Abstract: Zirconia and its modified forms such as Mo(VI)/ZrO 2 and Pt-SO 4 2-/ZrO 2 were coated on honeycomb monoliths. These materials were characterized for their, total surface acidity by NH 3 -TPD, crystallinity by PXRD and morphology by SEM techniques. They were then evaluated for their catalytic activity in o-acetylation of salicylic acid with acetic anhydride to synthesize acetyl salicylic acid. Honeycomb coated with zirconia and their modified forms were found to be eco-friendly, economical &amp; efficient catalysts for o-acetylation. These catalysts were found to be reusable

M Shyamsundar

Mohan Kumar

S R Pratap

S Z Mohamed Shamshuddin

Venkatesh

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ISSN: 2319-8753 
     International Journal of Innovative Research in Science, Engineering and Technology 
Vol. 2, Issue 3, March 2013 
 
      Copyright to IJIRSET                                                    www.ijirset.com                                                                                 599 
 
O-acetylation of salicylic acid with acetic 
anhydride over honeycomb coated with 
zirconia and its modified forms 
 
M. Shyamsundar
1
, S.Z. Mohamed Shamshuddin
2*
, S.R. Pratap
3
, Venkatesh
4
, T.E Mohan Kumar
5
, 
 
Research scholar M.Sc. Chemistry .Research Laboratory, HMS Institute of Technology, Tumkur, Karnataka, India
1 
Professor of Chemistry, Chemistry .Research Laboratory, HMS Institute of Technology, Tumkur, Karnataka, India
2 
Research scholar M.Sc. Chemistry .Research Laboratory, HMS Institute of Technology, Tumkur, Karnataka, India
3 
Research scholar M.Sc. Chemistry .Research Laboratory, HMS Institute of Technology, Tumkur, Karnataka, India
4 
Research scholar M.Sc. Chemistry .Research Laboratory, HMS Institute of Technology, Tumkur, Karnataka, India
5
 
 
Abstract:  Zirconia and its modified forms such as Mo(VI)/ZrO2 and Pt-SO4
2-
/ZrO2  were coated on honeycomb 
monoliths. These materials were characterized for their, total surface acidity by NH3-TPD, crystallinity by PXRD and 
morphology by SEM techniques. They were then evaluated for their catalytic activity in o-acetylation of salicylic acid 
with acetic anhydride to synthesize acetyl salicylic acid.  Honeycomb coated with zirconia and their modified forms 
were found to be eco-friendly, economical & efficient catalysts for o-acetylation.  These catalysts were found to be 
reusable. 
  
Keywords: Honeycomb; ZrO2; Mo(VI)/ZrO2; Pt-SO4
2-
/ZrO2; acetyl salicylic acid; o-acetylation. 
 
1.  INTRODUCTION 
Zirconia and its modified forms as solid acid catalysts are attracting much attention in recent years. For 
instance, sulfated zirconia proved to be a highly active solid acid catalyst for various organic transformations even at 
low temperature [1].  But, due to a major disadvantage associated with sulfated zirconia i.e., rapid deactivation at high 
temperatures, many efforts have been made to synthesize zirconia based solid acids modified with cations.  Zirconia 
based solid acids such as VOx/ZrO2, MoOx/ZrO2, WOx/ZrO2, Pt-SO4
2-
/ZrO2, etc have been synthesized and used as 
solid acid catalysts in a few liquid & vapor phase reactions [2,3]. 
Further, the physico-chemical, structural and catalytic properties of metal oxides such as zirconia, ceria, etc., 
can be modified by using proper catalyst carriers, adopting various synthesis and post synthesis routes, etc.  Cordierite 
(Mg2Al4Si5O18) honeycomb monoliths play a vital role as catalyst carriers in heterogeneous catalysis for fine chemical 
synthesis [4].   It is also reported that [5] the catalyst coated on HC are economical, since small amount of the active 
catalyst dispersed on HCs would be more effective than using the same catalyst in its powder form.  Effective and easy 
separation of the HC catalyst from the reaction mixture makes the use of HC as catalyst carrier more economical and 
environmental friendly. 
Acetyl salicylic acid which is also known as aspirin is used for the treatment of a number of conditions 
including: fever, pain, rheumatic fever, inflammatory diseases and strokes. Commercially, salicylic acid synthesized by 
Kolbe-Schmidt reaction is acetylated with acetic anhydride in presence of non-ecofriendly, corrosive, liquid acid 
catalysts such as H2SO4, H3PO4, etc [6,7].  
The present work deals with the synthesis of acetyl salicylic acid by o-acetylation of salicylic acid with acetic 
anhydride over honeycomb coated with solid acids like ZrO2 and its modified forms such as Mo(VI)/ZrO2 & Pt-SO4
2-
/ZrO2.  Since, these ZrO2 based solid acid catalysts have shown good catalytic activity in some of the acid catalyzed 
reactions, with an expectation that honeycomb coated forms of these catalysts would be more eco-friendly, economical 
& effective (triple e-concept) in o-acetylation, the present study was taken up.  Reactivation and reusability of these 
honeycomb catalysts was also taken up. 
 
