Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-03-27
2001-05-15
Owens, Amelia (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S266000, C549S273000
Reexamination Certificate
active
06232474
ABSTRACT:
FIELD OF THE INVENTION
This invention is in the field of synthetic organic chemistry. This invention pertains to a method to produce &agr;-methylenelactones and &agr;-substituted hydrocarbylidene lactones. More specifically, this invention pertains to a simple, efficient and economic method to produce &agr;-methylene-&ggr;-butyrolactone from &ggr;-butyrolactone.
TECHNICAL BACKGROUND OF THE INVENTION
&agr;-Methylenelactones have been the subject of intensive synthetic studies. Specifically, the &agr;-methylene-&ggr;-butyrolactone group is an important structural feature of many sesquiterpenes of biological importance. In addition, &agr;-methylene-&ggr;-butyrolactones are regarded as potential key monomers in both homopolymers and copolymers. Currently the cost of &agr;-methylene-&ggr;-butyrolactone is too high to warrant commercial production of the resulting polymers. Some of the current synthetic routes suffer from low yields, byproducts formation and expensive starting materials. The instant invention has overcome these problems and high yields of &agr;-methylene-&ggr;-butyrolactone are obtained by heating &ggr;-butyrolactone and paraformaldehyde in the presence of a base such as cesium carbonate or potassium carbonate.
An early synthesis of &agr;-methylene-&ggr;-butyrolactone involved two steps (Martin et al.,
J. Chem. Soc.
D 1:27 (1970)). The first is carboxylation of &ggr;-butyrolactone with methyl methoxymagnesium carbonate (Stiles' reagent) to produce the acid. Next, the acid is briefly treated with a mixture of aqueous formaldehyde and diethylamine, followed by a separate treatment of the crude product with sodium acetate in acetic acid. The first step requires 6-7 hours and affords almost quantitative yields, whereas the second step can be accomplished in less than 30 minutes but with yields of only 50%.
Murray et al. (
Synthesis
1:35-38 (1985); see also U.S. Pat. No. 5,166,357) disclose a route to &agr;-methylene-&ggr;-butyrolactone that also involves a two-step sequence consisting of the reaction of &ggr;-butyrolactone with ethyl formate in the presence of base, followed by refluxing the resulting &agr;-formyl-&ggr;-butyrolactone sodium salt under nitrogen with paraformaldehyde in tetrahydrofuran. Distillation affords the desired &agr;-methylene-&ggr;-butyrolactone as a colorless oil. This reaction sequence can best be explained by formyl transfer from carbon to oxygen followed by elimination of carboxylate anion.
Essentially all approaches to &agr;-methylene-&ggr;-butyrolactone are liquid-phase processes. One exception is the vapor-phase process described in JP 10120672. Production of &agr;-methylene-&ggr;-butyrolactone comprises subjecting &ggr;-butyrolactone or an alkyl-substituted &ggr;-butyrolactone, in which one or more hydrogen atoms at the &bgr;- or &ggr;-position of the &ggr;-butyrolactone are substituted with C
1
-C
18
alkyl groups, to a gaseous phase catalytic reaction using a raw material gas containing formaldehyde or its derivative in the presence of a catalyst. Molecular oxygen is preferably added to the raw material gas and the catalyst is preferably silica alumina catalyst. Specifically, a gaseous mixture of &ggr;-butyrolactone, formaldehyde, water, nitrogen and oxygen was passed through a reactor packed with Wakogel C-200, pretreated with an aqueous potassium hydroxide solution and heated, at 330° C., to afford &agr;-methylene-&ggr;-butyrolactone at a conversion of 35.5% and a selectivity of 46.9%.
Although the above methods for the production of &agr;-methylene-&ggr;-butyrolactone are useful, they are time consuming and are multipart processes. The present method represents an advance in the art by offering a process that is a single step, run at low temperature with high yields and good selectivity.
