Synthesis of cyclohexene dimethanol compounds

Details Synthesis of cyclohexene dimethanol compounds Synthesis of cyclohexene dimethanol compounds

2000-05-10

2002-06-25

Shippen, Michael L. (Department: 1621)

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

Organic compounds

Oxygen containing

C568S823000

Reexamination Certificate

active

06410807

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
This invention relates generally to methods for synthesizing cyclohexene dimethanol or cyclohexane dimethanol compounds, and, more particularly, to methods for obtaining cyclohexene dimethanol or cyclohexane dimethanol compounds in high yields and having high purity while eliminating certain costly and time-intensive procedures associated with solvent extraction and product recrystallization.
BACKGROUND OF THE INVENTION
Cyclohexene dimethanol compounds, such as 3-cyclohexene-1,1-dimethanol, have been used as monomers for synthesizing high performance active barrier polymers which are currently under intensive development as next generation food and beverage packaging technology. (See, for example, PCT Publication No. WO 99/48963, assigned to Chevron Chemical Co.). A prior synthesis approach for producing such compounds is based on the Cannizzaro reaction. For example, in synthesizing 3-cyclohexene-1,1-dimethanol by this approach, two mole of formaldehyde reacts with one mole of tetrahydrobenzaldehyde in the presence of one mole of base, e.g., sodium hydroxide or potassium hydroxide, in an aqueous alcoholic solution. The reaction presumably follows the course indicated by the following:
This process has typically involved a reaction stage in aqueous or aqueous-alcoholic medium, followed by a purification stage that requires multiple extraction steps with organic solvent, a distillation step and a recrystallization step from a suitable organic solvent. In one example (H. E. French and D. M. Gallagher, JACS 1942, p 1497), a reaction was conducted in an aqueous-alcoholic medium in the presence of potassium hydroxide at 70° C. The purification stage involved the extraction of the reaction medium with ether, followed by distillation to remove the solvent. The crude product was an oil residue that solidified upon standing over time. Recrystallization of the product gave a yield reported to be in the range of 50-60%. The melting point, which served as an indication of product purity, was reported to be 92.5° C.
In a separate report (Klaus Bruns and Jens Conard,
Tetrahydron
, Vol. 35, p2523, 1979), a reaction stage was carried out in aqueous sodium hydroxide, while the purification stage involved multiple extractions with methylisobutylketone, a specialty solvent. The crude yield, reported to be 92%, was based on the residue from the evaporation of the solvent, and no further purification was described. We performed this procedure and found that it does not provide a level of purity sufficient for making polymerization grade 3-cyclohexene-1,1-dimethanol. Moreover, further purification steps necessary to achieve a sufficient level of purity led to unacceptably low yields.
When considering the commercial scale production of 3-cyclohexene-1,1-dimethanol and other cyclohexene dimethanol or cyclohexane dimethanol compounds, the involvement of large quantities of expensive organic solvents and long cycle times for multiple organic/aqueous extractions and crystallizations make the prior processes undesirable from both a material and operational cost standpoint. Indeed, the number of operation units, such as organic solvent storage tanks, mixing tanks and distillation units contribute significantly to the overall cost of producing these compounds. In light of this, significant benefits could be realized by eliminating one or more of the operational steps associated with product extraction and/or recrystallization.
The present invention overcomes, or at least reduces the effects of, one or more of the aforementioned problems.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, a method is provided for producing a cyclohexene dimethanol or a cyclohexane dimethanol compound, comprising:
(a) adding a base solution to a formaldehyde solution to form a formaldehyde/base solution;
(b) adding an aldehyde to the formaldehyde/base solution to form a reaction solution; and
(c) recovering cyclohexene dimethanol or cyclohexane dimethanol product from said reaction solution.
According to another aspect of the invention, a method is provided for producing a cyclohexene dimethanol or a cyclohexane dimethanol compound, comprising:
(a) adding a base solution to a formaldehyde solution to form a formaldehyde/base solution;
(b) adding an aldehyde to the formaldehyde/base solution to form a reaction solution;
(c) heating the reaction solution to a temperature about 70° C. or less;
(d) cooling the reaction vessel contents to between about 10° C. and 30C; and
(e) recovering cyclohexene dimethanol or cyclohexane dimethanol product from said reaction solution.
According to another aspect of the invention, a method is provided for producing 3-cyclohexene-1,1-dimethanol having a yield greater than about 80% and a purity greater than about 95%, comprising:
(a) adding a base solution to a formaldehyde solution to form a formaldehyde/base solution, wherein the temperature of the formaldehyde/base solution is maintained between about 10° C. and about 20° C. during addition of said base solution;
(b) adding a tetrahydrobenzaldehyde, to the formaldehyde/base solution to form a reaction solution, wherein the temperature of the reaction solution is maintained between about 10° C. and about 20° C. during addition of said tetrahydrobenzaldehyde;
(c) maintaining the temperature of the reaction solution between about 15° C. and about 25° C. for at least about 4 hours following addition of said tetrahydrobenzaldehyde;
(d) heating the reaction solution to a temperature between about 50° C. and about 60° C. for at least about 0.5 hours to about 2 hours;
(e) cooling the reaction vessel contents to between about 10° C. and about 30° C.; and
(f) recovering crystalline-form 3-cyclohexene-1,1-dimethanol product from said reaction solution.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
In order to develop an economically viable process for making cyclohexene dimethanol or cyclohexane dimethanol compounds, we have investigated alternative processes effective for eliminating organic solvent-based extraction and/or recrystallization steps during the purification stage of the process. In addition, we also sought to further improve product yield while- maintaining sufficient product purity.
According to the present invention, high purity cyclohexene dimethanol or cyclohexane dimethanol can be obtained in a crystalline form by controlling certain process parameters during the progress of the synthesis reaction. In particular, we have found that by controlling the rate of addition of certain reagents and the temperature profile during the reaction stage, cyclohexene dimethanols or cyclohexane dimethanols can be produced having high purity while eliminating some or all of the steps of solvent extraction and/or recrystallization required by prior synthesis methods. In contrast to prior methods, the present invention provides high purity crystalline-form product that can be obtained directly from the reaction medium.
According to the present invention, a cyclohexene dimethanol or a cyclohexane dimethanol is synthesized by reacting formaldehyde with an aldehyde, preferably an aldehyde with from 2 to about 20 carbon atoms, more preferably tetrahydrobenzaldehyde or cyclohexane carboxyaldehyde, in the presence of base in an aqueous or aqueous-alcoholic solution. The reaction vessel empl

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