Formation of benzylidenes-diacetates catalyzed by activated zeolite "LZY-562" and clay (K10/ZnCl2): An unexpected functional selectivity

Article abstract of DOI:10.14233/ajchem.2015.15881

Activated zeolites LZY-562 and clay montmorillonite K10 at room temperature without solvent catalyzes the synthesis of benzylidenesdiacetates from carbonyl compounds. A chemoselectivity was observed between aldehydes and ketones, between the different aldehydes and ketones as well.

Full text of DOI:10.14233/ajchem.2015.15881

Asian Journal of Chemistry; Vol. 27, No. 6 (2015), 1973-1976
A
SIAN
J
OURNAL OF HEMISTRY
C
http://dx.doi.org/10.14233/ajchem.2015.15881
Formation of Benzylidenes-Diacetates Catalyzed by Activated Zeolite
“LZY-562” and Clay (K10/ZnCl2): An Unexpected Functional Selectivity
1
1
3
H. DOKARI , M. HAMMADI , N. BENFERRAH2,* and Y. RACHEDI
1Faculty of Sciences, UMBB, University of Boumerdes, 35000 Boumerdes, Algeria
2URMPE Research Unit for Materials, Processes and Environment, Faculty of Engineering Sciences, UMBB, 35000 Boumerdes, Algeria
3Faculty of Chemistry, USTHB, University of Bab Ezzouar, 16000 Alger, Algeria
*Corresponding author: E-mail: benferrahnassima@gmail.com
Received: 8 June 2013;
Accepted: 24 January 2015;
Published online: 17 March 2015;
AJC-16940
Activated zeolites LZY-562 and clay montmorillonite K10 at room temperature without solvent catalyzes the synthesis of benzylidenes-
diacetates from carbonyl compounds. A chemoselectivity was observed between aldehydes and ketones, between the different aldehydes
and ketones as well.
Keywords: Montmorillonite K10/ZnCl2, Zeolites LY-562, gem-Diacetates, Chemoselectivity, Carbonyl compounds.
chemoselectivity between aldehydes or between ketones in
the formation of derivatives gem-diacetates has not been
reported until now in the literature.
INTRODUCTION
The benzylidenes-diacetates have attracted great interest
in organic synthesis as an alternative to acetals for the protection
of aldehydes because of their remarkable stability in neutral
reaction media as well as towards aqueous acids1. The products
resulted by the condensation of aldehydes with the acetic
anhydride in the presence of catalytic acids are generally stable
in the weakly basic milieu2. In addition to carbonyl protection,
gem-diacetates derived from α,β-unsaturated aldehydes are
useful precursors for the preparation of acetoxybutadienes2,
nitrofuroxazines3 and vinyl acetates4 which turn useful as
dienes for Diels-Alder reactions. gem-Diacetates are useful as
carbonyl surrogates for asymmetric synthesis5,6 and for
nucleophilic displacement reactions7-9. Numerous methods
have been developed for the preparation of gem-diacetates10.
1,1-Diacetates (Acylals) are generally prepared from aldehydes
and acid anhydrides using either Bronsted acids (typically
sulphuric acid)11-13 or Lewis acids (e.g. ZnCl2 or PCl3)14-16. How-
ever, these methods are often accompanied by long reaction
times and low conversions.
We have reported the formation of a wide variety of useful
compounds (acetals, oxathiacetals, dithioacetals, thiochromanes,
enolthioethers)17-19 by the reaction of carbonyl compounds with
thiols catalyzed by clay (Mont K10-ZnCL2) in refluxing toluene.
The K10/ZnCl2 clay is inexpensive and offers several advantages
over the classical acids: strong acidity, no corrosive action,
selectivity and easy work-up. In these reactions, the clay acts
as a solid Lewis acid catalyst. To our best of knowledge, the
EXPERIMENTAL
Melting points (m.p) were identified with a [NETZSCH
STA 409 PC]. The IR spectra were recorded as KBr pellets on
[Jasco S-4000, FT-IR]. Proton NMR spectra (PMR) were
determined on Brucker AC 250 (250 MHz, CDCl3, Me4Si).
Spectrometer UV-visible spectra [λmax log (ε)] were obtained
with [spectrophotometer T60]. TLCAnalyses were performed
by using Kieselgel Schleicher and Shull F 1500 Ls 254 and
Merck 60F 254.The grinding of products were carried out on
a analytical grinderA 10 of Janke and Kenkel-IKA Labortechnik.