II. EXPERIMENTAL 
A. Preparation of honeycomb (HC) catalysts 
For coating ZrO2 (Z) on a honeycomb monolith, dilute solution of zirconyl nitrate with 50 mL of deionised 
water, was prepared.  The resulting solution was coated on a wash coated HC by dipping and drying in a furnace pre-
heated at 400 
o
C.  The dipping and drying steps were repeated 12 to 15 times till ~0.2 g of ZrO2 is coated on the 
honeycomb [5].   
ISSN: 2319-8753 
     International Journal of Innovative Research in Science, Engineering and Technology 
Vol. 2, Issue 3, March 2013 
 
      Copyright to IJIRSET                                                    www.ijirset.com                                                                                 600 
 
Similarly, Mo(VI)/ZrO2 (MZ) containing 6%Mo(VI) was coated on a HC by taking a dilute solution 
containing known amounts of zirconyl nitrate and  ammonium molybdate.  
Pt-SO4
2-
/ZrO2 (Pt-SZ) was prepared in its powder form by impregnation method.  This powder form of Pt-SZ 
was made into a slurry which was then coated on a wash coated HC by slurry coating method. 
HCs coated with Z or MZ or Pt-SZ was calcined at 550 
o
C for 5 h in a muffle furnace before their use as 
catalysts.   
 
B.Characterization of HC catalysts 
The total surface acidity was measured by NH3-TPD method, powder X-ray diffraction (PXRD) patterns were 
recorded by X-ray powder diffractometer (Philips X’pert) using CuKα radiation (λ = 1.5418 A
o
)
 
using graphite crystal 
monochromator and SEM pictures were obtained from JEOL JED-2300. 
 
C.Catalytic activity studies of HC catalysts in o-acetylation of salicylic acid 
O-acetylation was carried out by taking known amounts of salicylic acid, acetic anhydride and HC catalyst in 
a cylindrical shaped flask equipped with water cooled condenser. The reaction mixture was heated for 1 h at refluxing 
temperature with constant stirring.  After 1 h, the hot reaction mixture was filtered to separate the HC catalyst.  The 
reaction mixture was then cooled to obtain a white solid of acetyl salicylic acid. Thus obtained crude acetyl salicylic 
acid was filtered, washed with water, dried and characterized by melting point experiment and LC-MS (Varian).   
To study the re-usability of used HC catalysts, after removing it from the reaction mixture, washed with 
acetone, dried at 120 
o
C for 5 h and calcined at 550 
o
C for 1 h. Thus reactivated HC catalyst was subjected to 
acetylation reaction under same reaction condition. The reactivation and reusability of the used HC catalyst was 
repeated for 5 times by following the procedure described above. 
 
       III. RESULTS AND DISCUSSION 
A. Characterization of HC catalysts 
 HCs coated with Z, MZ and Pt-SZ was characterized for their physico-chemical properties such as total surface 
acidity (TSA), crystallinity and morphology. 
 
