repeated washing with DI water, dried at 70 °C for 4 h. A
part of this as prepared sample was calcined at 450 °C for 4 h to get the
desired MgO nanomaterial.
2
Fig. 1. Powder XRD patterns of the as-prepared Mg(OH) (a), fresh MgO (b) and reused
MgO materials after 5 reaction cycles (c).
conducted by using
a ASIQ MP BET analyser, Quantachrome
Instruments, USA at liquid nitrogen temperature (77 K). Prior to the
measurement the sample was outgassed in vacuum for 4 h at 200 °C.
The total surface area was calculated by Brunauer–Emmett–Teller
(
0
BET) method within the relative pressure (P/P ) range of 0.05-0.20.
2.3. Characterization
The pore size distribution was estimated by using the
Barrett–Joyner–Halenda (BJH) method. The total pore volume was
Powder X-ray diffraction (PXRD) pattern of the sample was studied
calculated from the amount of N adsorbed at the relative pressure (P/
2
) of ca. 0.99. For the TPD-CO analysis the sample was inserted into
2
by a Bruker D8 Advance X-ray diffractometer using the Ni-filtered Cu
Kα (λ= 0.15406 nm) radiation. The thermal stability of the MgO na-
nomaterial was measured by differential thermal analysis (DTA) and
thermogravimetric analysis (TGA) (Netzsch STA 449C, Germany) from
P
0
the U-type glass cell and subjected for outgassing under helium gas to
remove any surface adsorbed moisture. Then it was cooled down to
room temperature and CO
2
gas was purged through the sample for
−
1
3
0 to 1000 °C with a heating rate of 10 °C min under air atmosphere.
30 min followed by purging of helium gas for 45 min to get rid of excess
The characteristic vibration bands of the samples were collected by a
Perkin-Elmer FT-IR 783 spectrophotometer taking the sample in a KBr
2
CO gas from the cell. With increasing temperature at 5 °C per min the
TCD signal has been obtained. The morphology and nanostructure of
pellet. The N
2
adsorption-desorption analysis of MgO sample was
47