SUMMARY OF THE INVENTION
The instant invention relates to a process for preparing &agr;-methylenelactones of Formula II comprising heating lactones of Formula I and formaldehyde in the presence of a base:
wherein,
n=1-11;
R
1
, R
2
, R
3
and R
4
, taken independently are hydrogen, hydrocarbyl or substituted hydrocarbyl, C
1
-C
18
unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl, unsubstituted or substituted cylcoalkyl, unsubstituted or substituted cylcoalkyl containing at least one heteroatom, unsubstituted or substituted aromatic ring, and unsubstituted or substituted aromatic ring containing at least one heteroatom.
The invention further provides a process for the preparation of compounds of Formula II wherein any two of R
1
, R
2
, R
3
and R
4
are members of a ring structure selected from the group consisting of, unsubstituted or substituted cylcoalkyl, unsubstituted or substituted cylcoalkyl containing at least one heteroatom in the ring, unsubstituted or substituted aromatic ring, and unsubstituted or substituted aromatic ring containing at least one heteroatom in the ring.
In another embodiment of the invention, the invention provides a process for preparing &agr;-substituted hydrocarbylidene lactones of Formula III comprising heating lactones of Formula I and a formaldehyde derivative in the presence of a base
wherein,
n=1-11;
R is hydrocarbyl or substituted hydrocarbyl; and
R
1
, R
2
, R
3
and R
4
taken independently are hydrogen, hydrocarbyl or substituted hydrocarbyl, C
1
-C
18
unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl, unsubstituted or substituted cylcoalkyl, unsubstituted or substituted cylcoalkyl containing at least one heteroatom, unsubstituted or substituted aromatic ring, and unsubstituted or substituted aromatic ring containing at least one heteroatom.
The invention further provides a process for the preparation of compounds of Formula II wherein any two of R
1
, R
2
, R
3
and R
4
are members of a ring structure selected from the group consisting of, hydrocarbyl or substituted hydrocarbyl, C
1
-C
18
unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl, unsubstituted or substituted cylcoalkyl, unsubstituted or substituted cylcoalkyl containing at least one heteroatom in the ring, unsubstituted or substituted aromatic ring, and unsubstituted or substituted aromatic ring containing at least one heteroatom in the ring.
In both processes the base is metal carbonate, oxide, hydroxide or phosphate or mixtures thereof and may be supplied as a homogeneous or heterogeneous catalyst. The process is conducted at a temperature range of at least about 70° C. and a pressure less than or equal to 2000 psi. The reaction may optionally run at higher temperatures, at about 250° C. to about 300° C. under higher pressures of about 700 psi. The reaction may optionally employ an organic solvent and use a phase transfer catalyst. Additionally the reaction may optionally be run in the presence of a drying agent for the reduction of water.
DETAILED DESCRIPTION OF THE INVENTION
&agr;-Methylenelactones, &agr;-substituted hydrocarbylidene lactones and particularly &agr;-methylene-&ggr;-butyrolactone are useful as key monomers in both homopolymers and copolymers.
This invention pertains to a method to produce &agr;-methylenelactones. (Scheme 1)
wherein,
n=1-11;
R
1
, R
2
, R
3
and R
4
taken independently are hydrogen, hydrocarbyl or substituted hydrocarbyl, C
1
-C
18
unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl, unsubstituted or substituted cylcoalkyl, unsubstituted or substituted cylcoalkyl containing at least one heteroatom, unsubstituted or substituted aromatic ring, and unsubstituted or substituted aromatic ring containing at least one heteroatom.
The invention further pertains to a method to produce &agr;-substituted hydrocarbylidene lactones (Scheme 2)
wherein,
n=1-11;
R is hydrocarbyl or substituted hydrocarbyl; and
R
1
, R
2
, R
3
and R
4
taken independently are hydrogen, hydrocarbyl or substituted hydrocarbyl, C
1
-C
18
unsubstituted or substituted alkyl, unsubstituted or substituted alkenyl, unsubstituted or substituted cylcoalkyl, unsubstituted or substituted cylcoalkyl containing at least one h
Brandenburg Charles
King Randal
Manzer Leo E.
E. I. Du Pont de Nemours and Company
Owens Amelia
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