Molecular sieve abstract
The present invention relates to novel calix pyrroles and a process
for synthesis of calix (4) pyrroles by reacting pyrrole with cyclic
or acyclic ketones in dichloro methane (DCM) solvent over molecular
sieve catalysts which provides an eco-friendly, more economical
and selective heterogeneous method.
Molecular sieve claims
We claim:
1. A method of preparing a calix(4) pyrrole, said method comprising:
(a) refluxing a pyrrole with an acyclic or cyclic ketone in the
presence of a molecular sieve catalyst in an organic solvent at
a temperature of about 100.degree. C. for a period of between about
10 to about 72 hours; (b) cooling the reaction mixture of step (a)
to room temperature; (c) filtering the solution of step (b) and
washing the residue with an organic solvent to recover catalyst
and to obtain a mother liquor; (d) evaporating to dryness the mother
liquor of step (c) to obtain a solid; (e) washing the solid of step
(d) with deionized water; (f) drying the washed solid of step (e)
in air, followed by calcining at 373.degree. K in air; and (g) purifying
the calcined product of step (f) by column chromatography to obtain
the calix (4) pyrrole.
2. A method as defined claimed in claim 1 wherein said catalyst
is selected from the group consisting of MCM-41 HZSM-5 (30), H.beta.,
HY and SAPO-5.
3. A method as defined in claim 1 wherein said catalyst is employed
in an amount from about 0.1 to about 1.0 gram.
4. A method as defined in claim 1 wherein said catalyst is selected
from the group consisting of MCM-41 having a surface area of from
about 980 to about 1200 square meters per gram and a pore size of
from about 30 to about 100 Angstroms, HY having a surface area of
from about 525 to about 625 square meters per gram and a pore size
of from about 6 to about 8 Angstroms, HZSM-5(30) having a surface
area of from about 275 to about 340 square meters per gram and a
pore size of from about 5 to about 7.5 Angstroms, H.beta. having
a surface area of from about 600 to about 680 square meters per
gram and a pore size of from about 5.5.times.6.6 to about 7.5.times.8.5
Angstroms, and SAPO-5 having a surface area of from about 175 to
about 240 square meters per gram and a pore size of from about 6.5
to about 8.4 Angstroms.
5. A method as defined in claim 1 wherein said catalyst is selected
from the group consisting of HY having a surface area of about 593
square meters per gram and a pore size of about 7.3 Angstroms, HZSM-5(30)
having a surface area of about 310 square meters per gram and a
pore size of about 5.6 Angstroms, H.beta. having a surface area
of about 640 square meters per gram and a pore size of about 6.5.times.7.6
Angstroms, and SAPO-5 having a surface area of about 207 square
meters per gram and a pore size of about 7.4 Angstroms.
6. A method as defined in claim 1 wherein the organic solvent
used for refluxing is selected from the group consisting of dichloromethane,
methanol, and acetonitrile.
7. A method as defined in claim 1 wherein the molar ratio of the
pyrrole to the ketone is between about 1:1 to about 1:4.
8. A method as defined in claim 1 wherein a cyclic ketone is refluxed
with the pyrrole, said cyclic ketone being selected from the group
consisting of cyclohexanone, 2-methyl cyclohexanone, cycloheptanone,
cyclopentanone and cyclooctanone.
9. A method as defined in claim 1 wherein in an acyclic ketone
is refluxed with the pyrrole, said acyclic ketone being selected
from the group consisting of acetone, diethyl ketone, and methyl
ethyl ketone.
10. A method as defined in claim 1 wherein the catalyst is HY.
11. A method as defined in claim 1 wherein the catalyst is HZSM-5(30)
and the method forms a linear product.
12. A method as defined in claim 1 wherein the yield of the calix
(4) pyrrole is at least about 70%.
13. A method as defined in claim 1 wherein the selectivity of
the calix (4) pyrrole is at least about 90%.
14. A method as defined in claim 1 wherein the calix (4) pyrrole
is selected from the group consisting of: i) octamethyl calix (4)
pyrrole (formula 1a); ii) tetraethyl tetra methyl calix (4) pyrrole
(formula 2a); iii) octaethyl calix (4) pyrrole (formula 3a); iv)
tetraspiro cyclohexyl calix (4) pyrrole (formula 4a); v) tetraspiro
cyclopentyl calix (4) pyrrole (formula 5a); vi) tetraspiro cycloheptyl
calix (4) pyrrole (formula 6a); vii) tetraspiro cyclooctyl calix
(4) pyrrole (formula 7a); and viii) (2-methyl cyclohexyl) calix
(4) pyrrole (formula 8a): ##STR1##
15. A method as defined in claim 1 wherein an acyclic product
is formed by the method, said acyclic product being selected from
the group consisting of: ##STR2##
16. A method for preparing a calix (4) pyrrole, said method comprising
mixing a pyrrole with an acyclic or cyclic ketone over a molecular
sieve solid acid catalyst, subjecting the mixture to microwave radiation
for about 3 to about 10 minutes, and optionally, refluxing with
a solvent to extract the calix (4) pyrrole.
17. A method as defined in claim 16 wherein the solvent is selected
from the group consisting of dichloromethane, methanol, and acetonitrile.
18. A method as defined in claim 16 wherein the molar ratio of
pyrrole to ketone is about 1:1.
19. A method as defined in claim 16 wherein the ketone is cyclohexanone,
said pyrrole and said cyclohexanone being mixed in an equimolar
ratio.
20. A method as defined in claim 16 wherein the catalyst is MCM-41.
21. A method as defined in claim 16 wherein the catalyst has a
surface area of from about 980 to about 1200 meters squared per
gram.
