Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2002-10-31
2004-04-27
Morris, Patricia L. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
active
06727365
ABSTRACT:
FIELD OF INVENTION
The present invention relates to an improved process for preparing vinylpyridine from corresponding picoline. The present invention relates to a process for the preparation of 2-vinylpyridine or 4-vinylpyridine over modified zeolite catalysts. In particular, it relates to method for the synthesis of vinylpyridine from corresponding picoline with formaldehyde in vapour phase in an eco-friendly method with high yield and selectivity.
This invention provides a non-corrosive, eco-friendly process, where the catalyst can be recycled and reused for many times. 2-vinylpyridine and 4-vinylpyridine are useful starting material in polymer industry.
BACKGROUND OF THE INVENTION
2-vinylpyridine (2-VP) is an important monomer used in synthesizing various polymers. Butadiene and styrene monomers were used with 2-vinylpyridine to form latex terpolymer that bonded fabric cords to the rubber matrix of tires. The addition product of methanol and 2-vinylpyridine, 2-(2-methoxy-ethyl) pyridine is a veterinary anthelmintic. This monomer is prepared commercially by autoclaving acetylene, acrylonitrite using cobaltocene catalyst or oxidative dehydrogenation of 2-ethylpyridine on Cr—Nb catalyst (Y. Wakatsuki, synthesis, 1, 26 (1976)). (“Heterocyclic compounds: Pyridine and Pyridine derivatives part 2, Ed. E. Klingsberg, Chapt. V, p 203). Generally in most of the processes, the synthesis of 2-vinylpyridine is practiced by a two-step procedure, which involves a base catalyzed addition of 2-picoline to formaldehyde to give 2-(2-hydroxy ethyl) pyridine followed by dehydration to 2-vinylpyridine monomer. (S. Yasuda, H. Niwa and O. Tagano, Jpn. Kokai Tokyo, Koho 78, 141281 (1978)). 2-vinylpyridine was prepared with 70.8% selectivity at 35.8% conversion over ZrO
2
catalyst (Reddy B. N. and Subrahrnanyam M, Catalysis Present & Future, Eds. Kanta Rao P. & Beniwal R. S. p. 304(1995)). The synthesis of vinylpyridines are also reported by the dehydrogenation of alkyl pyridines over V
2
O
5
/MgO and MoO
3
/MgO catalysts in the presence of O
2
. The alkylation of pyridine, 2,3, and 4-picolines with methanol as alkylating agent over alkali metal ion exchanged X and Y type zeolites in N
2
atmosphere resulted in the formation of side-chain alkylated products like ethylpyridines and vinylpyridines were 22.2, and 5.3% at 82.0% conversion over CsY catalyst from 2-picoline and methanol at 450° C. However considerable amounts of ring-alkylated derivatives (lutidines) were formed simultaneously. (Kshiwagi H., Enomoto S., Chem. Pharm. Bull., 30(2), 404(1982)).
The alkylation of picolines with methanol was studied over modified X and Y zeolites in which the major products were ethylpyridine and vinylpyridine (Chem. Pharm. Bull., 30(2), 404, 1982). The yields of ethylpyridine were more when the CsY zeolite was used at 450° C. On the other hand the yields of vinylpyridines were more over CsX zeolite at about 425° C. The yields of vinylpyridines were <20-25%. The syntheses of vinylpyridines were also reported by the dehydrogenation of alkylpyridines over V
2
O
5
/MgO and MoO
3
/MgO catalysts in the presence of oxygen. However the yields and selectivities of 4-vinylpyridine were lower
OBJECTIVES OF THE INVENTION
The main objective of the present invention is to provide a process for the synthesis of vinylpyridines over modified zeolites in a heterogeneous eco-friendly method.
Another objective of the present invention is to provide a process for the preparation of 2-vinylpyridine in high yield and high selectivity.
Another object of the present invention is to provide a process for the preparation of 4-vinylpyridine in high yield and high selectivity.
Another object of the present invention is to provide a process for the preparation of 2-vinylpyridine from 2-picoline and formaldehyde in the presence of catalyst which comprises ZSM-5 containing one or two element(s) from alkali and/or alkaline earth metal ions, like Na
+
, K
+
, Rb
+
, Cs
+
, Mg
+2
, Ca
+2
, Sr
+2
, etc., which can be recycled and reused for several times.
