Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2002-07-09
2003-12-16
Owens, Amelia (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S508000
Reexamination Certificate
active
06664402
ABSTRACT:
FIELD OF INVENTION
Described is a continuous process, accomplished in two chemical steps for preparing 3-methyl-tetrahydrofuran a material that can be used as a comonomer in the production of modified poly(tetramethylene glycol), from alpha-methylene-gamma-butyrolactone
BACKGROUND OF THE INVENTION
Substituted tetrahydrofuran like 3-methyl-tetrahydrofuran of the present invention is in general useful in those areas of use of tetrahydrofuran. Examples include polymerization to obtain fibers and uses as a solvent.
Poly (tetra methylene ether glycol) is obtained by polymerization of tetrahydrofuran. This polymer is used as chain segments in polyurethanes and polyesters. Polyurethanes based on poly (tetra methylene ether glycol) soft-segment have improved hydrolytic stability, abrasion resistance and elastomeric properties. Other benefits include strength, toughness, durability, low compression set property, and high water vapor permeability. The largest end-use area is in spandex fibers for apparel. The products containing poly (tetra methylene ether glycol) are used in wheels, high-speed rolls, automotive parts, bushings, specialty hose, cable sheathing and coating, pipeline liners, roof, and floor coatings. The 3-methyl-tetrahydrofuran monomer can be utilized as a comonomer for modifying poly(tetra methylene ether glycol) to yield better elastomeric properties.
In use of tetrahydrofuran as a solvent where lower volatility is desired, 3-methyl-tetrahydrofuran is advantageous because tetrahydrofuran boils at 66° C. whereas 3-methyl-tetrahydrofuran boils at 86° C.
Processes for producing 3-methyl-tetrahydrofuran, by hydrogenation of an itaconic acid ester or a 3-formyl-2-methylpropionic acid ester, and by hydrogenation of a methyl-succinic ester are described in Japanese Patent Applications 219981/1994 and 217768/1996, respectively. Along with the objective 3-methyl-tetrahydrofuran, these reactions produce an alcohol, which has to be separated in a further step. The 3-methyl-tetrahydrofuran forms an azeotropic mixture with most of the lower alcohols, for example, with methanol having an azeotropic point at 64.5° C., and an azeotropic composition consisting of 25% by weight of 3-methyl-tetrahydrofuran and 75% by weight of methanol. The azeotropic distillation requires energy for separating the two components. In particular, the 3-methyl-tetrahydrofuran which is employed for modifying poly(tetramethylene glycol) can tolerate an alcohol impurity of less than 0.2%.
A process for producing 3-methyl-tetrahydrofuran, by hydrogenation of beta-formylisobutyric acid ester with the following general formula is described in U.S. Pat. No. 5,990,324: ROOC—CH(CH
3
)—CH
2
—CHO, wherein, R is an alkyl group having 1 to 3 carbon atoms and the formyl group may be present as an acetal having an alkanol with 1 to 8 carbon atoms. In this process, the alcohol is separated from 2-methyl-gamma-butyrolactone in the second step of the three-step process. This separation can be effected by simple distillation. Azeotropic distillation is not required. However, a separation of the alcohol is still a necessary step in the process.
The present invention describes a two-step route to produce 3-methyl-tetrahydrofuran from alpha-methylene-gamma-butyrolactone, without any alcohol production or separation during the two steps.
SUMMARY OF INVENTION
This invention relates to a continuous process for producing 3-methyl-tetrahydrofuran, which comprises the steps of:
(a) subjecting the compound represented by the formula (I), alpha-methylene-gamma-butyrolactone, to hydrogenation to yield 2-methyl-gamma-butytrolactone (II); and
(b) hydrogenating the 2-methyl-gamma-butytrolactone produced in step (a), to yield 3-methyl-tetrahydrofuran (III) as product.
DETAILED DESCRIPTION OF THE INVENTION
By “alpha-methylene-gamma-butyrolactone” is meant the compound described in the formula below.
By “acid promoter” is meant a compound acidic in nature that is added to enhance the physical or chemical function of a catalyst.
