Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1983-02-28
1986-01-21
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525366, C08F 000
Patent
active
045658480
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATION
This application is a national phase application corresponding to the international application PCT/FR82/00112 filed 29 June 1982 and based upon the French national application 81 13 286 filed 30 June 1981 under the International Convention.
FIELD OF THE INVENTION
This invention relates to a novel process for the preparation of polyacetylenes by dehydrochlorination of polyvinyl chloride, the products obtained by the application of the process and their applications, in particular as semiconductors.
BACKGROUND OF THE INVENTION
It is known that polyacetylenes are polymers showing the repeating unit CH.dbd.CH.sub.n.
There are already different types of polyacetylenes which differ by their molecular weight and the configuration of the conjugated double bond chains in space (G. Natta, G. Mazzanti and P. Corradini, C.R. Acad. Lincei 25, 3, (1958))--(L. B. Luttinger, Chem. Ind. London 1135 (1960))--(M. Hatano, J. Chem. Soc. Japan, Ind. Chem. Sert., 65, 723 (1962)).
These polyacetylenes are compounds that are insoluble in polar solvents, in particular, water and tetrahydrofuran. Up to now, they have been synthesized by polymerization of acetylene H--C.tbd.C--H on a Ziegler-Natta catalyst (H. Shirakawa and S. Ikeda, Polym. J., 2, 231 (1971))--(H. Shirakawa, Japanese patent No. 73, 32581).
Attempts have been further made to carry out the partial chemical dehydrochlorination of polyvinyl chloride; the methods suggested up to now have generally used, as a reactant, alcoholic potassium hydroxide. The percentage dehydrochlorination of the operation barely exceeds 1 to 5%; it is as high as 16% in only one case described by Wirsen and Flodin (J. Appl. Polym. Sc. 22, 3039 (1979)).
Japanese patent application No. 10 590/65 describes a process for obtaining crystalline polyacetylene by copolymerization of vinyl chloride and acetylene in an inert solvent such as acetone in the presence of a catalyst (azodiisobutyronitrile) followed by a dehydrochlorination under highly vigorous conditions using an inorganic base such as sodium hydroxide. The product obtained shows an infrared spectrum with a characteristic band at approximately 1000 cm.sup.-1.
The inventors have already studied the possibilities of using potassium tertiary butoxide (tBuOK) as a dehydrochlorination reagent for PVC (C.R. Acad. Sci. Paris, 281, 991 (1975) and 290, 65 (1980), for the purpose of studying the distribution of molecular weights by gel permeation chromatography and the distribution of polyene sequences of the dehydrochlorinated products by ultraviolet spectroscopy.
tBuOK, which has a high solubility in tetrahydrofuran (THF) (25 g per 100 g) seemed, indeed, to be a very good dehydrochlorinating agent due to its high basicity and the large size of the tBuO.sup.- anion which minimizes chances of substitution.
This work, however, has not led to the complete dehydrochlorination of PVC; it turns out, indeed (C.R. Acad. Sci. Paris, 281, 991 (1975)), that the UV spectrum of the dehydrochlorination product shows, both through its fine structure and UV absorption maximum (385 nm), the particular characteristics of an incomplete dehydrochlorination of PVC.
SUMMARY OF THE INVENTION
In the course of their research, the inventors have noted surprisingly that a judicious choice of experimental conditions provided a dehydrochlorination of polyvinyl chloride of up to 100% and gave polyacetylenes the UV spectrum of which, substantially different from that described above, no longer had a fine structure and showed a wavelength at the absorption maximum of approximately 450 nm.
The invention therefore relates to a process for the dehydrochlorination of polyvinyl chloride using potassium tertiary butoxide in anhydrous tetrahydrofuran medium, the originality of which resides in the fact that the number of moles of potassium tertiary butoxide reacted is greater than the number of polyvinyl chloride --CH.sub.2 CHCl units, this excess being directly related to the presence of oxygen in tetrahydrofuran.
It is thus possible to ob
REFERENCES:
patent: 3896091 (1975-07-01), Fabris et al.
patent: 4423193 (1983-12-01), Melby et al.
"Dehydrochlorination of Polyvinyl Chloride with Potassium Tertiary Butylate in Tetrahydrofuran", C. R. Academy of Science, Paris, 281, Perichaud et al., 1975, 991-993.
Dussoubs Daniele
Perichaud Alain
Savidon Louis
Dubno Herbert
Lipman Bernard
Ross Karl F.
Schofer Joseph L.
Universite d'Aix-Marseille II
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