22. A method as defined in claim 16 wherein the catalyst has a
pore size of from about 30 to about 100 Angstroms.
23. A method as defined in claim 16 wherein the microwave heating
is carried out for a period of from about 2 minutes to about 15
minutes.
24. A method as defined in claim 16 wherein the microwave heating
is carried out for a period of from about 3 minutes to about 10
minutes.
25. A method as defined in claim 16 wherein the microwave radiation
level is about 2450 Megahertz.
26. A method as defined in claim 16 wherein an acyclic ketone
is used that is selected from the group consisting of acetone, diethyl
ketone, and methy ethyl ketone.
27. A method as defined in claim 16 wherein a cyclic ketone is
used that is selected from the group consisting of cyclohexanone,
2-methyl cyclohexanone, cycloheptanone, cyclopentanone, and cyclooctane.
28. A method as defined in claim 16 wherein the calix (4) pyrrole
is selected from the group consisting of: i) octamethyl calix (4)
pyrrole (formula 1a); ii) tetraethyl tetra methyl calix (4) pyrrole
(formula 2a); iii) octaethyl calix (4) pyrrole (formula 3a); iv)
tetraspiro cyclohexyl calix (4) pyrrole (formula 4a); v) tetraspiro
cyclopentyl calix (4) pyrrole (5a); vi) tetraspiro cycloheptyl calix
(4) pyrrole (formula 6a); vii) tetraspiro cyclooctyl calix (4) pyrrole
(formula 7a); and viii) (2-methyl cyclohexyl) calix (4) pyrrole
(formula 8a): ##STR3##
29. A method as defined in claim 16 wherein an acyclic product
is formed by the method, said acyclic product being selected from
the group consisting of: ##STR4##
Molecular sieve description
FIELD OF THE INVENTION
The present invention relates to novel calix (4) pyrroles and preparation
of calix (4) pyrroles over zeolite molecular sieves. More particularly,
this invention relates to a method for synthesis of calix (4) pyrroles
directly from pyrroles and ketones in an eco-friendly zeolite catalyzed
heterogeneous method with high yields.
This invention provides a non-corrosive eco-friendly process, where
the catalyst is recyclable and reused many times, no work up procedure,
no-wastage of the compounds (i.e. high atom selectivity), simple
sample extraction and high selectivity of products.
BACKGROUND AND PRIOR ART REFERENCES
Calix pyrroles represent a subset of class of macrocycles that
was previously termed as porphyrinogens. Porphyrinogens are non-conjugated
macrocyclic species composed of four pyrrole rings linked to the
position via sp.sup.3 hybridized carbon atoms. Porphyrinogens that
carry meso-hydrogen atoms are prone to oxidation to the corresponding
phorphyrins and renamed the term porphyrinogen as calixpyrrole due
to the analogues properties of calixarenes. Fully meso non-hydrogen
substituted phorphyrongens are generally stable crystalline materials.
The first such macrocycle, meso octamethyl calix (4) pyrrole was
reported over a century ago by Bayer (Ber. Disctz. Chem. Ger. 1886
19 2184) using condensation between acetone and pyrrole catalyzed
by HCl, however, the structure of the molecule was not elucidated.
This method was refined by Dennstedt and Zimmerman (Ber. Disctz.
Chem. Ger. 1887 20 850) by replacing the HCl with "chlorzink"
and heating the reaction. Chelintzev and Toronov synthesized calix
(4) pyrrole by the method of condensing acetone and pyrrole, methyl
ethyl ketone and pyrrole, methyl hexyl ketone and pyrrole and a
mixture of acetone and methyl ethyl ketone with pyrrole (J. Russ.
Phys. Chem. Soc. 1916 48 1197; Chem Abstr. 1917 11 1418). Further,
Chelintzev, Tronov and Kurmunov reported the production of calixpyrroles
by condensing cyclohexanone with pyrrole and a mixture of acetone
and cyclohexanone with pyrrole (J. Russ. Phys. Chem. Soc. 1916
48 1210). Rothenmund and Gage refined Dennstedt and Zimmermann's
method by replacing the acid catalyst with methane sulphonic acid
(J. Am. Chem. Soc. 1955 55 3740). In 1971 Brown, Iluichioson
and Mackinon (Can. J. of Chem. 1971 49 4017) repeated the synthesis
of mesotetracyclohexyl calixpyrrole and assigned a tetrameric macrocyclic
structure. J. M. Lehn and coworkers have synthesized meso-octa-3-chloro
propyl calix (4) pyrrole by an unpublished procedure and converted
into meso-octa-3-cyano propyl calix pyrrole (B. Dietrich, P. Viout
and J. M. Lehn in macrocyclic chemistry, VCH, Publishers, Weinhein
1993 pg82). The metal cation binding of deprotanated calix (4)
pyrrole macrocyclics has been studied by Floriani and co-workers
(Chem. Commun. 1996 1257). Floriani has developed a method for
expanding the pyrrole rings of metal bound deprotanated calix (4)
pyrroles forming calix (1) pyridino (3) pyrroles and calix (2) pyridino
(2) pyrroles (J. Am. Chem. Soc. 1995 117 2793). A further a prior
art method reports using pyrrole, a C.sub.4 -C.sub.6 saturated acyclic
ketone and an acid containing vinyl groups are triple bonds to form
a polymerized resin (WO 93/13150). In this case, the resulting products
are undefined, since it appears to be unknown where the modifying
group is attached to the product. By making use of calixarenes as
templates P. A. Gale et al synthesized Calixarene-calix pyrrole
dimers (calixarene capped-calixpyrrole) and expanded calixpyrroles
(Tet Lett 37(44), 19967881) and also reported the synthesis of
calixpyridino pyrroles and calix pyridines from calixpyrroles (Chem
corn 1998 1). Macrocycles have unexpected properties that make
them particularly useful. Calixpyrroles bind anion and neutral molecular
species in solution and in the solid state in such an effective
and selective way the anions or neutral molecular species can be
separated from other anions and neutral molecular species. Further
the affinity a macrocycle has for a particular species can be `tuned`
by strategic choice of electron-donating or electron-withdrawing
peripheral substituents for the synthesis of macrocycles.
