Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-03-20
2001-11-06
Owens, Amelia (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S273000, C549S295000
Reexamination Certificate
active
06313318
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns a process for the addition of formaldehyde to the &agr; carbon atom of lactones to produce &agr;-methylenelactones, and specifically &agr;-methylene-&ggr;-butyrolactone.
TECHNICAL BACKGROUND
&agr;-Methylene-&ggr;-butyrolactone is useful as a monomer in the preparation of both homopolymers and copolymers.
An early synthesis of &agr;-methylene-&ggr;-butyrolactone involved two steps (Watts et al.,
J. Chem. Soc. Chem. Comm.
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%.
A. W. Murray et al.
Synthesis,
January 1985, p 35-38 report the development of a two-step route to &agr;-methylene-&ggr;-butyrolactone that consists of the reaction of &ggr;-butyrolactone with ethyl formate in the presence of sodium hydride base followed by the isolation of the resulting formyl derivative as its sodium salt and subsequent reaction with an aldehyde. B. S. Orlek et al., U.S. Pat. No. 5,166,357, use this same route specifying the use of formaldehyde as the aldehyde.
Although the above methods for the production of &agr;-methylene lactones are useful, they are time consuming and are multipart processes. The instant invention represents an advance in the art as it is a single step process that produces the desired product in high yields and good selectivity.
SUMMARY OF THE INVENTION
The invention provides a process for preparing &agr;-methylenelactones of Formula II comprising heating lactones of Formula I and formaldehyde in the vapor phase at a temperature of above 200° C. in the presence of a basic catalyst:
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 cycloalkyl, unsubstituted or substituted cycloalkyl containing at least one heteroatom, unsubstituted or substituted aromatic ring, and unsubstituted or substituted aromatic ring containing at least one heteroatom. In a specific embodiment the lactone of Formula I is &ggr;-butyrolactone and the &agr;-methylenelactone of Formula II is &agr;-methylene-&ggr;-butyrolactone.
Catalysts suitable in the present invention may be selected from the group consisting of metal oxides, metal hydroxides, and metal carbonates and may be supported or unsupported and may make use of catalyst promoters.
Additionally the invention provides a process for preparing &agr;-methylenelactones of Formula II comprising:
(a) heating lactones of Formula I and formaldehyde in the vapor phase at a temperature of above 200° C. in the presence of a basic catalyst for a time sufficient for the &agr;-methylenelactones of Formula II to be formed;
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 cycloalkyl, unsubstituted or substituted cycloalkyl containing at least one heteroatom, unsubstituted or substituted aromatic ring, and unsubstituted or substituted aromatic ring containing at least one heteroatom;
(b) separating the lactones of Formula I from the basic catalyst;
(c) contacting the basic catalyst with oxygen for a time sufficient to permit catalyst regeneration; and
(d) repeating steps (a) through (c).
Additionally the invention provides process for preparing &agr;-methylenelactones of Formula II comprising:
(a) heating lactones of Formula I and formaldehyde in the vapor phase at a temperature of above 200° C. in the presence of a basic catalyst for a time sufficient for the &agr;-methylenelactones of Formula II to be formed in a reactor effluent;
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 cycloalkyl, unsubstituted or substituted cycloalkyl containing at least one heteroatom, unsubstituted or substituted aromatic ring, and unsubstituted or substituted aromatic ring containing at least one heteroatom,
(b) collecting the reactor effluent of step (a); and
(c) contacting the collected effluent with the base catalyst at a temperature of above 200° C.
DETAILED DESCRIPTION OF THE INVENTION
The process of the present invention concerns an efficient methenylation of lactones to yield &agr;-methylenelactones of which &agr;-methylene-&ggr;-butyrolactone is a preferred member. The reaction proceeds according to the general scheme:
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 cycloalkyl, unsubstituted or substituted cycloalkyl containing at least one heteroatom, unsubstituted or substituted aromatic ring, and unsubstituted or substituted aromatic ring containing at least one heteroatom. In a specific embodiment the lactone of Formula I is &ggr;-butyrolactone and the &agr;-methylenelactone of Formula II is &agr;-methylene-&ggr;-butyrolactone. R
1
, R
2
, R
3
, and R
4
may join to form members of a ring structure selected from the group consisting of, unsubstituted or substituted cycloalkyl, unsubstituted or substituted cycloalkyl 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. Most preferred compounds are where the lactone of Formula I is &ggr;-butyrolactone and the &agr;-methylenelactone of Formula II is &agr;-methylene-&ggr;-butyrolactone.
In the context of this disclosure, a number of terms and abbreviations shall be utilized. The following definitions are provided.
When a group contains a substituent which can be hydrogen, for example R
1
, R
2
, R
3
, and R
4
then, when this substituent is taken as hydrogen, it is recognized that this is equivalent to said group being unsubstituted.
The term “alkyl” includes straight-chain or branched alkyl, such as, methyl, ethyl, n-propyl, i-propyl, or the different butyl, pentyl and hexyl isomers. Also included are all isomers up to and including octadecane.
A “hydrocarbyl group” is a univalent group containing only carbon and hydrogen. If not otherwise stated, it is preferred that hydrocarbyl groups herein contain 1 to about 30 carbon atoms.
By “substituted hydrocarbyl” herein is meant a hydrocarbyl group which contains one or more substituent groups which are inert under the process conditions to which the compound containing these groups is subjected. The substituent groups also do not substantially interfere with the process. If not otherwise stated, it is preferred that substituted hydrocarbyl groups herein contain 1 to about 30 carbon atoms. Included in the meaning of “substituted” are heteroaromatic rings.
One of skill in the art will know where and how to obtain the &agr;-methylenelactones reactant of the present invention. For example &ggr;-butyrolactone is readily available from commercial sources such as Aldrich Chemical Company (Millwaukee, Wis.).
The process of the present invention is carried out in the vapor state, at temperatures greater than 200° C., over highly basic catalysts. Although any temperature above 200° C. is useful, temperature in the range of about 250° C. to about 400° C. are preferred where ranges of about 300° C. to about 340° C. are most preferred. In one preferred embodiment the lactone and formaldehyde of the presen
Coulson Dale Robert
Herron Norman
Manzer Leo E.
Belopolsky Inna Y.
E.I. Du Pont de Nemours and Company
Owens Amelia
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