Table 1: Surface properties of HC catalysts used in the present study 
 
HC catalyst Amount of active catalyst 
loaded 
TSA 
(mmols/g) 
Z 0.193 0.32 
MZ 0.201 1.34 
Pt-SZ 0.208 1.49 
 
TSA values of HC catalysts followed the order: 
ZrO2 < MZ < Pt-SZ 
The surface acidity of pure zirconia was found to be least acidic when compared to either MZ or Pt-SZ (Table 
1).  Incorporation of Mo(VI) or Pt/SO4
2-
 ions on ZrO2 increased the TSA drastically, which can be attributed to the 
formation of electron deficient states formed upon modification. 
 
PXRD patterns of HC catalysts are shown in Figure 1.  HC coated with ZrO2 consisted of both monoclinic (M) 
and tetragonal (T) reflections.  However, incorporation of Mo(VI) or Pt/SO4
2-
 ions in ZrO2 resulted in transition of 
monoclinic phase of ZrO2 to tetragonal phase of ZrO2.  Both MZ and Pt/SZ consisted of only tetragonal phase of ZrO2 
with either very low or nil monoclinic phase. 
 
ISSN: 2319-8753 
     International Journal of Innovative Research in Science, Engineering and Technology 
Vol. 2, Issue 3, March 2013 
 
      Copyright to IJIRSET                                                    www.ijirset.com                                                                                 601 
 
 
Fig 1. PXRD patterns of ZrO2, MZ and Pt-SZ [M- monoclinic ZrO2, T- tetragonal ZrO2]. 
 
SEM images of HC catalysts are shown in Figure 2, showing flake like appearances indicating the strong 
adherence of the active catalyst on the surface of the HC.  This also indicates the suitability of the preparation route 
used for coating the active catalyst on the surface of the HC.  Further, lusty tinge in the SEM images of MZ or Pt-SZ 
shows the dispersion of Mo or Pt ions in ZrO2. 
 
 
Figure 2. SEM pictures of (a) HC coated with ZrO2; (b) HC coated with MZ and (c) HC coated with Pt-SZ. 
 
B.Catalytic activity studies of HC catalysts in o-acetylation of salicylic acid 
 O-acetylation of salicylic acid (SA) with acetic anhydride (AA) over HC catalysts was carried out in liquid 
phase (Scheme 1).   
Scheme 1. O-acetylation of salicylic acid with acetic anhydride over a solid acid. 
OHO
O
H
CH
3
O CH
3
O O
OHO
O
O
CH
3
(Salicylic acid) (Acetic anhydride) (Acetyl salicylic acid)
CH
3
O
O
H
(Acetic acid)
Solid acid+
+
 
 
Reactions were carried out at refluxing temperature (~80 
o
C) at a molar ratio of SA: AA = 1:3 for 1 h.  Since 
AC2O acts both as a reactant and a solvent in o-acetylation reaction, it plays a positive role as a solvent where SA and 
catalyst will be well dispersed in AA medium driving the reaction to go to completion.   
In general all the HC catalysts used in the present study were active in o-acetylation reaction.  But the order of 
catalytic activity was similar to that of the surface acidity i.e.,   
ISSN: 2319-8753 
     International Journal of Innovative Research in Science, Engineering and Technology 
Vol. 2, Issue 3, March 2013 
 
      Copyright to IJIRSET                                                    www.ijirset.com                                                                                 602 
 
 ZrO2 < MZ < Pt-SZ 
ZrO2 being amphoteric showed least yield of acetyl salicylic acid when compared to either MZ or Pt-SZ 
(Table 2; Column2).  Among MZ & Pt/SZ, Pt/SZ showed highest acidity when compared to MZ which indicates strong 
interaction of Pt on ZrO2. 
 
Table 2: Yield of acetyl salicylic acid over HC catalysts for 6 cycles. 
 
HC catalyst Yield (%) of acetyl salicylic acid 
Fresh I cycle II cycle III cycle IV cycle V cycle 
ZrO2 42 42 41 40 38 38 
MZ 91 91 90 90 90 89 
Pt-SZ 98 96 97 95 94 94 
 
Further, a good co-relation between TSA, PXRD phases and catalyst activity of HC catalysts was observed.  
HC coated with pure ZrO2 which is least acidic with both monoclinic and tetragonal phases was found to be least active 
in acetylation when compared to MZ or Pt-SZ HC-catalysts.  Since, Pt-SZ was highly active among other HC catalysts 
used in the present study, also consisted of only tetragonal phase which is more catalytically active compared to 
monoclinic phase showed highest activity in o-acetylation. 
The used and reactivated HC catalysts were used in o-acetylation for 5 more reaction cycles and the results are 
given in Table-2 (column 3-7).  It is clear that the HC catalysts used in the present study can be effectively reactivated 
and reused at least for 6 reaction cycles with good catalytic activity. 
 