According to W.O. Pat. No. 97/37995 various types of calixpyrroles
was synthesized using different ketones including tetrahydrothiopyran-4-one,
diphenylacetone, 10-nonadecanone, acetyl ferrocenes and chiral calixpyrroles
by using chiral ketones. And also reported the synthesis of expanded
calixpyrroles, where n>4 (i.e. Calix (5) pyrrole, Calix (6)
pyrrole, calix (8) pyrroles), calix pyridino pyrroles, calix pyridines
and their applications. Application of these properties for removal
of biological ions or neutral molecule species for medical uses,
removal of undesirable ions or neutral molecule species from environmental
sources provides only a few of the practical and important uses.
These calix (4) pyrroles can be used in the dialysis of bodily
fluids. Examples of dialyzable substrates include, but are not limited
to phosphate containing molecules or halide waste (i.e. diabetes
or drug overdoses and kidney dialysis).
Clean technology is fast replacing the various processes, which
were once catalyzed by highly corrosive liquid acids, due to the
growing concern for the environment. In these eco-friendly processes,
solid acids which are highly selective and active with strong proton
donating sites distributed uniformly within the pores, have been
found to be an attracting replacement for the non-reusable, hazardous
liquid acids. Porous materials created by nature or by synthetic
have found great utility in all aspects of human activity. The pore
structure of solids is usually formed in the stages of crystallization
or subsequent treatment. Depending on their predominant pore size,
the solid materials are classified as microporous, mesoporous and
macroporous materials. The only class of porous materials possessing
rigorously uniform pore sizes is that of Zeolites and related molecular
sieves. Zeolites are uniform porous crystalline aluminosilicates
and their lattice is composed by TO.sub.4 tetrahedral (T=Al and
Si) linked by sharing the apical oxygen atoms (Breck D. W., Zeolite
molecular sieves: Structure, Chemistry and Use; Wiley and Sons;
London 1974). As Zeolites act as sieves at the molecular level,
these are considered as a subclass of molecular sieves. Zeolites
have a number of interesting physical and chemical properties. The
classes of phenomena that are of greatest practical importance are
the availability to sorb organic and inorganic substances, to act
as cation exchangers and to catalyze a wide variety of reactions.
But due to the smaller pore size of these molecular sieves restricted
their wide range applications, especially in case of larger molecules.
But this has been overcome by the report of Mesoporous molecular
sieves by Mobil researchers (C. T. Kresge, M. E. Leonowicz, W. J.
Roth, J. C. Vartuli and J. S. Beck, Nature 359 (1992) 710) in 1992.
These Mesoporous molecular sieve (MCM-41) has been opened a new
era in the zeolite catalysis. Till then many reports have been published
on the applications of this material for the catalytic activity
towards oxidation, acylation and alkylation. And support material
for enzymes, whole cell immobilization, and nano particles.
The previous processes have the disadvantage that (a) in all the
cases mineral acids used as catalysts which are highly corrosive,
(b) in all the cases inert atmosphere should be maintained, (c)
in all the cases tedious work-up procedure is present, such as neutralization
of acid etc, (c) separation and reusability of the catalyst is not
possible, (d) in some cases more than a single step is carried out
to get a particular calix pyrrole selectively, and (e) in some cases
dry conditions should be maintained in order to obtain the corresponding
compound.
Increasing the applications of these calix pyrroles demands an
eco-friendly, environmentally clean, economical and free handling
process. The present invention provides an eco-friendly process,
which can overcome all the above drawbacks.
OBJECTS OF THE INVENTION
The main object of the present invention is to provide calix (4)
pyrroles over zeolite molecular sieves, which is an eco-friendly
heterogeneous catalytic method.
Another object of the present invention is to provide a process
for the synthesis of novel calix (4) pyrroles such as tetraspirocycloheptyl
calix (4) pyrrole, tetraspirocyclooctyl calix (4) pyrrole and tetraspiro
(2-methylcyclohexyl) calix (4) pyrrole with sufficiently good yields.
Still another object of the present invention is to synthesize
calix (4) pyrroles over molecular sieve catalysts under microwave
irradiation, which is a solvent free reaction.
Yet another object is to provide a method wherein the kind and
composition of calix (4) pyrrole can be varied within limits by
a proper selection of catalyst.
Yet another object of this invention is to provide an efficient
and economical method for synthesizing calix (4) pyrroles from pyrrole
and ketones over solid acid catalysts.
SUMMARY OF THE INVENTION
The present invention relates to novel calix (4) pyrroles and a
process for synthesis of calix (4) pyrroles as shown in FIGS. 1
to 8 of the accompanying drawings, from corresponding pyrrole and
ketone over mesoporous molecular sieves. Macrocycles of the present
invention can be selectively synthesized by taking the different
pore sizes of the zeolites and by varying the reaction conditions.