The montmorillonite K10 was obtained from the firm of Sud
Chemie. Zeolites (LZY562) as ammonium form were calcinated
at 500°C under dry flow before use (Linde).
Preparation of zeolites exchanged H+: 20 g of zeolite
(LZY562) are placed in a 100 mL flask and then treated with
a solution of NH4Cl (0.1 M) previously prepared with deioni-
zed water. The stoppered flask is allowed to stand overnight at
room temperature. The solid residue was recovered by filtration
and then activated in a muffle furnace at 500 °C for 24 h. The
zeolite in H+ (H+-ZY562) is stored in a dry container.
Preparation of montmorillonite K10 exchanged by
Zn2+: In a 250 mL flask, the montmorillonite K10 (20 g) was
added to a solution of ZnCl2 (0.2 mol) dissolved in 100 mL of
distilled water. The reaction mixture was stirred for 24 h at

1974 Dokari et al.
Asian J. Chem.
room temperature. The suspension was washed twice with disti-
lled water then centrifuged. The montmorillonite exchanged
by Zn2+ was washed with methanol and recentrifuged. The
solid was dried for 24 h in vacuum then finely ground. The
final product was a clear beige colour.
Formation of gem-diacetates from carbonyl compounds:
A mixture of aldehyde or ketone (30 mmol), acetic anhydride
(30 mmol) placed in a 25 mL of beaker, is adsorbed in alumino-
silicate acids (clay or zeolite during 10 h under room tempe-
rature. Dichloromethane (20 mL) is added to beaker to extract
of solid catalyzer followed by filteration through Buchner
funnel. The solvent is evaporated in vacuo using a rotative
evaporator. The obtained solid is identified by spectroscopic
methods.
crystallized in ethanol: m.p. = 111 °C); C12H14O4; MM = 222.23
g/mol; Yield: 68 %, UV-visible: λmax log (ε) (dioxane/H2O)
nm, 264, 272; IR (film) cm-1: 3060, 2940, 1725 (νOCOCH3),
1729 (νOCOCH3), 1470, 810.
Competition reactions between aldehydes and ketones:
Equimolecular quantities of aldehyde and ketone, were dissolved
in the minimum volume of methylene chloride mixed with
one equivalent of acetic anhydride and adsorbed on to zeolite
or montmorillonite Kio. The solvent was removed by evapo-
ration in vacuo. All products were characterized by their IR
and 1H NMR spectra. Yields of products were determined by
1H NMR spectroscopy.
RESULTS AND DISCUSSION
We report herein that the aldehydes react with one equi-
valent of acetic anhydride simply by adsorption on K10/ZnCl2
or activated zeolites LY-562 at room temperature without
solvent (Scheme-I).
Bis-(diacetoxy)methyl(benzene) (2a): Prepared from
benzaldehyde (30 mmol: 3.19 g), acetic anhydride (30 mmol:
3.06 g) in presence of H+-LZY562 (3 g); yellow solid
crystallized in ethanol; m.p. = 44 °C (lit.15: 45 °C); C11H12O4;
mol. mass = 208.21 g/mol; Yield: 73 %; UV-visible λmax log
(ε) (dioxane/H2O) nm: 226, 257, 263; IR (KBr) cm-1: 3106
(νCH arom), 1728 (νOCOCH3), 1512 (νC=C), 730 (δCH
O
OAc
Solid catalyst
R
R
C
(CH3CO)2O
+
without solvent, 25 °C
H
OAc
1
arom); H NMR (CDCl3).δ: 2,18 (s, 6H, CH3); 5,21 (s, 1H,
gem-diacetate
Scheme-I: Intermolecular chemoselectivity
CH); 7.18-7.97 (m, 5H, H arom); S.M m/z (%): M+• = 208.
1,4-Bis(diacetoxy)methyl(benzene) (3a): Prepared from
terephthaldehyde (30 mmol: 4.02 g) acetic anhydride (30
mmol: 3.06 g) in presence of H+-LZY562 (3 g); white solid
crystallized in ethanol; C16H18O8; mol. mass = 338.30 g/mol
Yield: 71 %, IR (KBr) cm-1: 2972 (νCH) (1731 (νOCOCH3),
1450 (νC=C), 730 (νCH arom); 1H NMR (CDCl3) δ: 2.21 (t,
12H, CH3); 5.23 (s, 2H, CH); 7.40 (m, 4H, H arom).
The results obtained for the synthesis of gem-diacetates
are reported in Table-1. The yields of diacetates are excellent.