By “metal promoter” is meant a metallic compound that is added to enhance the physical or chemical function of a catalyst.
This invention relates to synthesis of 3-methyl-tetrahydrofuran from alpha-methylene-gamma-butyrolactone reactant. More specifically, this invention relates to synthesis of 3-methyl-tetrahydrofuran in a two step continuous process from alpha-methylene-gamma-butyrolactone, which is free from an alcohol as a side product. The final product does not need separation or purification of alcohol. Owing to the high temperature of the catalytic reactions (greater than 150° C.), previous attempts to directly convert alpha-methylene-gamma-butyrolactone to 3-methyl-tetrahydrofuran have resulted in the formation of a polymer of methylene-gamma-butyrolactone monomer. Therefore, an improved process to synthesize 3-methyl-tetrahydrofuran was desired.
A process for making 3-methyl-tetrahydrofuran from an acid-catalyzed, two-step hydrogenation of alpha-methylene-gamma-butyrolactone is disclosed. In a preferred embodiment, the hydrogenation of alpha-methylene-gamma-butyrolactone is carried out in two steps wherein first, alpha-methylene-gamma-butyrolactone is hydrogenated to 2-methyl-gamma-butyrolactone and second, 2-methyl-gamma-butyrolactone is further reduced/hydrogenated to final product.
In the first step of the process, the -methylene double bond of the alpha-methylene-gamma-butyrolactone reactant is hydrogenated to yield 2-methyl-gamma-butyrolactone as the intermediate product. This reaction is carried out under mild conditions to avoid the formation of poly(alpha-methylene-gamma-butyrolactone). A metal catalyst, with or without a support may be present to effect the hydrogenation reaction. An acid material may optionally be used as a promoter to aid the reaction. A metal may also be optionally used as a promoter to aid the reaction.
In the second step of the process, the intermediate product, 2-methyl-gamma-butytrolactone is reduced by hydrogenation to yield 3-methyl-tetrahydrofuran, the desired product. This reaction is carried out at a higher temperature than the first hydrogenation step. A metal catalyst, with or without a support may be present to effect the reduction reaction. An acid system may be used as a promoter to effect the reaction. A metal may also be optionally used as a promoter to aid the reaction.
The process of the present invention may be carried out in batch, sequential batch (i.e., a series of batch reactors) or in continuous mode in any of the equipment customarily employed for continuous process. The condensate water is optionally removed from the reaction mass with the aid of an inert gas purge.
The temperature of the process is controlled in order to achieve a high yield of 2-methyl-gamma-butyrolactone in step (a) and a high yield of 3-methyl-tetrahydrofuran in step (b). Temperature range of from about 90° C. to about 250° is employed in step (a) of the synthesis and temperature range of from about 100° C. to about 250° C., in step (b). A temperature range of from about 135° C. to about 165° C. is preferred in step (a) of the synthesis and a temperature range of from about 200° C. to about 250° C. is preferred in step (b). Another preferred temperature range for step (a) is from about 215° C. to about 240° C. A further preferred range for step (b) is from about 215° C. to about 240° C.
A pressure range of from about 1.0 MPa to about 14.0 MPa is employed in step (a) of the synthesis and pressure range of from about 1.0 MPa to about 15 MPa, in step (b). Pressure range of from about 4.0 MPa to about 8.0 MPa is preferred in step (a) of the synthesis and pressure range of from about 8.0 MPa to about 10.0 MPa is preferred in step (b).
A catalyst is a substance that affects the rate of the reaction but not the reaction equilibrium, and emerges from the process, chemically unchanged. A chemical promoter generally augments the activity of a catalyst. The promoter may be incorporated into the catalyst during any step in the chemical processing of the catalyst constituent. The chemical promo
E. I. du Pont de Nemours and Company
Owens Amelia
LandOfFree
Manufacture of 3-methyl-tetrahydrofuran from... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Manufacture of 3-methyl-tetrahydrofuran from..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Manufacture of 3-methyl-tetrahydrofuran from... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3179761