DETAILED DESCRIPTION OF INVENTION
The present invention relates to novel calix (4) pyrroles and a
process for synthesis of calix (4) pyrroles over mesoporous molecular
sieves. The invention particularly relates to heterogeneous eco-friendly
methodology for the synthesis of calix (4) pyrroles by using pyrrole
and ketone in dichloromethane solvent. Specifically, the present
invention relates to the synthesis calix (4) pyrroles from corresponding
pyrrole and ketone over mesoporous (Mesoporous molecular sieve)
MCM-41 molecular sieves with a high yield and selectivity. In an
embodiment of the invention, the catalyst is selected from MCM-41
HZSM-5 (30), H.beta., HY and SAPO-5.
In another embodiment of the invention, the catalysts MCM-41 HZSM-5(30),
H.beta., HY and SAPO-5 are conventional zeolite catalysts.
In another embodiment of the invention, the amount of catalyst
used is ranging from 0.1 g to 1.0 g.
In still another embodiment of the invention, the solvent used
for refluxing is selected from dichloromethane, methanol, and acetonitrile.
In yet another embodiment of the invention, the catalysts used
are having the following surface area and pore size as given in
the table below.
Catalyst Surface area (m.sup.2 /g) Pore size (.ANG.) MCM-41 980-1200
30-100 HY 525-625 6-8 HZSM-5 (30) 275-340 5-7.5 SAPO-5 175-240 6.5-8.4
H.beta. 600-680 5.5 .times. 6.6 to 7.5 .times. 8.5
In yet another embodiment of the invention, the pore size and surface
area of the catalysts used in the reaction are given in the following
table.
Catalyst Surface area (m.sup.2 /g) Pore size (.ANG.) HY 593 7.3
HZSM-5 (30) 310 5.6 SAPO-5 207 7.4 H.beta. 640 6.5 .times. 7.6
In yet another embodiment of the invention, the molar ratio of
pyrrole to ketone is selected in between 1:1 to 1:4.
In yet another embodiment of the invention, the cycloketone is
selected from the group comprising cyclohexanone, cycloheptanone,
cyclopentanone and cyclooctanone.
In yet another embodiment of the invention, the acyclic ketone
is selected from the group comprising methyl ethyl ketone and 3-pentanone.
In yet another embodiment of the invention, acyclic products are
obtained using the catalyst HY.
In yet another embodiment of the invention, major amounts of liner
products are obtained using catalyst HZSM-5 (30).
In yet another embodiment of the invention, the yield of the calix
(4) pyrrole is up to 70%.
In yet another embodiment of the invention, the selectivity of
the calix (4) pyrrole is up to 90%.
In one more embodiment of preparing calix (4) pyrroles or tetraspiro
calix (4) pyrroles, said method comprising mixing a pyrrole with
a acyclic or cyclic ketones over a molecular sieve solid acid catalyst
and subjecting the mixture to microwave radiation at a radiation
level of about 2450 MHz (H1 power) for 3 to 10 minutes and optionally,
refluxing using a solvent for extracting the compounds.
In another embodiment, the solvent used for refluxing is selected
from dichloromethane, methanol, and acetonitrile.
In yet another embodiment of the present invention, in the equimolar
reaction, the molar ratio of pyrrole to ketone is 1:1 and dichloromethane
is used as a solvent for refluxing to obtain cyclic products.
In yet another embodiment, the catalyst used is mesoporus molecular
sieve catalyst (MCM-41).
In yet another embodiment, the acyclic ketone used is acetone.
In yet another embodiment, the cyclic ketone used is cyclohexanone.
In yet another embodiment, the preparation of calix (4) pyrroles
or tetraspiro calix (4) pyrroles is a solvent free process.
The catalyst can be synthesized from the well known defined methods.
The starting materials used in the process are acyclic or cyclic
ketones, which are readily available. Reacting the pyrrole with
acyclic ketones which are selected from acetone ethyl ketone and
3-pentanone leads to form octamethyl calix (4) pyrrole, tetramethyl
tetraethyl calix (4) pyrrole, and octaethyl calix (4) pyrroles correspondingly.
The catalyst MCM-41 (Mesoporous molecular sieve) prepared by an
aqueous solution of aluminum isopropoxide (0.38 g) and to it an
aqueous solution of sodium hydroxide (0.3 g) was added in 50 ml
beaker and stirred in hot conditions, till a clear solution was
formed. Then 9.4 ml of tetraethyl ammonium hydroxide (TEAOH) and
Ludox colloidal silica (9.26 g) were added drop wise while stirring
at room temperature. Then hexadecyl tri-methylammonium bromide (10.55
g) was added slowly to the above solution. The pH of the mixture
was maintained at 11.0-11.5. Finally, the gel mixture was transferred
into an autoclave and heated at 100.degree. C. for 24 h. The solid
product was recovered by filtration, washed with deionized water
and dried in air. All the as-synthesized samples were calcined at
773K in air.
The catalyst weight can be varied in this reaction from 0.1 g to
1 g. The pyrrole to acetone molar ratio can be varied from 1:1 to
1:4.
In the reaction, an equimolar ratio of pyrrole and cyclohexanone
was refluxed in dichloromethane (DCM) for 10 h in presence of MCM-41
catalyst. Along with the cyclized product, tetraspirocyclo hexyl
calix (4) pyrrole 4a, the acyclic condensed products viz., dimer,
trimer and tetramer (4b, 4c and 4d) were also formed.
In place of MCM-41 catalyst when HY was used, instead of cyclic
product only the acyclic products were formed.
When HZSM-5 (30) was used as catalyst, along with the cyclized
product calix (4) pyrrole, linear products also formed but the linear
products are in major.
When H.beta. was used as catalyst, along with the cyclized product
calix (4) pyrrole, linear products are also formed.
The reaction time will be varied depending upon the nature of ketone
and the catalyst.