In contrast with the results obtained in the homogeneous acidic
phase, yields are also good with sensitive aldehyde such as
thiophene-2-carbaldehyde (Yield: 80 %) dimethylamino-
benzaldehyde (Yield: 78 %).
Bis(diacetoxy)methyl(4-acetoxylbenzene) (4a): Prepared
from 4-hydroxybenzaldehyde (30 mmol: 3.66 g)acetic anhydride
(30 mmol: 3.06 g) in presence of clay K10/ZnCl2 (3 g); white
solid crystallized in ethanol; m.p. = 90 °C: C13H14O6; mol. mass
= 266.24 g/mol;Yield: 70 %, UV-visible λmax log (ε) (dioxane/
H2O) nm: 252, 261; IR (KBr) cm-1: 2948 (νCH-Arom), 1728
(νOCOCH3), 1467 (νC=C), 860 (δCH, arom disustitued); 1H
NMR (CDCl3) δ: 2.12 (s, 6H, CH3); 2.22 (s, 3H, CH3); 5.24 (s,
1H, CH); 7.18-7.97 (m, 4H, H arom).
As far as the ketones are concerned, the conversion to
gem-diacetates seems slower than that of the aldehydes in room
temperature and lasts at least 20 h.
For instance, the cyclododécanone is converted to
diacetate in 24 h; however, the reaction with light excess in
refluxing happens in 10 h. The results of the ketones conversion
to gem-diacetates are reported in Table-2 (Scheme-II).
The reaction is fast with aromatic aldehyde (10 to 12 h)
but slower with aliphatic aldehyde and with ketones.
Competition reactions between aldehydes and ketones:
Chemoselectivity between aldehydes and ketones was reported
by Fazaeli et al.20, Heravi et al.21 andWu et al.21 using Kegging-
type polyoxometalates. Ziyaei et al.22 used lithium perchlorate
in refluxing while Hajipour et al.23 used P2O5/Al2O3. We have
sought to exploit the kinetic difference in perspective of func-
tional selectivity and its use in the soft competitive reactions
between aldehydes and between ketones in the formation of
derivatives 1,1-diacetates using solid alumino-silicates such
as clay montmorillonite K10 or activated zeolites(H+)-
LZY562.
Qualitative kinetic results suggest the possibility of
Intermolecular chemoselectivity. In a typical competitive
experiment, an equimolar mixture (30 mmol) of benzaldehyde
(2), acetophenone (10) and acid anhydride was adsorbed on
K10/ZnCl2 (3 g) at room temperature.After 24 h, the products
were extracted with methylene chloride (20 mL) and the
solvent was removed by evaporation in vacuo. Only the
diacetate derivative of benzaldehyde was formed, in quantitative
yield.
Bis(diacetoxy)-methyl(4-chlorobenzene) (5a): Prepared
from 4-chlorobenzaldehyde (30 mmol: 4.22 g) acetic anhydride
(30 mmol: 3.06 g) in presence of clay K10/ZnCl2 (3 g); white
solid crystallized in ethanol : m.p. = 81 °C; C11H11O4Cl; mol.
mass = 242.65 g/mol Yield: 69 %; UV-visible λmax log (ε)
(dioxane/H2O) nm: 246, 253, 270, 274; IR (film) cm-1: 3080,
1
2960, 1730 (νOCOCH3) 1580, 940, 820, 727; H NMR
(CDCl3) δ: 2.11 (s, 6H, CH3); 5.25 (s, 1H, CH); 7.29-7.59 (m,
4H, H arom).
Bis(diacetoxy)-methyl(4-nitrobenzene) (7a): Prepared
from p-nitrobenzaldehyde (30 mmol: 4.53 g) acetic anhydride
(30 mmol: 3.06 g) in presence of H+-LZY562 (3 g); white
solid crystallized in ethanol: m.p. = 125 °C(lit.20: 124 °C);
C11H11O6N; mol. mass = 221.21 g/molYield: 77 %, UV-visible
λ
max log (ε) (dioxane/H2O) nm: 260, 282; IR (film) cm-1: 1732
(νOCOCH3); 1H NMR (CDCl3) δ: 2.15 (s, 6H, CH3); 5.24 (s,
1H, CH); 7.18-7.97 (m, 4H, H arom).
