Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1990-08-23
1992-12-29
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...
525403, 525404, 528424, 528421, 528417, 522 65, 522 53, 522 59, C08G 7304, C08G 6504
Patent
active
051752174
ABSTRACT:
The invention relates to a method for the photochemical conversion of tachysterol compounds into previtamin D compounds and of trans-vitamin D compounds into cis-vitamin D compounds under the influence of radiation, by exposing the tachysterol compound and trans-vitamin D compound, respectively, dissolved in a suitable solvent system, in the presence of a polymeric photosensitizer consisting of a polymer chain ("backbone") comprising covalently bound sensitizers suitable for the photochemical conversion, to light with a wavelength of preferably between approx. 300 and approx. 1,000 nm, and by then isolating the resulting previtamin D compound and cis-vitamin D compound, respectively, in which a polymeric photosensitizer is used, the polymer chain of which has been selected from the group consisting of a polyether chain, an amino groups-containing polymer chain and a block copolymer chain comprising polyether segments and/or amino groups-containing polymer segments, in such a manner that the polymeric photosensitizer dissolves in the solvent system during the exposure to radiation but either upon cooling precipitates from the solution and can be separated, or, in case said polymer chain comprises amino groups, can be protonated with a suitable acid substance and be removed in an after-treatment. The invention also relates to a polymeric photosensitizer to be used for the said method.
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Recueil des Travaux Chemiques des Pays Bas, J. Royal Netherlands Chemical Soc., vol. 89, No. 3, Mar. 1970, pp. 261-264.
Goethals Eric
Halkes Sebastianus J.
Koolstra Robert B.
Duphar International Research B.V.
Nagumo M.
Schofer Joseph L.
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