In the one of equimolar reaction, pyrrole and acetone was mixed
thoroughly and 0.5 gm of MCM-41 catalyst was added and then subjected
to microwave irradiation for 3 min at a radiation level of about
2450 MHz and extract the compound by using dichloromethane as solvent,
resulting low selectivity of cyclic product (1a). The reaction time
is varied from 3 min to 10 min.
In another equimolar reaction, pyrrole and cyclohexanone was mixed
thoroughly and added 0.5 gm of MCM-41 catalyst and then subjected
to microwave irradiation for 3 min and extracted the compound by
using dichloromethane as solvent, resulting low selectivity of cyclic
product (4a). The reaction time is varied from 3 min to 10 min.
The radiation level is maintained at about 2450 MHz.
Mixed calix pyrroles such as tetramethyl dicyclohexyl calix (4)
pyrrole, hexamethyl cyclohexyl calix (4) pyrrole, dimethyl tri cyclohexyl
calix (4) pyrrole has been obtained by reacting the acetone, cyclohexanone
in required molar ratio over MCM-41 catalyst in dicholoromethane
solvent by refluxing for 15 h.
Pore size and surface area of the catalysts plays a major role
in this reaction.
All the catalysts were characterized by X-ray diffraction, Infrared
spectroscopy, BET-surface area and NH.sub.3 -Temperature programmed
desorption.
The inventors found that the dichloromethane (DCM) was better solvent
than other solvents like methanol, acetonitrile. Acetone as solvent
did not found the selectivity towards higher selectivity of octamethyl
calix (4) pyrrole.
After the reaction was completed the catalyst was separated by
filtration, then the solvent was vacuum evaporated and the residue
was mounted on the silica column and the products were separated
through n-hexane: ethylacetate (95:5) media and confirmed by H.sup.1
NMR, C.sup.13 NMR and Mass spectroscopy and for 1a, single crystal
XRD also.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIG. 1 shows structure of octa alkyl substituted calix (4) pyrrole,
wherein R.sub.1 and R.sub.2.dbd.CH.sub.3 for octamethyl calix (4)
pyrrole (1a), R.sub.1.dbd.CH.sub.3 and R.sub.2.dbd.CH.sub.2 CH.sub.3
for Tetraethyl Tetra methyl calix (4) pyrrole (2a), and R.sub.1.dbd.R.sub.2.dbd.CH.sub.2
CH.sub.3 for octaethyl calix (4) pyrrole (3a).
FIG. 2 shows structure of tetraspiro cyclohexyl calix (4) pyrrole
(4a).
FIG. 3 shows structure of tetraspiro cycloalkyl substituted calix
(4) pyrrole wherein, n=1 for tetraspiro cyclopentyl calix (4) pyrrole
(5a), n=2 for tetraspiro cycloheptyl calix (4) pyrrole (6a), and
n=4 for tetraspiro cyclooctyl calix (4) pyrrole (7a).
FIG. 4 shows structure of (2-methyl cyclohexyl) calix (4) pyrrole
(8a).
FIG. 5 shows structures of condensed products viz. dimer (4b),
trimer (4c) and tetrameter (4d).
FIG. 6 shows structure of alkyl substituted linear (dimer) products,
wherein R.sub.1 and R.sub.2.dbd.CH.sub.3 for 1a, R.sub.1.dbd.CH.sub.3
and R.sub.2.dbd.CH.sub.2 CH.sub.3 for 2a, and R.sub.1.dbd.R.sub.2.dbd.CH.sub.2
CH.sub.3 for 3a.
FIG. 7 shows structure of cyclic products, wherein n=1 for 5b;
n=3 for 6b and n=4 for 7b.
FIG. 8 shows structure of dimer product of 2-methylcyclohexyl (8b).
The process of this invention is described in further detail herein
below by way of the following examples, which are only illustrative
and are not intended to limit the scope of this invention.
EXAMPLES
Example 1
Synthesis of Octamethyl Calix (4) Pyrrole
In a 50 ml round bottom flask, 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.503 ml of acetone, and 0.5 g
of MCM-41 catalyst were added to it. Then the reaction mixture was
refluxed for 10 h. The cooled reaction mixture filtered, washed
with DCM (5.times.10 ml). Then the solvent DCM was removed under
reduced pressure and product was purified by column chromatography
on silicagel (hexane eluent) affording the product as a white powder.
The product was confirmed by NMR and Mass spectrometry. Yield of
octamethyl calix (4) pyrrole was 67.5%; Selectivity was 73.0; Conversion
of pyrrole was 92.4%. Selectivity was calculated as follows
Selectivity=Yield/Conversion
1a: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=1.49 (s, 24H, --CH.sub.3),
5.85 (br, d, 8H; (pyrrole-.beta.H), 6.89-6.99 (br, S, 4H, pyrrole-NH);
HR-MS(EI): for calcd for C.sub.28 H.sub.36 N.sub.4 : calcd: 428.2939;
found: 428.2938.
Example 2
In a 50 ml round bottom flask 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.503 ml of acetone, and 0.5 g
of HZSM-5 (30) catalyst were added to it. Then the mixture was refluxed
for 10 h. The cooled reaction mixture filtered, washed with DCM
(5.times.10 ml). Then the solvent DCM was removed under reduced
pressure and product was purified by column chromatography on silicagel
(hexane eluent) the products were confirmed by NMR and estimation
was done by high pressure thin layer chromatography (HPTLC). The
Results are as follows: Conversion of pyrrole is 81.4%.
