Process for the preparation of...

Details Process for the preparation of... Process for the preparation of...

2000-11-10

2002-03-26

Owens, Amelia (Department: 1625)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C549S323000

Reexamination Certificate

active

06362346

ABSTRACT:

FIELD OF THE INVENTION
This invention is in the field of synthetic organic chemistry. This invention pertains to simple, efficient and economic methods to produce &agr;-methylene-&ggr;-butyrolactone from tetrahydro-3-furoic acid and &agr;-acetoxymethyl-&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;-butyrolactone, or its hydrogenated product, 3-methyltetra-hydrofuran, are regarded as a potential key monomers in both homopolymers and copolymers. Currently the cost of &agr;-methylene-&ggr;-butyrolactone is too high to warrant commercial production of its resulting polymers. Some of the current synthetic routes suffer from low yields, byproducts and expensive starting materials. In the instant invention, high yields of &agr;-methylene-&ggr;-butyrolactone are obtained by an acid-catalyzed rearrangement of tetrahydro-3-furoic acid or base-catalyzed reaction of &agr;-acetoxymethyl-&ggr;-butyrolactone.
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 heating, 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. Therefore, the problem to be solved is to find a simple and efficient method to produce &agr;-methylene-&ggr;-butyrolactone. The present methods represent an advance in the art by offering processes that are a single or double step with high yields and good selectivity.
SUMMARY OF THE INVENTION
The present invention provides a process for the preparation of &agr;-methylene-&ggr;-butyrolactone comprising heating a mixture of a furoic acid selected from the group consisting of tetrahydro-3-furoic acid and esters of tetrahydro-3-furoic acid, and a strong acid catalyst under conditions whereby &agr;-methylene-&ggr;-butyrolactone is formed and optionally recovering the &agr;-methylene-&ggr;-butyrolactone. Typically the acid catalyst is selected from the group consisting of fluorosulfonic acid, trifluoromethanesulfonic acid, sulfuric acid, benzenesulfonic acid, toluenesulfonic acid and phosphoric acid.
In an alternate embodiment the invention provides a process for preparing &agr;-acetoxymethyl-&ggr;-butyrolactone comprising heating a mixture of a furoic acid selected from the group consisting of tetrahydro-3-furoic acid and esters of tetrahydro-3-furoic acid, with acetic anhydride and a strong acid catalyst under conditions wherein &agr;-acetoxymethyl-&ggr;-butyrolactone is formed and optionally recovering the &agr;-acetoxymethyl-&ggr;-butyrolactone.
In another embodiment the present invention provides a process for preparing &agr;-methylene-&ggr;-butyrolactone comprising heating a mixture of a gaseous furoic acid selected from the group consisting of tetrahydro-3-furoic acid and esters of tetrahydro-3-furoic acid and a gas phase base catalyst under conditions whereby &agr;-methylene-&ggr;-butyrolactone is formed and optionally recovering the &agr;-methylene-&ggr;-butyrolactone. Gas phase catalysts may be supported on suitable supports such as silica for example.
The invention additionally provides a novel composition of &agr;-acetoxy-methyl-&ggr;-butyrolactone according to the formula
Another embodiment of the invention relates to a process for preparing &agr;-methylene-&ggr;-butyrolactone comprising heating a mixture of &agr;-acetoxymethyl-&ggr;-butyrolactone and base catalyst under conditions whereby &agr;-methylene-&ggr;-butyrolactone is formed and optionally recovering the &agr;-methylene-&ggr;-butyrolactone. Within the context of this embodiment the base catalyst may be any base which forms an acetate when reacted with acetic acid and is typically defined according to the formula, M(acetate)
x
; where x is an integer selected from the group consisting of 1 and 2; and M is a cation of charge +x selected from the group consisting of Li
+
, Na
+
, K
+
, Rb
+
, Cs
+
, Mg
++
, Ca
++
, Sr
++
, Ba
++
, (CH
3
)
4
N
+
, (C
2
H
5
)
4
N
+
, (CH
3
)
4
P
+
, (C
2
H
5
)
4
P
+
and 1-ethyl-3-methylimidazolium cation.
The invention additionally provides a process for preparing &agr;-methylene-&ggr;-butyrolactone comprising: (a) combining a furoic acid selected from the group consisting of tetrahydro-3-furoic acid and an ester of tetrahydro-3-furoic acid with an acid anhydride and a strong acid catalyst under conditions whereby a &agr;-carboxylatomethyl-&ggr;-butyrolactone is formed; (b) heating the product of step (a) under conditions whereby &agr;-methylene-&ggr;-butyrolactone is formed; and (c) optionally recovering the &agr;-methylene-&ggr;-butyrolactone. Typically the production of &agr;-carboxylatomethyl-&ggr;-butyrolactone will occur at temperatures of about 20° C. to about 200° C. whereas the heating step will occur at temperatures of about 100° C. to about 400° C. Optionally abase catalyst may be added to the product of step (a) to effect the conversion of o-carboxylatomethyl-&ggr;-butyrolactone to &agr;-methylene-&ggr;-butyrolactone. Under these conditions the temperature required for conversion is less, and will range from about 40° C. to about 200° C. Within the context of this embodiment the base catalyst may be defined according to the formula, M(carboxylate)
x
where x is an integer selected from the group consisting of 1 and 2; and M is a cation of charge +x chosen from the group consisting of Li
+
, Na
+
, K
+
, Rb
+
, Cs
+
, Mg
++
, Ca
++
, Sr
++
, Ba
++
, (CH
3
)
4
N
+
, (C
2
H
5
)
4
N
+
, (CH
3
)
4
P
+
, (C
2
H
5
)
4
P
+
and 1-ethyl-3-methylimidazolium cation; and carboxylate is

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