Bis(diacetoxy)-(methyl-phenyl)methane (10k): Prepared
from acetophenone (30 mmol: 3.60 g) acetic anhydride (30
mmol: 3.06 g) in presence of H+-LZY562 (3g); yellow solid

Vol. 27, No. 6 (2015)
Formation of Benzylidenes-Diacetates Catalyzed by Activated Zeolite “LZY-562” and Clay (K10/ZnCl2) 1975
TABLE-1
CONVERSION OF ALDEHYDE TO 1,1-DIACETATES IN THE PRESENCE OF ACID ALUMINOSILICATES
O
OAc
Solid catalyst
R
R
C
(CH3CO)2O
+
without solvent, 25 °C
H
OAc
gem-diacetate
Derivative diacetate
Aldehyde
Catalyst
Time (h)
20
Yield (%)
51
OAc
Heptanal (1)
(H+)-LZY562
(H+)-LZY562
(H+)-LZY562
K10/ZnCl2
OAc
[1a]
OAc
OAc
Benzaldehyde (2)
Terephthaldehyde (3)
10
10
12
12
73
71
70
69
[2a]
AcO
AcO
OAc
OAc
[3a]
OAc
AcO
Cl
p-Hydroxybenzaldehyde (4)
p-Chlorobenzaldehyde (5)
OAc
OAc
[4a]
K10/ZnCl2
OAc
[5a]
OAc
H3C
N
p-Dimethylaminobenzaldehyde (6)
K10/ZnCl2
11
78
H3C
OAc
[6a]
[7a]
OAc
OAc
O2N
p-Nitrobenzaldehyde (7)
(H+)-LZY562
(H+)-LZY562
11
10
77
80
OAc
OAc
Thiophene-2-carbaldehyde (8)
S
[8a]
TABLE-2
CONVERSION OF KETONES TO 1,1-DIACETATES IN THE PRESENCE OF ALUMINOSILICATES ACID
Ketone
Solid catalyst
Time (h)
Derivative diacetate
OAc
Yield (%)
51
Cyclohexanone (9)
(H+)-LZY562
24
OAc
[9k]
AcO
OAc
Acetophenone (10)
K10/ZnCl2
K10/ZnCl2
20
24
68
60
C
H3C
[10k]
[11k]
[12k]
OAc
Cyclododecanone (11)
OAc
OAc
AcO
Anthrone (12)
(H+)-LZY562
20
70
O
O
OAc
OAc
Solid catalyst
without solvent, 25 °C
(CH3CO)2O
C
H3C
O
H3C C
CHO
+
100 %
100 %
Scheme-II: Intramolecular chemoselectivity
When the molecule contains several different carbonyl
groups, as in 4-acetylbenzaldehyde (13), the only diacetate
derivative formed with one equivalent of acetic anhydride is
that of the aldehyde. The results obtained for the synthesis of
diacetates are reported in Table-3.
We also observed chemoselectivity between aromatic
aldehydes and aliphatic aldehydes. Only the aromatic diacetates
was formed in competition reaction. The competitive reaction
inter-aldehydes shows a noticeable and an unexpected chemo-
selectivity (Table-4).

1976 Dokari et al.
Asian J. Chem.
TABLE-3
TABLE-5
SELECTIVITY IN COMPETITION REACTIONS BETWEEN
CARBONYL COMPOUNDS (A AND K) IN FORMATION
OF BENZYLIDENES-DIACETATES (A’ AND K’)
COMPETITIVE REACTIONS BETWEEN KETONES IN
PRESENCE OF K10 AT ROOM TEMPERATURE
Aliph. ketone
Arom. ketone
Selectivity
OAc
AcO
Carbonyl compounds
(Selectivity)
O
O
O
Aldehyde
Ketone
A’ [100 %]
K’ [0 %]
H3C
C
+
C
H3C
H3C
+
OAc
100 %
100 %
O
(1)
(9)
OAc
AcO
H3C
OAc
O
O
O
100 %
100 %
100 %
[1a]
[2a]
[8a]
100 %
C
C
+
+
OAc
O
C
100 %
100 %
H3C
(2)
(8)
(10)
(11)
OAc
OAc
AcO
O
O
100 %
OAc
O
+
O
+
100 %
100 %
S
OAc
OAc
AcO
O
100 %
O
+
O
OAc
+
O
Cl
100 %
100 %
(5)
(12)
OAc
[5a]
100 %
100 %
tivity was observed between different aldehydes or between
aldehydes and ketones in the formation of derivatives gem-
diacetates. The determinative effect is the presence or absence
of aromatic rings. This may be related to the ease of aromatic
molecules to slot between the aluminosilicate sheets. The
lamellar nature of the montmorillonite clay as the phenomena
of adsorption and desorption are for sure responsible for this
selectivity.