Product Yield (wt %) Selectivity (%) Octamethyl calix(4)pyrrole
(1a) 40.0 49.2 Trimer + tetramer 29.8 36.6 Dimer (1b) 11.56 14.2
Example 3
In a 50 ml round bottom flask 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.503 ml of acetone, and 0.5 g
of HY catalyst was added to it. Then the mixture was refluxed for
10 h. The cooled reaction mixture filtered, washed with DCM (5.times.10
ml). Then the solvent DCM was removed under reduced pressure and
product was purified by column chromatography on silicagel (hexane
eluent) the products were confirmed by NMR and estimation was done
by high pressure thin layer chromatography (HPTLC). The results
as follows: conversion of pyrrole is 72.5%.
Product Yield (wt %) Selectivity (%) Octamethyl Calix(4)pyrrole
Trimer + tetramer 14.0 19.3 Dimer 58.5 80.7
1b: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=1.62 (s, 6H, --CH.sub.3),
6.01-6.11 (m, 4H, pyrrole-.beta.H), 6.48-6.56 (m, 2H, pyrrole-.alpha.H),
7.42-7.78 9br, s, 2H, NH), .sup.13 C NMR (50 MHz, CDCl.sub.3): .delta.=29.30
35.32 103.74 107.72 117.03 138.21; HR-MS (EI) for C.sub.11 H.sub.14
N.sub.2 : calcd: 174.1156; found: 174.1148
Example 4
Synthesis of tetramethyl tetraethyl calix (4) pyrrole
In a 50 ml round bottom flask 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.65 ml of Methyl ethyl ketone,
and 0.5 g of Al-MCM-41 catalyst was added to it. Then the mixture
was refluxed for 72 h. The cooled reaction mixture filtered, washed
with DCM (5.times.10 ml). Then the solvent DCM was removed under
reduced pressure and product was purified by column chromatography
on silicagel (hexane eluent) the products were confirmed by NMR
and estimation was done by high pressure thin layer chromatography
(HPTLC). The results as follows: conversion of pyrrole is 48.0%.
Product Yield (wt %) Selectivity (%) Tetraethyl tetramethyl calix(4)pyrrole
(2a) 34.8 72.5 Trimer + tetramer 4.5 9.4 Dimer (2b) 8.7 18.1
2a: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=0.63-0.8 (t, J(H,H)=2
Hz, 12H), 1.34-1.48 (br, s, 12H, --CH.sub.3), 1.86-1.96 (q, 8H,
CH.sub.2 CH.sub.3), 5.85 (br, d, 8H), 6.89-7.09 (br, s, 4H, NH);.sup.13
C NMR (50 MHz, CDCl.sub.3) 137.26 103.75 39.18 33.21 26.04
8.65; HR-MS (EI) for C.sub.32 H.sub.44 N.sub.4 : calcd: 484.3565
found: 484.3561.
2b: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=0.72-0.85 (t, J=8.37
3H. --CH.sub.2 CH.sub.3), 1.53 (s, 3H, --CH.sub.3), 1.92-2.06 (q,
J=4.65 6.97 Hz, 2H, --CH.sub.2 CH.sub.3), 6.0-6.10 (m, 4H, pyrrole-.beta.H),
6.50-6.58 (m, 2H,pyrrole-.alpha.H), 7.6 (BR, S, 2H, pyrrole-NH).
.sup.13 C NMR: 138.04 116.29 107.61 104.66 39.35 33.63 25.57
8.91; HR-MS (EI) for C.sub.12 H.sub.16 N.sub.2 : calcd: 188.1313
found: 188.1317.
Example 5
Synthesis of octaethyl calix (4) pyrrole
In a 50 ml round bottom flask 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.73 ml of 3-Pentanone, and 0.5
g of Al-MCM-41 catalyst was added to it. Then the mixture was refluxed
for 5 days. The cooled reaction mixture filtered, washed with DCM
(5.times.10 ml). Then the solvent DCM was removed under reduced
pressure and product was purified by column chromatography on silicagel
(hexane eluent) the products were confirmed by NMR and estimation
was done by high pressure thin layer chromatography (HPTLC). The
results as follows: conversion of pyrrole is 77.0%.
Product Yield (wt %) Selectivity (%) Octaethyl calix(4)pyrrole
(3a) 10.1 13.1 Trimer + tetramer 4.8 6.2 Dimer (3b) 62.1 80.7
3a: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=5.85-5.93 (br, d,
J (H,H)=2.27 Hz, 8H, pyrrole-.beta.H), 6.96-7.05 (br, s, 4H, pyrrole-NH);
HR-MS (EI) for C.sub.36 H.sub.52 N.sub.4 : calcd: 540.4191 found:540.4194.
3b: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=0.68-0.76 (t, J=7.17
6H, CH.sub.2 CH.sub.3), 1.88-2.01 (q, J=5.12 7.69 Hz, 4H, CH.sub.2
--CH.sub.3), 6.01-6.12 (br, s, 4H, pyrrole-.beta.H), 6.5-6.59 (br,
s, 2H), 7.45-7.65 (br, s, 2H, pyrrole-NH); HR-MS (EI) for C.sub.13
H.sub.19 N.sub.2 : calcd: 202.1469 found: 202.1475.
Example 6
Synthesis of tetraspiro cyclohexyl calix (4) pyrrole
In a 50 ml round bottom flask 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.75 ml of Cyclohexanone, and
0.5 g of calcined and dried Al-MCM-41 catalyst was added to it.
Then the mixture was refluxed for 10 h. The cooled reaction mixture
filtered, washed with DCM (5.times.10 ml). Then the solvent DCM
was removed under reduced pressure and product was purified by column
chromatography on silicagel (hexane eluent) the products were confirmed
by NMR and estimation was done by high pressure thin layer chromatography
(HPTLC). The results as follows: conversion of pyrrole is 95.0%.