Still another object of the present invention is to provide a process for the preparation of 4-vinylpyridine from 4-picoline and formaldehyde in the presence of a catalyst which comprises ZSM-5 containing one or two element(s) from alkali and alkaline earth metal ions, like Na, K, Rb, Cs, Mg, Ca, Sr, Ba etc., which can be recycled and reused for several times.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a process for the preparation of 2-vinylpyridine from 2-picoline and formaldehyde in vapour phase over 2-picoline and formaldehyde in vapour phase over modified zeolite/molecular sieve. The catalyst comprises of particularly ZSM-5 modified with sodium, potassium, rubidium, cesium, magnesium, calcium, and/or barium, etc as cation or species.
The present invention also provides a process for the preparation of 4-vinylpyrdine from 4-picoline and formaldehyde in vapour phase over modified zeolite/molecular sieve. The catalyst comprises of ZSM-5 modified with sodium, potassium, rubidium, cesium, magnesium, calcium or barium.
DETAILED DESCRIPTION OF THE INVENTION
Accordingly, the present invention provides an improved process for the preparation of vinylpyridine from corresponding picoline over modified zeolite catalyst in vapour phase which comprises reacting picoline with formaldehyde with a molar ratio of formaldehyde to picoline in the range of 1:1 to 4:1, at a temperature ranging between 200° C. to 450° C., at a weight hourly space velocity in the range of 0.25 hr
−1
-1.00 hr
−1
over a modified commercial zeolite catalyst to obtain the desired product.
In an embodiment of the present invention provides a process wherein, the vinylpyridine obtained is either 2-vinylpyridine or 4-vinylpyridine.
Still another embodiment, one of the reactant picoline is selected from 2-picoline and 4-picoline.
Still another embodiment, one of the catalyst is prepared by varying alkali and alkaline earth modified with a zeolite catalyst selected from a group consisting of ZSM-5, X, Y, mordenite and MCM-41.
In yet another embodiment, the catalyst used is preferably ZSM-5 pentasil type zeolite.
Yet another embodiment, the modification of the catalyst is carried out by alkali or alkaline earth metal ion selected from the group consisting of Li
+
, Na
+
, K
+
, Rb
+
, Cs
+
, Mg
+2
, Ca
+2
, Sr
+2
, Ba
+2
or two cation modified ZSM-5 like Cs—K-ZSM-5.
Still another embodiment the present invention provides a process, wherein the weight percent of the alkali or alkaline earth metal cation in ZSM-5 is varied from 1 weight percent to 4 weight percent.
Still another embodiment, the precursor to modify ZSM-5 catalyst by potassium ion or other elements is varied like K
t
OBu, KOH, KF, KNO
3
, K
3
PO
4
and KOAc to improve the yield and selectivity of vinylpyridine.
Still another embodiment, the calcination temperature of modified zeolite is varied from 400° C. to 700° C.
Still another embodiment the reaction temperature of the catalytic zone in the process is varied from 200° C. to 450° C.
Still another embodiment the weight hourly space velocity (WHSV) is in the range of 0.25 to 1.0 hr
−1
.
The following catalysts were used in the present process development HZSM-5 (SiO
2
/Al
2
O
3
=30), NaY (SiO
2
/Al
2
O
3
=5.0), H-Mordenite (SiO
2
/Al
2
O
3
=12), and H-MCM-41 (SiO
2
/Al
2
O
3
=31). Each zeolite was pelleted without binder, crushed and sized 18-30 mesh before the impregnation. The catalysts were modified by using required amount of alkali or alkaline earth cation nitrate by an impregnation method. In the case of potassium, different precursors like KO
t
Bu, KF, KOAc, K
3
PO
4
and KOH were used to modify ZSM-5 (30) catalyst. The required amount of precursor was taken in the form of nitrate or other soluble salts in 30 ml of distilled water. 4.0 g of the meshed catalyst was added to it and kept for soaking for 12 h. Then it was dried at 110° C. overnight and calcined at
Kulkarni Shivanand Janardan
Madhavi Gangapuram
Raghavan Kondapuram Vi jaya
Viswanathan Venkataraman
Feehery Maryellen
Kumar Nanda P. B. A.
Morris Patricia L.
Reed Smith LLP
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