IV. CONCLUSION 
O-acetylation of salicylic acid  with acetic anhydride over honeycomb monolith coated with 
zirconia & its modified forms such as Mo(VI)/ZrO2 or Pt-SO4
2-
/ZrO2 was found to be efficient and 
ecofriendly process.  Use of honeycomb as a catalyst carrier makes the process economical with 
easy separation, reactivation and reusability. 
 
 ACKNOWLEDGEMENT 
The authors especially Dr. S.Z.M.Shamshuddin thanks DST, New Delhi for providing financial assistance 
through a major research project.  Authors are thankful to the authorities of Department of Chemistry, St. Joseph’s 
College,  Bangalore for XRD analysis, Department of Chemical Engineering, University of Malaya, Malaysia for SEM 
analysis. 
 
                                                                 REFERENCES 
[1] B.M. Reddy, M.K. Patil, Chem. Rev., 109(6) (2009) 2185. 
[2] B.M. Reddy, V.R. Reddy, Synth. Commun. 29(16) (1999) 2789. 
[3] B.M. Reddy, V.R.  Reddy, B. Manohar, Synth. Commun. 29 (1999) 1235 
[4] T.A. Nijhuis, M.T. Kreutzer, A.C.J. Romijn, F. Kapteijn, J.A. Moulijn, Chem. Eng. Sci. 56 (2001) 823. 
[5], N. Thimmaraju, S.R. Pratap M. Senthilkumar, S.Z. Mohamed Shamshuddin, J. Korean Chem. Soc., 56(5) (2012) 563. 
[6] D.L. Pavia, G.M. Lampman, G.S. Kriz, Introduction to Organic Laboratory Techniques: A Contemporary Approach, Philadelphia: Saunders, 
(1976) 27. 
[7] J.A. Miller, E.F. Neuzil, Modern Experimental Organic Chemistry, Lexingon: Heath, (1982) 192. 
 
     BIOGRAPHY 
 
 
 
 
M.Shyamsundar is a research scholar working in the department of chemistry, HMS 
Institute of Technology,Tumkur,Karnataka,India.He has completed his Master of Science 
in Chemistry in 2008.He has been working in the field of catalytic chemistry.  
 
ISSN: 2319-8753 
     International Journal of Innovative Research in Science, Engineering and Technology 
Vol. 2, Issue 3, March 2013 
 
      Copyright to IJIRSET                                                    www.ijirset.com                                                                                 603 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Dr. S.Z. Mohamed Shamshuddin is working as a Professor and Head in the 
department of Chemistry, HMS Institute of Technology, Tumkur, Karnataka, India.  
He has completed his Master of Science in Chemistry in 1997 from Bangalore 
University, PhD from Bangalore University in 2006 and PDF from Indian Institute 
of Science in 2009.  He has been working in the field of Catalytic Chemistry since 
13 years. 
 
S.R Prathap is a research scholar working in the department of chemistry HMS 
institute of Technology, Tumkur, Karnataka, India .He has completed his Master of 
Science in Biochemistry in 2008.He has been working in the field of catalytic 
chemistry.  
 
Venkatesh is a research scholar working in the department of chemistry, HMS 
Institute of Technology,Tumkur,Karnataka,India.He has completed his Master of 
Science in Chemistry in 1997.He has been working in the field of catalytic 
chemistry.  
 
Mohan Kumar T.E is a research scholar working in the department of chemistry 
HMS Institute of Technology kyathsandra, Tumkur, Karnataka, India .He has 
completed his Master of Science in Biochemistry in 2008.He has been working in 
the field of catalytic chemistry.  
 


O-acetylation of salicylic acid with acetic anhydride over honeycomb coated with zirconia and its modified forms

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O-acetylation of salicylic acid with acetic anhydride over honeycomb coated with zirconia and its modified forms

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