Claims
- 1. A method of producing polytetramethylene ether glycol polymer or copolymer of improved color comprising the steps of:
- (a) subjecting 1,4-butanediol liquid distillate optionally containing one or more 2-alkyl-1,4-butanediol, wherein said distillate is characterized by the presence of lower alkyl glycol impurities at a concentration range of up to about 1,000 ppm, to continuous distillation while simultaneously removing overhead a stream containing undesirable lower alkyl glycol impurities and recovering there below a stream of 1,4-butanediol optionally containing one or more 2-alkyl-1,4-butanediol substantially free of said impurities;
- (b) subjecting the topped 1,4-butanediol stream produced in step (a) to catalytic cyclization thus producing tetrahydrofuran optionally containing one or more 3-alkyl-substituted tetrahydrofuran, wherein said cyclic product stream is characterized as substantially free of 1,3-dioxolane and 4-alkyl-1,3-dioxolane impurities; and
- (c) polymerizing the tetrahydrofuran optionally containing one or more 3-alkyl-substituted tetrahydrofuran produced in step (b) thus producing polytetramethylene ether glycol polymer of improved color index.
- 2. A method of claim 1 wherein 1,4-butanediol liquid distillate contains one or more 2-alkyl-1,4-butanediol wherein the alkyl group is selected from the group consisting of methyl, ethyl, propyl, and isopropyl.
- 3. A method of claim 2 wherein said 2-alkyl-1,4-butanediol is 2-methyl-1,4-butanediol, said lower alkyl glycol impurities are ethylene glycol and 1,2-propylene glycol, said 3-alkyl-substituted tetrahydrofuran is and said 4-alkyl-1,3-dioxolane impurity is 4-methyl-1,3-dioxolane.
- 4. A method of claim 3 further comprising the steps of drying the mixture of tetrahydrofuran and 3-methyltetrahydrofuran to a water content of about 0.03 wt % and hydrogenating the dried mixture before said polymerizing step.
Parent Case Info
This is a continuation of application Ser. No. 08/495,958 filed Jun. 28, 1995, now abandoned, which is a continuation of application Ser. No. 08/336,356 filed Nov. 8, 1994, now abandoned.
US Referenced Citations (16)
Non-Patent Literature Citations (1)
Entry |
Hill and Carothers, Cyclic And Polymeric Formals, J Am Chem Soc, 57, 925-928, 1935. |
Continuations (2)
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Number |
Date |
Country |
Parent |
495958 |
Jun 1995 |
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Parent |
336356 |
Nov 1994 |
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