Process for preparing polytetrahydrofuran

Details Process for preparing polytetrahydrofuran Process for preparing polytetrahydrofuran

1999-05-19

2001-04-03

Wilson, James O. (Department: 1623)

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

Organic compounds

Carboxylic acid esters

C560S103000, C568S605000, C568S617000

Reexamination Certificate

active

06211401

ABSTRACT:

SUMMARY
Polytetrahydrofuran, tetrahydrofuran copolymers, and diesters or monoesters of these polymers are prepared by the polymerization of tetrahydrofuran in the presence of at least one telogen and/or comonomer over a heterogeneous supported catalyst which contains an active component comprising a catalytically active amount of at least one oxygen-containing tungsten and/or molybdenum compound on an oxidic support material and which, following application of the precursor compounds of the active component to the support material precursor, has been calcined at temperatures of from 500° C. to 1000° C., where a catalyst is used which contains a promotor comprising at least one element of Group 2, 3 (including the lanthanides), 5, 6, 7, 8 or 14 of the Periodic Table or a compound of such element.
DESCRIPTION
The present invention relates to an improved process for the preparation of polytetrahydrofuran, tetrahydrofuran copolymers, and diesters or monoesters of these polymers by the polymerization of tetrahydrofuran in the presence of at least one telogen and/or comonomer over a heterogeneous supported catalyst, which contains as active composition a catalytically active amount of at least one oxygen-containing molybdenum and/or tungsten compound on an oxidic support material and which has been calcined, following application of the precursor compounds of the active composition to the support material precursor, at temperatures of from 500° C. to 1000° C.
Polytetrahydrofuran (“PTHF”), also known as poly(oxybutylene glycol), is a broadly used intermediate in the plastics and synthetic fiber industries and serves inter alia for the preparation of polyurethane, polyester and polyamide elastomers. In addition, it is, as are also some of its derivatives, a valuable auxiliary for many applications, such as dispersing agents, or for the process of decolorizing (“de-inking”) waste paper.
PTHF is advantageously prepared on an industrial scale by polymerization of tetrahydrofuran over catalysts in the presence of reagents, the addition of which makes it possible to control the chain length of the polymer chains and thus to set the average molecular weight to the desired value (chain-terminating agents or “telogens”). Control takes place in this case by varying the type and amount of the telogen. By selecting suitable telogens functional groups can be additionally introduced at one or both ends of the polymer chain. Thus for example by using carboxylic acids or carboxylic acid anhydrides as telogens the monoesters or diesters of PTHF can be prepared. Other telogens are effective not only as chain-terminating agents, but are also incorporated in the growing polymer chain of the PTHF, that is to say they not only operate as a telogen, but also as a comonomer and can therefore be equally well designated as a telogen or as a comonomer. Examples of such comonomers are telogens containing two hydroxyl groups such as the di-alcohols. Examples of such di-alcohols are ethylene glycol, propylene glycol, butylene glycol, 1,4-butanediol, 2-butyne-1,4-diol,1,6-hexanediol or low molecular weight PTHF. The use of such comonomers leads to the preparation of tetrahydrofuran copolymers. In this manner it is possible to chemically modify the PTHF. One example thereof is the use of the telogen 2-butyne-1,4-diol, the addition of which causes a proportion of C≡C triple bonds to be present in the polymer chains of the PTHF. Such modified PTHF can, due to the reactivity of these triple bonds at these sites, be further refined chemically, for example by hydrogenation of the triple bonds to double bonds, by subsequent addition polymerization of different monomers (“grafting”) for varying the properties of the polymer, cross linkage for the formation of polymers having a comparatively rigid structure, or other measures commonly used in polymer chemistry. Total hydrogenation of the triple bonds that are present is likewise possible and generally leads to PTHF having a particularly low color index.
DE-A 4,433,606 describes a process for the preparation of PTHF, PTHF diesters of C
2
-C
20
monocarboxylic acids or PTHF monoesters of C
1
-C
10
monocarboxylic acids by the polymerization of tetrahydrofuran over a heterogeneous catalyst in the presence of one of the telogens water, 1,4-butanediol, PTHF having a molecular weight of from 200 to 700 dalton, a C
1
-C
10
monocarboxylic acid or a carboxylic anhydride derived from C
2
-C
20
monocarboxylic acids or mixtures of these telogens, where the catalyst is a supported catalyst which contains a catalytically active amount of an oxygen-containing tungsten or molybdenum compound or mixtures of these compounds on an oxidic support material and which, following application of the precursor compounds of the oxygen-containing molybdenum and/or tungsten compounds to the support material precursor, has been calcined at temperatures of from 500° C. to 1000° C.
WO 96/09335 teaches a process for the preparation of PTHf or PTHF monoesters of C
1
-C
10
monocarboxylic acids by the polymerization of tetrahydrofuran over a heterogeneous catalyst in the presence of one of the telogens water, 1,4-butanediol, PTHF having a molecular weight of from 200 to 700 dalton, a C
1
-C
10
monocarboxylic acid or mixtures of these telogens, where the catalyst is a supported catalyst which contains a catalytically active amount of an oxygen-containing tungsten or molybdenum compound or mixtures of these compounds on an oxidic support material and which, following application of the precursor compounds of the oxygen-containing molybdenum and/or tungsten compounds to the support material precursor, has been calcined at temperatures of from 500° C. to 1000° C.
The prior German patent application DE-A 19641481.4 of Sep. 10, 1996 teaches a process for the preparation of polytetrahydrofuran, copolymers of tetrahydrofuran and 2-butyne-1,4-diol, diesters of these polymers with C
2
-C
20
monocarboxylic acids or monoesters of these polymers with C
1
-C
10
monocarboxylic acids by the polymerization of tetrahydrofuran in the presence of one of the telogens water, 1,4-butanediol, 2-butyne-1,4-diol, polytetrahydrofuran having a molecular weight of from 200 to 700 dalton, a C
1
-C
10
monocarboxylic acid or a carboxylic acid anhydride derived from C
2
-C
20
monocarboxylic acids or mixtures of these telogens over a heterogeneous supported catalyst which contains a catalytically active amount of an oxygen-containing tungsten or molybdenum compound or mixtures of these compounds on an oxidic support material and which, following application of the precursor compounds of the oxygen-containing molybdenum and/or tungsten compounds to the support material precursor, has been calcined at temperatures of from 500° C. to 1000° C. and which has been activated before use as polymerization catalyst by treatment with a reducing agent.
Since the economical value of a PTHF process catalyzed using a heterogenous catalyst greatly depends on the productivity of the catalyst, it is an object of the present invention to increase the catalyst activity of the known catalysts used in THF polymerization in order to achieve higher polymer yields and/or space-time yields.
Accordingly we have found a process for the preparation of polytetrahydrofuran, tetrahydrofuran copolymers, and diesters or monoesters of these polymers by the polymerization of tetrahydrofuran in the presence of at least one telogen and/or comonomer over a heterogeneous supported catalyst which contains an active component comprising a catalytically active amount of at least one oxygen-containing tungsten and/or molybdenum compound on an oxidic support material and which, following application of the precursor compounds of the active component to the support material precursor, has been calcined at temperatures of from 500° C. to 1000° C. and which is characterized in that a catalyst is used which contains a promotor comprising at least one element of Group 2, 3 (including the lanthanides), 5, 6, 7, 8 or 14 of the Periodic Table or a compound of such element.
The p

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