Product Yield (wt %) Selectivity (%) Tetraspirocyclohexyl 70.3
74.0 calix(4)pyrrole (4a) Trimer + tetramer 12.4 13.0 Dimer (4b)
12.3 13.0
4a: .sup.1 H NMR (200 MHz, CDCl.sub.3): .delta.=1.38-1.68(m,24H,
cyclohexyl), 1.88-2.12(m,16H, cyclohexyl), 5.86 (br.d, 8H; pyrrole-.beta.H),
6.95 (br.s, 4H, pyrrole NH), .sup.13 C NMR (50 MHz,CDCl.sub.3):
.delta.=22.75 26.04 37.17 39.63 103.44 (pyrrole-.beta.H), 136.50(pyrrole-.alpha.H);
HR-MS(EI) for C.sub.40 H.sub.52 N.sub.4 (H.sup.+): calcd: 588.4191;
found: 588.4169.
Example 7
In a 50 ml round bottom flask 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.75 ml of Cyclohexanone, and
0.5 g of HZSM-5 (30) catalyst was added to it. Then the mixture
was refluxed for 10 h. The cooled reaction mixture filtered, washed
with DCM (5.times.10 ml). Then the solvent DCM was removed under
reduced pressure and product was purified by column chromatography
on silicagel (hexane eluent) the products were confirmed by NMR
and estimation was done by high pressure thin layer chromatography
(HPTLC). The results as follows: Conversion of pyrrole is 69.6%.
Product Yield (wt %) Selectivity (%) Tetraspirocyclohexyl 10.7
15.4 Calix(4)pyrrole Trimer + tetramer 5.9 8.5 Dimer 53.0 76.1
Example 8
In a 50 ml round bottom flask 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.75 ml of Cyclohexanone, and
0.5 g of HY catalyst was added to it. Then the mixture was refluxed
for 10 h. The cooled reaction mixture filtered, washed with DCM
(5.times.10 ml). Then the solvent DCM was removed under reduced
pressure and product was purified by column chromatography on silicagel
(hexane eluent) the products were confirmed by NMR and estimation
was done by high pressure thin layer chromatography (HPTLC). The
results as follows: conversion of pyrrole is 78.9%.
Product Yield (wt %) Selectivity (%) Tetraspirocyclohexylcalix
(4) pyrrole Trimer + tetramer 16.2 20.5 Dimer 62.7 79.5
4b: .sup.1 H NMR (200 MHz, CDCl.sub.3): .delta.=1.36-1.65(m,6H,
cyclohexyl),1.95-2.12(m,4H,cyclohexyl,6.01-6.12(m,4H,pyrrole-.beta.H),
6.45(br.d, 2H; pyrrole-.alpha.H), 7.32-7.68 (br.s, 2H, pyrrole NH);
.sup.13 C NMR(50 MHz,CDCl.sub.3): .delta.=22.17 26.32 37.65 41.21
104.64 108.27116.99 139.21; HR-MS(EI) for C.sub.14 H.sub.18 N.sub.2
(H.sup.+): calcd: 214.1469; found: 214.1460.M+: 214(100%), 171148
4d: HR-MS (EI) for C H N: calcd: 508.3546; found=508.3565
Example 9
Synthesis of tetraspiro cyclopentyl calix (4) pyrrole
In a 50 ml round bottom flask 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.64 ml of Cyclopentanone, and
0.5 g of Al-MCM-41 catalyst was added to it. Then the mixture was
refluxed for 20 h. The cooled reaction mixture filtered, washed
with DCM (5.times.10 ml). Then the solvent DCM was removed under
reduced pressure and product was purified by column chromatography
on silicagel (hexane eluent) the products were confirmed by NMR
and estimation was done by high pressure thin layer chromatography
(HPTLC). The results as follows: conversion of pyrrole is 74.3%.
Product Yield (wt %) Selectivity (%) Tetraspiro cyclopentyl 62.7
84.4 calix(4)pyrrole (5a) Trimer + tetramer 7.3 9.8 Dimer 4.3 5.8
5a: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=1.55-1.8 (m, 16H,
cyclopentyl), 1.85-2.01 (m, 16H, cyclopentyl), 5.8 (br, d, J=0.38
Hz, 8H, pyrrole-.beta.H),7.0 (br, s, 4H, pyrrole-NH); .sup.13 C
NMR: (50 MHz, CDCl.sub.3): 137.20 (pyrrole-.alpha.H), 103.04 (pyrrole-.beta.H),
46.93 39.02 23.91; HR-MS (EI) for C.sub.36 H.sub.44 N.sub.4 :
calcd: 532.3565 found: 532.6575.
Example 10
Synthesis of tetraspiro cycloheptyl calix (4) pyrrole
In a 50 ml round bottom flask 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.85 ml of Cycloheptanone, and
0.5 g of Al-MCM-41 catalyst was added to it. Then the mixture was
refluxed for 3 days. The cooled reaction mixture filtered, washed
with DCM (5.times.10 ml). Then the solvent DCM was removed under
reduced pressure and product was purified by column chromatography
on silicagel (hexane eluent) the products were confirmed by NMR
and estimation was done by high pressure thin layer chromatography
(HPTLC). The results as follows: conversion of pyrrole is 69.8%.
Product Yield (wt %) Selectivity (%) Tetraspiro cycloheptyl 26.7
38.3 calix(4)pyrrole (6a) Trimer + tetramer 15.7 22.5 Dimer (6b)
27.4 39.2
6a: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=1.45-1.72 (m, 32H,
cycloheptyl), 1.94-2.12 (m,16H, Cycloheptyl), 5.83 (br, d,8H, pyrrole-.beta.H),
6.78-6.88 (br,s,4H,NH),; HR-MS (EI) for C.sub.44 H.sub.60 N.sub.4
: calcd: 644.4817 found: 644.4752.