O
OAc
OAc
O
H3C
C
C
H3C
CHO
(13)
[13a]
100 %
TABLE-4
SELECTIVITY IN COMPETITION REACTIONS BETWEEN
ALDEHYDES (A AND B) IN PRESENCE OF
ACTIVE ZEOLITES (H+)-LZY562
A
+
B
Selectivity
REFERENCES
OAc
OAc
CHO
1. T.W. Greene and P.G.M. Wuts, Protective Groups in Organic Synthesis,
Wiley, New York, edn 3 (1999).
+
(1)
(2)
100 %
100 %
[2a]
2. R.E. Banks, J.A. Miller, M.J. Nunn, P. Stanley, T.R. Weakley and J.
Ullah, J. Chem. Soc., Perkin Trans. 1, 1096 (1981).
3. A. Mouriño, Synth. Commun., 8, 117 (1978).
4. G.M. Whitesides and J. San Filippo, J. Am. Chem. Soc., 92, 6611 (1970).
5. B.M. Trost and C.B. Lee, J. Am. Chem. Soc., 123, 3671 (2001).
6. B.M. Trost and J. Vercauteran, Tetrahedron Lett., 26, 131 (1985).
7. M. Sandberg and L.K. Sydnes, Tetrahedron Lett., 39, 6361 (1998).
8. F.R. van Heerden, J.J. Huyser, D. Bradley, G. Williams and C.W.
Holzapfel, Tetrahedron Lett., 39, 5281 (1998).
9. J.S. Yadav, B.V. Subba Reddy and G.S. Kiran Kumar Reddy, Tetrahe-
dron Lett., 41, 2695 (2000).
10. L.K. Sydnes and M. Sandberg, Tetrahedron, 53, 12679 (1997).
11. M. Tomita, T. Kikuchi, K. Bessho, T. Hori and Y. Inubushi, Chem.
Pharm. Bull. (Tokyo), 11, 1484 (1963).
12. G.A. Olah and A.K. Mehrotra, Synthesis, 962 (1982).
13. F. Freeman and E.M. Karchefski, J. Chem. Eng. Data, 22, 355 (1977).
14. K.S. Kochhar, S.B. Bal, R.P. Deshpande, S.N. Rajadhyaksha and H.W.
Pinnick, J. Org. Chem., 48, 1765 (1983).
OAc
OAc
OAc
H3C
N
(6)
(5)
(2)
(2)
+
H3C
OAc
[6a]
57 %
43 % [2a]
OAc
OAc
Cl
+
OAc
OAc
45 %
OAc
[5a] 55 %
[2a]
[2a]
CHO
+
(14)
(2)
OAc
100 %
100 %
OAc
OAc
OAc
+
O2N
OAc
(7)
(5)
(2)
(7)
[7a]
38 %
55 %
62 % [2a]
OAc
OAc
OAc
O2N
+
Cl
15. I. Scriabine, Bull. Chem. Soc. Fr., 1194 (1961)
OAc
16. J.K. Michie and J.A. Miller, Synthesis, 824 (1981).
17. P. Laszlo and A. Mathy, Helv. Chim. Acta, 70, 577 (1987); S. Chalais,
A. Cornalis, A. Gerstmans, W. Kojodziejski, P. Laszlo, A. Mathy and
P. Mitra, Helv. Chim. Acta, 68, 1196 (1985) .
18. B. Labiad and D. Villemin, Synth. Commun., 19, 31 (1989).
19. R. Miranda, H. Cervantes and P. Joseph-Nathan, Synth. Commun., 20,
153 (1990).
20. R. Fazaeli, S. Tangestaninejad and H.Aliyan, Appl. Catal., 318, 218 (2007).
21. M.M. Heravi, K. Bakhtiari and F.F. Bamoharram, Catal. Commun., 7,
499 (2006); H. Wu, Y. Shen, L. Fan, Y. Wan and D. Shi, Tetrahedron,
62, 7995 (2006).
22. A. Ziyaei, N. Azizi and M. Saidi, J. Mol. Catal., 238, 138 (2005).
23. A.R. Hajipour, A. Zarei and A.E. Ruoho, Tetrahedron Lett., 48, 2881
(2007).
[5a]
45 %
[7a]
We also observed chemoselectivity between the ketones.
Only aromatic diacetates was formed in competitive reaction
after 24 h.
The competitive reaction between ketones is slow more
than that of aldehydes (minimum 24 h) and shows a remarkable
intermolecular chemoselectivity (Table-5).
Conclusion
Compared to conventional methods (homogeneous
catalysis), all reactions were conducted at room temperature
under favourable conditions. An unexpected functional selec-