Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Patent
1989-04-14
1991-06-25
Evans, J. E.
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
20415795, 526254, 570134, 570135, C07C 1704, C07C 1700, C07C 1908, C07C 2118
Patent
active
050269283
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the synthesis of new terminal olefins, perfluoro 2,4-dimethyl 3-ethylpentene and perfluoro 2-isopropyl 3,3-dimethylbutene, and to the subsequent fluorination thereof in order to obtain highly branched perfluoroalkanes, capable of providing perfluoroalkyl radicals, which are utilizable as initiators for the polymerization of ethylenically unsaturated monomers.
Object of the present invention are new initiators for the polymerization of ethylenically unsaturated products and in particular of fluorinated olefins. More in particular, the present invention relates to perfluorinated compounds capable of releasing radicals which are highly reactive under the polymerization conditions. Actually, the perfluoroalkyl radicals are very interesting as they do not exhibit the drawbacks caused by inorganic peroxides, such as for example the persulphates, which introduce reactive end groups into the polymer, what requires subsequent expensive treatments in order to convert again the polymer end groups to non-reactive groups (D.I. Mc Cane Encyclopedia of Polymer Science and Technology, vol. 12, pages 623-670).
However, at present, the generators of perfluoroalkyl radicals are often too stable, such as e.g. CF.sub.3 I, which requires too high utilization temperatures and which could interfere with the polymerization process, thereby causing undesirable drawbacks, or they are too expensive, such as the perfluoroacyl peroxides.
In EP 121,898, by partial fluorination of the C.sub.3 F.sub.6 trimers, stable perfluoroalkyl radicals are obtained. However, these products are obtained with not very high yields and in admixture with the reaction raw products. Therefore these radicals are little utilizable because the olefins can interfere with the monomers during the polymerization step.
In Italian patent application 20061 A/87 in the name of the Applicant hereof, the hexafluoropropene trimer of formula (I): ##STR1## prepared according to the process described in U.S. Pat. No. 3917724 was subjected to fluorination in the presence of U.V. radiation, so obtaining the compounds of formulae (II) and (III): ##STR2##
These perfluoroalkanes, when subjected to temperatures higher than 100.degree. C., decompose, thereby generating perfluoroalkyl radicals, which are utilized in radical polymerization.
Other perfluoroalkanes capable of providing perfluoroalkyl radicals to be utilized as initiators for radical polymerization have now surprisingly been found.
In fact, when the olefin of formula (I) is subjected to U.V. radiation, it isomerizes and provides the terminal olefins of formulas (IV) and (V): ##STR3## which, when subjected to fluorination, give rise to the perfluoroalkanes of formulas (VI) and (IX): ##STR4## which, since they are highly ramified, are capable of generating perfluoroalkyl radicals at temperatures higher than 100.degree. C.
The isomerization reaction is generally conducted at room temperature by irradiating with U.V. radiation (the source of which is a high pressure Hg-vapor lamp type Hanau TQ 150W) the perfluoroolefin of formula (I); the reaction raw product is then purified by rectification.
The further fluorination reaction to obtain the compound of formula (VI) and of formula (IX) from perfluorooilefins (IV) and (V) is generally conducted at room temperature, by introducing, at the beginning, the fluorine diluted with an inert gas and by gradually raising the fluorine flow as the reaction proceeds. The products of formulas (VI) and (IX) are isolated by rectification.
By the process according to the invention, besides the mentioned perfluoroalkanes, other perfluoroalkanes are obtained, in particular the product (VIII), which, however, is not utilizable as a generator of radicals
Furthermore, the perfluorooolefins of formulas (IV) and (V) according to the present invention, besides being useful intermediates for the preparation of perfluoroalkanes utilizable as sources of perfluoroalkyl radicals, prove to be advantageous starting products for the preparation of fine chemicals.
The followi
REFERENCES:
patent: 2918501 (1959-12-01), Brehm et al.
patent: 3917724 (1975-11-01), Martini
patent: 4173654 (1979-11-01), Scherer
patent: 4820883 (1989-04-01), Weigert
Chem. Abstracts, vol. 94, No. 7, (1976), Bell et al.
Patent Abstracts of Japan, vol. 9, No. 108 (C-280), Abstract of JP 60-1143, published Jan. 7, 1985.
Tonelli Claudio
Tortelli Vito
Ausimont S.r.l.
Evans J. E.
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