6b: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=2.12-2.26(m,8H,cycloheptyl),
2.42-2.58 (m,4H, cycloheptyl), 6.01-6.13 (m, 4H,pyrrole-.beta.H),
6.52-6.61 (m,2H, pyrrole-.alpha.H),7.51-7.71 (br,s,2H, pyrrole-NH);
HR-MS (EI) for C.sub.15 H.sub.20 N.sub.2 : calcd: 228.1626 found
228.1616.
Example 11
Synthesis of tetraspiro cyclo octyl calix (4) pyrrole
In a 50 ml round bottom flask 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.9 ml of Cyclooctanone, and 0.5
g of Al-MCM-41 catalyst was added to it. Then the mixture was refluxed
for 5days. The cooled reaction mixture filtered, washed with DCM
(5.times.10 ml). Then the solvent DCM was removed under reduced
pressure and product was purified by column chromatography on silicagel
(hexane eluent) the products were confirmed by NMR and estimation
was done by high pressure thin layer chromatography (HPTLC). The
results as follows: conversion of pyrrole is 78.0%.
Product Yield (wt %) Selectivity (%) Tetraspiro cyclooctyl 8.3
10.6 calix(4)pyrrole (7a) Trimer + tetramer 23.7 30.4 Dimer (7b)
46.0 59.0
7a: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=1.18-1.82 (m, 56H,
cyclooctyl), 5.93 (br,d,8H, pyrrole-.beta.H), 6.91-6.99 (br,s,4H,
pyrrole-NH); HR-MS (EI) for C.sub.48 N.sub.68 N.sub.4 : calcd; 700.5443
found: 700.5456.
7b: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=1.42-1.80(m,10H,
cyclooctyl), 2.09-2.21(m,4H, cyclooctyl), 5.99-6.16 (m,4H,pyrrole-.beta.H),
6.48-6.57 (m,2H,pyrrole-.alpha.H),7.42-7.69(br,s,2H,pyrrole-NH),;
HR-MS(EI) for C.sub.16 N.sub.22 N.sub.2 : calcd: 242.1782 found:
242.1777.
Example 12
Synthesis of tetraspiro (2-methylcyclohexyl) calix (4) pyrrole
In a 50 ml round bottom flask 20 ml of dichloromethane (DCM) was
introduced and 0.5 ml of pyrrole, 0.875 ml of 2-Methyl cyclohexanone,
and 0.5 g of Al-MCM-41 catalyst was added to it. Then the mixture
was refluxed for 10 h. The cooled reaction mixture filtered, washed
with DCM (5.times.10 ml). Then the solvent DCM was removed under
reduced pressure and product was purified by column chromatography
on silicagel (hexane eluent) the products were confirmed by NMR
and estimation was done by high pressure thin layer chromatography
(HPTLC). The results as follows: conversion of pyrrole is 60.2%.
Product Yield (wt %) Selectivity (%) Tetraspiro 5.1 8.5 (2-methylcyclohexyl)
calix(4)pyrrole (8a) Trimer + tetramer 21.3 35.4 Dimer (8b) 33.8
56.1
8a: HR-MS (EI) for C.sub.44 H.sub.60 N.sub.4 : calcd: 644.4817
found 644.4847.
8b: .sup.1 HNMR (200 MHz, CDCl.sub.3): .delta.=0.8(d,3H,J(H,H)=7.2
Hz,CH.sub.3), 1.24-2.34(m,9H,cyclohexyl), 6.01-6.14 (m,4H,pyrrole-.beta.H),
6.42-6.54 (m,2H,pyrrole-.alpha.H),7.48(br,s,2H,pyrrole-NH); HR-MS
(EI) for C.sub.15 H.sub.20 N.sub.2 : calcd: 228.1626 found: 228.1634.
The Main Advantages of the Present Invention Are 1. The present
invention is an improved process that comprises environmentally
clean technology with low wastage, easy separable and reusability
of the catalyst. 2. This method provides a selective heterogeneous
catalyst with longer life. 3. The catalysts used in this process
are easily separable by the simple filtration 4. It also provides
a method wherein the kind and composition of calix (4) pyrrole can
be varied within limits by a proper selection of catalyst. 5. Tetraspirocyclopentyl
calix (4) pyrrole has been synthesized for the first time over the
heterogeneous method as well as homogeneous method. 6. Tetraspirocycloheptyl
calix (4) pyrrole has been synthesized for the first time over the
heterogeneous method as well as homogeneous method. 7. Tetraspirocyclooctyl
calix (4) pyrrole has been synthesized for the first time over the
heterogeneous method as well as homogeneous method. 8. Tetraspiro
(2-Methylcyclohexyl) calix (4) pyrrole has been synthesized for
the first time over the heterogeneous method as well as homogeneous
method.
The Salient Futures of the Process are i) the present invention
provides an improved process that comprises environmentally clean
technology with low wastage, easy separable and reusability of the
catalyst, ii) the catalysts used in this process are easily separable
by the simple filtration, iii) this process provides an eco-friendly
method with higher selectivity, iv) a method provides a selective
heterogeneous catalyst with longer life, and v) a method wherein
the kind and composition of calix(4)pyrrole can be varied within
limits by a proper selection of catalyst and this invention provides
an efficient and economical method for synthesizing calix(4)pyrroles
from pyrrole and ketones over solid acid catalysts. |